b+tree for the incore extent list V2

b+tree for the incore extent list V2

[Christoph Hellwig]

Hi all,

this series first updates the incore extent list iteration to use
a cursor based scheme that hides the implementation details, and then
switch to use a b+tree to implement the in-core extent list.  This
reduces the need for a large contiguous allocation that the current
indirection array requires, and thus avoids stalls during workloads
using giant extent lists, especially on systems that are long running.

The algorithms also should be better in general, but due to the fact
the the operations on the on-disk b+tree have such a high overhead
not much that effect is seen on the usual benchmarks.

I also have a git tree available at:

    git://git.infradead.org/users/hch/xfs.git xfs-incore-btree

Gitweb:

    http://git.infradead.org/users/hch/xfs.git/shortlog/refs/heads/xfs-incore-btree

Changes from V1:
 - various spelling and indentation fixes
 - renamed various variables from ext to icur
 - add trace define for XFS_BMAPI_CONVERT_ONLY
 - move a few misplaced hunks into the right patch
 - fix encoding of the in-core extent format (Darrick J. Wong)
 - pass a xfs_bmbt_irec to xfs_validate_extent
 - move xfs_bmbt_irec to xfs_types.h
 - use a fixed 256 byte node size
 - use correct node entry numbers for 32-bit architectures

[PATCH 01/21] xfs: don't create overlapping extents in xfs_bmap_add_extent_delay_real

[Christoph Hellwig]

Two cases in xfs_bmap_add_extent_delay_real currently insert a new
extent before updating the existing one that is being split.  While
this works fine with a simple extent list, a more complex tree can't
easily cope with overlapping extent.  Reshuffle the code a bit to update
the slot of the existing delalloc extent to the new real extent before
inserting the shortened delalloc extent before or after it.  This
avoids the overlapping extents while still allowing to update the
br_startblock field of the delalloc extent with the updated indirect
block reservation.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
---
 fs/xfs/libxfs/xfs_bmap.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
index ebb5958f1c5c..db369653eb50 100644
--- a/fs/xfs/libxfs/xfs_bmap.c
+++ b/fs/xfs/libxfs/xfs_bmap.c
@@ -1791,7 +1791,7 @@ xfs_bmap_add_extent_delay_real(
 		 * Filling in the first part of a previous delayed allocation.
 		 * The left neighbor is not contiguous.
 		 */
-		xfs_iext_insert(bma->ip, bma->idx, 1, new, state);
+		xfs_iext_update_extent(bma->ip, state, bma->idx, new);
 		(*nextents)++;
 		if (bma->cur == NULL)
 			rval = XFS_ILOG_CORE | XFS_ILOG_DEXT;
@@ -1824,7 +1824,7 @@ xfs_bmap_add_extent_delay_real(
 		PREV.br_startoff = new_endoff;
 		PREV.br_blockcount = temp;
 		PREV.br_startblock = nullstartblock(da_new);
-		xfs_iext_update_extent(bma->ip, state, bma->idx + 1, &PREV);
+		xfs_iext_insert(bma->ip, bma->idx + 1, 1, &PREV, state);
 		break;
 
 	case BMAP_RIGHT_FILLING | BMAP_RIGHT_CONTIG:
@@ -1867,7 +1867,7 @@ xfs_bmap_add_extent_delay_real(
 		 * Filling in the last part of a previous delayed allocation.
 		 * The right neighbor is not contiguous.
 		 */
-		xfs_iext_insert(bma->ip, bma->idx + 1, 1, new, state);
+		xfs_iext_update_extent(bma->ip, state, bma->idx, new);
 		(*nextents)++;
 		if (bma->cur == NULL)
 			rval = XFS_ILOG_CORE | XFS_ILOG_DEXT;
@@ -1899,7 +1899,7 @@ xfs_bmap_add_extent_delay_real(
 
 		PREV.br_startblock = nullstartblock(da_new);
 		PREV.br_blockcount = temp;
-		xfs_iext_update_extent(bma->ip, state, bma->idx, &PREV);
+		xfs_iext_insert(bma->ip, bma->idx, 1, &PREV, state);
 
 		bma->idx++;
 		break;
-- 
2.14.2

[PATCH 02/21] xfs: remove a duplicate assignment in xfs_bmap_add_extent_delay_real

[Christoph Hellwig]

Reported-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 fs/xfs/libxfs/xfs_bmap.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
index db369653eb50..e1d61face277 100644
--- a/fs/xfs/libxfs/xfs_bmap.c
+++ b/fs/xfs/libxfs/xfs_bmap.c
@@ -1765,7 +1765,7 @@ xfs_bmap_add_extent_delay_real(
 		LEFT.br_blockcount += new->br_blockcount;
 		xfs_iext_update_extent(bma->ip, state, bma->idx - 1, &LEFT);
 
-		PREV.br_blockcount = temp = PREV.br_blockcount - new->br_blockcount;
+		PREV.br_blockcount = temp;
 		PREV.br_startoff += new->br_blockcount;
 		PREV.br_startblock = nullstartblock(da_new);
 		xfs_iext_update_extent(bma->ip, state, bma->idx, &PREV);
-- 
2.14.2

Re: [PATCH 02/21] xfs: remove a duplicate assignment in xfs_bmap_add_extent_delay_real

[Brian Foster]

On Fri, Nov 03, 2017 at 05:45:20PM +0300, Christoph Hellwig wrote:
> Reported-by: Brian Foster <bfoster@redhat.com>
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---

Reviewed-by: Brian Foster <bfoster@redhat.com>

>  fs/xfs/libxfs/xfs_bmap.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
> index db369653eb50..e1d61face277 100644
> --- a/fs/xfs/libxfs/xfs_bmap.c
> +++ b/fs/xfs/libxfs/xfs_bmap.c
> @@ -1765,7 +1765,7 @@ xfs_bmap_add_extent_delay_real(
>  		LEFT.br_blockcount += new->br_blockcount;
>  		xfs_iext_update_extent(bma->ip, state, bma->idx - 1, &LEFT);
>  
> -		PREV.br_blockcount = temp = PREV.br_blockcount - new->br_blockcount;
> +		PREV.br_blockcount = temp;
>  		PREV.br_startoff += new->br_blockcount;
>  		PREV.br_startblock = nullstartblock(da_new);
>  		xfs_iext_update_extent(bma->ip, state, bma->idx, &PREV);
> -- 
> 2.14.2
> 
> --
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Re: [PATCH 02/21] xfs: remove a duplicate assignment in xfs_bmap_add_extent_delay_real

[Darrick J. Wong]

On Fri, Nov 03, 2017 at 05:45:20PM +0300, Christoph Hellwig wrote:
> Reported-by: Brian Foster <bfoster@redhat.com>
> Signed-off-by: Christoph Hellwig <hch@lst.de>

Looks ok,
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>

> ---
>  fs/xfs/libxfs/xfs_bmap.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
> index db369653eb50..e1d61face277 100644
> --- a/fs/xfs/libxfs/xfs_bmap.c
> +++ b/fs/xfs/libxfs/xfs_bmap.c
> @@ -1765,7 +1765,7 @@ xfs_bmap_add_extent_delay_real(
>  		LEFT.br_blockcount += new->br_blockcount;
>  		xfs_iext_update_extent(bma->ip, state, bma->idx - 1, &LEFT);
>  
> -		PREV.br_blockcount = temp = PREV.br_blockcount - new->br_blockcount;
> +		PREV.br_blockcount = temp;
>  		PREV.br_startoff += new->br_blockcount;
>  		PREV.br_startblock = nullstartblock(da_new);
>  		xfs_iext_update_extent(bma->ip, state, bma->idx, &PREV);
> -- 
> 2.14.2
> 
> --
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> the body of a message to majordomo@vger.kernel.org
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[PATCH 03/21] xfs: treat idx as a cursor in xfs_bmap_add_extent_delay_real

[Christoph Hellwig]

Stop poking before and after the index and just increment or decrement
it while doing our operations on it to prepare for a new extent list
implementation.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
---
 fs/xfs/libxfs/xfs_bmap.c | 27 ++++++++++++++++-----------
 1 file changed, 16 insertions(+), 11 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
index e1d61face277..c0216e9e2af8 100644
--- a/fs/xfs/libxfs/xfs_bmap.c
+++ b/fs/xfs/libxfs/xfs_bmap.c
@@ -1648,12 +1648,13 @@ xfs_bmap_add_extent_delay_real(
 		 * Filling in all of a previously delayed allocation extent.
 		 * The left and right neighbors are both contiguous with new.
 		 */
-		bma->idx--;
 		LEFT.br_blockcount += PREV.br_blockcount + RIGHT.br_blockcount;
-		xfs_iext_update_extent(bma->ip, state, bma->idx, &LEFT);
 
-		xfs_iext_remove(bma->ip, bma->idx + 1, 2, state);
+		xfs_iext_remove(bma->ip, bma->idx, 2, state);
+		bma->idx--;
+		xfs_iext_update_extent(bma->ip, state, bma->idx, &LEFT);
 		(*nextents)--;
+
 		if (bma->cur == NULL)
 			rval = XFS_ILOG_CORE | XFS_ILOG_DEXT;
 		else {
@@ -1681,13 +1682,13 @@ xfs_bmap_add_extent_delay_real(
 		 * Filling in all of a previously delayed allocation extent.
 		 * The left neighbor is contiguous, the right is not.
 		 */
-		bma->idx--;
-
 		old = LEFT;
 		LEFT.br_blockcount += PREV.br_blockcount;
+
+		xfs_iext_remove(bma->ip, bma->idx, 1, state);
+		bma->idx--;
 		xfs_iext_update_extent(bma->ip, state, bma->idx, &LEFT);
 
-		xfs_iext_remove(bma->ip, bma->idx + 1, 1, state);
 		if (bma->cur == NULL)
 			rval = XFS_ILOG_DEXT;
 		else {
@@ -1709,9 +1710,12 @@ xfs_bmap_add_extent_delay_real(
 		 */
 		PREV.br_startblock = new->br_startblock;
 		PREV.br_blockcount += RIGHT.br_blockcount;
+
+		bma->idx++;
+		xfs_iext_remove(bma->ip, bma->idx, 1, state);
+		bma->idx--;
 		xfs_iext_update_extent(bma->ip, state, bma->idx, &PREV);
 
-		xfs_iext_remove(bma->ip, bma->idx + 1, 1, state);
 		if (bma->cur == NULL)
 			rval = XFS_ILOG_DEXT;
 		else {
@@ -1763,12 +1767,14 @@ xfs_bmap_add_extent_delay_real(
 				startblockval(PREV.br_startblock));
 
 		LEFT.br_blockcount += new->br_blockcount;
-		xfs_iext_update_extent(bma->ip, state, bma->idx - 1, &LEFT);
 
 		PREV.br_blockcount = temp;
 		PREV.br_startoff += new->br_blockcount;
 		PREV.br_startblock = nullstartblock(da_new);
+
 		xfs_iext_update_extent(bma->ip, state, bma->idx, &PREV);
+		bma->idx--;
+		xfs_iext_update_extent(bma->ip, state, bma->idx, &LEFT);
 
 		if (bma->cur == NULL)
 			rval = XFS_ILOG_DEXT;
@@ -1783,7 +1789,6 @@ xfs_bmap_add_extent_delay_real(
 				goto done;
 		}
 
-		bma->idx--;
 		break;
 
 	case BMAP_LEFT_FILLING:
@@ -1836,7 +1841,6 @@ xfs_bmap_add_extent_delay_real(
 		RIGHT.br_startoff = new->br_startoff;
 		RIGHT.br_startblock = new->br_startblock;
 		RIGHT.br_blockcount += new->br_blockcount;
-		xfs_iext_update_extent(bma->ip, state, bma->idx + 1, &RIGHT);
 
 		if (bma->cur == NULL)
 			rval = XFS_ILOG_DEXT;
@@ -1857,9 +1861,10 @@ xfs_bmap_add_extent_delay_real(
 
 		PREV.br_blockcount = temp;
 		PREV.br_startblock = nullstartblock(da_new);
-		xfs_iext_update_extent(bma->ip, state, bma->idx, &PREV);
 
+		xfs_iext_update_extent(bma->ip, state, bma->idx, &PREV);
 		bma->idx++;
+		xfs_iext_update_extent(bma->ip, state, bma->idx, &RIGHT);
 		break;
 
 	case BMAP_RIGHT_FILLING:
-- 
2.14.2

[PATCH 04/21] xfs: treat idx as a cursor in xfs_bmap_add_extent_hole_delay

[Christoph Hellwig]

Stop poking before and after the index and just increment or decrement
it while doing our operations on it to prepare for a new extent list
implementation.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
---
 fs/xfs/libxfs/xfs_bmap.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
index c0216e9e2af8..e2d8cbd054fe 100644
--- a/fs/xfs/libxfs/xfs_bmap.c
+++ b/fs/xfs/libxfs/xfs_bmap.c
@@ -2584,7 +2584,6 @@ xfs_bmap_add_extent_hole_delay(
 		 * on the left and on the right.
 		 * Merge all three into a single extent record.
 		 */
-		--*idx;
 		temp = left.br_blockcount + new->br_blockcount +
 			right.br_blockcount;
 
@@ -2595,9 +2594,10 @@ xfs_bmap_add_extent_hole_delay(
 					 oldlen);
 		left.br_startblock = nullstartblock(newlen);
 		left.br_blockcount = temp;
-		xfs_iext_update_extent(ip, state, *idx, &left);
 
-		xfs_iext_remove(ip, *idx + 1, 1, state);
+		xfs_iext_remove(ip, *idx, 1, state);
+		--*idx;
+		xfs_iext_update_extent(ip, state, *idx, &left);
 		break;
 
 	case BMAP_LEFT_CONTIG:
@@ -2606,7 +2606,6 @@ xfs_bmap_add_extent_hole_delay(
 		 * on the left.
 		 * Merge the new allocation with the left neighbor.
 		 */
-		--*idx;
 		temp = left.br_blockcount + new->br_blockcount;
 
 		oldlen = startblockval(left.br_startblock) +
@@ -2615,6 +2614,8 @@ xfs_bmap_add_extent_hole_delay(
 					 oldlen);
 		left.br_blockcount = temp;
 		left.br_startblock = nullstartblock(newlen);
+
+		--*idx;
 		xfs_iext_update_extent(ip, state, *idx, &left);
 		break;
 
-- 
2.14.2

[PATCH 05/21] xfs: treat idx as a cursor in xfs_bmap_add_extent_hole_real

[Christoph Hellwig]

Stop poking before and after the index and just increment or decrement
it while doing our operations on it to prepare for a new extent list
implementation.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
---
 fs/xfs/libxfs/xfs_bmap.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
index e2d8cbd054fe..117083b1d1ae 100644
--- a/fs/xfs/libxfs/xfs_bmap.c
+++ b/fs/xfs/libxfs/xfs_bmap.c
@@ -2742,11 +2742,11 @@ xfs_bmap_add_extent_hole_real(
 		 * left and on the right.
 		 * Merge all three into a single extent record.
 		 */
-		--*idx;
 		left.br_blockcount += new->br_blockcount + right.br_blockcount;
-		xfs_iext_update_extent(ip, state, *idx, &left);
 
-		xfs_iext_remove(ip, *idx + 1, 1, state);
+		xfs_iext_remove(ip, *idx, 1, state);
+		--*idx;
+		xfs_iext_update_extent(ip, state, *idx, &left);
 
 		XFS_IFORK_NEXT_SET(ip, whichfork,
 			XFS_IFORK_NEXTENTS(ip, whichfork) - 1);
@@ -2778,10 +2778,10 @@ xfs_bmap_add_extent_hole_real(
 		 * on the left.
 		 * Merge the new allocation with the left neighbor.
 		 */
-		--*idx;
 		old = left;
-
 		left.br_blockcount += new->br_blockcount;
+
+		--*idx;
 		xfs_iext_update_extent(ip, state, *idx, &left);
 
 		if (cur == NULL) {
-- 
2.14.2

[PATCH 06/21] xfs: treat idx as a cursor in xfs_bmap_add_extent_unwritten_real

[Christoph Hellwig]

Stop poking before and after the index and just increment or decrement
it while doing our operations on it to prepare for a new extent list
implementation.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
---
 fs/xfs/libxfs/xfs_bmap.c | 35 ++++++++++++++++++-----------------
 1 file changed, 18 insertions(+), 17 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
index 117083b1d1ae..3667fb1f3961 100644
--- a/fs/xfs/libxfs/xfs_bmap.c
+++ b/fs/xfs/libxfs/xfs_bmap.c
@@ -2152,12 +2152,11 @@ xfs_bmap_add_extent_unwritten_real(
 		 * Setting all of a previous oldext extent to newext.
 		 * The left and right neighbors are both contiguous with new.
 		 */
-		--*idx;
-
 		LEFT.br_blockcount += PREV.br_blockcount + RIGHT.br_blockcount;
-		xfs_iext_update_extent(ip, state, *idx, &LEFT);
 
-		xfs_iext_remove(ip, *idx + 1, 2, state);
+		xfs_iext_remove(ip, *idx, 2, state);
+		--*idx;
+		xfs_iext_update_extent(ip, state, *idx, &LEFT);
 		XFS_IFORK_NEXT_SET(ip, whichfork,
 				XFS_IFORK_NEXTENTS(ip, whichfork) - 2);
 		if (cur == NULL)
@@ -2191,12 +2190,11 @@ xfs_bmap_add_extent_unwritten_real(
 		 * Setting all of a previous oldext extent to newext.
 		 * The left neighbor is contiguous, the right is not.
 		 */
-		--*idx;
-
 		LEFT.br_blockcount += PREV.br_blockcount;
-		xfs_iext_update_extent(ip, state, *idx, &LEFT);
 
-		xfs_iext_remove(ip, *idx + 1, 1, state);
+		xfs_iext_remove(ip, *idx, 1, state);
+		--*idx;
+		xfs_iext_update_extent(ip, state, *idx, &LEFT);
 		XFS_IFORK_NEXT_SET(ip, whichfork,
 				XFS_IFORK_NEXTENTS(ip, whichfork) - 1);
 		if (cur == NULL)
@@ -2226,9 +2224,12 @@ xfs_bmap_add_extent_unwritten_real(
 		 */
 		PREV.br_blockcount += RIGHT.br_blockcount;
 		PREV.br_state = new->br_state;
+
+		++*idx;
+		xfs_iext_remove(ip, *idx, 1, state);
+		--*idx;
 		xfs_iext_update_extent(ip, state, *idx, &PREV);
 
-		xfs_iext_remove(ip, *idx + 1, 1, state);
 		XFS_IFORK_NEXT_SET(ip, whichfork,
 				XFS_IFORK_NEXTENTS(ip, whichfork) - 1);
 		if (cur == NULL)
@@ -2280,15 +2281,15 @@ xfs_bmap_add_extent_unwritten_real(
 		 * The left neighbor is contiguous.
 		 */
 		LEFT.br_blockcount += new->br_blockcount;
-		xfs_iext_update_extent(ip, state, *idx - 1, &LEFT);
 
 		old = PREV;
 		PREV.br_startoff += new->br_blockcount;
 		PREV.br_startblock += new->br_blockcount;
 		PREV.br_blockcount -= new->br_blockcount;
-		xfs_iext_update_extent(ip, state, *idx, &PREV);
 
+		xfs_iext_update_extent(ip, state, *idx, &PREV);
 		--*idx;
+		xfs_iext_update_extent(ip, state, *idx, &LEFT);
 
 		if (cur == NULL)
 			rval = XFS_ILOG_DEXT;
@@ -2319,8 +2320,8 @@ xfs_bmap_add_extent_unwritten_real(
 		PREV.br_startoff += new->br_blockcount;
 		PREV.br_startblock += new->br_blockcount;
 		PREV.br_blockcount -= new->br_blockcount;
-		xfs_iext_update_extent(ip, state, *idx, &PREV);
 
+		xfs_iext_update_extent(ip, state, *idx, &PREV);
 		xfs_iext_insert(ip, *idx, 1, new, state);
 		XFS_IFORK_NEXT_SET(ip, whichfork,
 				XFS_IFORK_NEXTENTS(ip, whichfork) + 1);
@@ -2349,13 +2350,13 @@ xfs_bmap_add_extent_unwritten_real(
 		 */
 		old = PREV;
 		PREV.br_blockcount -= new->br_blockcount;
-		xfs_iext_update_extent(ip, state, *idx, &PREV);
-
-		++*idx;
 
 		RIGHT.br_startoff = new->br_startoff;
 		RIGHT.br_startblock = new->br_startblock;
 		RIGHT.br_blockcount += new->br_blockcount;
+
+		xfs_iext_update_extent(ip, state, *idx, &PREV);
+		++*idx;
 		xfs_iext_update_extent(ip, state, *idx, &RIGHT);
 
 		if (cur == NULL)
@@ -2385,8 +2386,8 @@ xfs_bmap_add_extent_unwritten_real(
 		 */
 		old = PREV;
 		PREV.br_blockcount -= new->br_blockcount;
-		xfs_iext_update_extent(ip, state, *idx, &PREV);
 
+		xfs_iext_update_extent(ip, state, *idx, &PREV);
 		++*idx;
 		xfs_iext_insert(ip, *idx, 1, new, state);
 
@@ -2421,7 +2422,6 @@ xfs_bmap_add_extent_unwritten_real(
 		 */
 		old = PREV;
 		PREV.br_blockcount = new->br_startoff - PREV.br_startoff;
-		xfs_iext_update_extent(ip, state, *idx, &PREV);
 
 		r[0] = *new;
 		r[1].br_startoff = new_endoff;
@@ -2430,6 +2430,7 @@ xfs_bmap_add_extent_unwritten_real(
 		r[1].br_startblock = new->br_startblock + new->br_blockcount;
 		r[1].br_state = PREV.br_state;
 
+		xfs_iext_update_extent(ip, state, *idx, &PREV);
 		++*idx;
 		xfs_iext_insert(ip, *idx, 2, &r[0], state);
 
-- 
2.14.2

[PATCH 07/21] xfs: treat idx as a cursor in xfs_bmap_del_extent_*

[Christoph Hellwig]

Stop poking before and after the index and just increment or decrement
it while doing our operations on it to prepare for a new extent list
implementation.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
---
 fs/xfs/libxfs/xfs_bmap.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
index 3667fb1f3961..f64b6b74daa9 100644
--- a/fs/xfs/libxfs/xfs_bmap.c
+++ b/fs/xfs/libxfs/xfs_bmap.c
@@ -4750,12 +4750,12 @@ xfs_bmap_del_extent_delay(
 						       del->br_blockcount);
 
 		got->br_startblock = nullstartblock((int)got_indlen);
-		xfs_iext_update_extent(ip, state, *idx, got);
 
 		new.br_startoff = del_endoff;
 		new.br_state = got->br_state;
 		new.br_startblock = nullstartblock((int)new_indlen);
 
+		xfs_iext_update_extent(ip, state, *idx, got);
 		++*idx;
 		xfs_iext_insert(ip, *idx, 1, &new, state);
 
@@ -4832,13 +4832,13 @@ xfs_bmap_del_extent_cow(
 		 * Deleting the middle of the extent.
 		 */
 		got->br_blockcount = del->br_startoff - got->br_startoff;
-		xfs_iext_update_extent(ip, state, *idx, got);
 
 		new.br_startoff = del_endoff;
 		new.br_blockcount = got_endoff - del_endoff;
 		new.br_state = got->br_state;
 		new.br_startblock = del->br_startblock + del->br_blockcount;
 
+		xfs_iext_update_extent(ip, state, *idx, got);
 		++*idx;
 		xfs_iext_insert(ip, *idx, 1, &new, state);
 		break;
@@ -5054,8 +5054,8 @@ xfs_bmap_del_extent_real(
 			flags |= xfs_ilog_fext(whichfork);
 		XFS_IFORK_NEXT_SET(ip, whichfork,
 			XFS_IFORK_NEXTENTS(ip, whichfork) + 1);
-		xfs_iext_insert(ip, *idx + 1, 1, &new, state);
 		++*idx;
+		xfs_iext_insert(ip, *idx, 1, &new, state);
 		break;
 	}
 
-- 
2.14.2

[PATCH 08/21] xfs: treat idx as a cursor in xfs_bmap_collapse_extents

[Christoph Hellwig]

Stop poking before and after the index and just increment or decrement
it while doing our operations on it to prepare for a new extent list
implementation.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
---
 fs/xfs/libxfs/xfs_bmap.c | 17 ++++++-----------
 1 file changed, 6 insertions(+), 11 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
index f64b6b74daa9..62270b871d06 100644
--- a/fs/xfs/libxfs/xfs_bmap.c
+++ b/fs/xfs/libxfs/xfs_bmap.c
@@ -5517,7 +5517,7 @@ xfs_bmse_merge(
 	struct xfs_inode		*ip,
 	int				whichfork,
 	xfs_fileoff_t			shift,		/* shift fsb */
-	int				current_ext,	/* idx of gotp */
+	int				*current_ext,	/* idx of gotp */
 	struct xfs_bmbt_irec		*got,		/* extent to shift */
 	struct xfs_bmbt_irec		*left,		/* preceding extent */
 	struct xfs_btree_cur		*cur,
@@ -5572,9 +5572,10 @@ xfs_bmse_merge(
 		return error;
 
 done:
+	xfs_iext_remove(ip, *current_ext, 1, 0);
+	--*current_ext;
 	xfs_iext_update_extent(ip, xfs_bmap_fork_to_state(whichfork),
-			current_ext - 1, &new);
-	xfs_iext_remove(ip, current_ext, 1, 0);
+			*current_ext, &new);
 
 	/* update reverse mapping. rmap functions merge the rmaps for us */
 	error = xfs_rmap_unmap_extent(mp, dfops, ip, whichfork, got);
@@ -5688,16 +5689,10 @@ xfs_bmap_collapse_extents(
 
 		if (xfs_bmse_can_merge(&prev, &got, offset_shift_fsb)) {
 			error = xfs_bmse_merge(ip, whichfork, offset_shift_fsb,
-					current_ext, &got, &prev, cur,
+					&current_ext, &got, &prev, cur,
 					&logflags, dfops);
 			if (error)
 				goto del_cursor;
-
-			/* update got after merge */
-			if (!xfs_iext_get_extent(ifp, current_ext, &got)) {
-				*done = true;
-				goto del_cursor;
-			}
 			goto done;
 		}
 	} else {
@@ -5712,12 +5707,12 @@ xfs_bmap_collapse_extents(
 	if (error)
 		goto del_cursor;
 
+done:
 	if (!xfs_iext_get_extent(ifp, ++current_ext, &got)) {
 		 *done = true;
 		 goto del_cursor;
 	}
 
-done:
 	*next_fsb = got.br_startoff;
 del_cursor:
 	if (cur)
-- 
2.14.2

[PATCH 09/21] xfs: pass an on-disk extent to xfs_bmbt_validate_extent

[Christoph Hellwig]

This prepares for getting rid of the current in-memory extent format.
At the end of the series we will change the calling convention again
to pass the xfs_bmbt_irec structure once it is available everywhere.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 fs/xfs/libxfs/xfs_bmap.c       | 6 +++---
 fs/xfs/libxfs/xfs_bmap_btree.h | 4 ++--
 fs/xfs/libxfs/xfs_inode_fork.c | 9 ++++-----
 3 files changed, 9 insertions(+), 10 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
index 62270b871d06..8ce7bf19916f 100644
--- a/fs/xfs/libxfs/xfs_bmap.c
+++ b/fs/xfs/libxfs/xfs_bmap.c
@@ -1260,14 +1260,14 @@ xfs_iread_extents(
 		frp = XFS_BMBT_REC_ADDR(mp, block, 1);
 		for (j = 0; j < num_recs; j++, i++, frp++) {
 			xfs_bmbt_rec_host_t *trp = xfs_iext_get_ext(ifp, i);
-			trp->l0 = be64_to_cpu(frp->l0);
-			trp->l1 = be64_to_cpu(frp->l1);
-			if (!xfs_bmbt_validate_extent(mp, whichfork, trp)) {
+			if (!xfs_bmbt_validate_extent(mp, whichfork, frp)) {
 				XFS_ERROR_REPORT("xfs_bmap_read_extents(2)",
 						 XFS_ERRLEVEL_LOW, mp);
 				error = -EFSCORRUPTED;
 				goto out_brelse;
 			}
+			trp->l0 = be64_to_cpu(frp->l0);
+			trp->l1 = be64_to_cpu(frp->l1);
 			trace_xfs_read_extent(ip, i, state, _THIS_IP_);
 		}
 		xfs_trans_brelse(tp, bp);
diff --git a/fs/xfs/libxfs/xfs_bmap_btree.h b/fs/xfs/libxfs/xfs_bmap_btree.h
index 6f891eeb88f6..2fbfe2a24b15 100644
--- a/fs/xfs/libxfs/xfs_bmap_btree.h
+++ b/fs/xfs/libxfs/xfs_bmap_btree.h
@@ -127,9 +127,9 @@ extern struct xfs_btree_cur *xfs_bmbt_init_cursor(struct xfs_mount *,
  * Check that the extent does not contain an invalid unwritten extent flag.
  */
 static inline bool xfs_bmbt_validate_extent(struct xfs_mount *mp, int whichfork,
-		struct xfs_bmbt_rec_host *ep)
+		struct xfs_bmbt_rec *ep)
 {
-	if (ep->l0 >> (64 - BMBT_EXNTFLAG_BITLEN) == 0)
+	if (get_unaligned_be64(&ep->l0) >> (64 - BMBT_EXNTFLAG_BITLEN) == 0)
 		return true;
 	if (whichfork == XFS_DATA_FORK &&
 	    xfs_sb_version_hasextflgbit(&mp->m_sb))
diff --git a/fs/xfs/libxfs/xfs_inode_fork.c b/fs/xfs/libxfs/xfs_inode_fork.c
index bb63f38b97cc..abe601b48c9c 100644
--- a/fs/xfs/libxfs/xfs_inode_fork.c
+++ b/fs/xfs/libxfs/xfs_inode_fork.c
@@ -371,13 +371,13 @@ xfs_iformat_extents(
 		dp = (xfs_bmbt_rec_t *) XFS_DFORK_PTR(dip, whichfork);
 		for (i = 0; i < nex; i++, dp++) {
 			xfs_bmbt_rec_host_t *ep = xfs_iext_get_ext(ifp, i);
-			ep->l0 = get_unaligned_be64(&dp->l0);
-			ep->l1 = get_unaligned_be64(&dp->l1);
-			if (!xfs_bmbt_validate_extent(mp, whichfork, ep)) {
+			if (!xfs_bmbt_validate_extent(mp, whichfork, dp)) {
 				XFS_ERROR_REPORT("xfs_iformat_extents(2)",
 						 XFS_ERRLEVEL_LOW, mp);
 				return -EFSCORRUPTED;
 			}
+			ep->l0 = get_unaligned_be64(&dp->l0);
+			ep->l1 = get_unaligned_be64(&dp->l1);
 			trace_xfs_read_extent(ip, i, state, _THIS_IP_);
 		}
 	}
@@ -764,8 +764,6 @@ xfs_iextents_copy(
 	for (i = 0; i < nrecs; i++) {
 		xfs_bmbt_rec_host_t *ep = xfs_iext_get_ext(ifp, i);
 
-		ASSERT(xfs_bmbt_validate_extent(ip->i_mount, whichfork, ep));
-
 		start_block = xfs_bmbt_get_startblock(ep);
 		if (isnullstartblock(start_block)) {
 			/*
@@ -779,6 +777,7 @@ xfs_iextents_copy(
 		/* Translate to on disk format */
 		put_unaligned_be64(ep->l0, &dp->l0);
 		put_unaligned_be64(ep->l1, &dp->l1);
+		ASSERT(xfs_bmbt_validate_extent(ip->i_mount, whichfork, dp));
 
 		dp++;
 		copied++;
-- 
2.14.2

Re: [PATCH 09/21] xfs: pass an on-disk extent to xfs_bmbt_validate_extent

[Brian Foster]

On Fri, Nov 03, 2017 at 05:45:27PM +0300, Christoph Hellwig wrote:
> This prepares for getting rid of the current in-memory extent format.
> At the end of the series we will change the calling convention again
> to pass the xfs_bmbt_irec structure once it is available everywhere.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---

Reviewed-by: Brian Foster <bfoster@redhat.com>

>  fs/xfs/libxfs/xfs_bmap.c       | 6 +++---
>  fs/xfs/libxfs/xfs_bmap_btree.h | 4 ++--
>  fs/xfs/libxfs/xfs_inode_fork.c | 9 ++++-----
>  3 files changed, 9 insertions(+), 10 deletions(-)
> 
> diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
> index 62270b871d06..8ce7bf19916f 100644
> --- a/fs/xfs/libxfs/xfs_bmap.c
> +++ b/fs/xfs/libxfs/xfs_bmap.c
> @@ -1260,14 +1260,14 @@ xfs_iread_extents(
>  		frp = XFS_BMBT_REC_ADDR(mp, block, 1);
>  		for (j = 0; j < num_recs; j++, i++, frp++) {
>  			xfs_bmbt_rec_host_t *trp = xfs_iext_get_ext(ifp, i);
> -			trp->l0 = be64_to_cpu(frp->l0);
> -			trp->l1 = be64_to_cpu(frp->l1);
> -			if (!xfs_bmbt_validate_extent(mp, whichfork, trp)) {
> +			if (!xfs_bmbt_validate_extent(mp, whichfork, frp)) {
>  				XFS_ERROR_REPORT("xfs_bmap_read_extents(2)",
>  						 XFS_ERRLEVEL_LOW, mp);
>  				error = -EFSCORRUPTED;
>  				goto out_brelse;
>  			}
> +			trp->l0 = be64_to_cpu(frp->l0);
> +			trp->l1 = be64_to_cpu(frp->l1);
>  			trace_xfs_read_extent(ip, i, state, _THIS_IP_);
>  		}
>  		xfs_trans_brelse(tp, bp);
> diff --git a/fs/xfs/libxfs/xfs_bmap_btree.h b/fs/xfs/libxfs/xfs_bmap_btree.h
> index 6f891eeb88f6..2fbfe2a24b15 100644
> --- a/fs/xfs/libxfs/xfs_bmap_btree.h
> +++ b/fs/xfs/libxfs/xfs_bmap_btree.h
> @@ -127,9 +127,9 @@ extern struct xfs_btree_cur *xfs_bmbt_init_cursor(struct xfs_mount *,
>   * Check that the extent does not contain an invalid unwritten extent flag.
>   */
>  static inline bool xfs_bmbt_validate_extent(struct xfs_mount *mp, int whichfork,
> -		struct xfs_bmbt_rec_host *ep)
> +		struct xfs_bmbt_rec *ep)
>  {
> -	if (ep->l0 >> (64 - BMBT_EXNTFLAG_BITLEN) == 0)
> +	if (get_unaligned_be64(&ep->l0) >> (64 - BMBT_EXNTFLAG_BITLEN) == 0)
>  		return true;
>  	if (whichfork == XFS_DATA_FORK &&
>  	    xfs_sb_version_hasextflgbit(&mp->m_sb))
> diff --git a/fs/xfs/libxfs/xfs_inode_fork.c b/fs/xfs/libxfs/xfs_inode_fork.c
> index bb63f38b97cc..abe601b48c9c 100644
> --- a/fs/xfs/libxfs/xfs_inode_fork.c
> +++ b/fs/xfs/libxfs/xfs_inode_fork.c
> @@ -371,13 +371,13 @@ xfs_iformat_extents(
>  		dp = (xfs_bmbt_rec_t *) XFS_DFORK_PTR(dip, whichfork);
>  		for (i = 0; i < nex; i++, dp++) {
>  			xfs_bmbt_rec_host_t *ep = xfs_iext_get_ext(ifp, i);
> -			ep->l0 = get_unaligned_be64(&dp->l0);
> -			ep->l1 = get_unaligned_be64(&dp->l1);
> -			if (!xfs_bmbt_validate_extent(mp, whichfork, ep)) {
> +			if (!xfs_bmbt_validate_extent(mp, whichfork, dp)) {
>  				XFS_ERROR_REPORT("xfs_iformat_extents(2)",
>  						 XFS_ERRLEVEL_LOW, mp);
>  				return -EFSCORRUPTED;
>  			}
> +			ep->l0 = get_unaligned_be64(&dp->l0);
> +			ep->l1 = get_unaligned_be64(&dp->l1);
>  			trace_xfs_read_extent(ip, i, state, _THIS_IP_);
>  		}
>  	}
> @@ -764,8 +764,6 @@ xfs_iextents_copy(
>  	for (i = 0; i < nrecs; i++) {
>  		xfs_bmbt_rec_host_t *ep = xfs_iext_get_ext(ifp, i);
>  
> -		ASSERT(xfs_bmbt_validate_extent(ip->i_mount, whichfork, ep));
> -
>  		start_block = xfs_bmbt_get_startblock(ep);
>  		if (isnullstartblock(start_block)) {
>  			/*
> @@ -779,6 +777,7 @@ xfs_iextents_copy(
>  		/* Translate to on disk format */
>  		put_unaligned_be64(ep->l0, &dp->l0);
>  		put_unaligned_be64(ep->l1, &dp->l1);
> +		ASSERT(xfs_bmbt_validate_extent(ip->i_mount, whichfork, dp));
>  
>  		dp++;
>  		copied++;
> -- 
> 2.14.2
> 
> --
> To unsubscribe from this list: send the line "unsubscribe linux-xfs" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: [PATCH 09/21] xfs: pass an on-disk extent to xfs_bmbt_validate_extent

[Darrick J. Wong]

On Fri, Nov 03, 2017 at 05:45:27PM +0300, Christoph Hellwig wrote:
> This prepares for getting rid of the current in-memory extent format.
> At the end of the series we will change the calling convention again
> to pass the xfs_bmbt_irec structure once it is available everywhere.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>

Looks ok,
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>

> ---
>  fs/xfs/libxfs/xfs_bmap.c       | 6 +++---
>  fs/xfs/libxfs/xfs_bmap_btree.h | 4 ++--
>  fs/xfs/libxfs/xfs_inode_fork.c | 9 ++++-----
>  3 files changed, 9 insertions(+), 10 deletions(-)
> 
> diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
> index 62270b871d06..8ce7bf19916f 100644
> --- a/fs/xfs/libxfs/xfs_bmap.c
> +++ b/fs/xfs/libxfs/xfs_bmap.c
> @@ -1260,14 +1260,14 @@ xfs_iread_extents(
>  		frp = XFS_BMBT_REC_ADDR(mp, block, 1);
>  		for (j = 0; j < num_recs; j++, i++, frp++) {
>  			xfs_bmbt_rec_host_t *trp = xfs_iext_get_ext(ifp, i);
> -			trp->l0 = be64_to_cpu(frp->l0);
> -			trp->l1 = be64_to_cpu(frp->l1);
> -			if (!xfs_bmbt_validate_extent(mp, whichfork, trp)) {
> +			if (!xfs_bmbt_validate_extent(mp, whichfork, frp)) {
>  				XFS_ERROR_REPORT("xfs_bmap_read_extents(2)",
>  						 XFS_ERRLEVEL_LOW, mp);
>  				error = -EFSCORRUPTED;
>  				goto out_brelse;
>  			}
> +			trp->l0 = be64_to_cpu(frp->l0);
> +			trp->l1 = be64_to_cpu(frp->l1);
>  			trace_xfs_read_extent(ip, i, state, _THIS_IP_);
>  		}
>  		xfs_trans_brelse(tp, bp);
> diff --git a/fs/xfs/libxfs/xfs_bmap_btree.h b/fs/xfs/libxfs/xfs_bmap_btree.h
> index 6f891eeb88f6..2fbfe2a24b15 100644
> --- a/fs/xfs/libxfs/xfs_bmap_btree.h
> +++ b/fs/xfs/libxfs/xfs_bmap_btree.h
> @@ -127,9 +127,9 @@ extern struct xfs_btree_cur *xfs_bmbt_init_cursor(struct xfs_mount *,
>   * Check that the extent does not contain an invalid unwritten extent flag.
>   */
>  static inline bool xfs_bmbt_validate_extent(struct xfs_mount *mp, int whichfork,
> -		struct xfs_bmbt_rec_host *ep)
> +		struct xfs_bmbt_rec *ep)
>  {
> -	if (ep->l0 >> (64 - BMBT_EXNTFLAG_BITLEN) == 0)
> +	if (get_unaligned_be64(&ep->l0) >> (64 - BMBT_EXNTFLAG_BITLEN) == 0)
>  		return true;
>  	if (whichfork == XFS_DATA_FORK &&
>  	    xfs_sb_version_hasextflgbit(&mp->m_sb))
> diff --git a/fs/xfs/libxfs/xfs_inode_fork.c b/fs/xfs/libxfs/xfs_inode_fork.c
> index bb63f38b97cc..abe601b48c9c 100644
> --- a/fs/xfs/libxfs/xfs_inode_fork.c
> +++ b/fs/xfs/libxfs/xfs_inode_fork.c
> @@ -371,13 +371,13 @@ xfs_iformat_extents(
>  		dp = (xfs_bmbt_rec_t *) XFS_DFORK_PTR(dip, whichfork);
>  		for (i = 0; i < nex; i++, dp++) {
>  			xfs_bmbt_rec_host_t *ep = xfs_iext_get_ext(ifp, i);
> -			ep->l0 = get_unaligned_be64(&dp->l0);
> -			ep->l1 = get_unaligned_be64(&dp->l1);
> -			if (!xfs_bmbt_validate_extent(mp, whichfork, ep)) {
> +			if (!xfs_bmbt_validate_extent(mp, whichfork, dp)) {
>  				XFS_ERROR_REPORT("xfs_iformat_extents(2)",
>  						 XFS_ERRLEVEL_LOW, mp);
>  				return -EFSCORRUPTED;
>  			}
> +			ep->l0 = get_unaligned_be64(&dp->l0);
> +			ep->l1 = get_unaligned_be64(&dp->l1);
>  			trace_xfs_read_extent(ip, i, state, _THIS_IP_);
>  		}
>  	}
> @@ -764,8 +764,6 @@ xfs_iextents_copy(
>  	for (i = 0; i < nrecs; i++) {
>  		xfs_bmbt_rec_host_t *ep = xfs_iext_get_ext(ifp, i);
>  
> -		ASSERT(xfs_bmbt_validate_extent(ip->i_mount, whichfork, ep));
> -
>  		start_block = xfs_bmbt_get_startblock(ep);
>  		if (isnullstartblock(start_block)) {
>  			/*
> @@ -779,6 +777,7 @@ xfs_iextents_copy(
>  		/* Translate to on disk format */
>  		put_unaligned_be64(ep->l0, &dp->l0);
>  		put_unaligned_be64(ep->l1, &dp->l1);
> +		ASSERT(xfs_bmbt_validate_extent(ip->i_mount, whichfork, dp));
>  
>  		dp++;
>  		copied++;
> -- 
> 2.14.2
> 
> --
> To unsubscribe from this list: send the line "unsubscribe linux-xfs" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

[PATCH 10/21] xfs: iterate over extents in xfs_iextents_copy

[Christoph Hellwig]

This actually makes the function very slightly less efficient for now as we
detour through the expanded irect format between the in-core extent format
and the on-disk one instead of just endian swapping them.  But with the
incore extent btree the in-core one will use a different format and the
representation will be entirely hidden.  It also happens to make the
function a whole more readable.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
---
 fs/xfs/libxfs/xfs_inode_fork.c | 53 +++++++++++-------------------------------
 1 file changed, 13 insertions(+), 40 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_inode_fork.c b/fs/xfs/libxfs/xfs_inode_fork.c
index abe601b48c9c..7dd77b497fc2 100644
--- a/fs/xfs/libxfs/xfs_inode_fork.c
+++ b/fs/xfs/libxfs/xfs_inode_fork.c
@@ -725,9 +725,6 @@ xfs_iext_count(struct xfs_ifork *ifp)
 /*
  * Convert in-core extents to on-disk form
  *
- * For either the data or attr fork in extent format, we need to endian convert
- * the in-core extent as we place them into the on-disk inode.
- *
  * In the case of the data fork, the in-core and on-disk fork sizes can be
  * different due to delayed allocation extents. We only copy on-disk extents
  * here, so callers must always use the physical fork size to determine the
@@ -736,55 +733,31 @@ xfs_iext_count(struct xfs_ifork *ifp)
  */
 int
 xfs_iextents_copy(
-	xfs_inode_t		*ip,
-	xfs_bmbt_rec_t		*dp,
+	struct xfs_inode	*ip,
+	struct xfs_bmbt_rec	*dp,
 	int			whichfork)
 {
 	int			state = xfs_bmap_fork_to_state(whichfork);
-	int			copied;
-	int			i;
-	xfs_ifork_t		*ifp;
-	int			nrecs;
-	xfs_fsblock_t		start_block;
+	struct xfs_ifork	*ifp = XFS_IFORK_PTR(ip, whichfork);
+	struct xfs_bmbt_irec	rec;
+	int			copied = 0, i = 0;
 
-	ifp = XFS_IFORK_PTR(ip, whichfork);
-	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL|XFS_ILOCK_SHARED));
+	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL | XFS_ILOCK_SHARED));
 	ASSERT(ifp->if_bytes > 0);
 
-	nrecs = xfs_iext_count(ifp);
-	ASSERT(nrecs > 0);
-
-	/*
-	 * There are some delayed allocation extents in the
-	 * inode, so copy the extents one at a time and skip
-	 * the delayed ones.  There must be at least one
-	 * non-delayed extent.
-	 */
-	copied = 0;
-	for (i = 0; i < nrecs; i++) {
-		xfs_bmbt_rec_host_t *ep = xfs_iext_get_ext(ifp, i);
-
-		start_block = xfs_bmbt_get_startblock(ep);
-		if (isnullstartblock(start_block)) {
-			/*
-			 * It's a delayed allocation extent, so skip it.
-			 */
+	while (xfs_iext_get_extent(ifp, i++, &rec)) {
+		if (isnullstartblock(rec.br_startblock))
 			continue;
-		}
-
+		xfs_bmbt_disk_set_all(dp, &rec);
 		trace_xfs_write_extent(ip, i, state, _RET_IP_);
-
-		/* Translate to on disk format */
-		put_unaligned_be64(ep->l0, &dp->l0);
-		put_unaligned_be64(ep->l1, &dp->l1);
 		ASSERT(xfs_bmbt_validate_extent(ip->i_mount, whichfork, dp));
-
+		copied += sizeof(struct xfs_bmbt_rec);
 		dp++;
-		copied++;
 	}
-	ASSERT(copied != 0);
 
-	return (copied * (uint)sizeof(xfs_bmbt_rec_t));
+	ASSERT(copied > 0);
+	ASSERT(copied <= ifp->if_bytes);
+	return copied;
 }
 
 /*
-- 
2.14.2

[PATCH 11/21] xfs: iterate over extents in xfs_bmap_extents_to_btree

[Christoph Hellwig]

This actually makes the function very slightly less efficient for now as we
detour through the expanded irect format between the in-core extent format
and the on-disk one instead of just endian swapping them.  But with the
incore extent btree the in-core one will use a different format and the
representation will be entirely hidden.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
---
 fs/xfs/libxfs/xfs_bmap.c | 20 ++++++++------------
 1 file changed, 8 insertions(+), 12 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
index 8ce7bf19916f..f4d0639dc4ae 100644
--- a/fs/xfs/libxfs/xfs_bmap.c
+++ b/fs/xfs/libxfs/xfs_bmap.c
@@ -667,14 +667,13 @@ xfs_bmap_extents_to_btree(
 	xfs_bmbt_rec_t		*arp;		/* child record pointer */
 	struct xfs_btree_block	*block;		/* btree root block */
 	xfs_btree_cur_t		*cur;		/* bmap btree cursor */
-	xfs_bmbt_rec_host_t	*ep;		/* extent record pointer */
 	int			error;		/* error return value */
-	xfs_extnum_t		i, cnt;		/* extent record index */
 	xfs_ifork_t		*ifp;		/* inode fork pointer */
 	xfs_bmbt_key_t		*kp;		/* root block key pointer */
 	xfs_mount_t		*mp;		/* mount structure */
-	xfs_extnum_t		nextents;	/* number of file extents */
 	xfs_bmbt_ptr_t		*pp;		/* root block address pointer */
+	struct xfs_bmbt_irec	rec;
+	xfs_extnum_t		i = 0, cnt = 0;
 
 	mp = ip->i_mount;
 	ASSERT(whichfork != XFS_COW_FORK);
@@ -753,15 +752,12 @@ xfs_bmap_extents_to_btree(
 				XFS_BTNUM_BMAP, 0, 0, ip->i_ino,
 				XFS_BTREE_LONG_PTRS);
 
-	arp = XFS_BMBT_REC_ADDR(mp, ablock, 1);
-	nextents =  xfs_iext_count(ifp);
-	for (cnt = i = 0; i < nextents; i++) {
-		ep = xfs_iext_get_ext(ifp, i);
-		if (!isnullstartblock(xfs_bmbt_get_startblock(ep))) {
-			arp->l0 = cpu_to_be64(ep->l0);
-			arp->l1 = cpu_to_be64(ep->l1);
-			arp++; cnt++;
-		}
+	while (xfs_iext_get_extent(ifp, i++, &rec)) {
+		if (isnullstartblock(rec.br_startblock))
+			continue;
+		arp = XFS_BMBT_REC_ADDR(mp, ablock, 1 + cnt);
+		xfs_bmbt_disk_set_all(arp, &rec);
+		cnt++;
 	}
 	ASSERT(cnt == XFS_IFORK_NEXTENTS(ip, whichfork));
 	xfs_btree_set_numrecs(ablock, cnt);
-- 
2.14.2

[PATCH 12/21] xfs: introduce the xfs_iext_cursor abstraction

[Christoph Hellwig]

Add a new xfs_iext_cursor structure to hide the direct extent map
index manipulations. In addition to the existing lookup/get/insert/
remove and update routines new primitives to get the first and last
extent cursor, as well as moving up and down by one extent are
provided.  Also new are convenience to increment/decrement the
cursor and retreive the new extent, as well as to peek into the
previous/next extent without updating the cursor and last but not
least a macro to iterate over all extents in a fork.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 fs/xfs/libxfs/xfs_bmap.c       | 441 ++++++++++++++++++++---------------------
 fs/xfs/libxfs/xfs_bmap.h       |  12 +-
 fs/xfs/libxfs/xfs_inode_fork.c |  75 +++----
 fs/xfs/libxfs/xfs_inode_fork.h |  87 +++++++-
 fs/xfs/libxfs/xfs_types.h      |   3 +
 fs/xfs/scrub/bmap.c            |   6 +-
 fs/xfs/scrub/dir.c             |  14 +-
 fs/xfs/xfs_bmap_util.c         |  12 +-
 fs/xfs/xfs_dir2_readdir.c      |   8 +-
 fs/xfs/xfs_dquot.c             |   4 +-
 fs/xfs/xfs_iomap.c             |  14 +-
 fs/xfs/xfs_reflink.c           |  56 +++---
 fs/xfs/xfs_trace.h             |  12 +-
 13 files changed, 407 insertions(+), 337 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
index f4d0639dc4ae..b08c4863c2af 100644
--- a/fs/xfs/libxfs/xfs_bmap.c
+++ b/fs/xfs/libxfs/xfs_bmap.c
@@ -672,8 +672,9 @@ xfs_bmap_extents_to_btree(
 	xfs_bmbt_key_t		*kp;		/* root block key pointer */
 	xfs_mount_t		*mp;		/* mount structure */
 	xfs_bmbt_ptr_t		*pp;		/* root block address pointer */
+	struct xfs_iext_cursor	icur;
 	struct xfs_bmbt_irec	rec;
-	xfs_extnum_t		i = 0, cnt = 0;
+	xfs_extnum_t		cnt = 0;
 
 	mp = ip->i_mount;
 	ASSERT(whichfork != XFS_COW_FORK);
@@ -752,7 +753,7 @@ xfs_bmap_extents_to_btree(
 				XFS_BTNUM_BMAP, 0, 0, ip->i_ino,
 				XFS_BTREE_LONG_PTRS);
 
-	while (xfs_iext_get_extent(ifp, i++, &rec)) {
+	for_each_iext(ifp, &icur, &rec) {
 		if (isnullstartblock(rec.br_startblock))
 			continue;
 		arp = XFS_BMBT_REC_ADDR(mp, ablock, 1 + cnt);
@@ -828,6 +829,7 @@ xfs_bmap_local_to_extents(
 	xfs_alloc_arg_t	args;		/* allocation arguments */
 	xfs_buf_t	*bp;		/* buffer for extent block */
 	struct xfs_bmbt_irec rec;
+	struct xfs_iext_cursor icur;
 
 	/*
 	 * We don't want to deal with the case of keeping inode data inline yet.
@@ -894,7 +896,8 @@ xfs_bmap_local_to_extents(
 	rec.br_startblock = args.fsbno;
 	rec.br_blockcount = 1;
 	rec.br_state = XFS_EXT_NORM;
-	xfs_iext_insert(ip, 0, 1, &rec, 0);
+	xfs_iext_first(ifp, &icur);
+	xfs_iext_insert(ip, &icur, 1, &rec, 0);
 
 	XFS_IFORK_NEXT_SET(ip, whichfork, 1);
 	ip->i_d.di_nblocks = 1;
@@ -1174,6 +1177,7 @@ xfs_iread_extents(
 	struct xfs_ifork	*ifp = XFS_IFORK_PTR(ip, whichfork);
 	xfs_extnum_t		nextents = XFS_IFORK_NEXTENTS(ip, whichfork);
 	struct xfs_btree_block	*block = ifp->if_broot;
+	struct xfs_iext_cursor	icur;
 	xfs_fsblock_t		bno;
 	struct xfs_buf		*bp;
 	xfs_extnum_t		i, j;
@@ -1223,6 +1227,7 @@ xfs_iread_extents(
 	 * Here with bp and block set to the leftmost leaf node in the tree.
 	 */
 	i = 0;
+	xfs_iext_first(ifp, &icur);
 
 	/*
 	 * Loop over all leaf nodes.  Copy information to the extent records.
@@ -1264,7 +1269,8 @@ xfs_iread_extents(
 			}
 			trp->l0 = be64_to_cpu(frp->l0);
 			trp->l1 = be64_to_cpu(frp->l1);
-			trace_xfs_read_extent(ip, i, state, _THIS_IP_);
+			trace_xfs_read_extent(ip, &icur, state, _THIS_IP_);
+			xfs_iext_next(ifp, &icur);
 		}
 		xfs_trans_brelse(tp, bp);
 		bno = nextbno;
@@ -1312,7 +1318,7 @@ xfs_bmap_first_unused(
 {
 	struct xfs_ifork	*ifp = XFS_IFORK_PTR(ip, whichfork);
 	struct xfs_bmbt_irec	got;
-	xfs_extnum_t		idx = 0;
+	struct xfs_iext_cursor	icur;
 	xfs_fileoff_t		lastaddr = 0;
 	xfs_fileoff_t		lowest, max;
 	int			error;
@@ -1333,7 +1339,7 @@ xfs_bmap_first_unused(
 	}
 
 	lowest = max = *first_unused;
-	while (xfs_iext_get_extent(ifp, idx++, &got)) {
+	for_each_iext(ifp, &icur, &got) {
 		/*
 		 * See if the hole before this extent will work.
 		 */
@@ -1363,7 +1369,7 @@ xfs_bmap_last_before(
 {
 	struct xfs_ifork	*ifp = XFS_IFORK_PTR(ip, whichfork);
 	struct xfs_bmbt_irec	got;
-	xfs_extnum_t		idx;
+	struct xfs_iext_cursor	icur;
 	int			error;
 
 	switch (XFS_IFORK_FORMAT(ip, whichfork)) {
@@ -1383,7 +1389,7 @@ xfs_bmap_last_before(
 			return error;
 	}
 
-	if (!xfs_iext_lookup_extent_before(ip, ifp, last_block, &idx, &got))
+	if (!xfs_iext_lookup_extent_before(ip, ifp, last_block, &icur, &got))
 		*last_block = 0;
 	return 0;
 }
@@ -1397,8 +1403,8 @@ xfs_bmap_last_extent(
 	int			*is_empty)
 {
 	struct xfs_ifork	*ifp = XFS_IFORK_PTR(ip, whichfork);
+	struct xfs_iext_cursor	icur;
 	int			error;
-	int			nextents;
 
 	if (!(ifp->if_flags & XFS_IFEXTENTS)) {
 		error = xfs_iread_extents(tp, ip, whichfork);
@@ -1406,14 +1412,11 @@ xfs_bmap_last_extent(
 			return error;
 	}
 
-	nextents = xfs_iext_count(ifp);
-	if (nextents == 0) {
+	xfs_iext_last(ifp, &icur);
+	if (!xfs_iext_get_extent(ifp, &icur, rec))
 		*is_empty = 1;
-		return 0;
-	}
-
-	xfs_iext_get_extent(ifp, nextents - 1, rec);
-	*is_empty = 0;
+	else
+		*is_empty = 0;
 	return 0;
 }
 
@@ -1501,6 +1504,7 @@ xfs_bmap_one_block(
 	xfs_ifork_t	*ifp;		/* inode fork pointer */
 	int		rval;		/* return value */
 	xfs_bmbt_irec_t	s;		/* internal version of extent */
+	struct xfs_iext_cursor icur;
 
 #ifndef DEBUG
 	if (whichfork == XFS_DATA_FORK)
@@ -1512,7 +1516,8 @@ xfs_bmap_one_block(
 		return 0;
 	ifp = XFS_IFORK_PTR(ip, whichfork);
 	ASSERT(ifp->if_flags & XFS_IFEXTENTS);
-	xfs_iext_get_extent(ifp, 0, &s);
+	xfs_iext_first(ifp, &icur);
+	xfs_iext_get_extent(ifp, &icur, &s);
 	rval = s.br_startoff == 0 && s.br_blockcount == 1;
 	if (rval && whichfork == XFS_DATA_FORK)
 		ASSERT(XFS_ISIZE(ip) == ip->i_mount->m_sb.sb_blocksize);
@@ -1554,8 +1559,6 @@ xfs_bmap_add_extent_delay_real(
 	nextents = (whichfork == XFS_COW_FORK ? &bma->ip->i_cnextents :
 						&bma->ip->i_d.di_nextents);
 
-	ASSERT(bma->idx >= 0);
-	ASSERT(bma->idx <= xfs_iext_count(ifp));
 	ASSERT(!isnullstartblock(new->br_startblock));
 	ASSERT(!bma->cur ||
 	       (bma->cur->bc_private.b.flags & XFS_BTCUR_BPRV_WASDEL));
@@ -1569,7 +1572,7 @@ xfs_bmap_add_extent_delay_real(
 	/*
 	 * Set up a bunch of variables to make the tests simpler.
 	 */
-	xfs_iext_get_extent(ifp, bma->idx, &PREV);
+	xfs_iext_get_extent(ifp, &bma->icur, &PREV);
 	new_endoff = new->br_startoff + new->br_blockcount;
 	ASSERT(isnullstartblock(PREV.br_startblock));
 	ASSERT(PREV.br_startoff <= new->br_startoff);
@@ -1591,10 +1594,8 @@ xfs_bmap_add_extent_delay_real(
 	 * Check and set flags if this segment has a left neighbor.
 	 * Don't set contiguous if the combined extent would be too large.
 	 */
-	if (bma->idx > 0) {
+	if (xfs_iext_peek_prev_extent(ifp, &bma->icur, &LEFT)) {
 		state |= BMAP_LEFT_VALID;
-		xfs_iext_get_extent(ifp, bma->idx - 1, &LEFT);
-
 		if (isnullstartblock(LEFT.br_startblock))
 			state |= BMAP_LEFT_DELAY;
 	}
@@ -1611,10 +1612,8 @@ xfs_bmap_add_extent_delay_real(
 	 * Don't set contiguous if the combined extent would be too large.
 	 * Also check for all-three-contiguous being too large.
 	 */
-	if (bma->idx < xfs_iext_count(ifp) - 1) {
+	if (xfs_iext_peek_next_extent(ifp, &bma->icur, &RIGHT)) {
 		state |= BMAP_RIGHT_VALID;
-		xfs_iext_get_extent(ifp, bma->idx + 1, &RIGHT);
-
 		if (isnullstartblock(RIGHT.br_startblock))
 			state |= BMAP_RIGHT_DELAY;
 	}
@@ -1646,9 +1645,9 @@ xfs_bmap_add_extent_delay_real(
 		 */
 		LEFT.br_blockcount += PREV.br_blockcount + RIGHT.br_blockcount;
 
-		xfs_iext_remove(bma->ip, bma->idx, 2, state);
-		bma->idx--;
-		xfs_iext_update_extent(bma->ip, state, bma->idx, &LEFT);
+		xfs_iext_remove(bma->ip, &bma->icur, 2, state);
+		xfs_iext_prev(ifp, &bma->icur);
+		xfs_iext_update_extent(bma->ip, state, &bma->icur, &LEFT);
 		(*nextents)--;
 
 		if (bma->cur == NULL)
@@ -1681,9 +1680,9 @@ xfs_bmap_add_extent_delay_real(
 		old = LEFT;
 		LEFT.br_blockcount += PREV.br_blockcount;
 
-		xfs_iext_remove(bma->ip, bma->idx, 1, state);
-		bma->idx--;
-		xfs_iext_update_extent(bma->ip, state, bma->idx, &LEFT);
+		xfs_iext_remove(bma->ip, &bma->icur, 1, state);
+		xfs_iext_prev(ifp, &bma->icur);
+		xfs_iext_update_extent(bma->ip, state, &bma->icur, &LEFT);
 
 		if (bma->cur == NULL)
 			rval = XFS_ILOG_DEXT;
@@ -1707,10 +1706,10 @@ xfs_bmap_add_extent_delay_real(
 		PREV.br_startblock = new->br_startblock;
 		PREV.br_blockcount += RIGHT.br_blockcount;
 
-		bma->idx++;
-		xfs_iext_remove(bma->ip, bma->idx, 1, state);
-		bma->idx--;
-		xfs_iext_update_extent(bma->ip, state, bma->idx, &PREV);
+		xfs_iext_next(ifp, &bma->icur);
+		xfs_iext_remove(bma->ip, &bma->icur, 1, state);
+		xfs_iext_prev(ifp, &bma->icur);
+		xfs_iext_update_extent(bma->ip, state, &bma->icur, &PREV);
 
 		if (bma->cur == NULL)
 			rval = XFS_ILOG_DEXT;
@@ -1734,7 +1733,7 @@ xfs_bmap_add_extent_delay_real(
 		 */
 		PREV.br_startblock = new->br_startblock;
 		PREV.br_state = new->br_state;
-		xfs_iext_update_extent(bma->ip, state, bma->idx, &PREV);
+		xfs_iext_update_extent(bma->ip, state, &bma->icur, &PREV);
 
 		(*nextents)++;
 		if (bma->cur == NULL)
@@ -1768,9 +1767,9 @@ xfs_bmap_add_extent_delay_real(
 		PREV.br_startoff += new->br_blockcount;
 		PREV.br_startblock = nullstartblock(da_new);
 
-		xfs_iext_update_extent(bma->ip, state, bma->idx, &PREV);
-		bma->idx--;
-		xfs_iext_update_extent(bma->ip, state, bma->idx, &LEFT);
+		xfs_iext_update_extent(bma->ip, state, &bma->icur, &PREV);
+		xfs_iext_prev(ifp, &bma->icur);
+		xfs_iext_update_extent(bma->ip, state, &bma->icur, &LEFT);
 
 		if (bma->cur == NULL)
 			rval = XFS_ILOG_DEXT;
@@ -1784,7 +1783,6 @@ xfs_bmap_add_extent_delay_real(
 			if (error)
 				goto done;
 		}
-
 		break;
 
 	case BMAP_LEFT_FILLING:
@@ -1792,7 +1790,7 @@ xfs_bmap_add_extent_delay_real(
 		 * Filling in the first part of a previous delayed allocation.
 		 * The left neighbor is not contiguous.
 		 */
-		xfs_iext_update_extent(bma->ip, state, bma->idx, new);
+		xfs_iext_update_extent(bma->ip, state, &bma->icur, new);
 		(*nextents)++;
 		if (bma->cur == NULL)
 			rval = XFS_ILOG_CORE | XFS_ILOG_DEXT;
@@ -1825,7 +1823,9 @@ xfs_bmap_add_extent_delay_real(
 		PREV.br_startoff = new_endoff;
 		PREV.br_blockcount = temp;
 		PREV.br_startblock = nullstartblock(da_new);
-		xfs_iext_insert(bma->ip, bma->idx + 1, 1, &PREV, state);
+		xfs_iext_next(ifp, &bma->icur);
+		xfs_iext_insert(bma->ip, &bma->icur, 1, &PREV, state);
+		xfs_iext_prev(ifp, &bma->icur);
 		break;
 
 	case BMAP_RIGHT_FILLING | BMAP_RIGHT_CONTIG:
@@ -1858,9 +1858,9 @@ xfs_bmap_add_extent_delay_real(
 		PREV.br_blockcount = temp;
 		PREV.br_startblock = nullstartblock(da_new);
 
-		xfs_iext_update_extent(bma->ip, state, bma->idx, &PREV);
-		bma->idx++;
-		xfs_iext_update_extent(bma->ip, state, bma->idx, &RIGHT);
+		xfs_iext_update_extent(bma->ip, state, &bma->icur, &PREV);
+		xfs_iext_next(ifp, &bma->icur);
+		xfs_iext_update_extent(bma->ip, state, &bma->icur, &RIGHT);
 		break;
 
 	case BMAP_RIGHT_FILLING:
@@ -1868,7 +1868,7 @@ xfs_bmap_add_extent_delay_real(
 		 * Filling in the last part of a previous delayed allocation.
 		 * The right neighbor is not contiguous.
 		 */
-		xfs_iext_update_extent(bma->ip, state, bma->idx, new);
+		xfs_iext_update_extent(bma->ip, state, &bma->icur, new);
 		(*nextents)++;
 		if (bma->cur == NULL)
 			rval = XFS_ILOG_CORE | XFS_ILOG_DEXT;
@@ -1900,9 +1900,8 @@ xfs_bmap_add_extent_delay_real(
 
 		PREV.br_startblock = nullstartblock(da_new);
 		PREV.br_blockcount = temp;
-		xfs_iext_insert(bma->ip, bma->idx, 1, &PREV, state);
-
-		bma->idx++;
+		xfs_iext_insert(bma->ip, &bma->icur, 1, &PREV, state);
+		xfs_iext_next(ifp, &bma->icur);
 		break;
 
 	case 0:
@@ -1945,10 +1944,11 @@ xfs_bmap_add_extent_delay_real(
 		PREV.br_startblock =
 			nullstartblock(xfs_bmap_worst_indlen(bma->ip,
 					PREV.br_blockcount));
-		xfs_iext_update_extent(bma->ip, state, bma->idx, &PREV);
+		xfs_iext_update_extent(bma->ip, state, &bma->icur, &PREV);
 
 		/* insert LEFT (r[0]) and RIGHT (r[1]) at the same time */
-		xfs_iext_insert(bma->ip, bma->idx + 1, 2, &LEFT, state);
+		xfs_iext_next(ifp, &bma->icur);
+		xfs_iext_insert(bma->ip, &bma->icur, 2, &LEFT, state);
 		(*nextents)++;
 
 		if (bma->cur == NULL)
@@ -1976,7 +1976,6 @@ xfs_bmap_add_extent_delay_real(
 
 		da_new = startblockval(PREV.br_startblock) +
 			 startblockval(RIGHT.br_startblock);
-		bma->idx++;
 		break;
 
 	case BMAP_LEFT_FILLING | BMAP_LEFT_CONTIG | BMAP_RIGHT_CONTIG:
@@ -2040,7 +2039,7 @@ xfs_bmap_add_extent_unwritten_real(
 	struct xfs_trans	*tp,
 	xfs_inode_t		*ip,	/* incore inode pointer */
 	int			whichfork,
-	xfs_extnum_t		*idx,	/* extent number to update/insert */
+	struct xfs_iext_cursor	*icur,
 	xfs_btree_cur_t		**curp,	/* if *curp is null, not a btree */
 	xfs_bmbt_irec_t		*new,	/* new data to add to file extents */
 	xfs_fsblock_t		*first,	/* pointer to firstblock variable */
@@ -2064,8 +2063,6 @@ xfs_bmap_add_extent_unwritten_real(
 	cur = *curp;
 	ifp = XFS_IFORK_PTR(ip, whichfork);
 
-	ASSERT(*idx >= 0);
-	ASSERT(*idx <= xfs_iext_count(ifp));
 	ASSERT(!isnullstartblock(new->br_startblock));
 
 	XFS_STATS_INC(mp, xs_add_exlist);
@@ -2078,7 +2075,7 @@ xfs_bmap_add_extent_unwritten_real(
 	 * Set up a bunch of variables to make the tests simpler.
 	 */
 	error = 0;
-	xfs_iext_get_extent(ifp, *idx, &PREV);
+	xfs_iext_get_extent(ifp, icur, &PREV);
 	ASSERT(new->br_state != PREV.br_state);
 	new_endoff = new->br_startoff + new->br_blockcount;
 	ASSERT(PREV.br_startoff <= new->br_startoff);
@@ -2097,10 +2094,8 @@ xfs_bmap_add_extent_unwritten_real(
 	 * Check and set flags if this segment has a left neighbor.
 	 * Don't set contiguous if the combined extent would be too large.
 	 */
-	if (*idx > 0) {
+	if (xfs_iext_peek_prev_extent(ifp, icur, &LEFT)) {
 		state |= BMAP_LEFT_VALID;
-		xfs_iext_get_extent(ifp, *idx - 1, &LEFT);
-
 		if (isnullstartblock(LEFT.br_startblock))
 			state |= BMAP_LEFT_DELAY;
 	}
@@ -2117,9 +2112,8 @@ xfs_bmap_add_extent_unwritten_real(
 	 * Don't set contiguous if the combined extent would be too large.
 	 * Also check for all-three-contiguous being too large.
 	 */
-	if (*idx < xfs_iext_count(ifp) - 1) {
+	if (xfs_iext_peek_next_extent(ifp, icur, &RIGHT)) {
 		state |= BMAP_RIGHT_VALID;
-		xfs_iext_get_extent(ifp, *idx + 1, &RIGHT);
 		if (isnullstartblock(RIGHT.br_startblock))
 			state |= BMAP_RIGHT_DELAY;
 	}
@@ -2150,9 +2144,9 @@ xfs_bmap_add_extent_unwritten_real(
 		 */
 		LEFT.br_blockcount += PREV.br_blockcount + RIGHT.br_blockcount;
 
-		xfs_iext_remove(ip, *idx, 2, state);
-		--*idx;
-		xfs_iext_update_extent(ip, state, *idx, &LEFT);
+		xfs_iext_remove(ip, icur, 2, state);
+		xfs_iext_prev(ifp, icur);
+		xfs_iext_update_extent(ip, state, icur, &LEFT);
 		XFS_IFORK_NEXT_SET(ip, whichfork,
 				XFS_IFORK_NEXTENTS(ip, whichfork) - 2);
 		if (cur == NULL)
@@ -2188,9 +2182,9 @@ xfs_bmap_add_extent_unwritten_real(
 		 */
 		LEFT.br_blockcount += PREV.br_blockcount;
 
-		xfs_iext_remove(ip, *idx, 1, state);
-		--*idx;
-		xfs_iext_update_extent(ip, state, *idx, &LEFT);
+		xfs_iext_remove(ip, icur, 1, state);
+		xfs_iext_prev(ifp, icur);
+		xfs_iext_update_extent(ip, state, icur, &LEFT);
 		XFS_IFORK_NEXT_SET(ip, whichfork,
 				XFS_IFORK_NEXTENTS(ip, whichfork) - 1);
 		if (cur == NULL)
@@ -2221,10 +2215,10 @@ xfs_bmap_add_extent_unwritten_real(
 		PREV.br_blockcount += RIGHT.br_blockcount;
 		PREV.br_state = new->br_state;
 
-		++*idx;
-		xfs_iext_remove(ip, *idx, 1, state);
-		--*idx;
-		xfs_iext_update_extent(ip, state, *idx, &PREV);
+		xfs_iext_next(ifp, icur);
+		xfs_iext_remove(ip, icur, 1, state);
+		xfs_iext_prev(ifp, icur);
+		xfs_iext_update_extent(ip, state, icur, &PREV);
 
 		XFS_IFORK_NEXT_SET(ip, whichfork,
 				XFS_IFORK_NEXTENTS(ip, whichfork) - 1);
@@ -2255,7 +2249,7 @@ xfs_bmap_add_extent_unwritten_real(
 		 * the new one.
 		 */
 		PREV.br_state = new->br_state;
-		xfs_iext_update_extent(ip, state, *idx, &PREV);
+		xfs_iext_update_extent(ip, state, icur, &PREV);
 
 		if (cur == NULL)
 			rval = XFS_ILOG_DEXT;
@@ -2283,9 +2277,9 @@ xfs_bmap_add_extent_unwritten_real(
 		PREV.br_startblock += new->br_blockcount;
 		PREV.br_blockcount -= new->br_blockcount;
 
-		xfs_iext_update_extent(ip, state, *idx, &PREV);
-		--*idx;
-		xfs_iext_update_extent(ip, state, *idx, &LEFT);
+		xfs_iext_update_extent(ip, state, icur, &PREV);
+		xfs_iext_prev(ifp, icur);
+		xfs_iext_update_extent(ip, state, icur, &LEFT);
 
 		if (cur == NULL)
 			rval = XFS_ILOG_DEXT;
@@ -2317,8 +2311,8 @@ xfs_bmap_add_extent_unwritten_real(
 		PREV.br_startblock += new->br_blockcount;
 		PREV.br_blockcount -= new->br_blockcount;
 
-		xfs_iext_update_extent(ip, state, *idx, &PREV);
-		xfs_iext_insert(ip, *idx, 1, new, state);
+		xfs_iext_update_extent(ip, state, icur, &PREV);
+		xfs_iext_insert(ip, icur, 1, new, state);
 		XFS_IFORK_NEXT_SET(ip, whichfork,
 				XFS_IFORK_NEXTENTS(ip, whichfork) + 1);
 		if (cur == NULL)
@@ -2351,9 +2345,9 @@ xfs_bmap_add_extent_unwritten_real(
 		RIGHT.br_startblock = new->br_startblock;
 		RIGHT.br_blockcount += new->br_blockcount;
 
-		xfs_iext_update_extent(ip, state, *idx, &PREV);
-		++*idx;
-		xfs_iext_update_extent(ip, state, *idx, &RIGHT);
+		xfs_iext_update_extent(ip, state, icur, &PREV);
+		xfs_iext_next(ifp, icur);
+		xfs_iext_update_extent(ip, state, icur, &RIGHT);
 
 		if (cur == NULL)
 			rval = XFS_ILOG_DEXT;
@@ -2383,9 +2377,9 @@ xfs_bmap_add_extent_unwritten_real(
 		old = PREV;
 		PREV.br_blockcount -= new->br_blockcount;
 
-		xfs_iext_update_extent(ip, state, *idx, &PREV);
-		++*idx;
-		xfs_iext_insert(ip, *idx, 1, new, state);
+		xfs_iext_update_extent(ip, state, icur, &PREV);
+		xfs_iext_next(ifp, icur);
+		xfs_iext_insert(ip, icur, 1, new, state);
 
 		XFS_IFORK_NEXT_SET(ip, whichfork,
 				XFS_IFORK_NEXTENTS(ip, whichfork) + 1);
@@ -2426,9 +2420,9 @@ xfs_bmap_add_extent_unwritten_real(
 		r[1].br_startblock = new->br_startblock + new->br_blockcount;
 		r[1].br_state = PREV.br_state;
 
-		xfs_iext_update_extent(ip, state, *idx, &PREV);
-		++*idx;
-		xfs_iext_insert(ip, *idx, 2, &r[0], state);
+		xfs_iext_update_extent(ip, state, icur, &PREV);
+		xfs_iext_next(ifp, icur);
+		xfs_iext_insert(ip, icur, 2, &r[0], state);
 
 		XFS_IFORK_NEXT_SET(ip, whichfork,
 				XFS_IFORK_NEXTENTS(ip, whichfork) + 2);
@@ -2517,7 +2511,7 @@ STATIC void
 xfs_bmap_add_extent_hole_delay(
 	xfs_inode_t		*ip,	/* incore inode pointer */
 	int			whichfork,
-	xfs_extnum_t		*idx,	/* extent number to update/insert */
+	struct xfs_iext_cursor	*icur,
 	xfs_bmbt_irec_t		*new)	/* new data to add to file extents */
 {
 	xfs_ifork_t		*ifp;	/* inode fork pointer */
@@ -2534,10 +2528,8 @@ xfs_bmap_add_extent_hole_delay(
 	/*
 	 * Check and set flags if this segment has a left neighbor
 	 */
-	if (*idx > 0) {
+	if (xfs_iext_peek_prev_extent(ifp, icur, &left)) {
 		state |= BMAP_LEFT_VALID;
-		xfs_iext_get_extent(ifp, *idx - 1, &left);
-
 		if (isnullstartblock(left.br_startblock))
 			state |= BMAP_LEFT_DELAY;
 	}
@@ -2546,10 +2538,8 @@ xfs_bmap_add_extent_hole_delay(
 	 * Check and set flags if the current (right) segment exists.
 	 * If it doesn't exist, we're converting the hole at end-of-file.
 	 */
-	if (*idx < xfs_iext_count(ifp)) {
+	if (xfs_iext_get_extent(ifp, icur, &right)) {
 		state |= BMAP_RIGHT_VALID;
-		xfs_iext_get_extent(ifp, *idx, &right);
-
 		if (isnullstartblock(right.br_startblock))
 			state |= BMAP_RIGHT_DELAY;
 	}
@@ -2592,9 +2582,9 @@ xfs_bmap_add_extent_hole_delay(
 		left.br_startblock = nullstartblock(newlen);
 		left.br_blockcount = temp;
 
-		xfs_iext_remove(ip, *idx, 1, state);
-		--*idx;
-		xfs_iext_update_extent(ip, state, *idx, &left);
+		xfs_iext_remove(ip, icur, 1, state);
+		xfs_iext_prev(ifp, icur);
+		xfs_iext_update_extent(ip, state, icur, &left);
 		break;
 
 	case BMAP_LEFT_CONTIG:
@@ -2612,8 +2602,8 @@ xfs_bmap_add_extent_hole_delay(
 		left.br_blockcount = temp;
 		left.br_startblock = nullstartblock(newlen);
 
-		--*idx;
-		xfs_iext_update_extent(ip, state, *idx, &left);
+		xfs_iext_prev(ifp, icur);
+		xfs_iext_update_extent(ip, state, icur, &left);
 		break;
 
 	case BMAP_RIGHT_CONTIG:
@@ -2630,7 +2620,7 @@ xfs_bmap_add_extent_hole_delay(
 		right.br_startoff = new->br_startoff;
 		right.br_startblock = nullstartblock(newlen);
 		right.br_blockcount = temp;
-		xfs_iext_update_extent(ip, state, *idx, &right);
+		xfs_iext_update_extent(ip, state, icur, &right);
 		break;
 
 	case 0:
@@ -2640,7 +2630,7 @@ xfs_bmap_add_extent_hole_delay(
 		 * Insert a new entry.
 		 */
 		oldlen = newlen = 0;
-		xfs_iext_insert(ip, *idx, 1, new, state);
+		xfs_iext_insert(ip, icur, 1, new, state);
 		break;
 	}
 	if (oldlen != newlen) {
@@ -2661,7 +2651,7 @@ xfs_bmap_add_extent_hole_real(
 	struct xfs_trans	*tp,
 	struct xfs_inode	*ip,
 	int			whichfork,
-	xfs_extnum_t		*idx,
+	struct xfs_iext_cursor	*icur,
 	struct xfs_btree_cur	**curp,
 	struct xfs_bmbt_irec	*new,
 	xfs_fsblock_t		*first,
@@ -2679,8 +2669,6 @@ xfs_bmap_add_extent_hole_real(
 	int			state = xfs_bmap_fork_to_state(whichfork);
 	struct xfs_bmbt_irec	old;
 
-	ASSERT(*idx >= 0);
-	ASSERT(*idx <= xfs_iext_count(ifp));
 	ASSERT(!isnullstartblock(new->br_startblock));
 	ASSERT(!cur || !(cur->bc_private.b.flags & XFS_BTCUR_BPRV_WASDEL));
 
@@ -2689,9 +2677,8 @@ xfs_bmap_add_extent_hole_real(
 	/*
 	 * Check and set flags if this segment has a left neighbor.
 	 */
-	if (*idx > 0) {
+	if (xfs_iext_peek_prev_extent(ifp, icur, &left)) {
 		state |= BMAP_LEFT_VALID;
-		xfs_iext_get_extent(ifp, *idx - 1, &left);
 		if (isnullstartblock(left.br_startblock))
 			state |= BMAP_LEFT_DELAY;
 	}
@@ -2700,9 +2687,8 @@ xfs_bmap_add_extent_hole_real(
 	 * Check and set flags if this segment has a current value.
 	 * Not true if we're inserting into the "hole" at eof.
 	 */
-	if (*idx < xfs_iext_count(ifp)) {
+	if (xfs_iext_get_extent(ifp, icur, &right)) {
 		state |= BMAP_RIGHT_VALID;
-		xfs_iext_get_extent(ifp, *idx, &right);
 		if (isnullstartblock(right.br_startblock))
 			state |= BMAP_RIGHT_DELAY;
 	}
@@ -2741,9 +2727,9 @@ xfs_bmap_add_extent_hole_real(
 		 */
 		left.br_blockcount += new->br_blockcount + right.br_blockcount;
 
-		xfs_iext_remove(ip, *idx, 1, state);
-		--*idx;
-		xfs_iext_update_extent(ip, state, *idx, &left);
+		xfs_iext_remove(ip, icur, 1, state);
+		xfs_iext_prev(ifp, icur);
+		xfs_iext_update_extent(ip, state, icur, &left);
 
 		XFS_IFORK_NEXT_SET(ip, whichfork,
 			XFS_IFORK_NEXTENTS(ip, whichfork) - 1);
@@ -2778,8 +2764,8 @@ xfs_bmap_add_extent_hole_real(
 		old = left;
 		left.br_blockcount += new->br_blockcount;
 
-		--*idx;
-		xfs_iext_update_extent(ip, state, *idx, &left);
+		xfs_iext_prev(ifp, icur);
+		xfs_iext_update_extent(ip, state, icur, &left);
 
 		if (cur == NULL) {
 			rval = xfs_ilog_fext(whichfork);
@@ -2806,7 +2792,7 @@ xfs_bmap_add_extent_hole_real(
 		right.br_startoff = new->br_startoff;
 		right.br_startblock = new->br_startblock;
 		right.br_blockcount += new->br_blockcount;
-		xfs_iext_update_extent(ip, state, *idx, &right);
+		xfs_iext_update_extent(ip, state, icur, &right);
 
 		if (cur == NULL) {
 			rval = xfs_ilog_fext(whichfork);
@@ -2828,7 +2814,7 @@ xfs_bmap_add_extent_hole_real(
 		 * real allocation.
 		 * Insert a new entry.
 		 */
-		xfs_iext_insert(ip, *idx, 1, new, state);
+		xfs_iext_insert(ip, icur, 1, new, state);
 		XFS_IFORK_NEXT_SET(ip, whichfork,
 			XFS_IFORK_NEXTENTS(ip, whichfork) + 1);
 		if (cur == NULL) {
@@ -3778,7 +3764,7 @@ xfs_bmapi_read(
 	struct xfs_bmbt_irec	got;
 	xfs_fileoff_t		obno;
 	xfs_fileoff_t		end;
-	xfs_extnum_t		idx;
+	struct xfs_iext_cursor	icur;
 	int			error;
 	bool			eof = false;
 	int			n = 0;
@@ -3820,7 +3806,7 @@ xfs_bmapi_read(
 			return error;
 	}
 
-	if (!xfs_iext_lookup_extent(ip, ifp, bno, &idx, &got))
+	if (!xfs_iext_lookup_extent(ip, ifp, bno, &icur, &got))
 		eof = true;
 	end = bno + len;
 	obno = bno;
@@ -3852,7 +3838,7 @@ xfs_bmapi_read(
 			break;
 
 		/* Else go on to the next record. */
-		if (!xfs_iext_get_extent(ifp, ++idx, &got))
+		if (!xfs_iext_next_extent(ifp, &icur, &got))
 			eof = true;
 	}
 	*nmap = n;
@@ -3880,7 +3866,7 @@ xfs_bmapi_reserve_delalloc(
 	xfs_filblks_t		len,
 	xfs_filblks_t		prealloc,
 	struct xfs_bmbt_irec	*got,
-	xfs_extnum_t		*lastx,
+	struct xfs_iext_cursor	*icur,
 	int			eof)
 {
 	struct xfs_mount	*mp = ip->i_mount;
@@ -3910,7 +3896,7 @@ xfs_bmapi_reserve_delalloc(
 	if (extsz) {
 		struct xfs_bmbt_irec	prev;
 
-		if (!xfs_iext_get_extent(ifp, *lastx - 1, &prev))
+		if (!xfs_iext_peek_prev_extent(ifp, icur, &prev))
 			prev.br_startoff = NULLFILEOFF;
 
 		error = xfs_bmap_extsize_align(mp, got, &prev, extsz, rt, eof,
@@ -3959,7 +3945,7 @@ xfs_bmapi_reserve_delalloc(
 	got->br_blockcount = alen;
 	got->br_state = XFS_EXT_NORM;
 
-	xfs_bmap_add_extent_hole_delay(ip, whichfork, lastx, got);
+	xfs_bmap_add_extent_hole_delay(ip, whichfork, icur, got);
 
 	/*
 	 * Tag the inode if blocks were preallocated. Note that COW fork
@@ -4004,8 +3990,7 @@ xfs_bmapi_allocate(
 	if (bma->wasdel) {
 		bma->length = (xfs_extlen_t)bma->got.br_blockcount;
 		bma->offset = bma->got.br_startoff;
-		if (bma->idx)
-			xfs_iext_get_extent(ifp, bma->idx - 1, &bma->prev);
+		xfs_iext_peek_prev_extent(ifp, &bma->icur, &bma->prev);
 	} else {
 		bma->length = XFS_FILBLKS_MIN(bma->length, MAXEXTLEN);
 		if (!bma->eof)
@@ -4090,7 +4075,7 @@ xfs_bmapi_allocate(
 		error = xfs_bmap_add_extent_delay_real(bma, whichfork);
 	else
 		error = xfs_bmap_add_extent_hole_real(bma->tp, bma->ip,
-				whichfork, &bma->idx, &bma->cur, &bma->got,
+				whichfork, &bma->icur, &bma->cur, &bma->got,
 				bma->firstblock, bma->dfops, &bma->logflags);
 
 	bma->logflags |= tmp_logflags;
@@ -4102,7 +4087,7 @@ xfs_bmapi_allocate(
 	 * or xfs_bmap_add_extent_hole_real might have merged it into one of
 	 * the neighbouring ones.
 	 */
-	xfs_iext_get_extent(ifp, bma->idx, &bma->got);
+	xfs_iext_get_extent(ifp, &bma->icur, &bma->got);
 
 	ASSERT(bma->got.br_startoff <= bma->offset);
 	ASSERT(bma->got.br_startoff + bma->got.br_blockcount >=
@@ -4160,8 +4145,8 @@ xfs_bmapi_convert_unwritten(
 	}
 
 	error = xfs_bmap_add_extent_unwritten_real(bma->tp, bma->ip, whichfork,
-			&bma->idx, &bma->cur, mval, bma->firstblock, bma->dfops,
-			&tmp_logflags);
+			&bma->icur, &bma->cur, mval, bma->firstblock,
+			bma->dfops, &tmp_logflags);
 	/*
 	 * Log the inode core unconditionally in the unwritten extent conversion
 	 * path because the conversion might not have done so (e.g., if the
@@ -4183,7 +4168,7 @@ xfs_bmapi_convert_unwritten(
 	 * xfs_bmap_add_extent_unwritten_real might have merged it into one
 	 * of the neighbouring ones.
 	 */
-	xfs_iext_get_extent(ifp, bma->idx, &bma->got);
+	xfs_iext_get_extent(ifp, &bma->icur, &bma->got);
 
 	/*
 	 * We may have combined previously unwritten space with written space,
@@ -4302,9 +4287,9 @@ xfs_bmapi_write(
 	end = bno + len;
 	obno = bno;
 
-	if (!xfs_iext_lookup_extent(ip, ifp, bno, &bma.idx, &bma.got))
+	if (!xfs_iext_lookup_extent(ip, ifp, bno, &bma.icur, &bma.got))
 		eof = true;
-	if (!xfs_iext_get_extent(ifp, bma.idx - 1, &bma.prev))
+	if (!xfs_iext_peek_prev_extent(ifp, &bma.icur, &bma.prev))
 		bma.prev.br_startoff = NULLFILEOFF;
 	bma.tp = tp;
 	bma.ip = ip;
@@ -4409,7 +4394,7 @@ xfs_bmapi_write(
 
 		/* Else go on to the next record. */
 		bma.prev = bma.got;
-		if (!xfs_iext_get_extent(ifp, ++bma.idx, &bma.got))
+		if (!xfs_iext_next_extent(ifp, &bma.icur, &bma.got))
 			eof = true;
 	}
 	*nmap = n;
@@ -4482,7 +4467,7 @@ xfs_bmapi_remap(
 	struct xfs_btree_cur	*cur = NULL;
 	xfs_fsblock_t		firstblock = NULLFSBLOCK;
 	struct xfs_bmbt_irec	got;
-	xfs_extnum_t		idx;
+	struct xfs_iext_cursor	icur;
 	int			logflags = 0, error;
 
 	ASSERT(len > 0);
@@ -4506,7 +4491,7 @@ xfs_bmapi_remap(
 			return error;
 	}
 
-	if (xfs_iext_lookup_extent(ip, ifp, bno, &idx, &got)) {
+	if (xfs_iext_lookup_extent(ip, ifp, bno, &icur, &got)) {
 		/* make sure we only reflink into a hole. */
 		ASSERT(got.br_startoff > bno);
 		ASSERT(got.br_startoff - bno >= len);
@@ -4527,8 +4512,8 @@ xfs_bmapi_remap(
 	got.br_blockcount = len;
 	got.br_state = XFS_EXT_NORM;
 
-	error = xfs_bmap_add_extent_hole_real(tp, ip, XFS_DATA_FORK, &idx, &cur,
-			&got, &firstblock, dfops, &logflags);
+	error = xfs_bmap_add_extent_hole_real(tp, ip, XFS_DATA_FORK, &icur,
+			&cur, &got, &firstblock, dfops, &logflags);
 	if (error)
 		goto error0;
 
@@ -4644,7 +4629,7 @@ int
 xfs_bmap_del_extent_delay(
 	struct xfs_inode	*ip,
 	int			whichfork,
-	xfs_extnum_t		*idx,
+	struct xfs_iext_cursor	*icur,
 	struct xfs_bmbt_irec	*got,
 	struct xfs_bmbt_irec	*del)
 {
@@ -4666,8 +4651,6 @@ xfs_bmap_del_extent_delay(
 	da_old = startblockval(got->br_startblock);
 	da_new = 0;
 
-	ASSERT(*idx >= 0);
-	ASSERT(*idx <= xfs_iext_count(ifp));
 	ASSERT(del->br_blockcount > 0);
 	ASSERT(got->br_startoff <= del->br_startoff);
 	ASSERT(got_endoff >= del_endoff);
@@ -4701,8 +4684,8 @@ xfs_bmap_del_extent_delay(
 		/*
 		 * Matches the whole extent.  Delete the entry.
 		 */
-		xfs_iext_remove(ip, *idx, 1, state);
-		--*idx;
+		xfs_iext_remove(ip, icur, 1, state);
+		xfs_iext_prev(ifp, icur);
 		break;
 	case BMAP_LEFT_FILLING:
 		/*
@@ -4713,7 +4696,7 @@ xfs_bmap_del_extent_delay(
 		da_new = XFS_FILBLKS_MIN(xfs_bmap_worst_indlen(ip,
 				got->br_blockcount), da_old);
 		got->br_startblock = nullstartblock((int)da_new);
-		xfs_iext_update_extent(ip, state, *idx, got);
+		xfs_iext_update_extent(ip, state, icur, got);
 		break;
 	case BMAP_RIGHT_FILLING:
 		/*
@@ -4723,7 +4706,7 @@ xfs_bmap_del_extent_delay(
 		da_new = XFS_FILBLKS_MIN(xfs_bmap_worst_indlen(ip,
 				got->br_blockcount), da_old);
 		got->br_startblock = nullstartblock((int)da_new);
-		xfs_iext_update_extent(ip, state, *idx, got);
+		xfs_iext_update_extent(ip, state, icur, got);
 		break;
 	case 0:
 		/*
@@ -4751,9 +4734,9 @@ xfs_bmap_del_extent_delay(
 		new.br_state = got->br_state;
 		new.br_startblock = nullstartblock((int)new_indlen);
 
-		xfs_iext_update_extent(ip, state, *idx, got);
-		++*idx;
-		xfs_iext_insert(ip, *idx, 1, &new, state);
+		xfs_iext_update_extent(ip, state, icur, got);
+		xfs_iext_next(ifp, icur);
+		xfs_iext_insert(ip, icur, 1, &new, state);
 
 		da_new = got_indlen + new_indlen - stolen;
 		del->br_blockcount -= stolen;
@@ -4772,7 +4755,7 @@ xfs_bmap_del_extent_delay(
 void
 xfs_bmap_del_extent_cow(
 	struct xfs_inode	*ip,
-	xfs_extnum_t		*idx,
+	struct xfs_iext_cursor	*icur,
 	struct xfs_bmbt_irec	*got,
 	struct xfs_bmbt_irec	*del)
 {
@@ -4787,8 +4770,6 @@ xfs_bmap_del_extent_cow(
 	del_endoff = del->br_startoff + del->br_blockcount;
 	got_endoff = got->br_startoff + got->br_blockcount;
 
-	ASSERT(*idx >= 0);
-	ASSERT(*idx <= xfs_iext_count(ifp));
 	ASSERT(del->br_blockcount > 0);
 	ASSERT(got->br_startoff <= del->br_startoff);
 	ASSERT(got_endoff >= del_endoff);
@@ -4804,8 +4785,8 @@ xfs_bmap_del_extent_cow(
 		/*
 		 * Matches the whole extent.  Delete the entry.
 		 */
-		xfs_iext_remove(ip, *idx, 1, state);
-		--*idx;
+		xfs_iext_remove(ip, icur, 1, state);
+		xfs_iext_prev(ifp, icur);
 		break;
 	case BMAP_LEFT_FILLING:
 		/*
@@ -4814,14 +4795,14 @@ xfs_bmap_del_extent_cow(
 		got->br_startoff = del_endoff;
 		got->br_blockcount -= del->br_blockcount;
 		got->br_startblock = del->br_startblock + del->br_blockcount;
-		xfs_iext_update_extent(ip, state, *idx, got);
+		xfs_iext_update_extent(ip, state, icur, got);
 		break;
 	case BMAP_RIGHT_FILLING:
 		/*
 		 * Deleting the last part of the extent.
 		 */
 		got->br_blockcount -= del->br_blockcount;
-		xfs_iext_update_extent(ip, state, *idx, got);
+		xfs_iext_update_extent(ip, state, icur, got);
 		break;
 	case 0:
 		/*
@@ -4834,9 +4815,9 @@ xfs_bmap_del_extent_cow(
 		new.br_state = got->br_state;
 		new.br_startblock = del->br_startblock + del->br_blockcount;
 
-		xfs_iext_update_extent(ip, state, *idx, got);
-		++*idx;
-		xfs_iext_insert(ip, *idx, 1, &new, state);
+		xfs_iext_update_extent(ip, state, icur, got);
+		xfs_iext_next(ifp, icur);
+		xfs_iext_insert(ip, icur, 1, &new, state);
 		break;
 	}
 }
@@ -4849,7 +4830,7 @@ STATIC int				/* error */
 xfs_bmap_del_extent_real(
 	xfs_inode_t		*ip,	/* incore inode pointer */
 	xfs_trans_t		*tp,	/* current transaction pointer */
-	xfs_extnum_t		*idx,	/* extent number to update/delete */
+	struct xfs_iext_cursor	*icur,
 	struct xfs_defer_ops	*dfops,	/* list of extents to be freed */
 	xfs_btree_cur_t		*cur,	/* if null, not a btree */
 	xfs_bmbt_irec_t		*del,	/* data to remove from extents */
@@ -4878,9 +4859,8 @@ xfs_bmap_del_extent_real(
 	XFS_STATS_INC(mp, xs_del_exlist);
 
 	ifp = XFS_IFORK_PTR(ip, whichfork);
-	ASSERT((*idx >= 0) && (*idx < xfs_iext_count(ifp)));
 	ASSERT(del->br_blockcount > 0);
-	xfs_iext_get_extent(ifp, *idx, &got);
+	xfs_iext_get_extent(ifp, icur, &got);
 	ASSERT(got.br_startoff <= del->br_startoff);
 	del_endoff = del->br_startoff + del->br_blockcount;
 	got_endoff = got.br_startoff + got.br_blockcount;
@@ -4945,9 +4925,8 @@ xfs_bmap_del_extent_real(
 		/*
 		 * Matches the whole extent.  Delete the entry.
 		 */
-		xfs_iext_remove(ip, *idx, 1, state);
-		--*idx;
-
+		xfs_iext_remove(ip, icur, 1, state);
+		xfs_iext_prev(ifp, icur);
 		XFS_IFORK_NEXT_SET(ip, whichfork,
 			XFS_IFORK_NEXTENTS(ip, whichfork) - 1);
 		flags |= XFS_ILOG_CORE;
@@ -4966,7 +4945,7 @@ xfs_bmap_del_extent_real(
 		got.br_startoff = del_endoff;
 		got.br_startblock = del_endblock;
 		got.br_blockcount -= del->br_blockcount;
-		xfs_iext_update_extent(ip, state, *idx, &got);
+		xfs_iext_update_extent(ip, state, icur, &got);
 		if (!cur) {
 			flags |= xfs_ilog_fext(whichfork);
 			break;
@@ -4980,7 +4959,7 @@ xfs_bmap_del_extent_real(
 		 * Deleting the last part of the extent.
 		 */
 		got.br_blockcount -= del->br_blockcount;
-		xfs_iext_update_extent(ip, state, *idx, &got);
+		xfs_iext_update_extent(ip, state, icur, &got);
 		if (!cur) {
 			flags |= xfs_ilog_fext(whichfork);
 			break;
@@ -4996,7 +4975,7 @@ xfs_bmap_del_extent_real(
 		old = got;
 
 		got.br_blockcount = del->br_startoff - got.br_startoff;
-		xfs_iext_update_extent(ip, state, *idx, &got);
+		xfs_iext_update_extent(ip, state, icur, &got);
 
 		new.br_startoff = del_endoff;
 		new.br_blockcount = got_endoff - del_endoff;
@@ -5040,7 +5019,7 @@ xfs_bmap_del_extent_real(
 				 * Reset the extent record back
 				 * to the original value.
 				 */
-				xfs_iext_update_extent(ip, state, *idx, &old);
+				xfs_iext_update_extent(ip, state, icur, &old);
 				flags = 0;
 				error = -ENOSPC;
 				goto done;
@@ -5050,8 +5029,8 @@ xfs_bmap_del_extent_real(
 			flags |= xfs_ilog_fext(whichfork);
 		XFS_IFORK_NEXT_SET(ip, whichfork,
 			XFS_IFORK_NEXTENTS(ip, whichfork) + 1);
-		++*idx;
-		xfs_iext_insert(ip, *idx, 1, &new, state);
+		xfs_iext_next(ifp, icur);
+		xfs_iext_insert(ip, icur, 1, &new, state);
 		break;
 	}
 
@@ -5114,7 +5093,6 @@ __xfs_bunmapi(
 	xfs_bmbt_irec_t		got;		/* current extent record */
 	xfs_ifork_t		*ifp;		/* inode fork pointer */
 	int			isrt;		/* freeing in rt area */
-	xfs_extnum_t		lastx;		/* last extent index used */
 	int			logflags;	/* transaction logging flags */
 	xfs_extlen_t		mod;		/* rt extent offset */
 	xfs_mount_t		*mp;		/* mount structure */
@@ -5126,6 +5104,8 @@ __xfs_bunmapi(
 	xfs_fileoff_t		max_len;
 	xfs_agnumber_t		prev_agno = NULLAGNUMBER, agno;
 	xfs_fileoff_t		end;
+	struct xfs_iext_cursor	icur;
+	bool			done = false;
 
 	trace_xfs_bunmap(ip, start, len, flags, _RET_IP_);
 
@@ -5168,7 +5148,7 @@ __xfs_bunmapi(
 	isrt = (whichfork == XFS_DATA_FORK) && XFS_IS_REALTIME_INODE(ip);
 	end = start + len;
 
-	if (!xfs_iext_lookup_extent_before(ip, ifp, &end, &lastx, &got)) {
+	if (!xfs_iext_lookup_extent_before(ip, ifp, &end, &icur, &got)) {
 		*rlen = 0;
 		return 0;
 	}
@@ -5195,16 +5175,16 @@ __xfs_bunmapi(
 	}
 
 	extno = 0;
-	while (end != (xfs_fileoff_t)-1 && end >= start && lastx >= 0 &&
+	while (end != (xfs_fileoff_t)-1 && end >= start &&
 	       (nexts == 0 || extno < nexts) && max_len > 0) {
 		/*
 		 * Is the found extent after a hole in which end lives?
 		 * Just back up to the previous extent, if so.
 		 */
-		if (got.br_startoff > end) {
-			if (--lastx < 0)
-				break;
-			xfs_iext_get_extent(ifp, lastx, &got);
+		if (got.br_startoff > end &&
+		    !xfs_iext_prev_extent(ifp, &icur, &got)) {
+			done = true;
+			break;
 		}
 		/*
 		 * Is the last block of this extent before the range
@@ -5267,10 +5247,10 @@ __xfs_bunmapi(
 				ASSERT(end >= mod);
 				end -= mod > del.br_blockcount ?
 					del.br_blockcount : mod;
-				if (end < got.br_startoff) {
-					if (--lastx >= 0)
-						xfs_iext_get_extent(ifp, lastx,
-								&got);
+				if (end < got.br_startoff &&
+				    !xfs_iext_prev_extent(ifp, &icur, &got)) {
+					done = true;
+					break;
 				}
 				continue;
 			}
@@ -5291,7 +5271,7 @@ __xfs_bunmapi(
 			}
 			del.br_state = XFS_EXT_UNWRITTEN;
 			error = xfs_bmap_add_extent_unwritten_real(tp, ip,
-					whichfork, &lastx, &cur, &del,
+					whichfork, &icur, &cur, &del,
 					firstblock, dfops, &logflags);
 			if (error)
 				goto error0;
@@ -5318,8 +5298,11 @@ __xfs_bunmapi(
 				 */
 				ASSERT(end >= del.br_blockcount);
 				end -= del.br_blockcount;
-				if (got.br_startoff > end && --lastx >= 0)
-					xfs_iext_get_extent(ifp, lastx, &got);
+				if (got.br_startoff > end &&
+				    !xfs_iext_prev_extent(ifp, &icur, &got)) {
+					done = true;
+					break;
+				}
 				continue;
 			} else if (del.br_state == XFS_EXT_UNWRITTEN) {
 				struct xfs_bmbt_irec	prev;
@@ -5330,8 +5313,8 @@ __xfs_bunmapi(
 				 * Unwrite the killed part of that one and
 				 * try again.
 				 */
-				ASSERT(lastx > 0);
-				xfs_iext_get_extent(ifp, lastx - 1, &prev);
+				if (!xfs_iext_prev_extent(ifp, &icur, &prev))
+					ASSERT(0);
 				ASSERT(prev.br_state == XFS_EXT_NORM);
 				ASSERT(!isnullstartblock(prev.br_startblock));
 				ASSERT(del.br_startblock ==
@@ -5343,9 +5326,8 @@ __xfs_bunmapi(
 					prev.br_startoff = start;
 				}
 				prev.br_state = XFS_EXT_UNWRITTEN;
-				lastx--;
 				error = xfs_bmap_add_extent_unwritten_real(tp,
-						ip, whichfork, &lastx, &cur,
+						ip, whichfork, &icur, &cur,
 						&prev, firstblock, dfops,
 						&logflags);
 				if (error)
@@ -5355,7 +5337,7 @@ __xfs_bunmapi(
 				ASSERT(del.br_state == XFS_EXT_NORM);
 				del.br_state = XFS_EXT_UNWRITTEN;
 				error = xfs_bmap_add_extent_unwritten_real(tp,
-						ip, whichfork, &lastx, &cur,
+						ip, whichfork, &icur, &cur,
 						&del, firstblock, dfops,
 						&logflags);
 				if (error)
@@ -5365,10 +5347,10 @@ __xfs_bunmapi(
 		}
 
 		if (wasdel) {
-			error = xfs_bmap_del_extent_delay(ip, whichfork, &lastx,
+			error = xfs_bmap_del_extent_delay(ip, whichfork, &icur,
 					&got, &del);
 		} else {
-			error = xfs_bmap_del_extent_real(ip, tp, &lastx, dfops,
+			error = xfs_bmap_del_extent_real(ip, tp, &icur, dfops,
 					cur, &del, &tmp_logflags, whichfork,
 					flags);
 			logflags |= tmp_logflags;
@@ -5384,15 +5366,16 @@ __xfs_bunmapi(
 		 * If not done go on to the next (previous) record.
 		 */
 		if (end != (xfs_fileoff_t)-1 && end >= start) {
-			if (lastx >= 0) {
-				xfs_iext_get_extent(ifp, lastx, &got);
-				if (got.br_startoff > end && --lastx >= 0)
-					xfs_iext_get_extent(ifp, lastx, &got);
+			if (!xfs_iext_get_extent(ifp, &icur, &got) ||
+			    (got.br_startoff > end &&
+			     !xfs_iext_prev_extent(ifp, &icur, &got))) {
+				done = true;
+				break;
 			}
 			extno++;
 		}
 	}
-	if (end == (xfs_fileoff_t)-1 || end < start || lastx < 0)
+	if (done || end == (xfs_fileoff_t)-1 || end < start)
 		*rlen = 0;
 	else
 		*rlen = end - start + 1;
@@ -5513,7 +5496,7 @@ xfs_bmse_merge(
 	struct xfs_inode		*ip,
 	int				whichfork,
 	xfs_fileoff_t			shift,		/* shift fsb */
-	int				*current_ext,	/* idx of gotp */
+	struct xfs_iext_cursor		*icur,
 	struct xfs_bmbt_irec		*got,		/* extent to shift */
 	struct xfs_bmbt_irec		*left,		/* preceding extent */
 	struct xfs_btree_cur		*cur,
@@ -5568,10 +5551,10 @@ xfs_bmse_merge(
 		return error;
 
 done:
-	xfs_iext_remove(ip, *current_ext, 1, 0);
-	--*current_ext;
-	xfs_iext_update_extent(ip, xfs_bmap_fork_to_state(whichfork),
-			*current_ext, &new);
+	xfs_iext_remove(ip, icur, 1, 0);
+	xfs_iext_prev(XFS_IFORK_PTR(ip, whichfork), icur);
+	xfs_iext_update_extent(ip, xfs_bmap_fork_to_state(whichfork), icur,
+			&new);
 
 	/* update reverse mapping. rmap functions merge the rmaps for us */
 	error = xfs_rmap_unmap_extent(mp, dfops, ip, whichfork, got);
@@ -5586,7 +5569,7 @@ static int
 xfs_bmap_shift_update_extent(
 	struct xfs_inode	*ip,
 	int			whichfork,
-	xfs_extnum_t		idx,
+	struct xfs_iext_cursor	*icur,
 	struct xfs_bmbt_irec	*got,
 	struct xfs_btree_cur	*cur,
 	int			*logflags,
@@ -5614,7 +5597,8 @@ xfs_bmap_shift_update_extent(
 		*logflags |= XFS_ILOG_DEXT;
 	}
 
-	xfs_iext_update_extent(ip, xfs_bmap_fork_to_state(whichfork), idx, got);
+	xfs_iext_update_extent(ip, xfs_bmap_fork_to_state(whichfork), icur,
+			got);
 
 	/* update reverse mapping */
 	error = xfs_rmap_unmap_extent(mp, dfops, ip, whichfork, &prev);
@@ -5639,7 +5623,7 @@ xfs_bmap_collapse_extents(
 	struct xfs_ifork	*ifp = XFS_IFORK_PTR(ip, whichfork);
 	struct xfs_btree_cur	*cur = NULL;
 	struct xfs_bmbt_irec	got, prev;
-	xfs_extnum_t		current_ext;
+	struct xfs_iext_cursor	icur;
 	xfs_fileoff_t		new_startoff;
 	int			error = 0;
 	int			logflags = 0;
@@ -5670,14 +5654,14 @@ xfs_bmap_collapse_extents(
 		cur->bc_private.b.flags = 0;
 	}
 
-	if (!xfs_iext_lookup_extent(ip, ifp, *next_fsb, &current_ext, &got)) {
+	if (!xfs_iext_lookup_extent(ip, ifp, *next_fsb, &icur, &got)) {
 		*done = true;
 		goto del_cursor;
 	}
 	XFS_WANT_CORRUPTED_RETURN(mp, !isnullstartblock(got.br_startblock));
 
 	new_startoff = got.br_startoff - offset_shift_fsb;
-	if (xfs_iext_get_extent(ifp, current_ext - 1, &prev)) {
+	if (xfs_iext_peek_prev_extent(ifp, &icur, &prev)) {
 		if (new_startoff < prev.br_startoff + prev.br_blockcount) {
 			error = -EINVAL;
 			goto del_cursor;
@@ -5685,8 +5669,8 @@ xfs_bmap_collapse_extents(
 
 		if (xfs_bmse_can_merge(&prev, &got, offset_shift_fsb)) {
 			error = xfs_bmse_merge(ip, whichfork, offset_shift_fsb,
-					&current_ext, &got, &prev, cur,
-					&logflags, dfops);
+					&icur, &got, &prev, cur, &logflags,
+					dfops);
 			if (error)
 				goto del_cursor;
 			goto done;
@@ -5698,15 +5682,15 @@ xfs_bmap_collapse_extents(
 		}
 	}
 
-	error = xfs_bmap_shift_update_extent(ip, whichfork, current_ext, &got,
-			cur, &logflags, dfops, new_startoff);
+	error = xfs_bmap_shift_update_extent(ip, whichfork, &icur, &got, cur,
+			&logflags, dfops, new_startoff);
 	if (error)
 		goto del_cursor;
 
 done:
-	if (!xfs_iext_get_extent(ifp, ++current_ext, &got)) {
-		 *done = true;
-		 goto del_cursor;
+	if (!xfs_iext_next_extent(ifp, &icur, &got)) {
+		*done = true;
+		goto del_cursor;
 	}
 
 	*next_fsb = got.br_startoff;
@@ -5735,7 +5719,7 @@ xfs_bmap_insert_extents(
 	struct xfs_ifork	*ifp = XFS_IFORK_PTR(ip, whichfork);
 	struct xfs_btree_cur	*cur = NULL;
 	struct xfs_bmbt_irec	got, next;
-	xfs_extnum_t		current_ext;
+	struct xfs_iext_cursor	icur;
 	xfs_fileoff_t		new_startoff;
 	int			error = 0;
 	int			logflags = 0;
@@ -5767,15 +5751,14 @@ xfs_bmap_insert_extents(
 	}
 
 	if (*next_fsb == NULLFSBLOCK) {
-		current_ext = xfs_iext_count(ifp) - 1;
-		if (!xfs_iext_get_extent(ifp, current_ext, &got) ||
+		xfs_iext_last(ifp, &icur);
+		if (!xfs_iext_get_extent(ifp, &icur, &got) ||
 		    stop_fsb > got.br_startoff) {
 			*done = true;
 			goto del_cursor;
 		}
 	} else {
-		if (!xfs_iext_lookup_extent(ip, ifp, *next_fsb, &current_ext,
-				&got)) {
+		if (!xfs_iext_lookup_extent(ip, ifp, *next_fsb, &icur, &got)) {
 			*done = true;
 			goto del_cursor;
 		}
@@ -5788,7 +5771,7 @@ xfs_bmap_insert_extents(
 	}
 
 	new_startoff = got.br_startoff + offset_shift_fsb;
-	if (xfs_iext_get_extent(ifp, current_ext + 1, &next)) {
+	if (xfs_iext_peek_next_extent(ifp, &icur, &next)) {
 		if (new_startoff + got.br_blockcount > next.br_startoff) {
 			error = -EINVAL;
 			goto del_cursor;
@@ -5804,12 +5787,12 @@ xfs_bmap_insert_extents(
 			WARN_ON_ONCE(1);
 	}
 
-	error = xfs_bmap_shift_update_extent(ip, whichfork, current_ext, &got,
-			cur, &logflags, dfops, new_startoff);
+	error = xfs_bmap_shift_update_extent(ip, whichfork, &icur, &got, cur,
+			&logflags, dfops, new_startoff);
 	if (error)
 		goto del_cursor;
 
-	if (!xfs_iext_get_extent(ifp, --current_ext, &got) ||
+	if (!xfs_iext_prev_extent(ifp, &icur, &got) ||
 	    stop_fsb >= got.br_startoff + got.br_blockcount) {
 		*done = true;
 		goto del_cursor;
@@ -5826,10 +5809,10 @@ xfs_bmap_insert_extents(
 }
 
 /*
- * Splits an extent into two extents at split_fsb block such that it is
- * the first block of the current_ext. @current_ext is a target extent
- * to be split. @split_fsb is a block where the extents is split.
- * If split_fsb lies in a hole or the first block of extents, just return 0.
+ * Splits an extent into two extents at split_fsb block such that it is the
+ * first block of the current_ext. @ext is a target extent to be split.
+ * @split_fsb is a block where the extents is split.  If split_fsb lies in a
+ * hole or the first block of extents, just return 0.
  */
 STATIC int
 xfs_bmap_split_extent_at(
@@ -5846,7 +5829,7 @@ xfs_bmap_split_extent_at(
 	struct xfs_mount		*mp = ip->i_mount;
 	struct xfs_ifork		*ifp;
 	xfs_fsblock_t			gotblkcnt; /* new block count for got */
-	xfs_extnum_t			current_ext;
+	struct xfs_iext_cursor		icur;
 	int				error = 0;
 	int				logflags = 0;
 	int				i = 0;
@@ -5874,7 +5857,7 @@ xfs_bmap_split_extent_at(
 	/*
 	 * If there are not extents, or split_fsb lies in a hole we are done.
 	 */
-	if (!xfs_iext_lookup_extent(ip, ifp, split_fsb, &current_ext, &got) ||
+	if (!xfs_iext_lookup_extent(ip, ifp, split_fsb, &icur, &got) ||
 	    got.br_startoff >= split_fsb)
 		return 0;
 
@@ -5896,8 +5879,8 @@ xfs_bmap_split_extent_at(
 	}
 
 	got.br_blockcount = gotblkcnt;
-	xfs_iext_update_extent(ip, xfs_bmap_fork_to_state(whichfork),
-			current_ext, &got);
+	xfs_iext_update_extent(ip, xfs_bmap_fork_to_state(whichfork), &icur,
+			&got);
 
 	logflags = XFS_ILOG_CORE;
 	if (cur) {
@@ -5908,8 +5891,8 @@ xfs_bmap_split_extent_at(
 		logflags |= XFS_ILOG_DEXT;
 
 	/* Add new extent */
-	current_ext++;
-	xfs_iext_insert(ip, current_ext, 1, &new, 0);
+	xfs_iext_next(ifp, &icur);
+	xfs_iext_insert(ip, &icur, 1, &new, 0);
 	XFS_IFORK_NEXT_SET(ip, whichfork,
 			   XFS_IFORK_NEXTENTS(ip, whichfork) + 1);
 
diff --git a/fs/xfs/libxfs/xfs_bmap.h b/fs/xfs/libxfs/xfs_bmap.h
index a8777682ba57..b6a395949d0c 100644
--- a/fs/xfs/libxfs/xfs_bmap.h
+++ b/fs/xfs/libxfs/xfs_bmap.h
@@ -43,7 +43,7 @@ struct xfs_bmalloca {
 	xfs_fsblock_t		blkno;	/* starting block of new extent */
 
 	struct xfs_btree_cur	*cur;	/* btree cursor */
-	xfs_extnum_t		idx;	/* current extent index */
+	struct xfs_iext_cursor	icur;	/* incore extent cursor */
 	int			nallocs;/* number of extents alloc'd */
 	int			logflags;/* flags for transaction logging */
 
@@ -216,10 +216,11 @@ int	xfs_bunmapi(struct xfs_trans *tp, struct xfs_inode *ip,
 		xfs_extnum_t nexts, xfs_fsblock_t *firstblock,
 		struct xfs_defer_ops *dfops, int *done);
 int	xfs_bmap_del_extent_delay(struct xfs_inode *ip, int whichfork,
-		xfs_extnum_t *idx, struct xfs_bmbt_irec *got,
+		struct xfs_iext_cursor *cur, struct xfs_bmbt_irec *got,
+		struct xfs_bmbt_irec *del);
+void	xfs_bmap_del_extent_cow(struct xfs_inode *ip,
+		struct xfs_iext_cursor *cur, struct xfs_bmbt_irec *got,
 		struct xfs_bmbt_irec *del);
-void	xfs_bmap_del_extent_cow(struct xfs_inode *ip, xfs_extnum_t *idx,
-		struct xfs_bmbt_irec *got, struct xfs_bmbt_irec *del);
 uint	xfs_default_attroffset(struct xfs_inode *ip);
 int	xfs_bmap_collapse_extents(struct xfs_trans *tp, struct xfs_inode *ip,
 		xfs_fileoff_t *next_fsb, xfs_fileoff_t offset_shift_fsb,
@@ -232,7 +233,8 @@ int	xfs_bmap_insert_extents(struct xfs_trans *tp, struct xfs_inode *ip,
 int	xfs_bmap_split_extent(struct xfs_inode *ip, xfs_fileoff_t split_offset);
 int	xfs_bmapi_reserve_delalloc(struct xfs_inode *ip, int whichfork,
 		xfs_fileoff_t off, xfs_filblks_t len, xfs_filblks_t prealloc,
-		struct xfs_bmbt_irec *got, xfs_extnum_t *lastx, int eof);
+		struct xfs_bmbt_irec *got, struct xfs_iext_cursor *cur,
+		int eof);
 
 enum xfs_bmap_intent_type {
 	XFS_BMAP_MAP = 1,
diff --git a/fs/xfs/libxfs/xfs_inode_fork.c b/fs/xfs/libxfs/xfs_inode_fork.c
index 7dd77b497fc2..1e28532ff551 100644
--- a/fs/xfs/libxfs/xfs_inode_fork.c
+++ b/fs/xfs/libxfs/xfs_inode_fork.c
@@ -343,6 +343,7 @@ xfs_iformat_extents(
 	int			state = xfs_bmap_fork_to_state(whichfork);
 	int			nex = XFS_DFORK_NEXTENTS(dip, whichfork);
 	int			size = nex * sizeof(xfs_bmbt_rec_t);
+	struct xfs_iext_cursor	icur;
 	struct xfs_bmbt_rec	*dp;
 	int			i;
 
@@ -369,16 +370,21 @@ xfs_iformat_extents(
 	ifp->if_bytes = size;
 	if (size) {
 		dp = (xfs_bmbt_rec_t *) XFS_DFORK_PTR(dip, whichfork);
+
+		xfs_iext_first(ifp, &icur);
 		for (i = 0; i < nex; i++, dp++) {
 			xfs_bmbt_rec_host_t *ep = xfs_iext_get_ext(ifp, i);
+
 			if (!xfs_bmbt_validate_extent(mp, whichfork, dp)) {
 				XFS_ERROR_REPORT("xfs_iformat_extents(2)",
 						 XFS_ERRLEVEL_LOW, mp);
 				return -EFSCORRUPTED;
 			}
+
 			ep->l0 = get_unaligned_be64(&dp->l0);
 			ep->l1 = get_unaligned_be64(&dp->l1);
-			trace_xfs_read_extent(ip, i, state, _THIS_IP_);
+			trace_xfs_read_extent(ip, &icur, state, _THIS_IP_);
+			xfs_iext_next(ifp, &icur);
 		}
 	}
 	ifp->if_flags |= XFS_IFEXTENTS;
@@ -739,17 +745,18 @@ xfs_iextents_copy(
 {
 	int			state = xfs_bmap_fork_to_state(whichfork);
 	struct xfs_ifork	*ifp = XFS_IFORK_PTR(ip, whichfork);
+	struct xfs_iext_cursor	icur;
 	struct xfs_bmbt_irec	rec;
-	int			copied = 0, i = 0;
+	int			copied = 0;
 
 	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL | XFS_ILOCK_SHARED));
 	ASSERT(ifp->if_bytes > 0);
 
-	while (xfs_iext_get_extent(ifp, i++, &rec)) {
+	for_each_iext(ifp, &icur, &rec) {
 		if (isnullstartblock(rec.br_startblock))
 			continue;
 		xfs_bmbt_disk_set_all(dp, &rec);
-		trace_xfs_write_extent(ip, i, state, _RET_IP_);
+		trace_xfs_write_extent(ip, &icur, state, _RET_IP_);
 		ASSERT(xfs_bmbt_validate_extent(ip->i_mount, whichfork, dp));
 		copied += sizeof(struct xfs_bmbt_rec);
 		dp++;
@@ -894,7 +901,7 @@ xfs_iext_state_to_fork(
 void
 xfs_iext_insert(
 	xfs_inode_t	*ip,		/* incore inode pointer */
-	xfs_extnum_t	idx,		/* starting index of new items */
+	struct xfs_iext_cursor *cur,
 	xfs_extnum_t	count,		/* number of inserted items */
 	xfs_bmbt_irec_t	*new,		/* items to insert */
 	int		state)		/* type of extent conversion */
@@ -902,12 +909,12 @@ xfs_iext_insert(
 	xfs_ifork_t	*ifp = xfs_iext_state_to_fork(ip, state);
 	xfs_extnum_t	i;		/* extent record index */
 
-	trace_xfs_iext_insert(ip, idx, new, state, _RET_IP_);
+	trace_xfs_iext_insert(ip, cur->idx, new, state, _RET_IP_);
 
 	ASSERT(ifp->if_flags & XFS_IFEXTENTS);
-	xfs_iext_add(ifp, idx, count);
-	for (i = idx; i < idx + count; i++, new++)
-		xfs_bmbt_set_all(xfs_iext_get_ext(ifp, i), new);
+	xfs_iext_add(ifp, cur->idx, count);
+	for (i = 0; i < count; i++, new++)
+		xfs_bmbt_set_all(xfs_iext_get_ext(ifp, cur->idx + i), new);
 }
 
 /*
@@ -1145,7 +1152,7 @@ xfs_iext_add_indirect_multi(
 void
 xfs_iext_remove(
 	xfs_inode_t	*ip,		/* incore inode pointer */
-	xfs_extnum_t	idx,		/* index to begin removing exts */
+	struct xfs_iext_cursor *cur,
 	int		ext_diff,	/* number of extents to remove */
 	int		state)		/* type of extent conversion */
 {
@@ -1153,7 +1160,7 @@ xfs_iext_remove(
 	xfs_extnum_t	nextents;	/* number of extents in file */
 	int		new_size;	/* size of extents after removal */
 
-	trace_xfs_iext_remove(ip, idx, state, _RET_IP_);
+	trace_xfs_iext_remove(ip, cur, state, _RET_IP_);
 
 	ASSERT(ext_diff > 0);
 	nextents = xfs_iext_count(ifp);
@@ -1162,11 +1169,11 @@ xfs_iext_remove(
 	if (new_size == 0) {
 		xfs_iext_destroy(ifp);
 	} else if (ifp->if_flags & XFS_IFEXTIREC) {
-		xfs_iext_remove_indirect(ifp, idx, ext_diff);
+		xfs_iext_remove_indirect(ifp, cur->idx, ext_diff);
 	} else if (ifp->if_real_bytes) {
-		xfs_iext_remove_direct(ifp, idx, ext_diff);
+		xfs_iext_remove_direct(ifp, cur->idx, ext_diff);
 	} else {
-		xfs_iext_remove_inline(ifp, idx, ext_diff);
+		xfs_iext_remove_inline(ifp, cur->idx, ext_diff);
 	}
 	ifp->if_bytes = new_size;
 }
@@ -1913,26 +1920,26 @@ xfs_ifork_init_cow(
  * Lookup the extent covering bno.
  *
  * If there is an extent covering bno return the extent index, and store the
- * expanded extent structure in *gotp, and the extent index in *idx.
+ * expanded extent structure in *gotp, and the extent cursor in *cur.
  * If there is no extent covering bno, but there is an extent after it (e.g.
- * it lies in a hole) return that extent in *gotp and its index in *idx
+ * it lies in a hole) return that extent in *gotp and its cursor in *cur
  * instead.
- * If bno is beyond the last extent return false, and return the index after
- * the last valid index in *idxp.
+ * If bno is beyond the last extent return false, and return an invalid
+ * cursor value.
  */
 bool
 xfs_iext_lookup_extent(
 	struct xfs_inode	*ip,
 	struct xfs_ifork	*ifp,
 	xfs_fileoff_t		bno,
-	xfs_extnum_t		*idxp,
+	struct xfs_iext_cursor	*cur,
 	struct xfs_bmbt_irec	*gotp)
 {
 	struct xfs_bmbt_rec_host *ep;
 
 	XFS_STATS_INC(ip->i_mount, xs_look_exlist);
 
-	ep = xfs_iext_bno_to_ext(ifp, bno, idxp);
+	ep = xfs_iext_bno_to_ext(ifp, bno, &cur->idx);
 	if (!ep)
 		return false;
 	xfs_bmbt_get_all(ep, gotp);
@@ -1948,31 +1955,31 @@ xfs_iext_lookup_extent_before(
 	struct xfs_inode	*ip,
 	struct xfs_ifork	*ifp,
 	xfs_fileoff_t		*end,
-	xfs_extnum_t		*idxp,
+	struct xfs_iext_cursor	*cur,
 	struct xfs_bmbt_irec	*gotp)
 {
-	if (xfs_iext_lookup_extent(ip, ifp, *end - 1, idxp, gotp) &&
+	if (xfs_iext_lookup_extent(ip, ifp, *end - 1, cur, gotp) &&
 	    gotp->br_startoff <= *end - 1)
 		return true;
-	if (!xfs_iext_get_extent(ifp, --*idxp, gotp))
+	if (!xfs_iext_prev_extent(ifp, cur, gotp))
 		return false;
 	*end = gotp->br_startoff + gotp->br_blockcount;
 	return true;
 }
 
 /*
- * Return true if there is an extent at index idx, and return the expanded
- * extent structure at idx in that case.  Else return false.
+ * Return true if the cursor points at an extent and return the extent structure
+ * in gotp.  Else return false.
  */
 bool
 xfs_iext_get_extent(
 	struct xfs_ifork	*ifp,
-	xfs_extnum_t		idx,
+	struct xfs_iext_cursor	*cur,
 	struct xfs_bmbt_irec	*gotp)
 {
-	if (idx < 0 || idx >= xfs_iext_count(ifp))
+	if (cur->idx < 0 || cur->idx >= xfs_iext_count(ifp))
 		return false;
-	xfs_bmbt_get_all(xfs_iext_get_ext(ifp, idx), gotp);
+	xfs_bmbt_get_all(xfs_iext_get_ext(ifp, cur->idx), gotp);
 	return true;
 }
 
@@ -1980,15 +1987,15 @@ void
 xfs_iext_update_extent(
 	struct xfs_inode	*ip,
 	int			state,
-	xfs_extnum_t		idx,
+	struct xfs_iext_cursor	*cur,
 	struct xfs_bmbt_irec	*gotp)
 {
 	struct xfs_ifork	*ifp = xfs_iext_state_to_fork(ip, state);
 
-	ASSERT(idx >= 0);
-	ASSERT(idx < xfs_iext_count(ifp));
+	ASSERT(cur->idx >= 0);
+	ASSERT(cur->idx < xfs_iext_count(ifp));
 
-	trace_xfs_bmap_pre_update(ip, idx, state, _RET_IP_);
-	xfs_bmbt_set_all(xfs_iext_get_ext(ifp, idx), gotp);
-	trace_xfs_bmap_post_update(ip, idx, state, _RET_IP_);
+	trace_xfs_bmap_pre_update(ip, cur, state, _RET_IP_);
+	xfs_bmbt_set_all(xfs_iext_get_ext(ifp, cur->idx), gotp);
+	trace_xfs_bmap_post_update(ip, cur, state, _RET_IP_);
 }
diff --git a/fs/xfs/libxfs/xfs_inode_fork.h b/fs/xfs/libxfs/xfs_inode_fork.h
index 113fd42ec36d..7065544f446a 100644
--- a/fs/xfs/libxfs/xfs_inode_fork.h
+++ b/fs/xfs/libxfs/xfs_inode_fork.h
@@ -151,12 +151,13 @@ void		xfs_init_local_fork(struct xfs_inode *, int, const void *, int);
 struct xfs_bmbt_rec_host *
 		xfs_iext_get_ext(struct xfs_ifork *, xfs_extnum_t);
 xfs_extnum_t	xfs_iext_count(struct xfs_ifork *);
-void		xfs_iext_insert(struct xfs_inode *, xfs_extnum_t, xfs_extnum_t,
-				struct xfs_bmbt_irec *, int);
+void		xfs_iext_insert(struct xfs_inode *, struct xfs_iext_cursor *cur,
+			xfs_extnum_t, struct xfs_bmbt_irec *, int);
 void		xfs_iext_add(struct xfs_ifork *, xfs_extnum_t, int);
 void		xfs_iext_add_indirect_multi(struct xfs_ifork *, int,
 					    xfs_extnum_t, int);
-void		xfs_iext_remove(struct xfs_inode *, xfs_extnum_t, int, int);
+void		xfs_iext_remove(struct xfs_inode *, struct xfs_iext_cursor *,
+			int, int);
 void		xfs_iext_remove_inline(struct xfs_ifork *, xfs_extnum_t, int);
 void		xfs_iext_remove_direct(struct xfs_ifork *, xfs_extnum_t, int);
 void		xfs_iext_remove_indirect(struct xfs_ifork *, xfs_extnum_t, int);
@@ -182,15 +183,85 @@ void		xfs_iext_irec_update_extoffs(struct xfs_ifork *, int, int);
 
 bool		xfs_iext_lookup_extent(struct xfs_inode *ip,
 			struct xfs_ifork *ifp, xfs_fileoff_t bno,
-			xfs_extnum_t *idxp, struct xfs_bmbt_irec *gotp);
+			struct xfs_iext_cursor *cur,
+			struct xfs_bmbt_irec *gotp);
 bool		xfs_iext_lookup_extent_before(struct xfs_inode *ip,
 			struct xfs_ifork *ifp, xfs_fileoff_t *end,
-			xfs_extnum_t *idxp, struct xfs_bmbt_irec *gotp);
-
-bool		xfs_iext_get_extent(struct xfs_ifork *ifp, xfs_extnum_t idx,
+			struct xfs_iext_cursor *cur,
+			struct xfs_bmbt_irec *gotp);
+bool		xfs_iext_get_extent(struct xfs_ifork *ifp,
+			struct xfs_iext_cursor *cur,
 			struct xfs_bmbt_irec *gotp);
 void		xfs_iext_update_extent(struct xfs_inode *ip, int state,
-			xfs_extnum_t idx, struct xfs_bmbt_irec *gotp);
+			struct xfs_iext_cursor *cur,
+			struct xfs_bmbt_irec *gotp);
+
+static inline void xfs_iext_first(struct xfs_ifork *ifp,
+		struct xfs_iext_cursor *cur)
+{
+	cur->idx = 0;
+}
+
+static inline void xfs_iext_last(struct xfs_ifork *ifp,
+		struct xfs_iext_cursor *cur)
+{
+	cur->idx = xfs_iext_count(ifp) - 1;
+}
+
+static inline void xfs_iext_next(struct xfs_ifork *ifp,
+		struct xfs_iext_cursor *cur)
+{
+	cur->idx++;
+}
+
+static inline void xfs_iext_prev(struct xfs_ifork *ifp,
+		struct xfs_iext_cursor *cur)
+{
+	cur->idx--;
+}
+
+static inline bool xfs_iext_next_extent(struct xfs_ifork *ifp,
+		struct xfs_iext_cursor *cur, struct xfs_bmbt_irec *gotp)
+{
+	xfs_iext_next(ifp, cur);
+	return xfs_iext_get_extent(ifp, cur, gotp);
+}
+
+static inline bool xfs_iext_prev_extent(struct xfs_ifork *ifp,
+		struct xfs_iext_cursor *cur, struct xfs_bmbt_irec *gotp)
+{
+	xfs_iext_prev(ifp, cur);
+	return xfs_iext_get_extent(ifp, cur, gotp);
+}
+
+/*
+ * Return the extent after cur in gotp without updating the cursor.
+ */
+static inline bool xfs_iext_peek_next_extent(struct xfs_ifork *ifp,
+		struct xfs_iext_cursor *cur, struct xfs_bmbt_irec *gotp)
+{
+	struct xfs_iext_cursor ncur = *cur;
+
+	xfs_iext_next(ifp, &ncur);
+	return xfs_iext_get_extent(ifp, &ncur, gotp);
+}
+
+/*
+ * Return the extent before cur in gotp without updating the cursor.
+ */
+static inline bool xfs_iext_peek_prev_extent(struct xfs_ifork *ifp,
+		struct xfs_iext_cursor *cur, struct xfs_bmbt_irec *gotp)
+{
+	struct xfs_iext_cursor ncur = *cur;
+
+	xfs_iext_prev(ifp, &ncur);
+	return xfs_iext_get_extent(ifp, &ncur, gotp);
+}
+
+#define for_each_iext(ifp, ext, got)			\
+	for (xfs_iext_first((ifp), (ext));		\
+	     xfs_iext_get_extent((ifp), (ext), (got));	\
+	     xfs_iext_next((ifp), (ext)))
 
 extern struct kmem_zone	*xfs_ifork_zone;
 
diff --git a/fs/xfs/libxfs/xfs_types.h b/fs/xfs/libxfs/xfs_types.h
index f04dbfb2f50d..5da6382bdaf1 100644
--- a/fs/xfs/libxfs/xfs_types.h
+++ b/fs/xfs/libxfs/xfs_types.h
@@ -142,5 +142,8 @@ typedef uint32_t	xfs_dqid_t;
 #define	XFS_NBWORD	(1 << XFS_NBWORDLOG)
 #define	XFS_WORDMASK	((1 << XFS_WORDLOG) - 1)
 
+struct xfs_iext_cursor {
+	xfs_extnum_t		idx;
+};
 
 #endif	/* __XFS_TYPES_H__ */
diff --git a/fs/xfs/scrub/bmap.c b/fs/xfs/scrub/bmap.c
index 3c17b182616f..be0bc11b6594 100644
--- a/fs/xfs/scrub/bmap.c
+++ b/fs/xfs/scrub/bmap.c
@@ -237,7 +237,7 @@ xfs_scrub_bmap(
 	struct xfs_inode		*ip = sc->ip;
 	struct xfs_ifork		*ifp;
 	xfs_fileoff_t			endoff;
-	xfs_extnum_t			idx;
+	struct xfs_iext_cursor		icur;
 	bool				found;
 	int				error = 0;
 
@@ -317,9 +317,9 @@ xfs_scrub_bmap(
 	/* Scrub extent records. */
 	info.lastoff = 0;
 	ifp = XFS_IFORK_PTR(ip, whichfork);
-	for (found = xfs_iext_lookup_extent(ip, ifp, 0, &idx, &irec);
+	for (found = xfs_iext_lookup_extent(ip, ifp, 0, &icur, &irec);
 	     found != 0;
-	     found = xfs_iext_get_extent(ifp, ++idx, &irec)) {
+	     found = xfs_iext_next_extent(ifp, &icur, &irec)) {
 		if (xfs_scrub_should_terminate(sc, &error))
 			break;
 		if (isnullstartblock(irec.br_startblock))
diff --git a/fs/xfs/scrub/dir.c b/fs/xfs/scrub/dir.c
index c61362faed4a..73ac795aa6a5 100644
--- a/fs/xfs/scrub/dir.c
+++ b/fs/xfs/scrub/dir.c
@@ -614,7 +614,7 @@ xfs_scrub_directory_blocks(
 	xfs_fileoff_t			leaf_lblk;
 	xfs_fileoff_t			free_lblk;
 	xfs_fileoff_t			lblk;
-	xfs_extnum_t			idx;
+	struct xfs_iext_cursor		icur;
 	xfs_dablk_t			dabno;
 	bool				found;
 	int				is_block = 0;
@@ -639,7 +639,7 @@ xfs_scrub_directory_blocks(
 		goto out;
 
 	/* Iterate all the data extents in the directory... */
-	found = xfs_iext_lookup_extent(sc->ip, ifp, lblk, &idx, &got);
+	found = xfs_iext_lookup_extent(sc->ip, ifp, lblk, &icur, &got);
 	while (found) {
 		/* Block directories only have a single block at offset 0. */
 		if (is_block &&
@@ -676,17 +676,17 @@ xfs_scrub_directory_blocks(
 		}
 		dabno = got.br_startoff + got.br_blockcount;
 		lblk = roundup(dabno, args.geo->fsbcount);
-		found = xfs_iext_lookup_extent(sc->ip, ifp, lblk, &idx, &got);
+		found = xfs_iext_lookup_extent(sc->ip, ifp, lblk, &icur, &got);
 	}
 
 	if (sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
 		goto out;
 
 	/* Look for a leaf1 block, which has free info. */
-	if (xfs_iext_lookup_extent(sc->ip, ifp, leaf_lblk, &idx, &got) &&
+	if (xfs_iext_lookup_extent(sc->ip, ifp, leaf_lblk, &icur, &got) &&
 	    got.br_startoff == leaf_lblk &&
 	    got.br_blockcount == args.geo->fsbcount &&
-	    !xfs_iext_get_extent(ifp, ++idx, &got)) {
+	    !xfs_iext_next_extent(ifp, &icur, &got)) {
 		if (is_block) {
 			xfs_scrub_fblock_set_corrupt(sc, XFS_DATA_FORK, lblk);
 			goto out;
@@ -702,7 +702,7 @@ xfs_scrub_directory_blocks(
 
 	/* Scan for free blocks */
 	lblk = free_lblk;
-	found = xfs_iext_lookup_extent(sc->ip, ifp, lblk, &idx, &got);
+	found = xfs_iext_lookup_extent(sc->ip, ifp, lblk, &icur, &got);
 	while (found) {
 		/*
 		 * Dirs can't have blocks mapped above 2^32.
@@ -740,7 +740,7 @@ xfs_scrub_directory_blocks(
 		}
 		dabno = got.br_startoff + got.br_blockcount;
 		lblk = roundup(dabno, args.geo->fsbcount);
-		found = xfs_iext_lookup_extent(sc->ip, ifp, lblk, &idx, &got);
+		found = xfs_iext_lookup_extent(sc->ip, ifp, lblk, &icur, &got);
 	}
 out:
 	return error;
diff --git a/fs/xfs/xfs_bmap_util.c b/fs/xfs/xfs_bmap_util.c
index 170b74c7f2d5..515eec004971 100644
--- a/fs/xfs/xfs_bmap_util.c
+++ b/fs/xfs/xfs_bmap_util.c
@@ -229,15 +229,17 @@ xfs_bmap_count_leaves(
 	struct xfs_ifork	*ifp,
 	xfs_filblks_t		*count)
 {
+	struct xfs_iext_cursor	icur;
 	struct xfs_bmbt_irec	got;
-	xfs_extnum_t		numrecs = 0, i = 0;
+	xfs_extnum_t		numrecs = 0;
 
-	while (xfs_iext_get_extent(ifp, i++, &got)) {
+	for_each_iext(ifp, &icur, &got) {
 		if (!isnullstartblock(got.br_startblock)) {
 			*count += got.br_blockcount;
 			numrecs++;
 		}
 	}
+
 	return numrecs;
 }
 
@@ -525,7 +527,7 @@ xfs_getbmap(
 	struct xfs_ifork	*ifp;
 	struct xfs_bmbt_irec	got, rec;
 	xfs_filblks_t		len;
-	xfs_extnum_t		idx;
+	struct xfs_iext_cursor	icur;
 
 	if (bmv->bmv_iflags & ~BMV_IF_VALID)
 		return -EINVAL;
@@ -629,7 +631,7 @@ xfs_getbmap(
 			goto out_unlock_ilock;
 	}
 
-	if (!xfs_iext_lookup_extent(ip, ifp, bno, &idx, &got)) {
+	if (!xfs_iext_lookup_extent(ip, ifp, bno, &icur, &got)) {
 		/*
 		 * Report a whole-file hole if the delalloc flag is set to
 		 * stay compatible with the old implementation.
@@ -668,7 +670,7 @@ xfs_getbmap(
 				goto out_unlock_ilock;
 		} while (xfs_getbmap_next_rec(&rec, bno));
 
-		if (!xfs_iext_get_extent(ifp, ++idx, &got)) {
+		if (!xfs_iext_next_extent(ifp, &icur, &got)) {
 			xfs_fileoff_t	end = XFS_B_TO_FSB(mp, XFS_ISIZE(ip));
 
 			out[bmv->bmv_entries - 1].bmv_oflags |= BMV_OF_LAST;
diff --git a/fs/xfs/xfs_dir2_readdir.c b/fs/xfs/xfs_dir2_readdir.c
index 238e3650a9d2..0c58918bc0ad 100644
--- a/fs/xfs/xfs_dir2_readdir.c
+++ b/fs/xfs/xfs_dir2_readdir.c
@@ -266,7 +266,7 @@ xfs_dir2_leaf_readbuf(
 	xfs_dablk_t		next_ra;
 	xfs_dablk_t		map_off;
 	xfs_dablk_t		last_da;
-	xfs_extnum_t		idx;
+	struct xfs_iext_cursor	icur;
 	int			ra_want;
 	int			error = 0;
 
@@ -283,7 +283,7 @@ xfs_dir2_leaf_readbuf(
 	 */
 	last_da = xfs_dir2_byte_to_da(geo, XFS_DIR2_LEAF_OFFSET);
 	map_off = xfs_dir2_db_to_da(geo, xfs_dir2_byte_to_db(geo, *cur_off));
-	if (!xfs_iext_lookup_extent(dp, ifp, map_off, &idx, &map))
+	if (!xfs_iext_lookup_extent(dp, ifp, map_off, &icur, &map))
 		goto out;
 	if (map.br_startoff >= last_da)
 		goto out;
@@ -311,7 +311,7 @@ xfs_dir2_leaf_readbuf(
 	if (next_ra >= last_da)
 		goto out_no_ra;
 	if (map.br_blockcount < geo->fsbcount &&
-	    !xfs_iext_get_extent(ifp, ++idx, &map))
+	    !xfs_iext_next_extent(ifp, &icur, &map))
 		goto out_no_ra;
 	if (map.br_startoff >= last_da)
 		goto out_no_ra;
@@ -334,7 +334,7 @@ xfs_dir2_leaf_readbuf(
 			ra_want -= geo->fsbcount;
 			next_ra += geo->fsbcount;
 		}
-		if (!xfs_iext_get_extent(ifp, ++idx, &map)) {
+		if (!xfs_iext_next_extent(ifp, &icur, &map)) {
 			*ra_blk = last_da;
 			break;
 		}
diff --git a/fs/xfs/xfs_dquot.c b/fs/xfs/xfs_dquot.c
index cd82429d8df7..8338b894d54f 100644
--- a/fs/xfs/xfs_dquot.c
+++ b/fs/xfs/xfs_dquot.c
@@ -703,7 +703,7 @@ xfs_dq_get_next_id(
 	xfs_dqid_t		next_id = *id + 1; /* simple advance */
 	uint			lock_flags;
 	struct xfs_bmbt_irec	got;
-	xfs_extnum_t		idx;
+	struct xfs_iext_cursor	cur;
 	xfs_fsblock_t		start;
 	int			error = 0;
 
@@ -727,7 +727,7 @@ xfs_dq_get_next_id(
 			return error;
 	}
 
-	if (xfs_iext_lookup_extent(quotip, &quotip->i_df, start, &idx, &got)) {
+	if (xfs_iext_lookup_extent(quotip, &quotip->i_df, start, &cur, &got)) {
 		/* contiguous chunk, bump startoff for the id calculation */
 		if (got.br_startoff < start)
 			got.br_startoff = start;
diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c
index da0abc8a0725..ad48e2f24699 100644
--- a/fs/xfs/xfs_iomap.c
+++ b/fs/xfs/xfs_iomap.c
@@ -390,7 +390,7 @@ xfs_iomap_prealloc_size(
 	struct xfs_inode	*ip,
 	loff_t			offset,
 	loff_t			count,
-	xfs_extnum_t		idx)
+	struct xfs_iext_cursor	*icur)
 {
 	struct xfs_mount	*mp = ip->i_mount;
 	struct xfs_ifork	*ifp = XFS_IFORK_PTR(ip, XFS_DATA_FORK);
@@ -415,7 +415,7 @@ xfs_iomap_prealloc_size(
 	 */
 	if ((mp->m_flags & XFS_MOUNT_DFLT_IOSIZE) ||
 	    XFS_ISIZE(ip) < XFS_FSB_TO_B(mp, mp->m_dalign) ||
-	    !xfs_iext_get_extent(ifp, idx - 1, &prev) ||
+	    !xfs_iext_peek_prev_extent(ifp, icur, &prev) ||
 	    prev.br_startoff + prev.br_blockcount < offset_fsb)
 		return mp->m_writeio_blocks;
 
@@ -533,7 +533,7 @@ xfs_file_iomap_begin_delay(
 	xfs_fileoff_t		end_fsb;
 	int			error = 0, eof = 0;
 	struct xfs_bmbt_irec	got;
-	xfs_extnum_t		idx;
+	struct xfs_iext_cursor	icur;
 	xfs_fsblock_t		prealloc_blocks = 0;
 
 	ASSERT(!XFS_IS_REALTIME_INODE(ip));
@@ -558,7 +558,7 @@ xfs_file_iomap_begin_delay(
 			goto out_unlock;
 	}
 
-	eof = !xfs_iext_lookup_extent(ip, ifp, offset_fsb, &idx, &got);
+	eof = !xfs_iext_lookup_extent(ip, ifp, offset_fsb, &icur, &got);
 	if (!eof && got.br_startoff <= offset_fsb) {
 		if (xfs_is_reflink_inode(ip)) {
 			bool		shared;
@@ -592,7 +592,8 @@ xfs_file_iomap_begin_delay(
 	end_fsb = min(XFS_B_TO_FSB(mp, offset + count), maxbytes_fsb);
 
 	if (eof) {
-		prealloc_blocks = xfs_iomap_prealloc_size(ip, offset, count, idx);
+		prealloc_blocks = xfs_iomap_prealloc_size(ip, offset, count,
+				&icur);
 		if (prealloc_blocks) {
 			xfs_extlen_t	align;
 			xfs_off_t	end_offset;
@@ -614,7 +615,8 @@ xfs_file_iomap_begin_delay(
 
 retry:
 	error = xfs_bmapi_reserve_delalloc(ip, XFS_DATA_FORK, offset_fsb,
-			end_fsb - offset_fsb, prealloc_blocks, &got, &idx, eof);
+			end_fsb - offset_fsb, prealloc_blocks, &got, &icur,
+			eof);
 	switch (error) {
 	case 0:
 		break;
diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c
index 1205747e1409..d86c4378facf 100644
--- a/fs/xfs/xfs_reflink.c
+++ b/fs/xfs/xfs_reflink.c
@@ -273,7 +273,7 @@ xfs_reflink_reserve_cow(
 	struct xfs_bmbt_irec	got;
 	int			error = 0;
 	bool			eof = false, trimmed;
-	xfs_extnum_t		idx;
+	struct xfs_iext_cursor	icur;
 
 	/*
 	 * Search the COW fork extent list first.  This serves two purposes:
@@ -284,7 +284,7 @@ xfs_reflink_reserve_cow(
 	 * tree.
 	 */
 
-	if (!xfs_iext_lookup_extent(ip, ifp, imap->br_startoff, &idx, &got))
+	if (!xfs_iext_lookup_extent(ip, ifp, imap->br_startoff, &icur, &got))
 		eof = true;
 	if (!eof && got.br_startoff <= imap->br_startoff) {
 		trace_xfs_reflink_cow_found(ip, imap);
@@ -312,7 +312,7 @@ xfs_reflink_reserve_cow(
 		return error;
 
 	error = xfs_bmapi_reserve_delalloc(ip, XFS_COW_FORK, imap->br_startoff,
-			imap->br_blockcount, 0, &got, &idx, eof);
+			imap->br_blockcount, 0, &got, &icur, eof);
 	if (error == -ENOSPC || error == -EDQUOT)
 		trace_xfs_reflink_cow_enospc(ip, imap);
 	if (error)
@@ -359,16 +359,16 @@ xfs_reflink_convert_cow(
 	struct xfs_ifork	*ifp = XFS_IFORK_PTR(ip, XFS_COW_FORK);
 	xfs_fileoff_t		offset_fsb = XFS_B_TO_FSBT(mp, offset);
 	xfs_fileoff_t		end_fsb = XFS_B_TO_FSB(mp, offset + count);
-	xfs_extnum_t		idx;
+	struct xfs_iext_cursor	icur;
 	bool			found;
 	int			error = 0;
 
 	xfs_ilock(ip, XFS_ILOCK_EXCL);
 
 	/* Convert all the extents to real from unwritten. */
-	for (found = xfs_iext_lookup_extent(ip, ifp, offset_fsb, &idx, &got);
+	for (found = xfs_iext_lookup_extent(ip, ifp, offset_fsb, &icur, &got);
 	     found && got.br_startoff < end_fsb;
-	     found = xfs_iext_get_extent(ifp, ++idx, &got)) {
+	     found = xfs_iext_next_extent(ifp, &icur, &got)) {
 		error = xfs_reflink_convert_cow_extent(ip, &got, offset_fsb,
 				end_fsb - offset_fsb, &dfops);
 		if (error)
@@ -399,7 +399,7 @@ xfs_reflink_allocate_cow(
 	bool			trimmed;
 	xfs_filblks_t		resaligned;
 	xfs_extlen_t		resblks = 0;
-	xfs_extnum_t		idx;
+	struct xfs_iext_cursor	icur;
 
 retry:
 	ASSERT(xfs_is_reflink_inode(ip));
@@ -409,7 +409,7 @@ xfs_reflink_allocate_cow(
 	 * Even if the extent is not shared we might have a preallocation for
 	 * it in the COW fork.  If so use it.
 	 */
-	if (xfs_iext_lookup_extent(ip, ip->i_cowfp, offset_fsb, &idx, &got) &&
+	if (xfs_iext_lookup_extent(ip, ip->i_cowfp, offset_fsb, &icur, &got) &&
 	    got.br_startoff <= offset_fsb) {
 		*shared = true;
 
@@ -496,13 +496,13 @@ xfs_reflink_find_cow_mapping(
 	struct xfs_ifork		*ifp = XFS_IFORK_PTR(ip, XFS_COW_FORK);
 	xfs_fileoff_t			offset_fsb;
 	struct xfs_bmbt_irec		got;
-	xfs_extnum_t			idx;
+	struct xfs_iext_cursor		icur;
 
 	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL | XFS_ILOCK_SHARED));
 	ASSERT(xfs_is_reflink_inode(ip));
 
 	offset_fsb = XFS_B_TO_FSBT(ip->i_mount, offset);
-	if (!xfs_iext_lookup_extent(ip, ifp, offset_fsb, &idx, &got))
+	if (!xfs_iext_lookup_extent(ip, ifp, offset_fsb, &icur, &got))
 		return false;
 	if (got.br_startoff > offset_fsb)
 		return false;
@@ -524,18 +524,18 @@ xfs_reflink_trim_irec_to_next_cow(
 {
 	struct xfs_ifork		*ifp = XFS_IFORK_PTR(ip, XFS_COW_FORK);
 	struct xfs_bmbt_irec		got;
-	xfs_extnum_t			idx;
+	struct xfs_iext_cursor		icur;
 
 	if (!xfs_is_reflink_inode(ip))
 		return;
 
 	/* Find the extent in the CoW fork. */
-	if (!xfs_iext_lookup_extent(ip, ifp, offset_fsb, &idx, &got))
+	if (!xfs_iext_lookup_extent(ip, ifp, offset_fsb, &icur, &got))
 		return;
 
 	/* This is the extent before; try sliding up one. */
 	if (got.br_startoff < offset_fsb) {
-		if (!xfs_iext_get_extent(ifp, idx + 1, &got))
+		if (!xfs_iext_next_extent(ifp, &icur, &got))
 			return;
 	}
 
@@ -562,14 +562,14 @@ xfs_reflink_cancel_cow_blocks(
 {
 	struct xfs_ifork		*ifp = XFS_IFORK_PTR(ip, XFS_COW_FORK);
 	struct xfs_bmbt_irec		got, del;
-	xfs_extnum_t			idx;
+	struct xfs_iext_cursor		icur;
 	xfs_fsblock_t			firstfsb;
 	struct xfs_defer_ops		dfops;
 	int				error = 0;
 
 	if (!xfs_is_reflink_inode(ip))
 		return 0;
-	if (!xfs_iext_lookup_extent(ip, ifp, offset_fsb, &idx, &got))
+	if (!xfs_iext_lookup_extent(ip, ifp, offset_fsb, &icur, &got))
 		return 0;
 
 	while (got.br_startoff < end_fsb) {
@@ -579,7 +579,7 @@ xfs_reflink_cancel_cow_blocks(
 
 		if (isnullstartblock(del.br_startblock)) {
 			error = xfs_bmap_del_extent_delay(ip, XFS_COW_FORK,
-					&idx, &got, &del);
+					&icur, &got, &del);
 			if (error)
 				break;
 		} else if (del.br_state == XFS_EXT_UNWRITTEN || cancel_real) {
@@ -610,10 +610,10 @@ xfs_reflink_cancel_cow_blocks(
 			}
 
 			/* Remove the mapping from the CoW fork. */
-			xfs_bmap_del_extent_cow(ip, &idx, &got, &del);
+			xfs_bmap_del_extent_cow(ip, &icur, &got, &del);
 		}
 
-		if (!xfs_iext_get_extent(ifp, ++idx, &got))
+		if (!xfs_iext_next_extent(ifp, &icur, &got))
 			break;
 	}
 
@@ -698,7 +698,7 @@ xfs_reflink_end_cow(
 	int				error;
 	unsigned int			resblks;
 	xfs_filblks_t			rlen;
-	xfs_extnum_t			idx;
+	struct xfs_iext_cursor		icur;
 
 	trace_xfs_reflink_end_cow(ip, offset, count);
 
@@ -738,7 +738,7 @@ xfs_reflink_end_cow(
 	 * left by the time I/O completes for the loser of the race.  In that
 	 * case we are done.
 	 */
-	if (!xfs_iext_lookup_extent_before(ip, ifp, &end_fsb, &idx, &got))
+	if (!xfs_iext_lookup_extent_before(ip, ifp, &end_fsb, &icur, &got))
 		goto out_cancel;
 
 	/* Walk backwards until we're out of the I/O range... */
@@ -746,9 +746,9 @@ xfs_reflink_end_cow(
 		del = got;
 		xfs_trim_extent(&del, offset_fsb, end_fsb - offset_fsb);
 
-		/* Extent delete may have bumped idx forward */
+		/* Extent delete may have bumped ext forward */
 		if (!del.br_blockcount) {
-			idx--;
+			xfs_iext_prev(ifp, &icur);
 			goto next_extent;
 		}
 
@@ -760,7 +760,7 @@ xfs_reflink_end_cow(
 		 * allocated but have not yet been involved in a write.
 		 */
 		if (got.br_state == XFS_EXT_UNWRITTEN) {
-			idx--;
+			xfs_iext_prev(ifp, &icur);
 			goto next_extent;
 		}
 
@@ -791,14 +791,14 @@ xfs_reflink_end_cow(
 			goto out_defer;
 
 		/* Remove the mapping from the CoW fork. */
-		xfs_bmap_del_extent_cow(ip, &idx, &got, &del);
+		xfs_bmap_del_extent_cow(ip, &icur, &got, &del);
 
 		xfs_defer_ijoin(&dfops, ip);
 		error = xfs_defer_finish(&tp, &dfops);
 		if (error)
 			goto out_defer;
 next_extent:
-		if (!xfs_iext_get_extent(ifp, idx, &got))
+		if (!xfs_iext_get_extent(ifp, &icur, &got))
 			break;
 	}
 
@@ -1428,7 +1428,7 @@ xfs_reflink_inode_has_shared_extents(
 	xfs_extlen_t			aglen;
 	xfs_agblock_t			rbno;
 	xfs_extlen_t			rlen;
-	xfs_extnum_t			idx;
+	struct xfs_iext_cursor		icur;
 	bool				found;
 	int				error;
 
@@ -1440,7 +1440,7 @@ xfs_reflink_inode_has_shared_extents(
 	}
 
 	*has_shared = false;
-	found = xfs_iext_lookup_extent(ip, ifp, 0, &idx, &got);
+	found = xfs_iext_lookup_extent(ip, ifp, 0, &icur, &got);
 	while (found) {
 		if (isnullstartblock(got.br_startblock) ||
 		    got.br_state != XFS_EXT_NORM)
@@ -1459,7 +1459,7 @@ xfs_reflink_inode_has_shared_extents(
 			return 0;
 		}
 next:
-		found = xfs_iext_get_extent(ifp, ++idx, &got);
+		found = xfs_iext_next_extent(ifp, &icur, &got);
 	}
 
 	return 0;
diff --git a/fs/xfs/xfs_trace.h b/fs/xfs/xfs_trace.h
index 665ef6cca90c..667bfce802cd 100644
--- a/fs/xfs/xfs_trace.h
+++ b/fs/xfs/xfs_trace.h
@@ -258,9 +258,9 @@ TRACE_EVENT(xfs_iext_insert,
 );
 
 DECLARE_EVENT_CLASS(xfs_bmap_class,
-	TP_PROTO(struct xfs_inode *ip, xfs_extnum_t idx, int state,
+	TP_PROTO(struct xfs_inode *ip, struct xfs_iext_cursor *cur, int state,
 		 unsigned long caller_ip),
-	TP_ARGS(ip, idx, state, caller_ip),
+	TP_ARGS(ip, cur, state, caller_ip),
 	TP_STRUCT__entry(
 		__field(dev_t, dev)
 		__field(xfs_ino_t, ino)
@@ -277,10 +277,10 @@ DECLARE_EVENT_CLASS(xfs_bmap_class,
 		struct xfs_bmbt_irec	r;
 
 		ifp = xfs_iext_state_to_fork(ip, state);
-		xfs_iext_get_extent(ifp, idx, &r);
+		xfs_iext_get_extent(ifp, cur, &r);
 		__entry->dev = VFS_I(ip)->i_sb->s_dev;
 		__entry->ino = ip->i_ino;
-		__entry->idx = idx;
+		__entry->idx = cur->idx;
 		__entry->startoff = r.br_startoff;
 		__entry->startblock = r.br_startblock;
 		__entry->blockcount = r.br_blockcount;
@@ -303,9 +303,9 @@ DECLARE_EVENT_CLASS(xfs_bmap_class,
 
 #define DEFINE_BMAP_EVENT(name) \
 DEFINE_EVENT(xfs_bmap_class, name, \
-	TP_PROTO(struct xfs_inode *ip, xfs_extnum_t idx, int state, \
+	TP_PROTO(struct xfs_inode *ip, struct xfs_iext_cursor *cur, int state, \
 		 unsigned long caller_ip), \
-	TP_ARGS(ip, idx, state, caller_ip))
+	TP_ARGS(ip, cur, state, caller_ip))
 DEFINE_BMAP_EVENT(xfs_iext_remove);
 DEFINE_BMAP_EVENT(xfs_bmap_pre_update);
 DEFINE_BMAP_EVENT(xfs_bmap_post_update);
-- 
2.14.2

Re: [PATCH 12/21] xfs: introduce the xfs_iext_cursor abstraction

[Brian Foster]

On Fri, Nov 03, 2017 at 05:45:30PM +0300, Christoph Hellwig wrote:
> Add a new xfs_iext_cursor structure to hide the direct extent map
> index manipulations. In addition to the existing lookup/get/insert/
> remove and update routines new primitives to get the first and last
> extent cursor, as well as moving up and down by one extent are
> provided.  Also new are convenience to increment/decrement the
> cursor and retreive the new extent, as well as to peek into the
> previous/next extent without updating the cursor and last but not
> least a macro to iterate over all extents in a fork.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---

Reviewed-by: Brian Foster <bfoster@redhat.com>

>  fs/xfs/libxfs/xfs_bmap.c       | 441 ++++++++++++++++++++---------------------
>  fs/xfs/libxfs/xfs_bmap.h       |  12 +-
>  fs/xfs/libxfs/xfs_inode_fork.c |  75 +++----
>  fs/xfs/libxfs/xfs_inode_fork.h |  87 +++++++-
>  fs/xfs/libxfs/xfs_types.h      |   3 +
>  fs/xfs/scrub/bmap.c            |   6 +-
>  fs/xfs/scrub/dir.c             |  14 +-
>  fs/xfs/xfs_bmap_util.c         |  12 +-
>  fs/xfs/xfs_dir2_readdir.c      |   8 +-
>  fs/xfs/xfs_dquot.c             |   4 +-
>  fs/xfs/xfs_iomap.c             |  14 +-
>  fs/xfs/xfs_reflink.c           |  56 +++---
>  fs/xfs/xfs_trace.h             |  12 +-
>  13 files changed, 407 insertions(+), 337 deletions(-)
> 
> diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
> index f4d0639dc4ae..b08c4863c2af 100644
> --- a/fs/xfs/libxfs/xfs_bmap.c
> +++ b/fs/xfs/libxfs/xfs_bmap.c
> @@ -672,8 +672,9 @@ xfs_bmap_extents_to_btree(
>  	xfs_bmbt_key_t		*kp;		/* root block key pointer */
>  	xfs_mount_t		*mp;		/* mount structure */
>  	xfs_bmbt_ptr_t		*pp;		/* root block address pointer */
> +	struct xfs_iext_cursor	icur;
>  	struct xfs_bmbt_irec	rec;
> -	xfs_extnum_t		i = 0, cnt = 0;
> +	xfs_extnum_t		cnt = 0;
>  
>  	mp = ip->i_mount;
>  	ASSERT(whichfork != XFS_COW_FORK);
> @@ -752,7 +753,7 @@ xfs_bmap_extents_to_btree(
>  				XFS_BTNUM_BMAP, 0, 0, ip->i_ino,
>  				XFS_BTREE_LONG_PTRS);
>  
> -	while (xfs_iext_get_extent(ifp, i++, &rec)) {
> +	for_each_iext(ifp, &icur, &rec) {
>  		if (isnullstartblock(rec.br_startblock))
>  			continue;
>  		arp = XFS_BMBT_REC_ADDR(mp, ablock, 1 + cnt);
> @@ -828,6 +829,7 @@ xfs_bmap_local_to_extents(
>  	xfs_alloc_arg_t	args;		/* allocation arguments */
>  	xfs_buf_t	*bp;		/* buffer for extent block */
>  	struct xfs_bmbt_irec rec;
> +	struct xfs_iext_cursor icur;
>  
>  	/*
>  	 * We don't want to deal with the case of keeping inode data inline yet.
> @@ -894,7 +896,8 @@ xfs_bmap_local_to_extents(
>  	rec.br_startblock = args.fsbno;
>  	rec.br_blockcount = 1;
>  	rec.br_state = XFS_EXT_NORM;
> -	xfs_iext_insert(ip, 0, 1, &rec, 0);
> +	xfs_iext_first(ifp, &icur);
> +	xfs_iext_insert(ip, &icur, 1, &rec, 0);
>  
>  	XFS_IFORK_NEXT_SET(ip, whichfork, 1);
>  	ip->i_d.di_nblocks = 1;
> @@ -1174,6 +1177,7 @@ xfs_iread_extents(
>  	struct xfs_ifork	*ifp = XFS_IFORK_PTR(ip, whichfork);
>  	xfs_extnum_t		nextents = XFS_IFORK_NEXTENTS(ip, whichfork);
>  	struct xfs_btree_block	*block = ifp->if_broot;
> +	struct xfs_iext_cursor	icur;
>  	xfs_fsblock_t		bno;
>  	struct xfs_buf		*bp;
>  	xfs_extnum_t		i, j;
> @@ -1223,6 +1227,7 @@ xfs_iread_extents(
>  	 * Here with bp and block set to the leftmost leaf node in the tree.
>  	 */
>  	i = 0;
> +	xfs_iext_first(ifp, &icur);
>  
>  	/*
>  	 * Loop over all leaf nodes.  Copy information to the extent records.
> @@ -1264,7 +1269,8 @@ xfs_iread_extents(
>  			}
>  			trp->l0 = be64_to_cpu(frp->l0);
>  			trp->l1 = be64_to_cpu(frp->l1);
> -			trace_xfs_read_extent(ip, i, state, _THIS_IP_);
> +			trace_xfs_read_extent(ip, &icur, state, _THIS_IP_);
> +			xfs_iext_next(ifp, &icur);
>  		}
>  		xfs_trans_brelse(tp, bp);
>  		bno = nextbno;
> @@ -1312,7 +1318,7 @@ xfs_bmap_first_unused(
>  {
>  	struct xfs_ifork	*ifp = XFS_IFORK_PTR(ip, whichfork);
>  	struct xfs_bmbt_irec	got;
> -	xfs_extnum_t		idx = 0;
> +	struct xfs_iext_cursor	icur;
>  	xfs_fileoff_t		lastaddr = 0;
>  	xfs_fileoff_t		lowest, max;
>  	int			error;
> @@ -1333,7 +1339,7 @@ xfs_bmap_first_unused(
>  	}
>  
>  	lowest = max = *first_unused;
> -	while (xfs_iext_get_extent(ifp, idx++, &got)) {
> +	for_each_iext(ifp, &icur, &got) {
>  		/*
>  		 * See if the hole before this extent will work.
>  		 */
> @@ -1363,7 +1369,7 @@ xfs_bmap_last_before(
>  {
>  	struct xfs_ifork	*ifp = XFS_IFORK_PTR(ip, whichfork);
>  	struct xfs_bmbt_irec	got;
> -	xfs_extnum_t		idx;
> +	struct xfs_iext_cursor	icur;
>  	int			error;
>  
>  	switch (XFS_IFORK_FORMAT(ip, whichfork)) {
> @@ -1383,7 +1389,7 @@ xfs_bmap_last_before(
>  			return error;
>  	}
>  
> -	if (!xfs_iext_lookup_extent_before(ip, ifp, last_block, &idx, &got))
> +	if (!xfs_iext_lookup_extent_before(ip, ifp, last_block, &icur, &got))
>  		*last_block = 0;
>  	return 0;
>  }
> @@ -1397,8 +1403,8 @@ xfs_bmap_last_extent(
>  	int			*is_empty)
>  {
>  	struct xfs_ifork	*ifp = XFS_IFORK_PTR(ip, whichfork);
> +	struct xfs_iext_cursor	icur;
>  	int			error;
> -	int			nextents;
>  
>  	if (!(ifp->if_flags & XFS_IFEXTENTS)) {
>  		error = xfs_iread_extents(tp, ip, whichfork);
> @@ -1406,14 +1412,11 @@ xfs_bmap_last_extent(
>  			return error;
>  	}
>  
> -	nextents = xfs_iext_count(ifp);
> -	if (nextents == 0) {
> +	xfs_iext_last(ifp, &icur);
> +	if (!xfs_iext_get_extent(ifp, &icur, rec))
>  		*is_empty = 1;
> -		return 0;
> -	}
> -
> -	xfs_iext_get_extent(ifp, nextents - 1, rec);
> -	*is_empty = 0;
> +	else
> +		*is_empty = 0;
>  	return 0;
>  }
>  
> @@ -1501,6 +1504,7 @@ xfs_bmap_one_block(
>  	xfs_ifork_t	*ifp;		/* inode fork pointer */
>  	int		rval;		/* return value */
>  	xfs_bmbt_irec_t	s;		/* internal version of extent */
> +	struct xfs_iext_cursor icur;
>  
>  #ifndef DEBUG
>  	if (whichfork == XFS_DATA_FORK)
> @@ -1512,7 +1516,8 @@ xfs_bmap_one_block(
>  		return 0;
>  	ifp = XFS_IFORK_PTR(ip, whichfork);
>  	ASSERT(ifp->if_flags & XFS_IFEXTENTS);
> -	xfs_iext_get_extent(ifp, 0, &s);
> +	xfs_iext_first(ifp, &icur);
> +	xfs_iext_get_extent(ifp, &icur, &s);
>  	rval = s.br_startoff == 0 && s.br_blockcount == 1;
>  	if (rval && whichfork == XFS_DATA_FORK)
>  		ASSERT(XFS_ISIZE(ip) == ip->i_mount->m_sb.sb_blocksize);
> @@ -1554,8 +1559,6 @@ xfs_bmap_add_extent_delay_real(
>  	nextents = (whichfork == XFS_COW_FORK ? &bma->ip->i_cnextents :
>  						&bma->ip->i_d.di_nextents);
>  
> -	ASSERT(bma->idx >= 0);
> -	ASSERT(bma->idx <= xfs_iext_count(ifp));
>  	ASSERT(!isnullstartblock(new->br_startblock));
>  	ASSERT(!bma->cur ||
>  	       (bma->cur->bc_private.b.flags & XFS_BTCUR_BPRV_WASDEL));
> @@ -1569,7 +1572,7 @@ xfs_bmap_add_extent_delay_real(
>  	/*
>  	 * Set up a bunch of variables to make the tests simpler.
>  	 */
> -	xfs_iext_get_extent(ifp, bma->idx, &PREV);
> +	xfs_iext_get_extent(ifp, &bma->icur, &PREV);
>  	new_endoff = new->br_startoff + new->br_blockcount;
>  	ASSERT(isnullstartblock(PREV.br_startblock));
>  	ASSERT(PREV.br_startoff <= new->br_startoff);
> @@ -1591,10 +1594,8 @@ xfs_bmap_add_extent_delay_real(
>  	 * Check and set flags if this segment has a left neighbor.
>  	 * Don't set contiguous if the combined extent would be too large.
>  	 */
> -	if (bma->idx > 0) {
> +	if (xfs_iext_peek_prev_extent(ifp, &bma->icur, &LEFT)) {
>  		state |= BMAP_LEFT_VALID;
> -		xfs_iext_get_extent(ifp, bma->idx - 1, &LEFT);
> -
>  		if (isnullstartblock(LEFT.br_startblock))
>  			state |= BMAP_LEFT_DELAY;
>  	}
> @@ -1611,10 +1612,8 @@ xfs_bmap_add_extent_delay_real(
>  	 * Don't set contiguous if the combined extent would be too large.
>  	 * Also check for all-three-contiguous being too large.
>  	 */
> -	if (bma->idx < xfs_iext_count(ifp) - 1) {
> +	if (xfs_iext_peek_next_extent(ifp, &bma->icur, &RIGHT)) {
>  		state |= BMAP_RIGHT_VALID;
> -		xfs_iext_get_extent(ifp, bma->idx + 1, &RIGHT);
> -
>  		if (isnullstartblock(RIGHT.br_startblock))
>  			state |= BMAP_RIGHT_DELAY;
>  	}
> @@ -1646,9 +1645,9 @@ xfs_bmap_add_extent_delay_real(
>  		 */
>  		LEFT.br_blockcount += PREV.br_blockcount + RIGHT.br_blockcount;
>  
> -		xfs_iext_remove(bma->ip, bma->idx, 2, state);
> -		bma->idx--;
> -		xfs_iext_update_extent(bma->ip, state, bma->idx, &LEFT);
> +		xfs_iext_remove(bma->ip, &bma->icur, 2, state);
> +		xfs_iext_prev(ifp, &bma->icur);
> +		xfs_iext_update_extent(bma->ip, state, &bma->icur, &LEFT);
>  		(*nextents)--;
>  
>  		if (bma->cur == NULL)
> @@ -1681,9 +1680,9 @@ xfs_bmap_add_extent_delay_real(
>  		old = LEFT;
>  		LEFT.br_blockcount += PREV.br_blockcount;
>  
> -		xfs_iext_remove(bma->ip, bma->idx, 1, state);
> -		bma->idx--;
> -		xfs_iext_update_extent(bma->ip, state, bma->idx, &LEFT);
> +		xfs_iext_remove(bma->ip, &bma->icur, 1, state);
> +		xfs_iext_prev(ifp, &bma->icur);
> +		xfs_iext_update_extent(bma->ip, state, &bma->icur, &LEFT);
>  
>  		if (bma->cur == NULL)
>  			rval = XFS_ILOG_DEXT;
> @@ -1707,10 +1706,10 @@ xfs_bmap_add_extent_delay_real(
>  		PREV.br_startblock = new->br_startblock;
>  		PREV.br_blockcount += RIGHT.br_blockcount;
>  
> -		bma->idx++;
> -		xfs_iext_remove(bma->ip, bma->idx, 1, state);
> -		bma->idx--;
> -		xfs_iext_update_extent(bma->ip, state, bma->idx, &PREV);
> +		xfs_iext_next(ifp, &bma->icur);
> +		xfs_iext_remove(bma->ip, &bma->icur, 1, state);
> +		xfs_iext_prev(ifp, &bma->icur);
> +		xfs_iext_update_extent(bma->ip, state, &bma->icur, &PREV);
>  
>  		if (bma->cur == NULL)
>  			rval = XFS_ILOG_DEXT;
> @@ -1734,7 +1733,7 @@ xfs_bmap_add_extent_delay_real(
>  		 */
>  		PREV.br_startblock = new->br_startblock;
>  		PREV.br_state = new->br_state;
> -		xfs_iext_update_extent(bma->ip, state, bma->idx, &PREV);
> +		xfs_iext_update_extent(bma->ip, state, &bma->icur, &PREV);
>  
>  		(*nextents)++;
>  		if (bma->cur == NULL)
> @@ -1768,9 +1767,9 @@ xfs_bmap_add_extent_delay_real(
>  		PREV.br_startoff += new->br_blockcount;
>  		PREV.br_startblock = nullstartblock(da_new);
>  
> -		xfs_iext_update_extent(bma->ip, state, bma->idx, &PREV);
> -		bma->idx--;
> -		xfs_iext_update_extent(bma->ip, state, bma->idx, &LEFT);
> +		xfs_iext_update_extent(bma->ip, state, &bma->icur, &PREV);
> +		xfs_iext_prev(ifp, &bma->icur);
> +		xfs_iext_update_extent(bma->ip, state, &bma->icur, &LEFT);
>  
>  		if (bma->cur == NULL)
>  			rval = XFS_ILOG_DEXT;
> @@ -1784,7 +1783,6 @@ xfs_bmap_add_extent_delay_real(
>  			if (error)
>  				goto done;
>  		}
> -
>  		break;
>  
>  	case BMAP_LEFT_FILLING:
> @@ -1792,7 +1790,7 @@ xfs_bmap_add_extent_delay_real(
>  		 * Filling in the first part of a previous delayed allocation.
>  		 * The left neighbor is not contiguous.
>  		 */
> -		xfs_iext_update_extent(bma->ip, state, bma->idx, new);
> +		xfs_iext_update_extent(bma->ip, state, &bma->icur, new);
>  		(*nextents)++;
>  		if (bma->cur == NULL)
>  			rval = XFS_ILOG_CORE | XFS_ILOG_DEXT;
> @@ -1825,7 +1823,9 @@ xfs_bmap_add_extent_delay_real(
>  		PREV.br_startoff = new_endoff;
>  		PREV.br_blockcount = temp;
>  		PREV.br_startblock = nullstartblock(da_new);
> -		xfs_iext_insert(bma->ip, bma->idx + 1, 1, &PREV, state);
> +		xfs_iext_next(ifp, &bma->icur);
> +		xfs_iext_insert(bma->ip, &bma->icur, 1, &PREV, state);
> +		xfs_iext_prev(ifp, &bma->icur);
>  		break;
>  
>  	case BMAP_RIGHT_FILLING | BMAP_RIGHT_CONTIG:
> @@ -1858,9 +1858,9 @@ xfs_bmap_add_extent_delay_real(
>  		PREV.br_blockcount = temp;
>  		PREV.br_startblock = nullstartblock(da_new);
>  
> -		xfs_iext_update_extent(bma->ip, state, bma->idx, &PREV);
> -		bma->idx++;
> -		xfs_iext_update_extent(bma->ip, state, bma->idx, &RIGHT);
> +		xfs_iext_update_extent(bma->ip, state, &bma->icur, &PREV);
> +		xfs_iext_next(ifp, &bma->icur);
> +		xfs_iext_update_extent(bma->ip, state, &bma->icur, &RIGHT);
>  		break;
>  
>  	case BMAP_RIGHT_FILLING:
> @@ -1868,7 +1868,7 @@ xfs_bmap_add_extent_delay_real(
>  		 * Filling in the last part of a previous delayed allocation.
>  		 * The right neighbor is not contiguous.
>  		 */
> -		xfs_iext_update_extent(bma->ip, state, bma->idx, new);
> +		xfs_iext_update_extent(bma->ip, state, &bma->icur, new);
>  		(*nextents)++;
>  		if (bma->cur == NULL)
>  			rval = XFS_ILOG_CORE | XFS_ILOG_DEXT;
> @@ -1900,9 +1900,8 @@ xfs_bmap_add_extent_delay_real(
>  
>  		PREV.br_startblock = nullstartblock(da_new);
>  		PREV.br_blockcount = temp;
> -		xfs_iext_insert(bma->ip, bma->idx, 1, &PREV, state);
> -
> -		bma->idx++;
> +		xfs_iext_insert(bma->ip, &bma->icur, 1, &PREV, state);
> +		xfs_iext_next(ifp, &bma->icur);
>  		break;
>  
>  	case 0:
> @@ -1945,10 +1944,11 @@ xfs_bmap_add_extent_delay_real(
>  		PREV.br_startblock =
>  			nullstartblock(xfs_bmap_worst_indlen(bma->ip,
>  					PREV.br_blockcount));
> -		xfs_iext_update_extent(bma->ip, state, bma->idx, &PREV);
> +		xfs_iext_update_extent(bma->ip, state, &bma->icur, &PREV);
>  
>  		/* insert LEFT (r[0]) and RIGHT (r[1]) at the same time */
> -		xfs_iext_insert(bma->ip, bma->idx + 1, 2, &LEFT, state);
> +		xfs_iext_next(ifp, &bma->icur);
> +		xfs_iext_insert(bma->ip, &bma->icur, 2, &LEFT, state);
>  		(*nextents)++;
>  
>  		if (bma->cur == NULL)
> @@ -1976,7 +1976,6 @@ xfs_bmap_add_extent_delay_real(
>  
>  		da_new = startblockval(PREV.br_startblock) +
>  			 startblockval(RIGHT.br_startblock);
> -		bma->idx++;
>  		break;
>  
>  	case BMAP_LEFT_FILLING | BMAP_LEFT_CONTIG | BMAP_RIGHT_CONTIG:
> @@ -2040,7 +2039,7 @@ xfs_bmap_add_extent_unwritten_real(
>  	struct xfs_trans	*tp,
>  	xfs_inode_t		*ip,	/* incore inode pointer */
>  	int			whichfork,
> -	xfs_extnum_t		*idx,	/* extent number to update/insert */
> +	struct xfs_iext_cursor	*icur,
>  	xfs_btree_cur_t		**curp,	/* if *curp is null, not a btree */
>  	xfs_bmbt_irec_t		*new,	/* new data to add to file extents */
>  	xfs_fsblock_t		*first,	/* pointer to firstblock variable */
> @@ -2064,8 +2063,6 @@ xfs_bmap_add_extent_unwritten_real(
>  	cur = *curp;
>  	ifp = XFS_IFORK_PTR(ip, whichfork);
>  
> -	ASSERT(*idx >= 0);
> -	ASSERT(*idx <= xfs_iext_count(ifp));
>  	ASSERT(!isnullstartblock(new->br_startblock));
>  
>  	XFS_STATS_INC(mp, xs_add_exlist);
> @@ -2078,7 +2075,7 @@ xfs_bmap_add_extent_unwritten_real(
>  	 * Set up a bunch of variables to make the tests simpler.
>  	 */
>  	error = 0;
> -	xfs_iext_get_extent(ifp, *idx, &PREV);
> +	xfs_iext_get_extent(ifp, icur, &PREV);
>  	ASSERT(new->br_state != PREV.br_state);
>  	new_endoff = new->br_startoff + new->br_blockcount;
>  	ASSERT(PREV.br_startoff <= new->br_startoff);
> @@ -2097,10 +2094,8 @@ xfs_bmap_add_extent_unwritten_real(
>  	 * Check and set flags if this segment has a left neighbor.
>  	 * Don't set contiguous if the combined extent would be too large.
>  	 */
> -	if (*idx > 0) {
> +	if (xfs_iext_peek_prev_extent(ifp, icur, &LEFT)) {
>  		state |= BMAP_LEFT_VALID;
> -		xfs_iext_get_extent(ifp, *idx - 1, &LEFT);
> -
>  		if (isnullstartblock(LEFT.br_startblock))
>  			state |= BMAP_LEFT_DELAY;
>  	}
> @@ -2117,9 +2112,8 @@ xfs_bmap_add_extent_unwritten_real(
>  	 * Don't set contiguous if the combined extent would be too large.
>  	 * Also check for all-three-contiguous being too large.
>  	 */
> -	if (*idx < xfs_iext_count(ifp) - 1) {
> +	if (xfs_iext_peek_next_extent(ifp, icur, &RIGHT)) {
>  		state |= BMAP_RIGHT_VALID;
> -		xfs_iext_get_extent(ifp, *idx + 1, &RIGHT);
>  		if (isnullstartblock(RIGHT.br_startblock))
>  			state |= BMAP_RIGHT_DELAY;
>  	}
> @@ -2150,9 +2144,9 @@ xfs_bmap_add_extent_unwritten_real(
>  		 */
>  		LEFT.br_blockcount += PREV.br_blockcount + RIGHT.br_blockcount;
>  
> -		xfs_iext_remove(ip, *idx, 2, state);
> -		--*idx;
> -		xfs_iext_update_extent(ip, state, *idx, &LEFT);
> +		xfs_iext_remove(ip, icur, 2, state);
> +		xfs_iext_prev(ifp, icur);
> +		xfs_iext_update_extent(ip, state, icur, &LEFT);
>  		XFS_IFORK_NEXT_SET(ip, whichfork,
>  				XFS_IFORK_NEXTENTS(ip, whichfork) - 2);
>  		if (cur == NULL)
> @@ -2188,9 +2182,9 @@ xfs_bmap_add_extent_unwritten_real(
>  		 */
>  		LEFT.br_blockcount += PREV.br_blockcount;
>  
> -		xfs_iext_remove(ip, *idx, 1, state);
> -		--*idx;
> -		xfs_iext_update_extent(ip, state, *idx, &LEFT);
> +		xfs_iext_remove(ip, icur, 1, state);
> +		xfs_iext_prev(ifp, icur);
> +		xfs_iext_update_extent(ip, state, icur, &LEFT);
>  		XFS_IFORK_NEXT_SET(ip, whichfork,
>  				XFS_IFORK_NEXTENTS(ip, whichfork) - 1);
>  		if (cur == NULL)
> @@ -2221,10 +2215,10 @@ xfs_bmap_add_extent_unwritten_real(
>  		PREV.br_blockcount += RIGHT.br_blockcount;
>  		PREV.br_state = new->br_state;
>  
> -		++*idx;
> -		xfs_iext_remove(ip, *idx, 1, state);
> -		--*idx;
> -		xfs_iext_update_extent(ip, state, *idx, &PREV);
> +		xfs_iext_next(ifp, icur);
> +		xfs_iext_remove(ip, icur, 1, state);
> +		xfs_iext_prev(ifp, icur);
> +		xfs_iext_update_extent(ip, state, icur, &PREV);
>  
>  		XFS_IFORK_NEXT_SET(ip, whichfork,
>  				XFS_IFORK_NEXTENTS(ip, whichfork) - 1);
> @@ -2255,7 +2249,7 @@ xfs_bmap_add_extent_unwritten_real(
>  		 * the new one.
>  		 */
>  		PREV.br_state = new->br_state;
> -		xfs_iext_update_extent(ip, state, *idx, &PREV);
> +		xfs_iext_update_extent(ip, state, icur, &PREV);
>  
>  		if (cur == NULL)
>  			rval = XFS_ILOG_DEXT;
> @@ -2283,9 +2277,9 @@ xfs_bmap_add_extent_unwritten_real(
>  		PREV.br_startblock += new->br_blockcount;
>  		PREV.br_blockcount -= new->br_blockcount;
>  
> -		xfs_iext_update_extent(ip, state, *idx, &PREV);
> -		--*idx;
> -		xfs_iext_update_extent(ip, state, *idx, &LEFT);
> +		xfs_iext_update_extent(ip, state, icur, &PREV);
> +		xfs_iext_prev(ifp, icur);
> +		xfs_iext_update_extent(ip, state, icur, &LEFT);
>  
>  		if (cur == NULL)
>  			rval = XFS_ILOG_DEXT;
> @@ -2317,8 +2311,8 @@ xfs_bmap_add_extent_unwritten_real(
>  		PREV.br_startblock += new->br_blockcount;
>  		PREV.br_blockcount -= new->br_blockcount;
>  
> -		xfs_iext_update_extent(ip, state, *idx, &PREV);
> -		xfs_iext_insert(ip, *idx, 1, new, state);
> +		xfs_iext_update_extent(ip, state, icur, &PREV);
> +		xfs_iext_insert(ip, icur, 1, new, state);
>  		XFS_IFORK_NEXT_SET(ip, whichfork,
>  				XFS_IFORK_NEXTENTS(ip, whichfork) + 1);
>  		if (cur == NULL)
> @@ -2351,9 +2345,9 @@ xfs_bmap_add_extent_unwritten_real(
>  		RIGHT.br_startblock = new->br_startblock;
>  		RIGHT.br_blockcount += new->br_blockcount;
>  
> -		xfs_iext_update_extent(ip, state, *idx, &PREV);
> -		++*idx;
> -		xfs_iext_update_extent(ip, state, *idx, &RIGHT);
> +		xfs_iext_update_extent(ip, state, icur, &PREV);
> +		xfs_iext_next(ifp, icur);
> +		xfs_iext_update_extent(ip, state, icur, &RIGHT);
>  
>  		if (cur == NULL)
>  			rval = XFS_ILOG_DEXT;
> @@ -2383,9 +2377,9 @@ xfs_bmap_add_extent_unwritten_real(
>  		old = PREV;
>  		PREV.br_blockcount -= new->br_blockcount;
>  
> -		xfs_iext_update_extent(ip, state, *idx, &PREV);
> -		++*idx;
> -		xfs_iext_insert(ip, *idx, 1, new, state);
> +		xfs_iext_update_extent(ip, state, icur, &PREV);
> +		xfs_iext_next(ifp, icur);
> +		xfs_iext_insert(ip, icur, 1, new, state);
>  
>  		XFS_IFORK_NEXT_SET(ip, whichfork,
>  				XFS_IFORK_NEXTENTS(ip, whichfork) + 1);
> @@ -2426,9 +2420,9 @@ xfs_bmap_add_extent_unwritten_real(
>  		r[1].br_startblock = new->br_startblock + new->br_blockcount;
>  		r[1].br_state = PREV.br_state;
>  
> -		xfs_iext_update_extent(ip, state, *idx, &PREV);
> -		++*idx;
> -		xfs_iext_insert(ip, *idx, 2, &r[0], state);
> +		xfs_iext_update_extent(ip, state, icur, &PREV);
> +		xfs_iext_next(ifp, icur);
> +		xfs_iext_insert(ip, icur, 2, &r[0], state);
>  
>  		XFS_IFORK_NEXT_SET(ip, whichfork,
>  				XFS_IFORK_NEXTENTS(ip, whichfork) + 2);
> @@ -2517,7 +2511,7 @@ STATIC void
>  xfs_bmap_add_extent_hole_delay(
>  	xfs_inode_t		*ip,	/* incore inode pointer */
>  	int			whichfork,
> -	xfs_extnum_t		*idx,	/* extent number to update/insert */
> +	struct xfs_iext_cursor	*icur,
>  	xfs_bmbt_irec_t		*new)	/* new data to add to file extents */
>  {
>  	xfs_ifork_t		*ifp;	/* inode fork pointer */
> @@ -2534,10 +2528,8 @@ xfs_bmap_add_extent_hole_delay(
>  	/*
>  	 * Check and set flags if this segment has a left neighbor
>  	 */
> -	if (*idx > 0) {
> +	if (xfs_iext_peek_prev_extent(ifp, icur, &left)) {
>  		state |= BMAP_LEFT_VALID;
> -		xfs_iext_get_extent(ifp, *idx - 1, &left);
> -
>  		if (isnullstartblock(left.br_startblock))
>  			state |= BMAP_LEFT_DELAY;
>  	}
> @@ -2546,10 +2538,8 @@ xfs_bmap_add_extent_hole_delay(
>  	 * Check and set flags if the current (right) segment exists.
>  	 * If it doesn't exist, we're converting the hole at end-of-file.
>  	 */
> -	if (*idx < xfs_iext_count(ifp)) {
> +	if (xfs_iext_get_extent(ifp, icur, &right)) {
>  		state |= BMAP_RIGHT_VALID;
> -		xfs_iext_get_extent(ifp, *idx, &right);
> -
>  		if (isnullstartblock(right.br_startblock))
>  			state |= BMAP_RIGHT_DELAY;
>  	}
> @@ -2592,9 +2582,9 @@ xfs_bmap_add_extent_hole_delay(
>  		left.br_startblock = nullstartblock(newlen);
>  		left.br_blockcount = temp;
>  
> -		xfs_iext_remove(ip, *idx, 1, state);
> -		--*idx;
> -		xfs_iext_update_extent(ip, state, *idx, &left);
> +		xfs_iext_remove(ip, icur, 1, state);
> +		xfs_iext_prev(ifp, icur);
> +		xfs_iext_update_extent(ip, state, icur, &left);
>  		break;
>  
>  	case BMAP_LEFT_CONTIG:
> @@ -2612,8 +2602,8 @@ xfs_bmap_add_extent_hole_delay(
>  		left.br_blockcount = temp;
>  		left.br_startblock = nullstartblock(newlen);
>  
> -		--*idx;
> -		xfs_iext_update_extent(ip, state, *idx, &left);
> +		xfs_iext_prev(ifp, icur);
> +		xfs_iext_update_extent(ip, state, icur, &left);
>  		break;
>  
>  	case BMAP_RIGHT_CONTIG:
> @@ -2630,7 +2620,7 @@ xfs_bmap_add_extent_hole_delay(
>  		right.br_startoff = new->br_startoff;
>  		right.br_startblock = nullstartblock(newlen);
>  		right.br_blockcount = temp;
> -		xfs_iext_update_extent(ip, state, *idx, &right);
> +		xfs_iext_update_extent(ip, state, icur, &right);
>  		break;
>  
>  	case 0:
> @@ -2640,7 +2630,7 @@ xfs_bmap_add_extent_hole_delay(
>  		 * Insert a new entry.
>  		 */
>  		oldlen = newlen = 0;
> -		xfs_iext_insert(ip, *idx, 1, new, state);
> +		xfs_iext_insert(ip, icur, 1, new, state);
>  		break;
>  	}
>  	if (oldlen != newlen) {
> @@ -2661,7 +2651,7 @@ xfs_bmap_add_extent_hole_real(
>  	struct xfs_trans	*tp,
>  	struct xfs_inode	*ip,
>  	int			whichfork,
> -	xfs_extnum_t		*idx,
> +	struct xfs_iext_cursor	*icur,
>  	struct xfs_btree_cur	**curp,
>  	struct xfs_bmbt_irec	*new,
>  	xfs_fsblock_t		*first,
> @@ -2679,8 +2669,6 @@ xfs_bmap_add_extent_hole_real(
>  	int			state = xfs_bmap_fork_to_state(whichfork);
>  	struct xfs_bmbt_irec	old;
>  
> -	ASSERT(*idx >= 0);
> -	ASSERT(*idx <= xfs_iext_count(ifp));
>  	ASSERT(!isnullstartblock(new->br_startblock));
>  	ASSERT(!cur || !(cur->bc_private.b.flags & XFS_BTCUR_BPRV_WASDEL));
>  
> @@ -2689,9 +2677,8 @@ xfs_bmap_add_extent_hole_real(
>  	/*
>  	 * Check and set flags if this segment has a left neighbor.
>  	 */
> -	if (*idx > 0) {
> +	if (xfs_iext_peek_prev_extent(ifp, icur, &left)) {
>  		state |= BMAP_LEFT_VALID;
> -		xfs_iext_get_extent(ifp, *idx - 1, &left);
>  		if (isnullstartblock(left.br_startblock))
>  			state |= BMAP_LEFT_DELAY;
>  	}
> @@ -2700,9 +2687,8 @@ xfs_bmap_add_extent_hole_real(
>  	 * Check and set flags if this segment has a current value.
>  	 * Not true if we're inserting into the "hole" at eof.
>  	 */
> -	if (*idx < xfs_iext_count(ifp)) {
> +	if (xfs_iext_get_extent(ifp, icur, &right)) {
>  		state |= BMAP_RIGHT_VALID;
> -		xfs_iext_get_extent(ifp, *idx, &right);
>  		if (isnullstartblock(right.br_startblock))
>  			state |= BMAP_RIGHT_DELAY;
>  	}
> @@ -2741,9 +2727,9 @@ xfs_bmap_add_extent_hole_real(
>  		 */
>  		left.br_blockcount += new->br_blockcount + right.br_blockcount;
>  
> -		xfs_iext_remove(ip, *idx, 1, state);
> -		--*idx;
> -		xfs_iext_update_extent(ip, state, *idx, &left);
> +		xfs_iext_remove(ip, icur, 1, state);
> +		xfs_iext_prev(ifp, icur);
> +		xfs_iext_update_extent(ip, state, icur, &left);
>  
>  		XFS_IFORK_NEXT_SET(ip, whichfork,
>  			XFS_IFORK_NEXTENTS(ip, whichfork) - 1);
> @@ -2778,8 +2764,8 @@ xfs_bmap_add_extent_hole_real(
>  		old = left;
>  		left.br_blockcount += new->br_blockcount;
>  
> -		--*idx;
> -		xfs_iext_update_extent(ip, state, *idx, &left);
> +		xfs_iext_prev(ifp, icur);
> +		xfs_iext_update_extent(ip, state, icur, &left);
>  
>  		if (cur == NULL) {
>  			rval = xfs_ilog_fext(whichfork);
> @@ -2806,7 +2792,7 @@ xfs_bmap_add_extent_hole_real(
>  		right.br_startoff = new->br_startoff;
>  		right.br_startblock = new->br_startblock;
>  		right.br_blockcount += new->br_blockcount;
> -		xfs_iext_update_extent(ip, state, *idx, &right);
> +		xfs_iext_update_extent(ip, state, icur, &right);
>  
>  		if (cur == NULL) {
>  			rval = xfs_ilog_fext(whichfork);
> @@ -2828,7 +2814,7 @@ xfs_bmap_add_extent_hole_real(
>  		 * real allocation.
>  		 * Insert a new entry.
>  		 */
> -		xfs_iext_insert(ip, *idx, 1, new, state);
> +		xfs_iext_insert(ip, icur, 1, new, state);
>  		XFS_IFORK_NEXT_SET(ip, whichfork,
>  			XFS_IFORK_NEXTENTS(ip, whichfork) + 1);
>  		if (cur == NULL) {
> @@ -3778,7 +3764,7 @@ xfs_bmapi_read(
>  	struct xfs_bmbt_irec	got;
>  	xfs_fileoff_t		obno;
>  	xfs_fileoff_t		end;
> -	xfs_extnum_t		idx;
> +	struct xfs_iext_cursor	icur;
>  	int			error;
>  	bool			eof = false;
>  	int			n = 0;
> @@ -3820,7 +3806,7 @@ xfs_bmapi_read(
>  			return error;
>  	}
>  
> -	if (!xfs_iext_lookup_extent(ip, ifp, bno, &idx, &got))
> +	if (!xfs_iext_lookup_extent(ip, ifp, bno, &icur, &got))
>  		eof = true;
>  	end = bno + len;
>  	obno = bno;
> @@ -3852,7 +3838,7 @@ xfs_bmapi_read(
>  			break;
>  
>  		/* Else go on to the next record. */
> -		if (!xfs_iext_get_extent(ifp, ++idx, &got))
> +		if (!xfs_iext_next_extent(ifp, &icur, &got))
>  			eof = true;
>  	}
>  	*nmap = n;
> @@ -3880,7 +3866,7 @@ xfs_bmapi_reserve_delalloc(
>  	xfs_filblks_t		len,
>  	xfs_filblks_t		prealloc,
>  	struct xfs_bmbt_irec	*got,
> -	xfs_extnum_t		*lastx,
> +	struct xfs_iext_cursor	*icur,
>  	int			eof)
>  {
>  	struct xfs_mount	*mp = ip->i_mount;
> @@ -3910,7 +3896,7 @@ xfs_bmapi_reserve_delalloc(
>  	if (extsz) {
>  		struct xfs_bmbt_irec	prev;
>  
> -		if (!xfs_iext_get_extent(ifp, *lastx - 1, &prev))
> +		if (!xfs_iext_peek_prev_extent(ifp, icur, &prev))
>  			prev.br_startoff = NULLFILEOFF;
>  
>  		error = xfs_bmap_extsize_align(mp, got, &prev, extsz, rt, eof,
> @@ -3959,7 +3945,7 @@ xfs_bmapi_reserve_delalloc(
>  	got->br_blockcount = alen;
>  	got->br_state = XFS_EXT_NORM;
>  
> -	xfs_bmap_add_extent_hole_delay(ip, whichfork, lastx, got);
> +	xfs_bmap_add_extent_hole_delay(ip, whichfork, icur, got);
>  
>  	/*
>  	 * Tag the inode if blocks were preallocated. Note that COW fork
> @@ -4004,8 +3990,7 @@ xfs_bmapi_allocate(
>  	if (bma->wasdel) {
>  		bma->length = (xfs_extlen_t)bma->got.br_blockcount;
>  		bma->offset = bma->got.br_startoff;
> -		if (bma->idx)
> -			xfs_iext_get_extent(ifp, bma->idx - 1, &bma->prev);
> +		xfs_iext_peek_prev_extent(ifp, &bma->icur, &bma->prev);
>  	} else {
>  		bma->length = XFS_FILBLKS_MIN(bma->length, MAXEXTLEN);
>  		if (!bma->eof)
> @@ -4090,7 +4075,7 @@ xfs_bmapi_allocate(
>  		error = xfs_bmap_add_extent_delay_real(bma, whichfork);
>  	else
>  		error = xfs_bmap_add_extent_hole_real(bma->tp, bma->ip,
> -				whichfork, &bma->idx, &bma->cur, &bma->got,
> +				whichfork, &bma->icur, &bma->cur, &bma->got,
>  				bma->firstblock, bma->dfops, &bma->logflags);
>  
>  	bma->logflags |= tmp_logflags;
> @@ -4102,7 +4087,7 @@ xfs_bmapi_allocate(
>  	 * or xfs_bmap_add_extent_hole_real might have merged it into one of
>  	 * the neighbouring ones.
>  	 */
> -	xfs_iext_get_extent(ifp, bma->idx, &bma->got);
> +	xfs_iext_get_extent(ifp, &bma->icur, &bma->got);
>  
>  	ASSERT(bma->got.br_startoff <= bma->offset);
>  	ASSERT(bma->got.br_startoff + bma->got.br_blockcount >=
> @@ -4160,8 +4145,8 @@ xfs_bmapi_convert_unwritten(
>  	}
>  
>  	error = xfs_bmap_add_extent_unwritten_real(bma->tp, bma->ip, whichfork,
> -			&bma->idx, &bma->cur, mval, bma->firstblock, bma->dfops,
> -			&tmp_logflags);
> +			&bma->icur, &bma->cur, mval, bma->firstblock,
> +			bma->dfops, &tmp_logflags);
>  	/*
>  	 * Log the inode core unconditionally in the unwritten extent conversion
>  	 * path because the conversion might not have done so (e.g., if the
> @@ -4183,7 +4168,7 @@ xfs_bmapi_convert_unwritten(
>  	 * xfs_bmap_add_extent_unwritten_real might have merged it into one
>  	 * of the neighbouring ones.
>  	 */
> -	xfs_iext_get_extent(ifp, bma->idx, &bma->got);
> +	xfs_iext_get_extent(ifp, &bma->icur, &bma->got);
>  
>  	/*
>  	 * We may have combined previously unwritten space with written space,
> @@ -4302,9 +4287,9 @@ xfs_bmapi_write(
>  	end = bno + len;
>  	obno = bno;
>  
> -	if (!xfs_iext_lookup_extent(ip, ifp, bno, &bma.idx, &bma.got))
> +	if (!xfs_iext_lookup_extent(ip, ifp, bno, &bma.icur, &bma.got))
>  		eof = true;
> -	if (!xfs_iext_get_extent(ifp, bma.idx - 1, &bma.prev))
> +	if (!xfs_iext_peek_prev_extent(ifp, &bma.icur, &bma.prev))
>  		bma.prev.br_startoff = NULLFILEOFF;
>  	bma.tp = tp;
>  	bma.ip = ip;
> @@ -4409,7 +4394,7 @@ xfs_bmapi_write(
>  
>  		/* Else go on to the next record. */
>  		bma.prev = bma.got;
> -		if (!xfs_iext_get_extent(ifp, ++bma.idx, &bma.got))
> +		if (!xfs_iext_next_extent(ifp, &bma.icur, &bma.got))
>  			eof = true;
>  	}
>  	*nmap = n;
> @@ -4482,7 +4467,7 @@ xfs_bmapi_remap(
>  	struct xfs_btree_cur	*cur = NULL;
>  	xfs_fsblock_t		firstblock = NULLFSBLOCK;
>  	struct xfs_bmbt_irec	got;
> -	xfs_extnum_t		idx;
> +	struct xfs_iext_cursor	icur;
>  	int			logflags = 0, error;
>  
>  	ASSERT(len > 0);
> @@ -4506,7 +4491,7 @@ xfs_bmapi_remap(
>  			return error;
>  	}
>  
> -	if (xfs_iext_lookup_extent(ip, ifp, bno, &idx, &got)) {
> +	if (xfs_iext_lookup_extent(ip, ifp, bno, &icur, &got)) {
>  		/* make sure we only reflink into a hole. */
>  		ASSERT(got.br_startoff > bno);
>  		ASSERT(got.br_startoff - bno >= len);
> @@ -4527,8 +4512,8 @@ xfs_bmapi_remap(
>  	got.br_blockcount = len;
>  	got.br_state = XFS_EXT_NORM;
>  
> -	error = xfs_bmap_add_extent_hole_real(tp, ip, XFS_DATA_FORK, &idx, &cur,
> -			&got, &firstblock, dfops, &logflags);
> +	error = xfs_bmap_add_extent_hole_real(tp, ip, XFS_DATA_FORK, &icur,
> +			&cur, &got, &firstblock, dfops, &logflags);
>  	if (error)
>  		goto error0;
>  
> @@ -4644,7 +4629,7 @@ int
>  xfs_bmap_del_extent_delay(
>  	struct xfs_inode	*ip,
>  	int			whichfork,
> -	xfs_extnum_t		*idx,
> +	struct xfs_iext_cursor	*icur,
>  	struct xfs_bmbt_irec	*got,
>  	struct xfs_bmbt_irec	*del)
>  {
> @@ -4666,8 +4651,6 @@ xfs_bmap_del_extent_delay(
>  	da_old = startblockval(got->br_startblock);
>  	da_new = 0;
>  
> -	ASSERT(*idx >= 0);
> -	ASSERT(*idx <= xfs_iext_count(ifp));
>  	ASSERT(del->br_blockcount > 0);
>  	ASSERT(got->br_startoff <= del->br_startoff);
>  	ASSERT(got_endoff >= del_endoff);
> @@ -4701,8 +4684,8 @@ xfs_bmap_del_extent_delay(
>  		/*
>  		 * Matches the whole extent.  Delete the entry.
>  		 */
> -		xfs_iext_remove(ip, *idx, 1, state);
> -		--*idx;
> +		xfs_iext_remove(ip, icur, 1, state);
> +		xfs_iext_prev(ifp, icur);
>  		break;
>  	case BMAP_LEFT_FILLING:
>  		/*
> @@ -4713,7 +4696,7 @@ xfs_bmap_del_extent_delay(
>  		da_new = XFS_FILBLKS_MIN(xfs_bmap_worst_indlen(ip,
>  				got->br_blockcount), da_old);
>  		got->br_startblock = nullstartblock((int)da_new);
> -		xfs_iext_update_extent(ip, state, *idx, got);
> +		xfs_iext_update_extent(ip, state, icur, got);
>  		break;
>  	case BMAP_RIGHT_FILLING:
>  		/*
> @@ -4723,7 +4706,7 @@ xfs_bmap_del_extent_delay(
>  		da_new = XFS_FILBLKS_MIN(xfs_bmap_worst_indlen(ip,
>  				got->br_blockcount), da_old);
>  		got->br_startblock = nullstartblock((int)da_new);
> -		xfs_iext_update_extent(ip, state, *idx, got);
> +		xfs_iext_update_extent(ip, state, icur, got);
>  		break;
>  	case 0:
>  		/*
> @@ -4751,9 +4734,9 @@ xfs_bmap_del_extent_delay(
>  		new.br_state = got->br_state;
>  		new.br_startblock = nullstartblock((int)new_indlen);
>  
> -		xfs_iext_update_extent(ip, state, *idx, got);
> -		++*idx;
> -		xfs_iext_insert(ip, *idx, 1, &new, state);
> +		xfs_iext_update_extent(ip, state, icur, got);
> +		xfs_iext_next(ifp, icur);
> +		xfs_iext_insert(ip, icur, 1, &new, state);
>  
>  		da_new = got_indlen + new_indlen - stolen;
>  		del->br_blockcount -= stolen;
> @@ -4772,7 +4755,7 @@ xfs_bmap_del_extent_delay(
>  void
>  xfs_bmap_del_extent_cow(
>  	struct xfs_inode	*ip,
> -	xfs_extnum_t		*idx,
> +	struct xfs_iext_cursor	*icur,
>  	struct xfs_bmbt_irec	*got,
>  	struct xfs_bmbt_irec	*del)
>  {
> @@ -4787,8 +4770,6 @@ xfs_bmap_del_extent_cow(
>  	del_endoff = del->br_startoff + del->br_blockcount;
>  	got_endoff = got->br_startoff + got->br_blockcount;
>  
> -	ASSERT(*idx >= 0);
> -	ASSERT(*idx <= xfs_iext_count(ifp));
>  	ASSERT(del->br_blockcount > 0);
>  	ASSERT(got->br_startoff <= del->br_startoff);
>  	ASSERT(got_endoff >= del_endoff);
> @@ -4804,8 +4785,8 @@ xfs_bmap_del_extent_cow(
>  		/*
>  		 * Matches the whole extent.  Delete the entry.
>  		 */
> -		xfs_iext_remove(ip, *idx, 1, state);
> -		--*idx;
> +		xfs_iext_remove(ip, icur, 1, state);
> +		xfs_iext_prev(ifp, icur);
>  		break;
>  	case BMAP_LEFT_FILLING:
>  		/*
> @@ -4814,14 +4795,14 @@ xfs_bmap_del_extent_cow(
>  		got->br_startoff = del_endoff;
>  		got->br_blockcount -= del->br_blockcount;
>  		got->br_startblock = del->br_startblock + del->br_blockcount;
> -		xfs_iext_update_extent(ip, state, *idx, got);
> +		xfs_iext_update_extent(ip, state, icur, got);
>  		break;
>  	case BMAP_RIGHT_FILLING:
>  		/*
>  		 * Deleting the last part of the extent.
>  		 */
>  		got->br_blockcount -= del->br_blockcount;
> -		xfs_iext_update_extent(ip, state, *idx, got);
> +		xfs_iext_update_extent(ip, state, icur, got);
>  		break;
>  	case 0:
>  		/*
> @@ -4834,9 +4815,9 @@ xfs_bmap_del_extent_cow(
>  		new.br_state = got->br_state;
>  		new.br_startblock = del->br_startblock + del->br_blockcount;
>  
> -		xfs_iext_update_extent(ip, state, *idx, got);
> -		++*idx;
> -		xfs_iext_insert(ip, *idx, 1, &new, state);
> +		xfs_iext_update_extent(ip, state, icur, got);
> +		xfs_iext_next(ifp, icur);
> +		xfs_iext_insert(ip, icur, 1, &new, state);
>  		break;
>  	}
>  }
> @@ -4849,7 +4830,7 @@ STATIC int				/* error */
>  xfs_bmap_del_extent_real(
>  	xfs_inode_t		*ip,	/* incore inode pointer */
>  	xfs_trans_t		*tp,	/* current transaction pointer */
> -	xfs_extnum_t		*idx,	/* extent number to update/delete */
> +	struct xfs_iext_cursor	*icur,
>  	struct xfs_defer_ops	*dfops,	/* list of extents to be freed */
>  	xfs_btree_cur_t		*cur,	/* if null, not a btree */
>  	xfs_bmbt_irec_t		*del,	/* data to remove from extents */
> @@ -4878,9 +4859,8 @@ xfs_bmap_del_extent_real(
>  	XFS_STATS_INC(mp, xs_del_exlist);
>  
>  	ifp = XFS_IFORK_PTR(ip, whichfork);
> -	ASSERT((*idx >= 0) && (*idx < xfs_iext_count(ifp)));
>  	ASSERT(del->br_blockcount > 0);
> -	xfs_iext_get_extent(ifp, *idx, &got);
> +	xfs_iext_get_extent(ifp, icur, &got);
>  	ASSERT(got.br_startoff <= del->br_startoff);
>  	del_endoff = del->br_startoff + del->br_blockcount;
>  	got_endoff = got.br_startoff + got.br_blockcount;
> @@ -4945,9 +4925,8 @@ xfs_bmap_del_extent_real(
>  		/*
>  		 * Matches the whole extent.  Delete the entry.
>  		 */
> -		xfs_iext_remove(ip, *idx, 1, state);
> -		--*idx;
> -
> +		xfs_iext_remove(ip, icur, 1, state);
> +		xfs_iext_prev(ifp, icur);
>  		XFS_IFORK_NEXT_SET(ip, whichfork,
>  			XFS_IFORK_NEXTENTS(ip, whichfork) - 1);
>  		flags |= XFS_ILOG_CORE;
> @@ -4966,7 +4945,7 @@ xfs_bmap_del_extent_real(
>  		got.br_startoff = del_endoff;
>  		got.br_startblock = del_endblock;
>  		got.br_blockcount -= del->br_blockcount;
> -		xfs_iext_update_extent(ip, state, *idx, &got);
> +		xfs_iext_update_extent(ip, state, icur, &got);
>  		if (!cur) {
>  			flags |= xfs_ilog_fext(whichfork);
>  			break;
> @@ -4980,7 +4959,7 @@ xfs_bmap_del_extent_real(
>  		 * Deleting the last part of the extent.
>  		 */
>  		got.br_blockcount -= del->br_blockcount;
> -		xfs_iext_update_extent(ip, state, *idx, &got);
> +		xfs_iext_update_extent(ip, state, icur, &got);
>  		if (!cur) {
>  			flags |= xfs_ilog_fext(whichfork);
>  			break;
> @@ -4996,7 +4975,7 @@ xfs_bmap_del_extent_real(
>  		old = got;
>  
>  		got.br_blockcount = del->br_startoff - got.br_startoff;
> -		xfs_iext_update_extent(ip, state, *idx, &got);
> +		xfs_iext_update_extent(ip, state, icur, &got);
>  
>  		new.br_startoff = del_endoff;
>  		new.br_blockcount = got_endoff - del_endoff;
> @@ -5040,7 +5019,7 @@ xfs_bmap_del_extent_real(
>  				 * Reset the extent record back
>  				 * to the original value.
>  				 */
> -				xfs_iext_update_extent(ip, state, *idx, &old);
> +				xfs_iext_update_extent(ip, state, icur, &old);
>  				flags = 0;
>  				error = -ENOSPC;
>  				goto done;
> @@ -5050,8 +5029,8 @@ xfs_bmap_del_extent_real(
>  			flags |= xfs_ilog_fext(whichfork);
>  		XFS_IFORK_NEXT_SET(ip, whichfork,
>  			XFS_IFORK_NEXTENTS(ip, whichfork) + 1);
> -		++*idx;
> -		xfs_iext_insert(ip, *idx, 1, &new, state);
> +		xfs_iext_next(ifp, icur);
> +		xfs_iext_insert(ip, icur, 1, &new, state);
>  		break;
>  	}
>  
> @@ -5114,7 +5093,6 @@ __xfs_bunmapi(
>  	xfs_bmbt_irec_t		got;		/* current extent record */
>  	xfs_ifork_t		*ifp;		/* inode fork pointer */
>  	int			isrt;		/* freeing in rt area */
> -	xfs_extnum_t		lastx;		/* last extent index used */
>  	int			logflags;	/* transaction logging flags */
>  	xfs_extlen_t		mod;		/* rt extent offset */
>  	xfs_mount_t		*mp;		/* mount structure */
> @@ -5126,6 +5104,8 @@ __xfs_bunmapi(
>  	xfs_fileoff_t		max_len;
>  	xfs_agnumber_t		prev_agno = NULLAGNUMBER, agno;
>  	xfs_fileoff_t		end;
> +	struct xfs_iext_cursor	icur;
> +	bool			done = false;
>  
>  	trace_xfs_bunmap(ip, start, len, flags, _RET_IP_);
>  
> @@ -5168,7 +5148,7 @@ __xfs_bunmapi(
>  	isrt = (whichfork == XFS_DATA_FORK) && XFS_IS_REALTIME_INODE(ip);
>  	end = start + len;
>  
> -	if (!xfs_iext_lookup_extent_before(ip, ifp, &end, &lastx, &got)) {
> +	if (!xfs_iext_lookup_extent_before(ip, ifp, &end, &icur, &got)) {
>  		*rlen = 0;
>  		return 0;
>  	}
> @@ -5195,16 +5175,16 @@ __xfs_bunmapi(
>  	}
>  
>  	extno = 0;
> -	while (end != (xfs_fileoff_t)-1 && end >= start && lastx >= 0 &&
> +	while (end != (xfs_fileoff_t)-1 && end >= start &&
>  	       (nexts == 0 || extno < nexts) && max_len > 0) {
>  		/*
>  		 * Is the found extent after a hole in which end lives?
>  		 * Just back up to the previous extent, if so.
>  		 */
> -		if (got.br_startoff > end) {
> -			if (--lastx < 0)
> -				break;
> -			xfs_iext_get_extent(ifp, lastx, &got);
> +		if (got.br_startoff > end &&
> +		    !xfs_iext_prev_extent(ifp, &icur, &got)) {
> +			done = true;
> +			break;
>  		}
>  		/*
>  		 * Is the last block of this extent before the range
> @@ -5267,10 +5247,10 @@ __xfs_bunmapi(
>  				ASSERT(end >= mod);
>  				end -= mod > del.br_blockcount ?
>  					del.br_blockcount : mod;
> -				if (end < got.br_startoff) {
> -					if (--lastx >= 0)
> -						xfs_iext_get_extent(ifp, lastx,
> -								&got);
> +				if (end < got.br_startoff &&
> +				    !xfs_iext_prev_extent(ifp, &icur, &got)) {
> +					done = true;
> +					break;
>  				}
>  				continue;
>  			}
> @@ -5291,7 +5271,7 @@ __xfs_bunmapi(
>  			}
>  			del.br_state = XFS_EXT_UNWRITTEN;
>  			error = xfs_bmap_add_extent_unwritten_real(tp, ip,
> -					whichfork, &lastx, &cur, &del,
> +					whichfork, &icur, &cur, &del,
>  					firstblock, dfops, &logflags);
>  			if (error)
>  				goto error0;
> @@ -5318,8 +5298,11 @@ __xfs_bunmapi(
>  				 */
>  				ASSERT(end >= del.br_blockcount);
>  				end -= del.br_blockcount;
> -				if (got.br_startoff > end && --lastx >= 0)
> -					xfs_iext_get_extent(ifp, lastx, &got);
> +				if (got.br_startoff > end &&
> +				    !xfs_iext_prev_extent(ifp, &icur, &got)) {
> +					done = true;
> +					break;
> +				}
>  				continue;
>  			} else if (del.br_state == XFS_EXT_UNWRITTEN) {
>  				struct xfs_bmbt_irec	prev;
> @@ -5330,8 +5313,8 @@ __xfs_bunmapi(
>  				 * Unwrite the killed part of that one and
>  				 * try again.
>  				 */
> -				ASSERT(lastx > 0);
> -				xfs_iext_get_extent(ifp, lastx - 1, &prev);
> +				if (!xfs_iext_prev_extent(ifp, &icur, &prev))
> +					ASSERT(0);
>  				ASSERT(prev.br_state == XFS_EXT_NORM);
>  				ASSERT(!isnullstartblock(prev.br_startblock));
>  				ASSERT(del.br_startblock ==
> @@ -5343,9 +5326,8 @@ __xfs_bunmapi(
>  					prev.br_startoff = start;
>  				}
>  				prev.br_state = XFS_EXT_UNWRITTEN;
> -				lastx--;
>  				error = xfs_bmap_add_extent_unwritten_real(tp,
> -						ip, whichfork, &lastx, &cur,
> +						ip, whichfork, &icur, &cur,
>  						&prev, firstblock, dfops,
>  						&logflags);
>  				if (error)
> @@ -5355,7 +5337,7 @@ __xfs_bunmapi(
>  				ASSERT(del.br_state == XFS_EXT_NORM);
>  				del.br_state = XFS_EXT_UNWRITTEN;
>  				error = xfs_bmap_add_extent_unwritten_real(tp,
> -						ip, whichfork, &lastx, &cur,
> +						ip, whichfork, &icur, &cur,
>  						&del, firstblock, dfops,
>  						&logflags);
>  				if (error)
> @@ -5365,10 +5347,10 @@ __xfs_bunmapi(
>  		}
>  
>  		if (wasdel) {
> -			error = xfs_bmap_del_extent_delay(ip, whichfork, &lastx,
> +			error = xfs_bmap_del_extent_delay(ip, whichfork, &icur,
>  					&got, &del);
>  		} else {
> -			error = xfs_bmap_del_extent_real(ip, tp, &lastx, dfops,
> +			error = xfs_bmap_del_extent_real(ip, tp, &icur, dfops,
>  					cur, &del, &tmp_logflags, whichfork,
>  					flags);
>  			logflags |= tmp_logflags;
> @@ -5384,15 +5366,16 @@ __xfs_bunmapi(
>  		 * If not done go on to the next (previous) record.
>  		 */
>  		if (end != (xfs_fileoff_t)-1 && end >= start) {
> -			if (lastx >= 0) {
> -				xfs_iext_get_extent(ifp, lastx, &got);
> -				if (got.br_startoff > end && --lastx >= 0)
> -					xfs_iext_get_extent(ifp, lastx, &got);
> +			if (!xfs_iext_get_extent(ifp, &icur, &got) ||
> +			    (got.br_startoff > end &&
> +			     !xfs_iext_prev_extent(ifp, &icur, &got))) {
> +				done = true;
> +				break;
>  			}
>  			extno++;
>  		}
>  	}
> -	if (end == (xfs_fileoff_t)-1 || end < start || lastx < 0)
> +	if (done || end == (xfs_fileoff_t)-1 || end < start)
>  		*rlen = 0;
>  	else
>  		*rlen = end - start + 1;
> @@ -5513,7 +5496,7 @@ xfs_bmse_merge(
>  	struct xfs_inode		*ip,
>  	int				whichfork,
>  	xfs_fileoff_t			shift,		/* shift fsb */
> -	int				*current_ext,	/* idx of gotp */
> +	struct xfs_iext_cursor		*icur,
>  	struct xfs_bmbt_irec		*got,		/* extent to shift */
>  	struct xfs_bmbt_irec		*left,		/* preceding extent */
>  	struct xfs_btree_cur		*cur,
> @@ -5568,10 +5551,10 @@ xfs_bmse_merge(
>  		return error;
>  
>  done:
> -	xfs_iext_remove(ip, *current_ext, 1, 0);
> -	--*current_ext;
> -	xfs_iext_update_extent(ip, xfs_bmap_fork_to_state(whichfork),
> -			*current_ext, &new);
> +	xfs_iext_remove(ip, icur, 1, 0);
> +	xfs_iext_prev(XFS_IFORK_PTR(ip, whichfork), icur);
> +	xfs_iext_update_extent(ip, xfs_bmap_fork_to_state(whichfork), icur,
> +			&new);
>  
>  	/* update reverse mapping. rmap functions merge the rmaps for us */
>  	error = xfs_rmap_unmap_extent(mp, dfops, ip, whichfork, got);
> @@ -5586,7 +5569,7 @@ static int
>  xfs_bmap_shift_update_extent(
>  	struct xfs_inode	*ip,
>  	int			whichfork,
> -	xfs_extnum_t		idx,
> +	struct xfs_iext_cursor	*icur,
>  	struct xfs_bmbt_irec	*got,
>  	struct xfs_btree_cur	*cur,
>  	int			*logflags,
> @@ -5614,7 +5597,8 @@ xfs_bmap_shift_update_extent(
>  		*logflags |= XFS_ILOG_DEXT;
>  	}
>  
> -	xfs_iext_update_extent(ip, xfs_bmap_fork_to_state(whichfork), idx, got);
> +	xfs_iext_update_extent(ip, xfs_bmap_fork_to_state(whichfork), icur,
> +			got);
>  
>  	/* update reverse mapping */
>  	error = xfs_rmap_unmap_extent(mp, dfops, ip, whichfork, &prev);
> @@ -5639,7 +5623,7 @@ xfs_bmap_collapse_extents(
>  	struct xfs_ifork	*ifp = XFS_IFORK_PTR(ip, whichfork);
>  	struct xfs_btree_cur	*cur = NULL;
>  	struct xfs_bmbt_irec	got, prev;
> -	xfs_extnum_t		current_ext;
> +	struct xfs_iext_cursor	icur;
>  	xfs_fileoff_t		new_startoff;
>  	int			error = 0;
>  	int			logflags = 0;
> @@ -5670,14 +5654,14 @@ xfs_bmap_collapse_extents(
>  		cur->bc_private.b.flags = 0;
>  	}
>  
> -	if (!xfs_iext_lookup_extent(ip, ifp, *next_fsb, &current_ext, &got)) {
> +	if (!xfs_iext_lookup_extent(ip, ifp, *next_fsb, &icur, &got)) {
>  		*done = true;
>  		goto del_cursor;
>  	}
>  	XFS_WANT_CORRUPTED_RETURN(mp, !isnullstartblock(got.br_startblock));
>  
>  	new_startoff = got.br_startoff - offset_shift_fsb;
> -	if (xfs_iext_get_extent(ifp, current_ext - 1, &prev)) {
> +	if (xfs_iext_peek_prev_extent(ifp, &icur, &prev)) {
>  		if (new_startoff < prev.br_startoff + prev.br_blockcount) {
>  			error = -EINVAL;
>  			goto del_cursor;
> @@ -5685,8 +5669,8 @@ xfs_bmap_collapse_extents(
>  
>  		if (xfs_bmse_can_merge(&prev, &got, offset_shift_fsb)) {
>  			error = xfs_bmse_merge(ip, whichfork, offset_shift_fsb,
> -					&current_ext, &got, &prev, cur,
> -					&logflags, dfops);
> +					&icur, &got, &prev, cur, &logflags,
> +					dfops);
>  			if (error)
>  				goto del_cursor;
>  			goto done;
> @@ -5698,15 +5682,15 @@ xfs_bmap_collapse_extents(
>  		}
>  	}
>  
> -	error = xfs_bmap_shift_update_extent(ip, whichfork, current_ext, &got,
> -			cur, &logflags, dfops, new_startoff);
> +	error = xfs_bmap_shift_update_extent(ip, whichfork, &icur, &got, cur,
> +			&logflags, dfops, new_startoff);
>  	if (error)
>  		goto del_cursor;
>  
>  done:
> -	if (!xfs_iext_get_extent(ifp, ++current_ext, &got)) {
> -		 *done = true;
> -		 goto del_cursor;
> +	if (!xfs_iext_next_extent(ifp, &icur, &got)) {
> +		*done = true;
> +		goto del_cursor;
>  	}
>  
>  	*next_fsb = got.br_startoff;
> @@ -5735,7 +5719,7 @@ xfs_bmap_insert_extents(
>  	struct xfs_ifork	*ifp = XFS_IFORK_PTR(ip, whichfork);
>  	struct xfs_btree_cur	*cur = NULL;
>  	struct xfs_bmbt_irec	got, next;
> -	xfs_extnum_t		current_ext;
> +	struct xfs_iext_cursor	icur;
>  	xfs_fileoff_t		new_startoff;
>  	int			error = 0;
>  	int			logflags = 0;
> @@ -5767,15 +5751,14 @@ xfs_bmap_insert_extents(
>  	}
>  
>  	if (*next_fsb == NULLFSBLOCK) {
> -		current_ext = xfs_iext_count(ifp) - 1;
> -		if (!xfs_iext_get_extent(ifp, current_ext, &got) ||
> +		xfs_iext_last(ifp, &icur);
> +		if (!xfs_iext_get_extent(ifp, &icur, &got) ||
>  		    stop_fsb > got.br_startoff) {
>  			*done = true;
>  			goto del_cursor;
>  		}
>  	} else {
> -		if (!xfs_iext_lookup_extent(ip, ifp, *next_fsb, &current_ext,
> -				&got)) {
> +		if (!xfs_iext_lookup_extent(ip, ifp, *next_fsb, &icur, &got)) {
>  			*done = true;
>  			goto del_cursor;
>  		}
> @@ -5788,7 +5771,7 @@ xfs_bmap_insert_extents(
>  	}
>  
>  	new_startoff = got.br_startoff + offset_shift_fsb;
> -	if (xfs_iext_get_extent(ifp, current_ext + 1, &next)) {
> +	if (xfs_iext_peek_next_extent(ifp, &icur, &next)) {
>  		if (new_startoff + got.br_blockcount > next.br_startoff) {
>  			error = -EINVAL;
>  			goto del_cursor;
> @@ -5804,12 +5787,12 @@ xfs_bmap_insert_extents(
>  			WARN_ON_ONCE(1);
>  	}
>  
> -	error = xfs_bmap_shift_update_extent(ip, whichfork, current_ext, &got,
> -			cur, &logflags, dfops, new_startoff);
> +	error = xfs_bmap_shift_update_extent(ip, whichfork, &icur, &got, cur,
> +			&logflags, dfops, new_startoff);
>  	if (error)
>  		goto del_cursor;
>  
> -	if (!xfs_iext_get_extent(ifp, --current_ext, &got) ||
> +	if (!xfs_iext_prev_extent(ifp, &icur, &got) ||
>  	    stop_fsb >= got.br_startoff + got.br_blockcount) {
>  		*done = true;
>  		goto del_cursor;
> @@ -5826,10 +5809,10 @@ xfs_bmap_insert_extents(
>  }
>  
>  /*
> - * Splits an extent into two extents at split_fsb block such that it is
> - * the first block of the current_ext. @current_ext is a target extent
> - * to be split. @split_fsb is a block where the extents is split.
> - * If split_fsb lies in a hole or the first block of extents, just return 0.
> + * Splits an extent into two extents at split_fsb block such that it is the
> + * first block of the current_ext. @ext is a target extent to be split.
> + * @split_fsb is a block where the extents is split.  If split_fsb lies in a
> + * hole or the first block of extents, just return 0.
>   */
>  STATIC int
>  xfs_bmap_split_extent_at(
> @@ -5846,7 +5829,7 @@ xfs_bmap_split_extent_at(
>  	struct xfs_mount		*mp = ip->i_mount;
>  	struct xfs_ifork		*ifp;
>  	xfs_fsblock_t			gotblkcnt; /* new block count for got */
> -	xfs_extnum_t			current_ext;
> +	struct xfs_iext_cursor		icur;
>  	int				error = 0;
>  	int				logflags = 0;
>  	int				i = 0;
> @@ -5874,7 +5857,7 @@ xfs_bmap_split_extent_at(
>  	/*
>  	 * If there are not extents, or split_fsb lies in a hole we are done.
>  	 */
> -	if (!xfs_iext_lookup_extent(ip, ifp, split_fsb, &current_ext, &got) ||
> +	if (!xfs_iext_lookup_extent(ip, ifp, split_fsb, &icur, &got) ||
>  	    got.br_startoff >= split_fsb)
>  		return 0;
>  
> @@ -5896,8 +5879,8 @@ xfs_bmap_split_extent_at(
>  	}
>  
>  	got.br_blockcount = gotblkcnt;
> -	xfs_iext_update_extent(ip, xfs_bmap_fork_to_state(whichfork),
> -			current_ext, &got);
> +	xfs_iext_update_extent(ip, xfs_bmap_fork_to_state(whichfork), &icur,
> +			&got);
>  
>  	logflags = XFS_ILOG_CORE;
>  	if (cur) {
> @@ -5908,8 +5891,8 @@ xfs_bmap_split_extent_at(
>  		logflags |= XFS_ILOG_DEXT;
>  
>  	/* Add new extent */
> -	current_ext++;
> -	xfs_iext_insert(ip, current_ext, 1, &new, 0);
> +	xfs_iext_next(ifp, &icur);
> +	xfs_iext_insert(ip, &icur, 1, &new, 0);
>  	XFS_IFORK_NEXT_SET(ip, whichfork,
>  			   XFS_IFORK_NEXTENTS(ip, whichfork) + 1);
>  
> diff --git a/fs/xfs/libxfs/xfs_bmap.h b/fs/xfs/libxfs/xfs_bmap.h
> index a8777682ba57..b6a395949d0c 100644
> --- a/fs/xfs/libxfs/xfs_bmap.h
> +++ b/fs/xfs/libxfs/xfs_bmap.h
> @@ -43,7 +43,7 @@ struct xfs_bmalloca {
>  	xfs_fsblock_t		blkno;	/* starting block of new extent */
>  
>  	struct xfs_btree_cur	*cur;	/* btree cursor */
> -	xfs_extnum_t		idx;	/* current extent index */
> +	struct xfs_iext_cursor	icur;	/* incore extent cursor */
>  	int			nallocs;/* number of extents alloc'd */
>  	int			logflags;/* flags for transaction logging */
>  
> @@ -216,10 +216,11 @@ int	xfs_bunmapi(struct xfs_trans *tp, struct xfs_inode *ip,
>  		xfs_extnum_t nexts, xfs_fsblock_t *firstblock,
>  		struct xfs_defer_ops *dfops, int *done);
>  int	xfs_bmap_del_extent_delay(struct xfs_inode *ip, int whichfork,
> -		xfs_extnum_t *idx, struct xfs_bmbt_irec *got,
> +		struct xfs_iext_cursor *cur, struct xfs_bmbt_irec *got,
> +		struct xfs_bmbt_irec *del);
> +void	xfs_bmap_del_extent_cow(struct xfs_inode *ip,
> +		struct xfs_iext_cursor *cur, struct xfs_bmbt_irec *got,
>  		struct xfs_bmbt_irec *del);
> -void	xfs_bmap_del_extent_cow(struct xfs_inode *ip, xfs_extnum_t *idx,
> -		struct xfs_bmbt_irec *got, struct xfs_bmbt_irec *del);
>  uint	xfs_default_attroffset(struct xfs_inode *ip);
>  int	xfs_bmap_collapse_extents(struct xfs_trans *tp, struct xfs_inode *ip,
>  		xfs_fileoff_t *next_fsb, xfs_fileoff_t offset_shift_fsb,
> @@ -232,7 +233,8 @@ int	xfs_bmap_insert_extents(struct xfs_trans *tp, struct xfs_inode *ip,
>  int	xfs_bmap_split_extent(struct xfs_inode *ip, xfs_fileoff_t split_offset);
>  int	xfs_bmapi_reserve_delalloc(struct xfs_inode *ip, int whichfork,
>  		xfs_fileoff_t off, xfs_filblks_t len, xfs_filblks_t prealloc,
> -		struct xfs_bmbt_irec *got, xfs_extnum_t *lastx, int eof);
> +		struct xfs_bmbt_irec *got, struct xfs_iext_cursor *cur,
> +		int eof);
>  
>  enum xfs_bmap_intent_type {
>  	XFS_BMAP_MAP = 1,
> diff --git a/fs/xfs/libxfs/xfs_inode_fork.c b/fs/xfs/libxfs/xfs_inode_fork.c
> index 7dd77b497fc2..1e28532ff551 100644
> --- a/fs/xfs/libxfs/xfs_inode_fork.c
> +++ b/fs/xfs/libxfs/xfs_inode_fork.c
> @@ -343,6 +343,7 @@ xfs_iformat_extents(
>  	int			state = xfs_bmap_fork_to_state(whichfork);
>  	int			nex = XFS_DFORK_NEXTENTS(dip, whichfork);
>  	int			size = nex * sizeof(xfs_bmbt_rec_t);
> +	struct xfs_iext_cursor	icur;
>  	struct xfs_bmbt_rec	*dp;
>  	int			i;
>  
> @@ -369,16 +370,21 @@ xfs_iformat_extents(
>  	ifp->if_bytes = size;
>  	if (size) {
>  		dp = (xfs_bmbt_rec_t *) XFS_DFORK_PTR(dip, whichfork);
> +
> +		xfs_iext_first(ifp, &icur);
>  		for (i = 0; i < nex; i++, dp++) {
>  			xfs_bmbt_rec_host_t *ep = xfs_iext_get_ext(ifp, i);
> +
>  			if (!xfs_bmbt_validate_extent(mp, whichfork, dp)) {
>  				XFS_ERROR_REPORT("xfs_iformat_extents(2)",
>  						 XFS_ERRLEVEL_LOW, mp);
>  				return -EFSCORRUPTED;
>  			}
> +
>  			ep->l0 = get_unaligned_be64(&dp->l0);
>  			ep->l1 = get_unaligned_be64(&dp->l1);
> -			trace_xfs_read_extent(ip, i, state, _THIS_IP_);
> +			trace_xfs_read_extent(ip, &icur, state, _THIS_IP_);
> +			xfs_iext_next(ifp, &icur);
>  		}
>  	}
>  	ifp->if_flags |= XFS_IFEXTENTS;
> @@ -739,17 +745,18 @@ xfs_iextents_copy(
>  {
>  	int			state = xfs_bmap_fork_to_state(whichfork);
>  	struct xfs_ifork	*ifp = XFS_IFORK_PTR(ip, whichfork);
> +	struct xfs_iext_cursor	icur;
>  	struct xfs_bmbt_irec	rec;
> -	int			copied = 0, i = 0;
> +	int			copied = 0;
>  
>  	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL | XFS_ILOCK_SHARED));
>  	ASSERT(ifp->if_bytes > 0);
>  
> -	while (xfs_iext_get_extent(ifp, i++, &rec)) {
> +	for_each_iext(ifp, &icur, &rec) {
>  		if (isnullstartblock(rec.br_startblock))
>  			continue;
>  		xfs_bmbt_disk_set_all(dp, &rec);
> -		trace_xfs_write_extent(ip, i, state, _RET_IP_);
> +		trace_xfs_write_extent(ip, &icur, state, _RET_IP_);
>  		ASSERT(xfs_bmbt_validate_extent(ip->i_mount, whichfork, dp));
>  		copied += sizeof(struct xfs_bmbt_rec);
>  		dp++;
> @@ -894,7 +901,7 @@ xfs_iext_state_to_fork(
>  void
>  xfs_iext_insert(
>  	xfs_inode_t	*ip,		/* incore inode pointer */
> -	xfs_extnum_t	idx,		/* starting index of new items */
> +	struct xfs_iext_cursor *cur,
>  	xfs_extnum_t	count,		/* number of inserted items */
>  	xfs_bmbt_irec_t	*new,		/* items to insert */
>  	int		state)		/* type of extent conversion */
> @@ -902,12 +909,12 @@ xfs_iext_insert(
>  	xfs_ifork_t	*ifp = xfs_iext_state_to_fork(ip, state);
>  	xfs_extnum_t	i;		/* extent record index */
>  
> -	trace_xfs_iext_insert(ip, idx, new, state, _RET_IP_);
> +	trace_xfs_iext_insert(ip, cur->idx, new, state, _RET_IP_);
>  
>  	ASSERT(ifp->if_flags & XFS_IFEXTENTS);
> -	xfs_iext_add(ifp, idx, count);
> -	for (i = idx; i < idx + count; i++, new++)
> -		xfs_bmbt_set_all(xfs_iext_get_ext(ifp, i), new);
> +	xfs_iext_add(ifp, cur->idx, count);
> +	for (i = 0; i < count; i++, new++)
> +		xfs_bmbt_set_all(xfs_iext_get_ext(ifp, cur->idx + i), new);
>  }
>  
>  /*
> @@ -1145,7 +1152,7 @@ xfs_iext_add_indirect_multi(
>  void
>  xfs_iext_remove(
>  	xfs_inode_t	*ip,		/* incore inode pointer */
> -	xfs_extnum_t	idx,		/* index to begin removing exts */
> +	struct xfs_iext_cursor *cur,
>  	int		ext_diff,	/* number of extents to remove */
>  	int		state)		/* type of extent conversion */
>  {
> @@ -1153,7 +1160,7 @@ xfs_iext_remove(
>  	xfs_extnum_t	nextents;	/* number of extents in file */
>  	int		new_size;	/* size of extents after removal */
>  
> -	trace_xfs_iext_remove(ip, idx, state, _RET_IP_);
> +	trace_xfs_iext_remove(ip, cur, state, _RET_IP_);
>  
>  	ASSERT(ext_diff > 0);
>  	nextents = xfs_iext_count(ifp);
> @@ -1162,11 +1169,11 @@ xfs_iext_remove(
>  	if (new_size == 0) {
>  		xfs_iext_destroy(ifp);
>  	} else if (ifp->if_flags & XFS_IFEXTIREC) {
> -		xfs_iext_remove_indirect(ifp, idx, ext_diff);
> +		xfs_iext_remove_indirect(ifp, cur->idx, ext_diff);
>  	} else if (ifp->if_real_bytes) {
> -		xfs_iext_remove_direct(ifp, idx, ext_diff);
> +		xfs_iext_remove_direct(ifp, cur->idx, ext_diff);
>  	} else {
> -		xfs_iext_remove_inline(ifp, idx, ext_diff);
> +		xfs_iext_remove_inline(ifp, cur->idx, ext_diff);
>  	}
>  	ifp->if_bytes = new_size;
>  }
> @@ -1913,26 +1920,26 @@ xfs_ifork_init_cow(
>   * Lookup the extent covering bno.
>   *
>   * If there is an extent covering bno return the extent index, and store the
> - * expanded extent structure in *gotp, and the extent index in *idx.
> + * expanded extent structure in *gotp, and the extent cursor in *cur.
>   * If there is no extent covering bno, but there is an extent after it (e.g.
> - * it lies in a hole) return that extent in *gotp and its index in *idx
> + * it lies in a hole) return that extent in *gotp and its cursor in *cur
>   * instead.
> - * If bno is beyond the last extent return false, and return the index after
> - * the last valid index in *idxp.
> + * If bno is beyond the last extent return false, and return an invalid
> + * cursor value.
>   */
>  bool
>  xfs_iext_lookup_extent(
>  	struct xfs_inode	*ip,
>  	struct xfs_ifork	*ifp,
>  	xfs_fileoff_t		bno,
> -	xfs_extnum_t		*idxp,
> +	struct xfs_iext_cursor	*cur,
>  	struct xfs_bmbt_irec	*gotp)
>  {
>  	struct xfs_bmbt_rec_host *ep;
>  
>  	XFS_STATS_INC(ip->i_mount, xs_look_exlist);
>  
> -	ep = xfs_iext_bno_to_ext(ifp, bno, idxp);
> +	ep = xfs_iext_bno_to_ext(ifp, bno, &cur->idx);
>  	if (!ep)
>  		return false;
>  	xfs_bmbt_get_all(ep, gotp);
> @@ -1948,31 +1955,31 @@ xfs_iext_lookup_extent_before(
>  	struct xfs_inode	*ip,
>  	struct xfs_ifork	*ifp,
>  	xfs_fileoff_t		*end,
> -	xfs_extnum_t		*idxp,
> +	struct xfs_iext_cursor	*cur,
>  	struct xfs_bmbt_irec	*gotp)
>  {
> -	if (xfs_iext_lookup_extent(ip, ifp, *end - 1, idxp, gotp) &&
> +	if (xfs_iext_lookup_extent(ip, ifp, *end - 1, cur, gotp) &&
>  	    gotp->br_startoff <= *end - 1)
>  		return true;
> -	if (!xfs_iext_get_extent(ifp, --*idxp, gotp))
> +	if (!xfs_iext_prev_extent(ifp, cur, gotp))
>  		return false;
>  	*end = gotp->br_startoff + gotp->br_blockcount;
>  	return true;
>  }
>  
>  /*
> - * Return true if there is an extent at index idx, and return the expanded
> - * extent structure at idx in that case.  Else return false.
> + * Return true if the cursor points at an extent and return the extent structure
> + * in gotp.  Else return false.
>   */
>  bool
>  xfs_iext_get_extent(
>  	struct xfs_ifork	*ifp,
> -	xfs_extnum_t		idx,
> +	struct xfs_iext_cursor	*cur,
>  	struct xfs_bmbt_irec	*gotp)
>  {
> -	if (idx < 0 || idx >= xfs_iext_count(ifp))
> +	if (cur->idx < 0 || cur->idx >= xfs_iext_count(ifp))
>  		return false;
> -	xfs_bmbt_get_all(xfs_iext_get_ext(ifp, idx), gotp);
> +	xfs_bmbt_get_all(xfs_iext_get_ext(ifp, cur->idx), gotp);
>  	return true;
>  }
>  
> @@ -1980,15 +1987,15 @@ void
>  xfs_iext_update_extent(
>  	struct xfs_inode	*ip,
>  	int			state,
> -	xfs_extnum_t		idx,
> +	struct xfs_iext_cursor	*cur,
>  	struct xfs_bmbt_irec	*gotp)
>  {
>  	struct xfs_ifork	*ifp = xfs_iext_state_to_fork(ip, state);
>  
> -	ASSERT(idx >= 0);
> -	ASSERT(idx < xfs_iext_count(ifp));
> +	ASSERT(cur->idx >= 0);
> +	ASSERT(cur->idx < xfs_iext_count(ifp));
>  
> -	trace_xfs_bmap_pre_update(ip, idx, state, _RET_IP_);
> -	xfs_bmbt_set_all(xfs_iext_get_ext(ifp, idx), gotp);
> -	trace_xfs_bmap_post_update(ip, idx, state, _RET_IP_);
> +	trace_xfs_bmap_pre_update(ip, cur, state, _RET_IP_);
> +	xfs_bmbt_set_all(xfs_iext_get_ext(ifp, cur->idx), gotp);
> +	trace_xfs_bmap_post_update(ip, cur, state, _RET_IP_);
>  }
> diff --git a/fs/xfs/libxfs/xfs_inode_fork.h b/fs/xfs/libxfs/xfs_inode_fork.h
> index 113fd42ec36d..7065544f446a 100644
> --- a/fs/xfs/libxfs/xfs_inode_fork.h
> +++ b/fs/xfs/libxfs/xfs_inode_fork.h
> @@ -151,12 +151,13 @@ void		xfs_init_local_fork(struct xfs_inode *, int, const void *, int);
>  struct xfs_bmbt_rec_host *
>  		xfs_iext_get_ext(struct xfs_ifork *, xfs_extnum_t);
>  xfs_extnum_t	xfs_iext_count(struct xfs_ifork *);
> -void		xfs_iext_insert(struct xfs_inode *, xfs_extnum_t, xfs_extnum_t,
> -				struct xfs_bmbt_irec *, int);
> +void		xfs_iext_insert(struct xfs_inode *, struct xfs_iext_cursor *cur,
> +			xfs_extnum_t, struct xfs_bmbt_irec *, int);
>  void		xfs_iext_add(struct xfs_ifork *, xfs_extnum_t, int);
>  void		xfs_iext_add_indirect_multi(struct xfs_ifork *, int,
>  					    xfs_extnum_t, int);
> -void		xfs_iext_remove(struct xfs_inode *, xfs_extnum_t, int, int);
> +void		xfs_iext_remove(struct xfs_inode *, struct xfs_iext_cursor *,
> +			int, int);
>  void		xfs_iext_remove_inline(struct xfs_ifork *, xfs_extnum_t, int);
>  void		xfs_iext_remove_direct(struct xfs_ifork *, xfs_extnum_t, int);
>  void		xfs_iext_remove_indirect(struct xfs_ifork *, xfs_extnum_t, int);
> @@ -182,15 +183,85 @@ void		xfs_iext_irec_update_extoffs(struct xfs_ifork *, int, int);
>  
>  bool		xfs_iext_lookup_extent(struct xfs_inode *ip,
>  			struct xfs_ifork *ifp, xfs_fileoff_t bno,
> -			xfs_extnum_t *idxp, struct xfs_bmbt_irec *gotp);
> +			struct xfs_iext_cursor *cur,
> +			struct xfs_bmbt_irec *gotp);
>  bool		xfs_iext_lookup_extent_before(struct xfs_inode *ip,
>  			struct xfs_ifork *ifp, xfs_fileoff_t *end,
> -			xfs_extnum_t *idxp, struct xfs_bmbt_irec *gotp);
> -
> -bool		xfs_iext_get_extent(struct xfs_ifork *ifp, xfs_extnum_t idx,
> +			struct xfs_iext_cursor *cur,
> +			struct xfs_bmbt_irec *gotp);
> +bool		xfs_iext_get_extent(struct xfs_ifork *ifp,
> +			struct xfs_iext_cursor *cur,
>  			struct xfs_bmbt_irec *gotp);
>  void		xfs_iext_update_extent(struct xfs_inode *ip, int state,
> -			xfs_extnum_t idx, struct xfs_bmbt_irec *gotp);
> +			struct xfs_iext_cursor *cur,
> +			struct xfs_bmbt_irec *gotp);
> +
> +static inline void xfs_iext_first(struct xfs_ifork *ifp,
> +		struct xfs_iext_cursor *cur)
> +{
> +	cur->idx = 0;
> +}
> +
> +static inline void xfs_iext_last(struct xfs_ifork *ifp,
> +		struct xfs_iext_cursor *cur)
> +{
> +	cur->idx = xfs_iext_count(ifp) - 1;
> +}
> +
> +static inline void xfs_iext_next(struct xfs_ifork *ifp,
> +		struct xfs_iext_cursor *cur)
> +{
> +	cur->idx++;
> +}
> +
> +static inline void xfs_iext_prev(struct xfs_ifork *ifp,
> +		struct xfs_iext_cursor *cur)
> +{
> +	cur->idx--;
> +}
> +
> +static inline bool xfs_iext_next_extent(struct xfs_ifork *ifp,
> +		struct xfs_iext_cursor *cur, struct xfs_bmbt_irec *gotp)
> +{
> +	xfs_iext_next(ifp, cur);
> +	return xfs_iext_get_extent(ifp, cur, gotp);
> +}
> +
> +static inline bool xfs_iext_prev_extent(struct xfs_ifork *ifp,
> +		struct xfs_iext_cursor *cur, struct xfs_bmbt_irec *gotp)
> +{
> +	xfs_iext_prev(ifp, cur);
> +	return xfs_iext_get_extent(ifp, cur, gotp);
> +}
> +
> +/*
> + * Return the extent after cur in gotp without updating the cursor.
> + */
> +static inline bool xfs_iext_peek_next_extent(struct xfs_ifork *ifp,
> +		struct xfs_iext_cursor *cur, struct xfs_bmbt_irec *gotp)
> +{
> +	struct xfs_iext_cursor ncur = *cur;
> +
> +	xfs_iext_next(ifp, &ncur);
> +	return xfs_iext_get_extent(ifp, &ncur, gotp);
> +}
> +
> +/*
> + * Return the extent before cur in gotp without updating the cursor.
> + */
> +static inline bool xfs_iext_peek_prev_extent(struct xfs_ifork *ifp,
> +		struct xfs_iext_cursor *cur, struct xfs_bmbt_irec *gotp)
> +{
> +	struct xfs_iext_cursor ncur = *cur;
> +
> +	xfs_iext_prev(ifp, &ncur);
> +	return xfs_iext_get_extent(ifp, &ncur, gotp);
> +}
> +
> +#define for_each_iext(ifp, ext, got)			\
> +	for (xfs_iext_first((ifp), (ext));		\
> +	     xfs_iext_get_extent((ifp), (ext), (got));	\
> +	     xfs_iext_next((ifp), (ext)))
>  
>  extern struct kmem_zone	*xfs_ifork_zone;
>  
> diff --git a/fs/xfs/libxfs/xfs_types.h b/fs/xfs/libxfs/xfs_types.h
> index f04dbfb2f50d..5da6382bdaf1 100644
> --- a/fs/xfs/libxfs/xfs_types.h
> +++ b/fs/xfs/libxfs/xfs_types.h
> @@ -142,5 +142,8 @@ typedef uint32_t	xfs_dqid_t;
>  #define	XFS_NBWORD	(1 << XFS_NBWORDLOG)
>  #define	XFS_WORDMASK	((1 << XFS_WORDLOG) - 1)
>  
> +struct xfs_iext_cursor {
> +	xfs_extnum_t		idx;
> +};
>  
>  #endif	/* __XFS_TYPES_H__ */
> diff --git a/fs/xfs/scrub/bmap.c b/fs/xfs/scrub/bmap.c
> index 3c17b182616f..be0bc11b6594 100644
> --- a/fs/xfs/scrub/bmap.c
> +++ b/fs/xfs/scrub/bmap.c
> @@ -237,7 +237,7 @@ xfs_scrub_bmap(
>  	struct xfs_inode		*ip = sc->ip;
>  	struct xfs_ifork		*ifp;
>  	xfs_fileoff_t			endoff;
> -	xfs_extnum_t			idx;
> +	struct xfs_iext_cursor		icur;
>  	bool				found;
>  	int				error = 0;
>  
> @@ -317,9 +317,9 @@ xfs_scrub_bmap(
>  	/* Scrub extent records. */
>  	info.lastoff = 0;
>  	ifp = XFS_IFORK_PTR(ip, whichfork);
> -	for (found = xfs_iext_lookup_extent(ip, ifp, 0, &idx, &irec);
> +	for (found = xfs_iext_lookup_extent(ip, ifp, 0, &icur, &irec);
>  	     found != 0;
> -	     found = xfs_iext_get_extent(ifp, ++idx, &irec)) {
> +	     found = xfs_iext_next_extent(ifp, &icur, &irec)) {
>  		if (xfs_scrub_should_terminate(sc, &error))
>  			break;
>  		if (isnullstartblock(irec.br_startblock))
> diff --git a/fs/xfs/scrub/dir.c b/fs/xfs/scrub/dir.c
> index c61362faed4a..73ac795aa6a5 100644
> --- a/fs/xfs/scrub/dir.c
> +++ b/fs/xfs/scrub/dir.c
> @@ -614,7 +614,7 @@ xfs_scrub_directory_blocks(
>  	xfs_fileoff_t			leaf_lblk;
>  	xfs_fileoff_t			free_lblk;
>  	xfs_fileoff_t			lblk;
> -	xfs_extnum_t			idx;
> +	struct xfs_iext_cursor		icur;
>  	xfs_dablk_t			dabno;
>  	bool				found;
>  	int				is_block = 0;
> @@ -639,7 +639,7 @@ xfs_scrub_directory_blocks(
>  		goto out;
>  
>  	/* Iterate all the data extents in the directory... */
> -	found = xfs_iext_lookup_extent(sc->ip, ifp, lblk, &idx, &got);
> +	found = xfs_iext_lookup_extent(sc->ip, ifp, lblk, &icur, &got);
>  	while (found) {
>  		/* Block directories only have a single block at offset 0. */
>  		if (is_block &&
> @@ -676,17 +676,17 @@ xfs_scrub_directory_blocks(
>  		}
>  		dabno = got.br_startoff + got.br_blockcount;
>  		lblk = roundup(dabno, args.geo->fsbcount);
> -		found = xfs_iext_lookup_extent(sc->ip, ifp, lblk, &idx, &got);
> +		found = xfs_iext_lookup_extent(sc->ip, ifp, lblk, &icur, &got);
>  	}
>  
>  	if (sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
>  		goto out;
>  
>  	/* Look for a leaf1 block, which has free info. */
> -	if (xfs_iext_lookup_extent(sc->ip, ifp, leaf_lblk, &idx, &got) &&
> +	if (xfs_iext_lookup_extent(sc->ip, ifp, leaf_lblk, &icur, &got) &&
>  	    got.br_startoff == leaf_lblk &&
>  	    got.br_blockcount == args.geo->fsbcount &&
> -	    !xfs_iext_get_extent(ifp, ++idx, &got)) {
> +	    !xfs_iext_next_extent(ifp, &icur, &got)) {
>  		if (is_block) {
>  			xfs_scrub_fblock_set_corrupt(sc, XFS_DATA_FORK, lblk);
>  			goto out;
> @@ -702,7 +702,7 @@ xfs_scrub_directory_blocks(
>  
>  	/* Scan for free blocks */
>  	lblk = free_lblk;
> -	found = xfs_iext_lookup_extent(sc->ip, ifp, lblk, &idx, &got);
> +	found = xfs_iext_lookup_extent(sc->ip, ifp, lblk, &icur, &got);
>  	while (found) {
>  		/*
>  		 * Dirs can't have blocks mapped above 2^32.
> @@ -740,7 +740,7 @@ xfs_scrub_directory_blocks(
>  		}
>  		dabno = got.br_startoff + got.br_blockcount;
>  		lblk = roundup(dabno, args.geo->fsbcount);
> -		found = xfs_iext_lookup_extent(sc->ip, ifp, lblk, &idx, &got);
> +		found = xfs_iext_lookup_extent(sc->ip, ifp, lblk, &icur, &got);
>  	}
>  out:
>  	return error;
> diff --git a/fs/xfs/xfs_bmap_util.c b/fs/xfs/xfs_bmap_util.c
> index 170b74c7f2d5..515eec004971 100644
> --- a/fs/xfs/xfs_bmap_util.c
> +++ b/fs/xfs/xfs_bmap_util.c
> @@ -229,15 +229,17 @@ xfs_bmap_count_leaves(
>  	struct xfs_ifork	*ifp,
>  	xfs_filblks_t		*count)
>  {
> +	struct xfs_iext_cursor	icur;
>  	struct xfs_bmbt_irec	got;
> -	xfs_extnum_t		numrecs = 0, i = 0;
> +	xfs_extnum_t		numrecs = 0;
>  
> -	while (xfs_iext_get_extent(ifp, i++, &got)) {
> +	for_each_iext(ifp, &icur, &got) {
>  		if (!isnullstartblock(got.br_startblock)) {
>  			*count += got.br_blockcount;
>  			numrecs++;
>  		}
>  	}
> +
>  	return numrecs;
>  }
>  
> @@ -525,7 +527,7 @@ xfs_getbmap(
>  	struct xfs_ifork	*ifp;
>  	struct xfs_bmbt_irec	got, rec;
>  	xfs_filblks_t		len;
> -	xfs_extnum_t		idx;
> +	struct xfs_iext_cursor	icur;
>  
>  	if (bmv->bmv_iflags & ~BMV_IF_VALID)
>  		return -EINVAL;
> @@ -629,7 +631,7 @@ xfs_getbmap(
>  			goto out_unlock_ilock;
>  	}
>  
> -	if (!xfs_iext_lookup_extent(ip, ifp, bno, &idx, &got)) {
> +	if (!xfs_iext_lookup_extent(ip, ifp, bno, &icur, &got)) {
>  		/*
>  		 * Report a whole-file hole if the delalloc flag is set to
>  		 * stay compatible with the old implementation.
> @@ -668,7 +670,7 @@ xfs_getbmap(
>  				goto out_unlock_ilock;
>  		} while (xfs_getbmap_next_rec(&rec, bno));
>  
> -		if (!xfs_iext_get_extent(ifp, ++idx, &got)) {
> +		if (!xfs_iext_next_extent(ifp, &icur, &got)) {
>  			xfs_fileoff_t	end = XFS_B_TO_FSB(mp, XFS_ISIZE(ip));
>  
>  			out[bmv->bmv_entries - 1].bmv_oflags |= BMV_OF_LAST;
> diff --git a/fs/xfs/xfs_dir2_readdir.c b/fs/xfs/xfs_dir2_readdir.c
> index 238e3650a9d2..0c58918bc0ad 100644
> --- a/fs/xfs/xfs_dir2_readdir.c
> +++ b/fs/xfs/xfs_dir2_readdir.c
> @@ -266,7 +266,7 @@ xfs_dir2_leaf_readbuf(
>  	xfs_dablk_t		next_ra;
>  	xfs_dablk_t		map_off;
>  	xfs_dablk_t		last_da;
> -	xfs_extnum_t		idx;
> +	struct xfs_iext_cursor	icur;
>  	int			ra_want;
>  	int			error = 0;
>  
> @@ -283,7 +283,7 @@ xfs_dir2_leaf_readbuf(
>  	 */
>  	last_da = xfs_dir2_byte_to_da(geo, XFS_DIR2_LEAF_OFFSET);
>  	map_off = xfs_dir2_db_to_da(geo, xfs_dir2_byte_to_db(geo, *cur_off));
> -	if (!xfs_iext_lookup_extent(dp, ifp, map_off, &idx, &map))
> +	if (!xfs_iext_lookup_extent(dp, ifp, map_off, &icur, &map))
>  		goto out;
>  	if (map.br_startoff >= last_da)
>  		goto out;
> @@ -311,7 +311,7 @@ xfs_dir2_leaf_readbuf(
>  	if (next_ra >= last_da)
>  		goto out_no_ra;
>  	if (map.br_blockcount < geo->fsbcount &&
> -	    !xfs_iext_get_extent(ifp, ++idx, &map))
> +	    !xfs_iext_next_extent(ifp, &icur, &map))
>  		goto out_no_ra;
>  	if (map.br_startoff >= last_da)
>  		goto out_no_ra;
> @@ -334,7 +334,7 @@ xfs_dir2_leaf_readbuf(
>  			ra_want -= geo->fsbcount;
>  			next_ra += geo->fsbcount;
>  		}
> -		if (!xfs_iext_get_extent(ifp, ++idx, &map)) {
> +		if (!xfs_iext_next_extent(ifp, &icur, &map)) {
>  			*ra_blk = last_da;
>  			break;
>  		}
> diff --git a/fs/xfs/xfs_dquot.c b/fs/xfs/xfs_dquot.c
> index cd82429d8df7..8338b894d54f 100644
> --- a/fs/xfs/xfs_dquot.c
> +++ b/fs/xfs/xfs_dquot.c
> @@ -703,7 +703,7 @@ xfs_dq_get_next_id(
>  	xfs_dqid_t		next_id = *id + 1; /* simple advance */
>  	uint			lock_flags;
>  	struct xfs_bmbt_irec	got;
> -	xfs_extnum_t		idx;
> +	struct xfs_iext_cursor	cur;
>  	xfs_fsblock_t		start;
>  	int			error = 0;
>  
> @@ -727,7 +727,7 @@ xfs_dq_get_next_id(
>  			return error;
>  	}
>  
> -	if (xfs_iext_lookup_extent(quotip, &quotip->i_df, start, &idx, &got)) {
> +	if (xfs_iext_lookup_extent(quotip, &quotip->i_df, start, &cur, &got)) {
>  		/* contiguous chunk, bump startoff for the id calculation */
>  		if (got.br_startoff < start)
>  			got.br_startoff = start;
> diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c
> index da0abc8a0725..ad48e2f24699 100644
> --- a/fs/xfs/xfs_iomap.c
> +++ b/fs/xfs/xfs_iomap.c
> @@ -390,7 +390,7 @@ xfs_iomap_prealloc_size(
>  	struct xfs_inode	*ip,
>  	loff_t			offset,
>  	loff_t			count,
> -	xfs_extnum_t		idx)
> +	struct xfs_iext_cursor	*icur)
>  {
>  	struct xfs_mount	*mp = ip->i_mount;
>  	struct xfs_ifork	*ifp = XFS_IFORK_PTR(ip, XFS_DATA_FORK);
> @@ -415,7 +415,7 @@ xfs_iomap_prealloc_size(
>  	 */
>  	if ((mp->m_flags & XFS_MOUNT_DFLT_IOSIZE) ||
>  	    XFS_ISIZE(ip) < XFS_FSB_TO_B(mp, mp->m_dalign) ||
> -	    !xfs_iext_get_extent(ifp, idx - 1, &prev) ||
> +	    !xfs_iext_peek_prev_extent(ifp, icur, &prev) ||
>  	    prev.br_startoff + prev.br_blockcount < offset_fsb)
>  		return mp->m_writeio_blocks;
>  
> @@ -533,7 +533,7 @@ xfs_file_iomap_begin_delay(
>  	xfs_fileoff_t		end_fsb;
>  	int			error = 0, eof = 0;
>  	struct xfs_bmbt_irec	got;
> -	xfs_extnum_t		idx;
> +	struct xfs_iext_cursor	icur;
>  	xfs_fsblock_t		prealloc_blocks = 0;
>  
>  	ASSERT(!XFS_IS_REALTIME_INODE(ip));
> @@ -558,7 +558,7 @@ xfs_file_iomap_begin_delay(
>  			goto out_unlock;
>  	}
>  
> -	eof = !xfs_iext_lookup_extent(ip, ifp, offset_fsb, &idx, &got);
> +	eof = !xfs_iext_lookup_extent(ip, ifp, offset_fsb, &icur, &got);
>  	if (!eof && got.br_startoff <= offset_fsb) {
>  		if (xfs_is_reflink_inode(ip)) {
>  			bool		shared;
> @@ -592,7 +592,8 @@ xfs_file_iomap_begin_delay(
>  	end_fsb = min(XFS_B_TO_FSB(mp, offset + count), maxbytes_fsb);
>  
>  	if (eof) {
> -		prealloc_blocks = xfs_iomap_prealloc_size(ip, offset, count, idx);
> +		prealloc_blocks = xfs_iomap_prealloc_size(ip, offset, count,
> +				&icur);
>  		if (prealloc_blocks) {
>  			xfs_extlen_t	align;
>  			xfs_off_t	end_offset;
> @@ -614,7 +615,8 @@ xfs_file_iomap_begin_delay(
>  
>  retry:
>  	error = xfs_bmapi_reserve_delalloc(ip, XFS_DATA_FORK, offset_fsb,
> -			end_fsb - offset_fsb, prealloc_blocks, &got, &idx, eof);
> +			end_fsb - offset_fsb, prealloc_blocks, &got, &icur,
> +			eof);
>  	switch (error) {
>  	case 0:
>  		break;
> diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c
> index 1205747e1409..d86c4378facf 100644
> --- a/fs/xfs/xfs_reflink.c
> +++ b/fs/xfs/xfs_reflink.c
> @@ -273,7 +273,7 @@ xfs_reflink_reserve_cow(
>  	struct xfs_bmbt_irec	got;
>  	int			error = 0;
>  	bool			eof = false, trimmed;
> -	xfs_extnum_t		idx;
> +	struct xfs_iext_cursor	icur;
>  
>  	/*
>  	 * Search the COW fork extent list first.  This serves two purposes:
> @@ -284,7 +284,7 @@ xfs_reflink_reserve_cow(
>  	 * tree.
>  	 */
>  
> -	if (!xfs_iext_lookup_extent(ip, ifp, imap->br_startoff, &idx, &got))
> +	if (!xfs_iext_lookup_extent(ip, ifp, imap->br_startoff, &icur, &got))
>  		eof = true;
>  	if (!eof && got.br_startoff <= imap->br_startoff) {
>  		trace_xfs_reflink_cow_found(ip, imap);
> @@ -312,7 +312,7 @@ xfs_reflink_reserve_cow(
>  		return error;
>  
>  	error = xfs_bmapi_reserve_delalloc(ip, XFS_COW_FORK, imap->br_startoff,
> -			imap->br_blockcount, 0, &got, &idx, eof);
> +			imap->br_blockcount, 0, &got, &icur, eof);
>  	if (error == -ENOSPC || error == -EDQUOT)
>  		trace_xfs_reflink_cow_enospc(ip, imap);
>  	if (error)
> @@ -359,16 +359,16 @@ xfs_reflink_convert_cow(
>  	struct xfs_ifork	*ifp = XFS_IFORK_PTR(ip, XFS_COW_FORK);
>  	xfs_fileoff_t		offset_fsb = XFS_B_TO_FSBT(mp, offset);
>  	xfs_fileoff_t		end_fsb = XFS_B_TO_FSB(mp, offset + count);
> -	xfs_extnum_t		idx;
> +	struct xfs_iext_cursor	icur;
>  	bool			found;
>  	int			error = 0;
>  
>  	xfs_ilock(ip, XFS_ILOCK_EXCL);
>  
>  	/* Convert all the extents to real from unwritten. */
> -	for (found = xfs_iext_lookup_extent(ip, ifp, offset_fsb, &idx, &got);
> +	for (found = xfs_iext_lookup_extent(ip, ifp, offset_fsb, &icur, &got);
>  	     found && got.br_startoff < end_fsb;
> -	     found = xfs_iext_get_extent(ifp, ++idx, &got)) {
> +	     found = xfs_iext_next_extent(ifp, &icur, &got)) {
>  		error = xfs_reflink_convert_cow_extent(ip, &got, offset_fsb,
>  				end_fsb - offset_fsb, &dfops);
>  		if (error)
> @@ -399,7 +399,7 @@ xfs_reflink_allocate_cow(
>  	bool			trimmed;
>  	xfs_filblks_t		resaligned;
>  	xfs_extlen_t		resblks = 0;
> -	xfs_extnum_t		idx;
> +	struct xfs_iext_cursor	icur;
>  
>  retry:
>  	ASSERT(xfs_is_reflink_inode(ip));
> @@ -409,7 +409,7 @@ xfs_reflink_allocate_cow(
>  	 * Even if the extent is not shared we might have a preallocation for
>  	 * it in the COW fork.  If so use it.
>  	 */
> -	if (xfs_iext_lookup_extent(ip, ip->i_cowfp, offset_fsb, &idx, &got) &&
> +	if (xfs_iext_lookup_extent(ip, ip->i_cowfp, offset_fsb, &icur, &got) &&
>  	    got.br_startoff <= offset_fsb) {
>  		*shared = true;
>  
> @@ -496,13 +496,13 @@ xfs_reflink_find_cow_mapping(
>  	struct xfs_ifork		*ifp = XFS_IFORK_PTR(ip, XFS_COW_FORK);
>  	xfs_fileoff_t			offset_fsb;
>  	struct xfs_bmbt_irec		got;
> -	xfs_extnum_t			idx;
> +	struct xfs_iext_cursor		icur;
>  
>  	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL | XFS_ILOCK_SHARED));
>  	ASSERT(xfs_is_reflink_inode(ip));
>  
>  	offset_fsb = XFS_B_TO_FSBT(ip->i_mount, offset);
> -	if (!xfs_iext_lookup_extent(ip, ifp, offset_fsb, &idx, &got))
> +	if (!xfs_iext_lookup_extent(ip, ifp, offset_fsb, &icur, &got))
>  		return false;
>  	if (got.br_startoff > offset_fsb)
>  		return false;
> @@ -524,18 +524,18 @@ xfs_reflink_trim_irec_to_next_cow(
>  {
>  	struct xfs_ifork		*ifp = XFS_IFORK_PTR(ip, XFS_COW_FORK);
>  	struct xfs_bmbt_irec		got;
> -	xfs_extnum_t			idx;
> +	struct xfs_iext_cursor		icur;
>  
>  	if (!xfs_is_reflink_inode(ip))
>  		return;
>  
>  	/* Find the extent in the CoW fork. */
> -	if (!xfs_iext_lookup_extent(ip, ifp, offset_fsb, &idx, &got))
> +	if (!xfs_iext_lookup_extent(ip, ifp, offset_fsb, &icur, &got))
>  		return;
>  
>  	/* This is the extent before; try sliding up one. */
>  	if (got.br_startoff < offset_fsb) {
> -		if (!xfs_iext_get_extent(ifp, idx + 1, &got))
> +		if (!xfs_iext_next_extent(ifp, &icur, &got))
>  			return;
>  	}
>  
> @@ -562,14 +562,14 @@ xfs_reflink_cancel_cow_blocks(
>  {
>  	struct xfs_ifork		*ifp = XFS_IFORK_PTR(ip, XFS_COW_FORK);
>  	struct xfs_bmbt_irec		got, del;
> -	xfs_extnum_t			idx;
> +	struct xfs_iext_cursor		icur;
>  	xfs_fsblock_t			firstfsb;
>  	struct xfs_defer_ops		dfops;
>  	int				error = 0;
>  
>  	if (!xfs_is_reflink_inode(ip))
>  		return 0;
> -	if (!xfs_iext_lookup_extent(ip, ifp, offset_fsb, &idx, &got))
> +	if (!xfs_iext_lookup_extent(ip, ifp, offset_fsb, &icur, &got))
>  		return 0;
>  
>  	while (got.br_startoff < end_fsb) {
> @@ -579,7 +579,7 @@ xfs_reflink_cancel_cow_blocks(
>  
>  		if (isnullstartblock(del.br_startblock)) {
>  			error = xfs_bmap_del_extent_delay(ip, XFS_COW_FORK,
> -					&idx, &got, &del);
> +					&icur, &got, &del);
>  			if (error)
>  				break;
>  		} else if (del.br_state == XFS_EXT_UNWRITTEN || cancel_real) {
> @@ -610,10 +610,10 @@ xfs_reflink_cancel_cow_blocks(
>  			}
>  
>  			/* Remove the mapping from the CoW fork. */
> -			xfs_bmap_del_extent_cow(ip, &idx, &got, &del);
> +			xfs_bmap_del_extent_cow(ip, &icur, &got, &del);
>  		}
>  
> -		if (!xfs_iext_get_extent(ifp, ++idx, &got))
> +		if (!xfs_iext_next_extent(ifp, &icur, &got))
>  			break;
>  	}
>  
> @@ -698,7 +698,7 @@ xfs_reflink_end_cow(
>  	int				error;
>  	unsigned int			resblks;
>  	xfs_filblks_t			rlen;
> -	xfs_extnum_t			idx;
> +	struct xfs_iext_cursor		icur;
>  
>  	trace_xfs_reflink_end_cow(ip, offset, count);
>  
> @@ -738,7 +738,7 @@ xfs_reflink_end_cow(
>  	 * left by the time I/O completes for the loser of the race.  In that
>  	 * case we are done.
>  	 */
> -	if (!xfs_iext_lookup_extent_before(ip, ifp, &end_fsb, &idx, &got))
> +	if (!xfs_iext_lookup_extent_before(ip, ifp, &end_fsb, &icur, &got))
>  		goto out_cancel;
>  
>  	/* Walk backwards until we're out of the I/O range... */
> @@ -746,9 +746,9 @@ xfs_reflink_end_cow(
>  		del = got;
>  		xfs_trim_extent(&del, offset_fsb, end_fsb - offset_fsb);
>  
> -		/* Extent delete may have bumped idx forward */
> +		/* Extent delete may have bumped ext forward */
>  		if (!del.br_blockcount) {
> -			idx--;
> +			xfs_iext_prev(ifp, &icur);
>  			goto next_extent;
>  		}
>  
> @@ -760,7 +760,7 @@ xfs_reflink_end_cow(
>  		 * allocated but have not yet been involved in a write.
>  		 */
>  		if (got.br_state == XFS_EXT_UNWRITTEN) {
> -			idx--;
> +			xfs_iext_prev(ifp, &icur);
>  			goto next_extent;
>  		}
>  
> @@ -791,14 +791,14 @@ xfs_reflink_end_cow(
>  			goto out_defer;
>  
>  		/* Remove the mapping from the CoW fork. */
> -		xfs_bmap_del_extent_cow(ip, &idx, &got, &del);
> +		xfs_bmap_del_extent_cow(ip, &icur, &got, &del);
>  
>  		xfs_defer_ijoin(&dfops, ip);
>  		error = xfs_defer_finish(&tp, &dfops);
>  		if (error)
>  			goto out_defer;
>  next_extent:
> -		if (!xfs_iext_get_extent(ifp, idx, &got))
> +		if (!xfs_iext_get_extent(ifp, &icur, &got))
>  			break;
>  	}
>  
> @@ -1428,7 +1428,7 @@ xfs_reflink_inode_has_shared_extents(
>  	xfs_extlen_t			aglen;
>  	xfs_agblock_t			rbno;
>  	xfs_extlen_t			rlen;
> -	xfs_extnum_t			idx;
> +	struct xfs_iext_cursor		icur;
>  	bool				found;
>  	int				error;
>  
> @@ -1440,7 +1440,7 @@ xfs_reflink_inode_has_shared_extents(
>  	}
>  
>  	*has_shared = false;
> -	found = xfs_iext_lookup_extent(ip, ifp, 0, &idx, &got);
> +	found = xfs_iext_lookup_extent(ip, ifp, 0, &icur, &got);
>  	while (found) {
>  		if (isnullstartblock(got.br_startblock) ||
>  		    got.br_state != XFS_EXT_NORM)
> @@ -1459,7 +1459,7 @@ xfs_reflink_inode_has_shared_extents(
>  			return 0;
>  		}
>  next:
> -		found = xfs_iext_get_extent(ifp, ++idx, &got);
> +		found = xfs_iext_next_extent(ifp, &icur, &got);
>  	}
>  
>  	return 0;
> diff --git a/fs/xfs/xfs_trace.h b/fs/xfs/xfs_trace.h
> index 665ef6cca90c..667bfce802cd 100644
> --- a/fs/xfs/xfs_trace.h
> +++ b/fs/xfs/xfs_trace.h
> @@ -258,9 +258,9 @@ TRACE_EVENT(xfs_iext_insert,
>  );
>  
>  DECLARE_EVENT_CLASS(xfs_bmap_class,
> -	TP_PROTO(struct xfs_inode *ip, xfs_extnum_t idx, int state,
> +	TP_PROTO(struct xfs_inode *ip, struct xfs_iext_cursor *cur, int state,
>  		 unsigned long caller_ip),
> -	TP_ARGS(ip, idx, state, caller_ip),
> +	TP_ARGS(ip, cur, state, caller_ip),
>  	TP_STRUCT__entry(
>  		__field(dev_t, dev)
>  		__field(xfs_ino_t, ino)
> @@ -277,10 +277,10 @@ DECLARE_EVENT_CLASS(xfs_bmap_class,
>  		struct xfs_bmbt_irec	r;
>  
>  		ifp = xfs_iext_state_to_fork(ip, state);
> -		xfs_iext_get_extent(ifp, idx, &r);
> +		xfs_iext_get_extent(ifp, cur, &r);
>  		__entry->dev = VFS_I(ip)->i_sb->s_dev;
>  		__entry->ino = ip->i_ino;
> -		__entry->idx = idx;
> +		__entry->idx = cur->idx;
>  		__entry->startoff = r.br_startoff;
>  		__entry->startblock = r.br_startblock;
>  		__entry->blockcount = r.br_blockcount;
> @@ -303,9 +303,9 @@ DECLARE_EVENT_CLASS(xfs_bmap_class,
>  
>  #define DEFINE_BMAP_EVENT(name) \
>  DEFINE_EVENT(xfs_bmap_class, name, \
> -	TP_PROTO(struct xfs_inode *ip, xfs_extnum_t idx, int state, \
> +	TP_PROTO(struct xfs_inode *ip, struct xfs_iext_cursor *cur, int state, \
>  		 unsigned long caller_ip), \
> -	TP_ARGS(ip, idx, state, caller_ip))
> +	TP_ARGS(ip, cur, state, caller_ip))
>  DEFINE_BMAP_EVENT(xfs_iext_remove);
>  DEFINE_BMAP_EVENT(xfs_bmap_pre_update);
>  DEFINE_BMAP_EVENT(xfs_bmap_post_update);
> -- 
> 2.14.2
> 
> --
> To unsubscribe from this list: send the line "unsubscribe linux-xfs" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: [PATCH 12/21] xfs: introduce the xfs_iext_cursor abstraction

[Darrick J. Wong]

On Fri, Nov 03, 2017 at 05:45:30PM +0300, Christoph Hellwig wrote:
> Add a new xfs_iext_cursor structure to hide the direct extent map
> index manipulations. In addition to the existing lookup/get/insert/
> remove and update routines new primitives to get the first and last
> extent cursor, as well as moving up and down by one extent are
> provided.  Also new are convenience to increment/decrement the
> cursor and retreive the new extent, as well as to peek into the
> previous/next extent without updating the cursor and last but not
> least a macro to iterate over all extents in a fork.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>  fs/xfs/libxfs/xfs_bmap.c       | 441 ++++++++++++++++++++---------------------
>  fs/xfs/libxfs/xfs_bmap.h       |  12 +-
>  fs/xfs/libxfs/xfs_inode_fork.c |  75 +++----
>  fs/xfs/libxfs/xfs_inode_fork.h |  87 +++++++-
>  fs/xfs/libxfs/xfs_types.h      |   3 +
>  fs/xfs/scrub/bmap.c            |   6 +-
>  fs/xfs/scrub/dir.c             |  14 +-
>  fs/xfs/xfs_bmap_util.c         |  12 +-
>  fs/xfs/xfs_dir2_readdir.c      |   8 +-
>  fs/xfs/xfs_dquot.c             |   4 +-
>  fs/xfs/xfs_iomap.c             |  14 +-
>  fs/xfs/xfs_reflink.c           |  56 +++---
>  fs/xfs/xfs_trace.h             |  12 +-
>  13 files changed, 407 insertions(+), 337 deletions(-)
> 
> diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
> index f4d0639dc4ae..b08c4863c2af 100644
> --- a/fs/xfs/libxfs/xfs_bmap.c
> +++ b/fs/xfs/libxfs/xfs_bmap.c
> @@ -672,8 +672,9 @@ xfs_bmap_extents_to_btree(
>  	xfs_bmbt_key_t		*kp;		/* root block key pointer */
>  	xfs_mount_t		*mp;		/* mount structure */
>  	xfs_bmbt_ptr_t		*pp;		/* root block address pointer */
> +	struct xfs_iext_cursor	icur;
>  	struct xfs_bmbt_irec	rec;
> -	xfs_extnum_t		i = 0, cnt = 0;
> +	xfs_extnum_t		cnt = 0;
>  
>  	mp = ip->i_mount;
>  	ASSERT(whichfork != XFS_COW_FORK);
> @@ -752,7 +753,7 @@ xfs_bmap_extents_to_btree(
>  				XFS_BTNUM_BMAP, 0, 0, ip->i_ino,
>  				XFS_BTREE_LONG_PTRS);
>  
> -	while (xfs_iext_get_extent(ifp, i++, &rec)) {
> +	for_each_iext(ifp, &icur, &rec) {

I stand by my previous mutterings that 'xfs' ought to be in the name
somewhere, so if you don't mind I'll change this to 'for_each_xfs_iext'
on the way in.

Otherwise looks ok,
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>

>  		if (isnullstartblock(rec.br_startblock))
>  			continue;
>  		arp = XFS_BMBT_REC_ADDR(mp, ablock, 1 + cnt);
> @@ -828,6 +829,7 @@ xfs_bmap_local_to_extents(
>  	xfs_alloc_arg_t	args;		/* allocation arguments */
>  	xfs_buf_t	*bp;		/* buffer for extent block */
>  	struct xfs_bmbt_irec rec;
> +	struct xfs_iext_cursor icur;
>  
>  	/*
>  	 * We don't want to deal with the case of keeping inode data inline yet.
> @@ -894,7 +896,8 @@ xfs_bmap_local_to_extents(
>  	rec.br_startblock = args.fsbno;
>  	rec.br_blockcount = 1;
>  	rec.br_state = XFS_EXT_NORM;
> -	xfs_iext_insert(ip, 0, 1, &rec, 0);
> +	xfs_iext_first(ifp, &icur);
> +	xfs_iext_insert(ip, &icur, 1, &rec, 0);
>  
>  	XFS_IFORK_NEXT_SET(ip, whichfork, 1);
>  	ip->i_d.di_nblocks = 1;
> @@ -1174,6 +1177,7 @@ xfs_iread_extents(
>  	struct xfs_ifork	*ifp = XFS_IFORK_PTR(ip, whichfork);
>  	xfs_extnum_t		nextents = XFS_IFORK_NEXTENTS(ip, whichfork);
>  	struct xfs_btree_block	*block = ifp->if_broot;
> +	struct xfs_iext_cursor	icur;
>  	xfs_fsblock_t		bno;
>  	struct xfs_buf		*bp;
>  	xfs_extnum_t		i, j;
> @@ -1223,6 +1227,7 @@ xfs_iread_extents(
>  	 * Here with bp and block set to the leftmost leaf node in the tree.
>  	 */
>  	i = 0;
> +	xfs_iext_first(ifp, &icur);
>  
>  	/*
>  	 * Loop over all leaf nodes.  Copy information to the extent records.
> @@ -1264,7 +1269,8 @@ xfs_iread_extents(
>  			}
>  			trp->l0 = be64_to_cpu(frp->l0);
>  			trp->l1 = be64_to_cpu(frp->l1);
> -			trace_xfs_read_extent(ip, i, state, _THIS_IP_);
> +			trace_xfs_read_extent(ip, &icur, state, _THIS_IP_);
> +			xfs_iext_next(ifp, &icur);
>  		}
>  		xfs_trans_brelse(tp, bp);
>  		bno = nextbno;
> @@ -1312,7 +1318,7 @@ xfs_bmap_first_unused(
>  {
>  	struct xfs_ifork	*ifp = XFS_IFORK_PTR(ip, whichfork);
>  	struct xfs_bmbt_irec	got;
> -	xfs_extnum_t		idx = 0;
> +	struct xfs_iext_cursor	icur;
>  	xfs_fileoff_t		lastaddr = 0;
>  	xfs_fileoff_t		lowest, max;
>  	int			error;
> @@ -1333,7 +1339,7 @@ xfs_bmap_first_unused(
>  	}
>  
>  	lowest = max = *first_unused;
> -	while (xfs_iext_get_extent(ifp, idx++, &got)) {
> +	for_each_iext(ifp, &icur, &got) {
>  		/*
>  		 * See if the hole before this extent will work.
>  		 */
> @@ -1363,7 +1369,7 @@ xfs_bmap_last_before(
>  {
>  	struct xfs_ifork	*ifp = XFS_IFORK_PTR(ip, whichfork);
>  	struct xfs_bmbt_irec	got;
> -	xfs_extnum_t		idx;
> +	struct xfs_iext_cursor	icur;
>  	int			error;
>  
>  	switch (XFS_IFORK_FORMAT(ip, whichfork)) {
> @@ -1383,7 +1389,7 @@ xfs_bmap_last_before(
>  			return error;
>  	}
>  
> -	if (!xfs_iext_lookup_extent_before(ip, ifp, last_block, &idx, &got))
> +	if (!xfs_iext_lookup_extent_before(ip, ifp, last_block, &icur, &got))
>  		*last_block = 0;
>  	return 0;
>  }
> @@ -1397,8 +1403,8 @@ xfs_bmap_last_extent(
>  	int			*is_empty)
>  {
>  	struct xfs_ifork	*ifp = XFS_IFORK_PTR(ip, whichfork);
> +	struct xfs_iext_cursor	icur;
>  	int			error;
> -	int			nextents;
>  
>  	if (!(ifp->if_flags & XFS_IFEXTENTS)) {
>  		error = xfs_iread_extents(tp, ip, whichfork);
> @@ -1406,14 +1412,11 @@ xfs_bmap_last_extent(
>  			return error;
>  	}
>  
> -	nextents = xfs_iext_count(ifp);
> -	if (nextents == 0) {
> +	xfs_iext_last(ifp, &icur);
> +	if (!xfs_iext_get_extent(ifp, &icur, rec))
>  		*is_empty = 1;
> -		return 0;
> -	}
> -
> -	xfs_iext_get_extent(ifp, nextents - 1, rec);
> -	*is_empty = 0;
> +	else
> +		*is_empty = 0;
>  	return 0;
>  }
>  
> @@ -1501,6 +1504,7 @@ xfs_bmap_one_block(
>  	xfs_ifork_t	*ifp;		/* inode fork pointer */
>  	int		rval;		/* return value */
>  	xfs_bmbt_irec_t	s;		/* internal version of extent */
> +	struct xfs_iext_cursor icur;
>  
>  #ifndef DEBUG
>  	if (whichfork == XFS_DATA_FORK)
> @@ -1512,7 +1516,8 @@ xfs_bmap_one_block(
>  		return 0;
>  	ifp = XFS_IFORK_PTR(ip, whichfork);
>  	ASSERT(ifp->if_flags & XFS_IFEXTENTS);
> -	xfs_iext_get_extent(ifp, 0, &s);
> +	xfs_iext_first(ifp, &icur);
> +	xfs_iext_get_extent(ifp, &icur, &s);
>  	rval = s.br_startoff == 0 && s.br_blockcount == 1;
>  	if (rval && whichfork == XFS_DATA_FORK)
>  		ASSERT(XFS_ISIZE(ip) == ip->i_mount->m_sb.sb_blocksize);
> @@ -1554,8 +1559,6 @@ xfs_bmap_add_extent_delay_real(
>  	nextents = (whichfork == XFS_COW_FORK ? &bma->ip->i_cnextents :
>  						&bma->ip->i_d.di_nextents);
>  
> -	ASSERT(bma->idx >= 0);
> -	ASSERT(bma->idx <= xfs_iext_count(ifp));
>  	ASSERT(!isnullstartblock(new->br_startblock));
>  	ASSERT(!bma->cur ||
>  	       (bma->cur->bc_private.b.flags & XFS_BTCUR_BPRV_WASDEL));
> @@ -1569,7 +1572,7 @@ xfs_bmap_add_extent_delay_real(
>  	/*
>  	 * Set up a bunch of variables to make the tests simpler.
>  	 */
> -	xfs_iext_get_extent(ifp, bma->idx, &PREV);
> +	xfs_iext_get_extent(ifp, &bma->icur, &PREV);
>  	new_endoff = new->br_startoff + new->br_blockcount;
>  	ASSERT(isnullstartblock(PREV.br_startblock));
>  	ASSERT(PREV.br_startoff <= new->br_startoff);
> @@ -1591,10 +1594,8 @@ xfs_bmap_add_extent_delay_real(
>  	 * Check and set flags if this segment has a left neighbor.
>  	 * Don't set contiguous if the combined extent would be too large.
>  	 */
> -	if (bma->idx > 0) {
> +	if (xfs_iext_peek_prev_extent(ifp, &bma->icur, &LEFT)) {
>  		state |= BMAP_LEFT_VALID;
> -		xfs_iext_get_extent(ifp, bma->idx - 1, &LEFT);
> -
>  		if (isnullstartblock(LEFT.br_startblock))
>  			state |= BMAP_LEFT_DELAY;
>  	}
> @@ -1611,10 +1612,8 @@ xfs_bmap_add_extent_delay_real(
>  	 * Don't set contiguous if the combined extent would be too large.
>  	 * Also check for all-three-contiguous being too large.
>  	 */
> -	if (bma->idx < xfs_iext_count(ifp) - 1) {
> +	if (xfs_iext_peek_next_extent(ifp, &bma->icur, &RIGHT)) {
>  		state |= BMAP_RIGHT_VALID;
> -		xfs_iext_get_extent(ifp, bma->idx + 1, &RIGHT);
> -
>  		if (isnullstartblock(RIGHT.br_startblock))
>  			state |= BMAP_RIGHT_DELAY;
>  	}
> @@ -1646,9 +1645,9 @@ xfs_bmap_add_extent_delay_real(
>  		 */
>  		LEFT.br_blockcount += PREV.br_blockcount + RIGHT.br_blockcount;
>  
> -		xfs_iext_remove(bma->ip, bma->idx, 2, state);
> -		bma->idx--;
> -		xfs_iext_update_extent(bma->ip, state, bma->idx, &LEFT);
> +		xfs_iext_remove(bma->ip, &bma->icur, 2, state);
> +		xfs_iext_prev(ifp, &bma->icur);
> +		xfs_iext_update_extent(bma->ip, state, &bma->icur, &LEFT);
>  		(*nextents)--;
>  
>  		if (bma->cur == NULL)
> @@ -1681,9 +1680,9 @@ xfs_bmap_add_extent_delay_real(
>  		old = LEFT;
>  		LEFT.br_blockcount += PREV.br_blockcount;
>  
> -		xfs_iext_remove(bma->ip, bma->idx, 1, state);
> -		bma->idx--;
> -		xfs_iext_update_extent(bma->ip, state, bma->idx, &LEFT);
> +		xfs_iext_remove(bma->ip, &bma->icur, 1, state);
> +		xfs_iext_prev(ifp, &bma->icur);
> +		xfs_iext_update_extent(bma->ip, state, &bma->icur, &LEFT);
>  
>  		if (bma->cur == NULL)
>  			rval = XFS_ILOG_DEXT;
> @@ -1707,10 +1706,10 @@ xfs_bmap_add_extent_delay_real(
>  		PREV.br_startblock = new->br_startblock;
>  		PREV.br_blockcount += RIGHT.br_blockcount;
>  
> -		bma->idx++;
> -		xfs_iext_remove(bma->ip, bma->idx, 1, state);
> -		bma->idx--;
> -		xfs_iext_update_extent(bma->ip, state, bma->idx, &PREV);
> +		xfs_iext_next(ifp, &bma->icur);
> +		xfs_iext_remove(bma->ip, &bma->icur, 1, state);
> +		xfs_iext_prev(ifp, &bma->icur);
> +		xfs_iext_update_extent(bma->ip, state, &bma->icur, &PREV);
>  
>  		if (bma->cur == NULL)
>  			rval = XFS_ILOG_DEXT;
> @@ -1734,7 +1733,7 @@ xfs_bmap_add_extent_delay_real(
>  		 */
>  		PREV.br_startblock = new->br_startblock;
>  		PREV.br_state = new->br_state;
> -		xfs_iext_update_extent(bma->ip, state, bma->idx, &PREV);
> +		xfs_iext_update_extent(bma->ip, state, &bma->icur, &PREV);
>  
>  		(*nextents)++;
>  		if (bma->cur == NULL)
> @@ -1768,9 +1767,9 @@ xfs_bmap_add_extent_delay_real(
>  		PREV.br_startoff += new->br_blockcount;
>  		PREV.br_startblock = nullstartblock(da_new);
>  
> -		xfs_iext_update_extent(bma->ip, state, bma->idx, &PREV);
> -		bma->idx--;
> -		xfs_iext_update_extent(bma->ip, state, bma->idx, &LEFT);
> +		xfs_iext_update_extent(bma->ip, state, &bma->icur, &PREV);
> +		xfs_iext_prev(ifp, &bma->icur);
> +		xfs_iext_update_extent(bma->ip, state, &bma->icur, &LEFT);
>  
>  		if (bma->cur == NULL)
>  			rval = XFS_ILOG_DEXT;
> @@ -1784,7 +1783,6 @@ xfs_bmap_add_extent_delay_real(
>  			if (error)
>  				goto done;
>  		}
> -
>  		break;
>  
>  	case BMAP_LEFT_FILLING:
> @@ -1792,7 +1790,7 @@ xfs_bmap_add_extent_delay_real(
>  		 * Filling in the first part of a previous delayed allocation.
>  		 * The left neighbor is not contiguous.
>  		 */
> -		xfs_iext_update_extent(bma->ip, state, bma->idx, new);
> +		xfs_iext_update_extent(bma->ip, state, &bma->icur, new);
>  		(*nextents)++;
>  		if (bma->cur == NULL)
>  			rval = XFS_ILOG_CORE | XFS_ILOG_DEXT;
> @@ -1825,7 +1823,9 @@ xfs_bmap_add_extent_delay_real(
>  		PREV.br_startoff = new_endoff;
>  		PREV.br_blockcount = temp;
>  		PREV.br_startblock = nullstartblock(da_new);
> -		xfs_iext_insert(bma->ip, bma->idx + 1, 1, &PREV, state);
> +		xfs_iext_next(ifp, &bma->icur);
> +		xfs_iext_insert(bma->ip, &bma->icur, 1, &PREV, state);
> +		xfs_iext_prev(ifp, &bma->icur);
>  		break;
>  
>  	case BMAP_RIGHT_FILLING | BMAP_RIGHT_CONTIG:
> @@ -1858,9 +1858,9 @@ xfs_bmap_add_extent_delay_real(
>  		PREV.br_blockcount = temp;
>  		PREV.br_startblock = nullstartblock(da_new);
>  
> -		xfs_iext_update_extent(bma->ip, state, bma->idx, &PREV);
> -		bma->idx++;
> -		xfs_iext_update_extent(bma->ip, state, bma->idx, &RIGHT);
> +		xfs_iext_update_extent(bma->ip, state, &bma->icur, &PREV);
> +		xfs_iext_next(ifp, &bma->icur);
> +		xfs_iext_update_extent(bma->ip, state, &bma->icur, &RIGHT);
>  		break;
>  
>  	case BMAP_RIGHT_FILLING:
> @@ -1868,7 +1868,7 @@ xfs_bmap_add_extent_delay_real(
>  		 * Filling in the last part of a previous delayed allocation.
>  		 * The right neighbor is not contiguous.
>  		 */
> -		xfs_iext_update_extent(bma->ip, state, bma->idx, new);
> +		xfs_iext_update_extent(bma->ip, state, &bma->icur, new);
>  		(*nextents)++;
>  		if (bma->cur == NULL)
>  			rval = XFS_ILOG_CORE | XFS_ILOG_DEXT;
> @@ -1900,9 +1900,8 @@ xfs_bmap_add_extent_delay_real(
>  
>  		PREV.br_startblock = nullstartblock(da_new);
>  		PREV.br_blockcount = temp;
> -		xfs_iext_insert(bma->ip, bma->idx, 1, &PREV, state);
> -
> -		bma->idx++;
> +		xfs_iext_insert(bma->ip, &bma->icur, 1, &PREV, state);
> +		xfs_iext_next(ifp, &bma->icur);
>  		break;
>  
>  	case 0:
> @@ -1945,10 +1944,11 @@ xfs_bmap_add_extent_delay_real(
>  		PREV.br_startblock =
>  			nullstartblock(xfs_bmap_worst_indlen(bma->ip,
>  					PREV.br_blockcount));
> -		xfs_iext_update_extent(bma->ip, state, bma->idx, &PREV);
> +		xfs_iext_update_extent(bma->ip, state, &bma->icur, &PREV);
>  
>  		/* insert LEFT (r[0]) and RIGHT (r[1]) at the same time */
> -		xfs_iext_insert(bma->ip, bma->idx + 1, 2, &LEFT, state);
> +		xfs_iext_next(ifp, &bma->icur);
> +		xfs_iext_insert(bma->ip, &bma->icur, 2, &LEFT, state);
>  		(*nextents)++;
>  
>  		if (bma->cur == NULL)
> @@ -1976,7 +1976,6 @@ xfs_bmap_add_extent_delay_real(
>  
>  		da_new = startblockval(PREV.br_startblock) +
>  			 startblockval(RIGHT.br_startblock);
> -		bma->idx++;
>  		break;
>  
>  	case BMAP_LEFT_FILLING | BMAP_LEFT_CONTIG | BMAP_RIGHT_CONTIG:
> @@ -2040,7 +2039,7 @@ xfs_bmap_add_extent_unwritten_real(
>  	struct xfs_trans	*tp,
>  	xfs_inode_t		*ip,	/* incore inode pointer */
>  	int			whichfork,
> -	xfs_extnum_t		*idx,	/* extent number to update/insert */
> +	struct xfs_iext_cursor	*icur,
>  	xfs_btree_cur_t		**curp,	/* if *curp is null, not a btree */
>  	xfs_bmbt_irec_t		*new,	/* new data to add to file extents */
>  	xfs_fsblock_t		*first,	/* pointer to firstblock variable */
> @@ -2064,8 +2063,6 @@ xfs_bmap_add_extent_unwritten_real(
>  	cur = *curp;
>  	ifp = XFS_IFORK_PTR(ip, whichfork);
>  
> -	ASSERT(*idx >= 0);
> -	ASSERT(*idx <= xfs_iext_count(ifp));
>  	ASSERT(!isnullstartblock(new->br_startblock));
>  
>  	XFS_STATS_INC(mp, xs_add_exlist);
> @@ -2078,7 +2075,7 @@ xfs_bmap_add_extent_unwritten_real(
>  	 * Set up a bunch of variables to make the tests simpler.
>  	 */
>  	error = 0;
> -	xfs_iext_get_extent(ifp, *idx, &PREV);
> +	xfs_iext_get_extent(ifp, icur, &PREV);
>  	ASSERT(new->br_state != PREV.br_state);
>  	new_endoff = new->br_startoff + new->br_blockcount;
>  	ASSERT(PREV.br_startoff <= new->br_startoff);
> @@ -2097,10 +2094,8 @@ xfs_bmap_add_extent_unwritten_real(
>  	 * Check and set flags if this segment has a left neighbor.
>  	 * Don't set contiguous if the combined extent would be too large.
>  	 */
> -	if (*idx > 0) {
> +	if (xfs_iext_peek_prev_extent(ifp, icur, &LEFT)) {
>  		state |= BMAP_LEFT_VALID;
> -		xfs_iext_get_extent(ifp, *idx - 1, &LEFT);
> -
>  		if (isnullstartblock(LEFT.br_startblock))
>  			state |= BMAP_LEFT_DELAY;
>  	}
> @@ -2117,9 +2112,8 @@ xfs_bmap_add_extent_unwritten_real(
>  	 * Don't set contiguous if the combined extent would be too large.
>  	 * Also check for all-three-contiguous being too large.
>  	 */
> -	if (*idx < xfs_iext_count(ifp) - 1) {
> +	if (xfs_iext_peek_next_extent(ifp, icur, &RIGHT)) {
>  		state |= BMAP_RIGHT_VALID;
> -		xfs_iext_get_extent(ifp, *idx + 1, &RIGHT);
>  		if (isnullstartblock(RIGHT.br_startblock))
>  			state |= BMAP_RIGHT_DELAY;
>  	}
> @@ -2150,9 +2144,9 @@ xfs_bmap_add_extent_unwritten_real(
>  		 */
>  		LEFT.br_blockcount += PREV.br_blockcount + RIGHT.br_blockcount;
>  
> -		xfs_iext_remove(ip, *idx, 2, state);
> -		--*idx;
> -		xfs_iext_update_extent(ip, state, *idx, &LEFT);
> +		xfs_iext_remove(ip, icur, 2, state);
> +		xfs_iext_prev(ifp, icur);
> +		xfs_iext_update_extent(ip, state, icur, &LEFT);
>  		XFS_IFORK_NEXT_SET(ip, whichfork,
>  				XFS_IFORK_NEXTENTS(ip, whichfork) - 2);
>  		if (cur == NULL)
> @@ -2188,9 +2182,9 @@ xfs_bmap_add_extent_unwritten_real(
>  		 */
>  		LEFT.br_blockcount += PREV.br_blockcount;
>  
> -		xfs_iext_remove(ip, *idx, 1, state);
> -		--*idx;
> -		xfs_iext_update_extent(ip, state, *idx, &LEFT);
> +		xfs_iext_remove(ip, icur, 1, state);
> +		xfs_iext_prev(ifp, icur);
> +		xfs_iext_update_extent(ip, state, icur, &LEFT);
>  		XFS_IFORK_NEXT_SET(ip, whichfork,
>  				XFS_IFORK_NEXTENTS(ip, whichfork) - 1);
>  		if (cur == NULL)
> @@ -2221,10 +2215,10 @@ xfs_bmap_add_extent_unwritten_real(
>  		PREV.br_blockcount += RIGHT.br_blockcount;
>  		PREV.br_state = new->br_state;
>  
> -		++*idx;
> -		xfs_iext_remove(ip, *idx, 1, state);
> -		--*idx;
> -		xfs_iext_update_extent(ip, state, *idx, &PREV);
> +		xfs_iext_next(ifp, icur);
> +		xfs_iext_remove(ip, icur, 1, state);
> +		xfs_iext_prev(ifp, icur);
> +		xfs_iext_update_extent(ip, state, icur, &PREV);
>  
>  		XFS_IFORK_NEXT_SET(ip, whichfork,
>  				XFS_IFORK_NEXTENTS(ip, whichfork) - 1);
> @@ -2255,7 +2249,7 @@ xfs_bmap_add_extent_unwritten_real(
>  		 * the new one.
>  		 */
>  		PREV.br_state = new->br_state;
> -		xfs_iext_update_extent(ip, state, *idx, &PREV);
> +		xfs_iext_update_extent(ip, state, icur, &PREV);
>  
>  		if (cur == NULL)
>  			rval = XFS_ILOG_DEXT;
> @@ -2283,9 +2277,9 @@ xfs_bmap_add_extent_unwritten_real(
>  		PREV.br_startblock += new->br_blockcount;
>  		PREV.br_blockcount -= new->br_blockcount;
>  
> -		xfs_iext_update_extent(ip, state, *idx, &PREV);
> -		--*idx;
> -		xfs_iext_update_extent(ip, state, *idx, &LEFT);
> +		xfs_iext_update_extent(ip, state, icur, &PREV);
> +		xfs_iext_prev(ifp, icur);
> +		xfs_iext_update_extent(ip, state, icur, &LEFT);
>  
>  		if (cur == NULL)
>  			rval = XFS_ILOG_DEXT;
> @@ -2317,8 +2311,8 @@ xfs_bmap_add_extent_unwritten_real(
>  		PREV.br_startblock += new->br_blockcount;
>  		PREV.br_blockcount -= new->br_blockcount;
>  
> -		xfs_iext_update_extent(ip, state, *idx, &PREV);
> -		xfs_iext_insert(ip, *idx, 1, new, state);
> +		xfs_iext_update_extent(ip, state, icur, &PREV);
> +		xfs_iext_insert(ip, icur, 1, new, state);
>  		XFS_IFORK_NEXT_SET(ip, whichfork,
>  				XFS_IFORK_NEXTENTS(ip, whichfork) + 1);
>  		if (cur == NULL)
> @@ -2351,9 +2345,9 @@ xfs_bmap_add_extent_unwritten_real(
>  		RIGHT.br_startblock = new->br_startblock;
>  		RIGHT.br_blockcount += new->br_blockcount;
>  
> -		xfs_iext_update_extent(ip, state, *idx, &PREV);
> -		++*idx;
> -		xfs_iext_update_extent(ip, state, *idx, &RIGHT);
> +		xfs_iext_update_extent(ip, state, icur, &PREV);
> +		xfs_iext_next(ifp, icur);
> +		xfs_iext_update_extent(ip, state, icur, &RIGHT);
>  
>  		if (cur == NULL)
>  			rval = XFS_ILOG_DEXT;
> @@ -2383,9 +2377,9 @@ xfs_bmap_add_extent_unwritten_real(
>  		old = PREV;
>  		PREV.br_blockcount -= new->br_blockcount;
>  
> -		xfs_iext_update_extent(ip, state, *idx, &PREV);
> -		++*idx;
> -		xfs_iext_insert(ip, *idx, 1, new, state);
> +		xfs_iext_update_extent(ip, state, icur, &PREV);
> +		xfs_iext_next(ifp, icur);
> +		xfs_iext_insert(ip, icur, 1, new, state);
>  
>  		XFS_IFORK_NEXT_SET(ip, whichfork,
>  				XFS_IFORK_NEXTENTS(ip, whichfork) + 1);
> @@ -2426,9 +2420,9 @@ xfs_bmap_add_extent_unwritten_real(
>  		r[1].br_startblock = new->br_startblock + new->br_blockcount;
>  		r[1].br_state = PREV.br_state;
>  
> -		xfs_iext_update_extent(ip, state, *idx, &PREV);
> -		++*idx;
> -		xfs_iext_insert(ip, *idx, 2, &r[0], state);
> +		xfs_iext_update_extent(ip, state, icur, &PREV);
> +		xfs_iext_next(ifp, icur);
> +		xfs_iext_insert(ip, icur, 2, &r[0], state);
>  
>  		XFS_IFORK_NEXT_SET(ip, whichfork,
>  				XFS_IFORK_NEXTENTS(ip, whichfork) + 2);
> @@ -2517,7 +2511,7 @@ STATIC void
>  xfs_bmap_add_extent_hole_delay(
>  	xfs_inode_t		*ip,	/* incore inode pointer */
>  	int			whichfork,
> -	xfs_extnum_t		*idx,	/* extent number to update/insert */
> +	struct xfs_iext_cursor	*icur,
>  	xfs_bmbt_irec_t		*new)	/* new data to add to file extents */
>  {
>  	xfs_ifork_t		*ifp;	/* inode fork pointer */
> @@ -2534,10 +2528,8 @@ xfs_bmap_add_extent_hole_delay(
>  	/*
>  	 * Check and set flags if this segment has a left neighbor
>  	 */
> -	if (*idx > 0) {
> +	if (xfs_iext_peek_prev_extent(ifp, icur, &left)) {
>  		state |= BMAP_LEFT_VALID;
> -		xfs_iext_get_extent(ifp, *idx - 1, &left);
> -
>  		if (isnullstartblock(left.br_startblock))
>  			state |= BMAP_LEFT_DELAY;
>  	}
> @@ -2546,10 +2538,8 @@ xfs_bmap_add_extent_hole_delay(
>  	 * Check and set flags if the current (right) segment exists.
>  	 * If it doesn't exist, we're converting the hole at end-of-file.
>  	 */
> -	if (*idx < xfs_iext_count(ifp)) {
> +	if (xfs_iext_get_extent(ifp, icur, &right)) {
>  		state |= BMAP_RIGHT_VALID;
> -		xfs_iext_get_extent(ifp, *idx, &right);
> -
>  		if (isnullstartblock(right.br_startblock))
>  			state |= BMAP_RIGHT_DELAY;
>  	}
> @@ -2592,9 +2582,9 @@ xfs_bmap_add_extent_hole_delay(
>  		left.br_startblock = nullstartblock(newlen);
>  		left.br_blockcount = temp;
>  
> -		xfs_iext_remove(ip, *idx, 1, state);
> -		--*idx;
> -		xfs_iext_update_extent(ip, state, *idx, &left);
> +		xfs_iext_remove(ip, icur, 1, state);
> +		xfs_iext_prev(ifp, icur);
> +		xfs_iext_update_extent(ip, state, icur, &left);
>  		break;
>  
>  	case BMAP_LEFT_CONTIG:
> @@ -2612,8 +2602,8 @@ xfs_bmap_add_extent_hole_delay(
>  		left.br_blockcount = temp;
>  		left.br_startblock = nullstartblock(newlen);
>  
> -		--*idx;
> -		xfs_iext_update_extent(ip, state, *idx, &left);
> +		xfs_iext_prev(ifp, icur);
> +		xfs_iext_update_extent(ip, state, icur, &left);
>  		break;
>  
>  	case BMAP_RIGHT_CONTIG:
> @@ -2630,7 +2620,7 @@ xfs_bmap_add_extent_hole_delay(
>  		right.br_startoff = new->br_startoff;
>  		right.br_startblock = nullstartblock(newlen);
>  		right.br_blockcount = temp;
> -		xfs_iext_update_extent(ip, state, *idx, &right);
> +		xfs_iext_update_extent(ip, state, icur, &right);
>  		break;
>  
>  	case 0:
> @@ -2640,7 +2630,7 @@ xfs_bmap_add_extent_hole_delay(
>  		 * Insert a new entry.
>  		 */
>  		oldlen = newlen = 0;
> -		xfs_iext_insert(ip, *idx, 1, new, state);
> +		xfs_iext_insert(ip, icur, 1, new, state);
>  		break;
>  	}
>  	if (oldlen != newlen) {
> @@ -2661,7 +2651,7 @@ xfs_bmap_add_extent_hole_real(
>  	struct xfs_trans	*tp,
>  	struct xfs_inode	*ip,
>  	int			whichfork,
> -	xfs_extnum_t		*idx,
> +	struct xfs_iext_cursor	*icur,
>  	struct xfs_btree_cur	**curp,
>  	struct xfs_bmbt_irec	*new,
>  	xfs_fsblock_t		*first,
> @@ -2679,8 +2669,6 @@ xfs_bmap_add_extent_hole_real(
>  	int			state = xfs_bmap_fork_to_state(whichfork);
>  	struct xfs_bmbt_irec	old;
>  
> -	ASSERT(*idx >= 0);
> -	ASSERT(*idx <= xfs_iext_count(ifp));
>  	ASSERT(!isnullstartblock(new->br_startblock));
>  	ASSERT(!cur || !(cur->bc_private.b.flags & XFS_BTCUR_BPRV_WASDEL));
>  
> @@ -2689,9 +2677,8 @@ xfs_bmap_add_extent_hole_real(
>  	/*
>  	 * Check and set flags if this segment has a left neighbor.
>  	 */
> -	if (*idx > 0) {
> +	if (xfs_iext_peek_prev_extent(ifp, icur, &left)) {
>  		state |= BMAP_LEFT_VALID;
> -		xfs_iext_get_extent(ifp, *idx - 1, &left);
>  		if (isnullstartblock(left.br_startblock))
>  			state |= BMAP_LEFT_DELAY;
>  	}
> @@ -2700,9 +2687,8 @@ xfs_bmap_add_extent_hole_real(
>  	 * Check and set flags if this segment has a current value.
>  	 * Not true if we're inserting into the "hole" at eof.
>  	 */
> -	if (*idx < xfs_iext_count(ifp)) {
> +	if (xfs_iext_get_extent(ifp, icur, &right)) {
>  		state |= BMAP_RIGHT_VALID;
> -		xfs_iext_get_extent(ifp, *idx, &right);
>  		if (isnullstartblock(right.br_startblock))
>  			state |= BMAP_RIGHT_DELAY;
>  	}
> @@ -2741,9 +2727,9 @@ xfs_bmap_add_extent_hole_real(
>  		 */
>  		left.br_blockcount += new->br_blockcount + right.br_blockcount;
>  
> -		xfs_iext_remove(ip, *idx, 1, state);
> -		--*idx;
> -		xfs_iext_update_extent(ip, state, *idx, &left);
> +		xfs_iext_remove(ip, icur, 1, state);
> +		xfs_iext_prev(ifp, icur);
> +		xfs_iext_update_extent(ip, state, icur, &left);
>  
>  		XFS_IFORK_NEXT_SET(ip, whichfork,
>  			XFS_IFORK_NEXTENTS(ip, whichfork) - 1);
> @@ -2778,8 +2764,8 @@ xfs_bmap_add_extent_hole_real(
>  		old = left;
>  		left.br_blockcount += new->br_blockcount;
>  
> -		--*idx;
> -		xfs_iext_update_extent(ip, state, *idx, &left);
> +		xfs_iext_prev(ifp, icur);
> +		xfs_iext_update_extent(ip, state, icur, &left);
>  
>  		if (cur == NULL) {
>  			rval = xfs_ilog_fext(whichfork);
> @@ -2806,7 +2792,7 @@ xfs_bmap_add_extent_hole_real(
>  		right.br_startoff = new->br_startoff;
>  		right.br_startblock = new->br_startblock;
>  		right.br_blockcount += new->br_blockcount;
> -		xfs_iext_update_extent(ip, state, *idx, &right);
> +		xfs_iext_update_extent(ip, state, icur, &right);
>  
>  		if (cur == NULL) {
>  			rval = xfs_ilog_fext(whichfork);
> @@ -2828,7 +2814,7 @@ xfs_bmap_add_extent_hole_real(
>  		 * real allocation.
>  		 * Insert a new entry.
>  		 */
> -		xfs_iext_insert(ip, *idx, 1, new, state);
> +		xfs_iext_insert(ip, icur, 1, new, state);
>  		XFS_IFORK_NEXT_SET(ip, whichfork,
>  			XFS_IFORK_NEXTENTS(ip, whichfork) + 1);
>  		if (cur == NULL) {
> @@ -3778,7 +3764,7 @@ xfs_bmapi_read(
>  	struct xfs_bmbt_irec	got;
>  	xfs_fileoff_t		obno;
>  	xfs_fileoff_t		end;
> -	xfs_extnum_t		idx;
> +	struct xfs_iext_cursor	icur;
>  	int			error;
>  	bool			eof = false;
>  	int			n = 0;
> @@ -3820,7 +3806,7 @@ xfs_bmapi_read(
>  			return error;
>  	}
>  
> -	if (!xfs_iext_lookup_extent(ip, ifp, bno, &idx, &got))
> +	if (!xfs_iext_lookup_extent(ip, ifp, bno, &icur, &got))
>  		eof = true;
>  	end = bno + len;
>  	obno = bno;
> @@ -3852,7 +3838,7 @@ xfs_bmapi_read(
>  			break;
>  
>  		/* Else go on to the next record. */
> -		if (!xfs_iext_get_extent(ifp, ++idx, &got))
> +		if (!xfs_iext_next_extent(ifp, &icur, &got))
>  			eof = true;
>  	}
>  	*nmap = n;
> @@ -3880,7 +3866,7 @@ xfs_bmapi_reserve_delalloc(
>  	xfs_filblks_t		len,
>  	xfs_filblks_t		prealloc,
>  	struct xfs_bmbt_irec	*got,
> -	xfs_extnum_t		*lastx,
> +	struct xfs_iext_cursor	*icur,
>  	int			eof)
>  {
>  	struct xfs_mount	*mp = ip->i_mount;
> @@ -3910,7 +3896,7 @@ xfs_bmapi_reserve_delalloc(
>  	if (extsz) {
>  		struct xfs_bmbt_irec	prev;
>  
> -		if (!xfs_iext_get_extent(ifp, *lastx - 1, &prev))
> +		if (!xfs_iext_peek_prev_extent(ifp, icur, &prev))
>  			prev.br_startoff = NULLFILEOFF;
>  
>  		error = xfs_bmap_extsize_align(mp, got, &prev, extsz, rt, eof,
> @@ -3959,7 +3945,7 @@ xfs_bmapi_reserve_delalloc(
>  	got->br_blockcount = alen;
>  	got->br_state = XFS_EXT_NORM;
>  
> -	xfs_bmap_add_extent_hole_delay(ip, whichfork, lastx, got);
> +	xfs_bmap_add_extent_hole_delay(ip, whichfork, icur, got);
>  
>  	/*
>  	 * Tag the inode if blocks were preallocated. Note that COW fork
> @@ -4004,8 +3990,7 @@ xfs_bmapi_allocate(
>  	if (bma->wasdel) {
>  		bma->length = (xfs_extlen_t)bma->got.br_blockcount;
>  		bma->offset = bma->got.br_startoff;
> -		if (bma->idx)
> -			xfs_iext_get_extent(ifp, bma->idx - 1, &bma->prev);
> +		xfs_iext_peek_prev_extent(ifp, &bma->icur, &bma->prev);
>  	} else {
>  		bma->length = XFS_FILBLKS_MIN(bma->length, MAXEXTLEN);
>  		if (!bma->eof)
> @@ -4090,7 +4075,7 @@ xfs_bmapi_allocate(
>  		error = xfs_bmap_add_extent_delay_real(bma, whichfork);
>  	else
>  		error = xfs_bmap_add_extent_hole_real(bma->tp, bma->ip,
> -				whichfork, &bma->idx, &bma->cur, &bma->got,
> +				whichfork, &bma->icur, &bma->cur, &bma->got,
>  				bma->firstblock, bma->dfops, &bma->logflags);
>  
>  	bma->logflags |= tmp_logflags;
> @@ -4102,7 +4087,7 @@ xfs_bmapi_allocate(
>  	 * or xfs_bmap_add_extent_hole_real might have merged it into one of
>  	 * the neighbouring ones.
>  	 */
> -	xfs_iext_get_extent(ifp, bma->idx, &bma->got);
> +	xfs_iext_get_extent(ifp, &bma->icur, &bma->got);
>  
>  	ASSERT(bma->got.br_startoff <= bma->offset);
>  	ASSERT(bma->got.br_startoff + bma->got.br_blockcount >=
> @@ -4160,8 +4145,8 @@ xfs_bmapi_convert_unwritten(
>  	}
>  
>  	error = xfs_bmap_add_extent_unwritten_real(bma->tp, bma->ip, whichfork,
> -			&bma->idx, &bma->cur, mval, bma->firstblock, bma->dfops,
> -			&tmp_logflags);
> +			&bma->icur, &bma->cur, mval, bma->firstblock,
> +			bma->dfops, &tmp_logflags);
>  	/*
>  	 * Log the inode core unconditionally in the unwritten extent conversion
>  	 * path because the conversion might not have done so (e.g., if the
> @@ -4183,7 +4168,7 @@ xfs_bmapi_convert_unwritten(
>  	 * xfs_bmap_add_extent_unwritten_real might have merged it into one
>  	 * of the neighbouring ones.
>  	 */
> -	xfs_iext_get_extent(ifp, bma->idx, &bma->got);
> +	xfs_iext_get_extent(ifp, &bma->icur, &bma->got);
>  
>  	/*
>  	 * We may have combined previously unwritten space with written space,
> @@ -4302,9 +4287,9 @@ xfs_bmapi_write(
>  	end = bno + len;
>  	obno = bno;
>  
> -	if (!xfs_iext_lookup_extent(ip, ifp, bno, &bma.idx, &bma.got))
> +	if (!xfs_iext_lookup_extent(ip, ifp, bno, &bma.icur, &bma.got))
>  		eof = true;
> -	if (!xfs_iext_get_extent(ifp, bma.idx - 1, &bma.prev))
> +	if (!xfs_iext_peek_prev_extent(ifp, &bma.icur, &bma.prev))
>  		bma.prev.br_startoff = NULLFILEOFF;
>  	bma.tp = tp;
>  	bma.ip = ip;
> @@ -4409,7 +4394,7 @@ xfs_bmapi_write(
>  
>  		/* Else go on to the next record. */
>  		bma.prev = bma.got;
> -		if (!xfs_iext_get_extent(ifp, ++bma.idx, &bma.got))
> +		if (!xfs_iext_next_extent(ifp, &bma.icur, &bma.got))
>  			eof = true;
>  	}
>  	*nmap = n;
> @@ -4482,7 +4467,7 @@ xfs_bmapi_remap(
>  	struct xfs_btree_cur	*cur = NULL;
>  	xfs_fsblock_t		firstblock = NULLFSBLOCK;
>  	struct xfs_bmbt_irec	got;
> -	xfs_extnum_t		idx;
> +	struct xfs_iext_cursor	icur;
>  	int			logflags = 0, error;
>  
>  	ASSERT(len > 0);
> @@ -4506,7 +4491,7 @@ xfs_bmapi_remap(
>  			return error;
>  	}
>  
> -	if (xfs_iext_lookup_extent(ip, ifp, bno, &idx, &got)) {
> +	if (xfs_iext_lookup_extent(ip, ifp, bno, &icur, &got)) {
>  		/* make sure we only reflink into a hole. */
>  		ASSERT(got.br_startoff > bno);
>  		ASSERT(got.br_startoff - bno >= len);
> @@ -4527,8 +4512,8 @@ xfs_bmapi_remap(
>  	got.br_blockcount = len;
>  	got.br_state = XFS_EXT_NORM;
>  
> -	error = xfs_bmap_add_extent_hole_real(tp, ip, XFS_DATA_FORK, &idx, &cur,
> -			&got, &firstblock, dfops, &logflags);
> +	error = xfs_bmap_add_extent_hole_real(tp, ip, XFS_DATA_FORK, &icur,
> +			&cur, &got, &firstblock, dfops, &logflags);
>  	if (error)
>  		goto error0;
>  
> @@ -4644,7 +4629,7 @@ int
>  xfs_bmap_del_extent_delay(
>  	struct xfs_inode	*ip,
>  	int			whichfork,
> -	xfs_extnum_t		*idx,
> +	struct xfs_iext_cursor	*icur,
>  	struct xfs_bmbt_irec	*got,
>  	struct xfs_bmbt_irec	*del)
>  {
> @@ -4666,8 +4651,6 @@ xfs_bmap_del_extent_delay(
>  	da_old = startblockval(got->br_startblock);
>  	da_new = 0;
>  
> -	ASSERT(*idx >= 0);
> -	ASSERT(*idx <= xfs_iext_count(ifp));
>  	ASSERT(del->br_blockcount > 0);
>  	ASSERT(got->br_startoff <= del->br_startoff);
>  	ASSERT(got_endoff >= del_endoff);
> @@ -4701,8 +4684,8 @@ xfs_bmap_del_extent_delay(
>  		/*
>  		 * Matches the whole extent.  Delete the entry.
>  		 */
> -		xfs_iext_remove(ip, *idx, 1, state);
> -		--*idx;
> +		xfs_iext_remove(ip, icur, 1, state);
> +		xfs_iext_prev(ifp, icur);
>  		break;
>  	case BMAP_LEFT_FILLING:
>  		/*
> @@ -4713,7 +4696,7 @@ xfs_bmap_del_extent_delay(
>  		da_new = XFS_FILBLKS_MIN(xfs_bmap_worst_indlen(ip,
>  				got->br_blockcount), da_old);
>  		got->br_startblock = nullstartblock((int)da_new);
> -		xfs_iext_update_extent(ip, state, *idx, got);
> +		xfs_iext_update_extent(ip, state, icur, got);
>  		break;
>  	case BMAP_RIGHT_FILLING:
>  		/*
> @@ -4723,7 +4706,7 @@ xfs_bmap_del_extent_delay(
>  		da_new = XFS_FILBLKS_MIN(xfs_bmap_worst_indlen(ip,
>  				got->br_blockcount), da_old);
>  		got->br_startblock = nullstartblock((int)da_new);
> -		xfs_iext_update_extent(ip, state, *idx, got);
> +		xfs_iext_update_extent(ip, state, icur, got);
>  		break;
>  	case 0:
>  		/*
> @@ -4751,9 +4734,9 @@ xfs_bmap_del_extent_delay(
>  		new.br_state = got->br_state;
>  		new.br_startblock = nullstartblock((int)new_indlen);
>  
> -		xfs_iext_update_extent(ip, state, *idx, got);
> -		++*idx;
> -		xfs_iext_insert(ip, *idx, 1, &new, state);
> +		xfs_iext_update_extent(ip, state, icur, got);
> +		xfs_iext_next(ifp, icur);
> +		xfs_iext_insert(ip, icur, 1, &new, state);
>  
>  		da_new = got_indlen + new_indlen - stolen;
>  		del->br_blockcount -= stolen;
> @@ -4772,7 +4755,7 @@ xfs_bmap_del_extent_delay(
>  void
>  xfs_bmap_del_extent_cow(
>  	struct xfs_inode	*ip,
> -	xfs_extnum_t		*idx,
> +	struct xfs_iext_cursor	*icur,
>  	struct xfs_bmbt_irec	*got,
>  	struct xfs_bmbt_irec	*del)
>  {
> @@ -4787,8 +4770,6 @@ xfs_bmap_del_extent_cow(
>  	del_endoff = del->br_startoff + del->br_blockcount;
>  	got_endoff = got->br_startoff + got->br_blockcount;
>  
> -	ASSERT(*idx >= 0);
> -	ASSERT(*idx <= xfs_iext_count(ifp));
>  	ASSERT(del->br_blockcount > 0);
>  	ASSERT(got->br_startoff <= del->br_startoff);
>  	ASSERT(got_endoff >= del_endoff);
> @@ -4804,8 +4785,8 @@ xfs_bmap_del_extent_cow(
>  		/*
>  		 * Matches the whole extent.  Delete the entry.
>  		 */
> -		xfs_iext_remove(ip, *idx, 1, state);
> -		--*idx;
> +		xfs_iext_remove(ip, icur, 1, state);
> +		xfs_iext_prev(ifp, icur);
>  		break;
>  	case BMAP_LEFT_FILLING:
>  		/*
> @@ -4814,14 +4795,14 @@ xfs_bmap_del_extent_cow(
>  		got->br_startoff = del_endoff;
>  		got->br_blockcount -= del->br_blockcount;
>  		got->br_startblock = del->br_startblock + del->br_blockcount;
> -		xfs_iext_update_extent(ip, state, *idx, got);
> +		xfs_iext_update_extent(ip, state, icur, got);
>  		break;
>  	case BMAP_RIGHT_FILLING:
>  		/*
>  		 * Deleting the last part of the extent.
>  		 */
>  		got->br_blockcount -= del->br_blockcount;
> -		xfs_iext_update_extent(ip, state, *idx, got);
> +		xfs_iext_update_extent(ip, state, icur, got);
>  		break;
>  	case 0:
>  		/*
> @@ -4834,9 +4815,9 @@ xfs_bmap_del_extent_cow(
>  		new.br_state = got->br_state;
>  		new.br_startblock = del->br_startblock + del->br_blockcount;
>  
> -		xfs_iext_update_extent(ip, state, *idx, got);
> -		++*idx;
> -		xfs_iext_insert(ip, *idx, 1, &new, state);
> +		xfs_iext_update_extent(ip, state, icur, got);
> +		xfs_iext_next(ifp, icur);
> +		xfs_iext_insert(ip, icur, 1, &new, state);
>  		break;
>  	}
>  }
> @@ -4849,7 +4830,7 @@ STATIC int				/* error */
>  xfs_bmap_del_extent_real(
>  	xfs_inode_t		*ip,	/* incore inode pointer */
>  	xfs_trans_t		*tp,	/* current transaction pointer */
> -	xfs_extnum_t		*idx,	/* extent number to update/delete */
> +	struct xfs_iext_cursor	*icur,
>  	struct xfs_defer_ops	*dfops,	/* list of extents to be freed */
>  	xfs_btree_cur_t		*cur,	/* if null, not a btree */
>  	xfs_bmbt_irec_t		*del,	/* data to remove from extents */
> @@ -4878,9 +4859,8 @@ xfs_bmap_del_extent_real(
>  	XFS_STATS_INC(mp, xs_del_exlist);
>  
>  	ifp = XFS_IFORK_PTR(ip, whichfork);
> -	ASSERT((*idx >= 0) && (*idx < xfs_iext_count(ifp)));
>  	ASSERT(del->br_blockcount > 0);
> -	xfs_iext_get_extent(ifp, *idx, &got);
> +	xfs_iext_get_extent(ifp, icur, &got);
>  	ASSERT(got.br_startoff <= del->br_startoff);
>  	del_endoff = del->br_startoff + del->br_blockcount;
>  	got_endoff = got.br_startoff + got.br_blockcount;
> @@ -4945,9 +4925,8 @@ xfs_bmap_del_extent_real(
>  		/*
>  		 * Matches the whole extent.  Delete the entry.
>  		 */
> -		xfs_iext_remove(ip, *idx, 1, state);
> -		--*idx;
> -
> +		xfs_iext_remove(ip, icur, 1, state);
> +		xfs_iext_prev(ifp, icur);
>  		XFS_IFORK_NEXT_SET(ip, whichfork,
>  			XFS_IFORK_NEXTENTS(ip, whichfork) - 1);
>  		flags |= XFS_ILOG_CORE;
> @@ -4966,7 +4945,7 @@ xfs_bmap_del_extent_real(
>  		got.br_startoff = del_endoff;
>  		got.br_startblock = del_endblock;
>  		got.br_blockcount -= del->br_blockcount;
> -		xfs_iext_update_extent(ip, state, *idx, &got);
> +		xfs_iext_update_extent(ip, state, icur, &got);
>  		if (!cur) {
>  			flags |= xfs_ilog_fext(whichfork);
>  			break;
> @@ -4980,7 +4959,7 @@ xfs_bmap_del_extent_real(
>  		 * Deleting the last part of the extent.
>  		 */
>  		got.br_blockcount -= del->br_blockcount;
> -		xfs_iext_update_extent(ip, state, *idx, &got);
> +		xfs_iext_update_extent(ip, state, icur, &got);
>  		if (!cur) {
>  			flags |= xfs_ilog_fext(whichfork);
>  			break;
> @@ -4996,7 +4975,7 @@ xfs_bmap_del_extent_real(
>  		old = got;
>  
>  		got.br_blockcount = del->br_startoff - got.br_startoff;
> -		xfs_iext_update_extent(ip, state, *idx, &got);
> +		xfs_iext_update_extent(ip, state, icur, &got);
>  
>  		new.br_startoff = del_endoff;
>  		new.br_blockcount = got_endoff - del_endoff;
> @@ -5040,7 +5019,7 @@ xfs_bmap_del_extent_real(
>  				 * Reset the extent record back
>  				 * to the original value.
>  				 */
> -				xfs_iext_update_extent(ip, state, *idx, &old);
> +				xfs_iext_update_extent(ip, state, icur, &old);
>  				flags = 0;
>  				error = -ENOSPC;
>  				goto done;
> @@ -5050,8 +5029,8 @@ xfs_bmap_del_extent_real(
>  			flags |= xfs_ilog_fext(whichfork);
>  		XFS_IFORK_NEXT_SET(ip, whichfork,
>  			XFS_IFORK_NEXTENTS(ip, whichfork) + 1);
> -		++*idx;
> -		xfs_iext_insert(ip, *idx, 1, &new, state);
> +		xfs_iext_next(ifp, icur);
> +		xfs_iext_insert(ip, icur, 1, &new, state);
>  		break;
>  	}
>  
> @@ -5114,7 +5093,6 @@ __xfs_bunmapi(
>  	xfs_bmbt_irec_t		got;		/* current extent record */
>  	xfs_ifork_t		*ifp;		/* inode fork pointer */
>  	int			isrt;		/* freeing in rt area */
> -	xfs_extnum_t		lastx;		/* last extent index used */
>  	int			logflags;	/* transaction logging flags */
>  	xfs_extlen_t		mod;		/* rt extent offset */
>  	xfs_mount_t		*mp;		/* mount structure */
> @@ -5126,6 +5104,8 @@ __xfs_bunmapi(
>  	xfs_fileoff_t		max_len;
>  	xfs_agnumber_t		prev_agno = NULLAGNUMBER, agno;
>  	xfs_fileoff_t		end;
> +	struct xfs_iext_cursor	icur;
> +	bool			done = false;
>  
>  	trace_xfs_bunmap(ip, start, len, flags, _RET_IP_);
>  
> @@ -5168,7 +5148,7 @@ __xfs_bunmapi(
>  	isrt = (whichfork == XFS_DATA_FORK) && XFS_IS_REALTIME_INODE(ip);
>  	end = start + len;
>  
> -	if (!xfs_iext_lookup_extent_before(ip, ifp, &end, &lastx, &got)) {
> +	if (!xfs_iext_lookup_extent_before(ip, ifp, &end, &icur, &got)) {
>  		*rlen = 0;
>  		return 0;
>  	}
> @@ -5195,16 +5175,16 @@ __xfs_bunmapi(
>  	}
>  
>  	extno = 0;
> -	while (end != (xfs_fileoff_t)-1 && end >= start && lastx >= 0 &&
> +	while (end != (xfs_fileoff_t)-1 && end >= start &&
>  	       (nexts == 0 || extno < nexts) && max_len > 0) {
>  		/*
>  		 * Is the found extent after a hole in which end lives?
>  		 * Just back up to the previous extent, if so.
>  		 */
> -		if (got.br_startoff > end) {
> -			if (--lastx < 0)
> -				break;
> -			xfs_iext_get_extent(ifp, lastx, &got);
> +		if (got.br_startoff > end &&
> +		    !xfs_iext_prev_extent(ifp, &icur, &got)) {
> +			done = true;
> +			break;
>  		}
>  		/*
>  		 * Is the last block of this extent before the range
> @@ -5267,10 +5247,10 @@ __xfs_bunmapi(
>  				ASSERT(end >= mod);
>  				end -= mod > del.br_blockcount ?
>  					del.br_blockcount : mod;
> -				if (end < got.br_startoff) {
> -					if (--lastx >= 0)
> -						xfs_iext_get_extent(ifp, lastx,
> -								&got);
> +				if (end < got.br_startoff &&
> +				    !xfs_iext_prev_extent(ifp, &icur, &got)) {
> +					done = true;
> +					break;
>  				}
>  				continue;
>  			}
> @@ -5291,7 +5271,7 @@ __xfs_bunmapi(
>  			}
>  			del.br_state = XFS_EXT_UNWRITTEN;
>  			error = xfs_bmap_add_extent_unwritten_real(tp, ip,
> -					whichfork, &lastx, &cur, &del,
> +					whichfork, &icur, &cur, &del,
>  					firstblock, dfops, &logflags);
>  			if (error)
>  				goto error0;
> @@ -5318,8 +5298,11 @@ __xfs_bunmapi(
>  				 */
>  				ASSERT(end >= del.br_blockcount);
>  				end -= del.br_blockcount;
> -				if (got.br_startoff > end && --lastx >= 0)
> -					xfs_iext_get_extent(ifp, lastx, &got);
> +				if (got.br_startoff > end &&
> +				    !xfs_iext_prev_extent(ifp, &icur, &got)) {
> +					done = true;
> +					break;
> +				}
>  				continue;
>  			} else if (del.br_state == XFS_EXT_UNWRITTEN) {
>  				struct xfs_bmbt_irec	prev;
> @@ -5330,8 +5313,8 @@ __xfs_bunmapi(
>  				 * Unwrite the killed part of that one and
>  				 * try again.
>  				 */
> -				ASSERT(lastx > 0);
> -				xfs_iext_get_extent(ifp, lastx - 1, &prev);
> +				if (!xfs_iext_prev_extent(ifp, &icur, &prev))
> +					ASSERT(0);
>  				ASSERT(prev.br_state == XFS_EXT_NORM);
>  				ASSERT(!isnullstartblock(prev.br_startblock));
>  				ASSERT(del.br_startblock ==
> @@ -5343,9 +5326,8 @@ __xfs_bunmapi(
>  					prev.br_startoff = start;
>  				}
>  				prev.br_state = XFS_EXT_UNWRITTEN;
> -				lastx--;
>  				error = xfs_bmap_add_extent_unwritten_real(tp,
> -						ip, whichfork, &lastx, &cur,
> +						ip, whichfork, &icur, &cur,
>  						&prev, firstblock, dfops,
>  						&logflags);
>  				if (error)
> @@ -5355,7 +5337,7 @@ __xfs_bunmapi(
>  				ASSERT(del.br_state == XFS_EXT_NORM);
>  				del.br_state = XFS_EXT_UNWRITTEN;
>  				error = xfs_bmap_add_extent_unwritten_real(tp,
> -						ip, whichfork, &lastx, &cur,
> +						ip, whichfork, &icur, &cur,
>  						&del, firstblock, dfops,
>  						&logflags);
>  				if (error)
> @@ -5365,10 +5347,10 @@ __xfs_bunmapi(
>  		}
>  
>  		if (wasdel) {
> -			error = xfs_bmap_del_extent_delay(ip, whichfork, &lastx,
> +			error = xfs_bmap_del_extent_delay(ip, whichfork, &icur,
>  					&got, &del);
>  		} else {
> -			error = xfs_bmap_del_extent_real(ip, tp, &lastx, dfops,
> +			error = xfs_bmap_del_extent_real(ip, tp, &icur, dfops,
>  					cur, &del, &tmp_logflags, whichfork,
>  					flags);
>  			logflags |= tmp_logflags;
> @@ -5384,15 +5366,16 @@ __xfs_bunmapi(
>  		 * If not done go on to the next (previous) record.
>  		 */
>  		if (end != (xfs_fileoff_t)-1 && end >= start) {
> -			if (lastx >= 0) {
> -				xfs_iext_get_extent(ifp, lastx, &got);
> -				if (got.br_startoff > end && --lastx >= 0)
> -					xfs_iext_get_extent(ifp, lastx, &got);
> +			if (!xfs_iext_get_extent(ifp, &icur, &got) ||
> +			    (got.br_startoff > end &&
> +			     !xfs_iext_prev_extent(ifp, &icur, &got))) {
> +				done = true;
> +				break;
>  			}
>  			extno++;
>  		}
>  	}
> -	if (end == (xfs_fileoff_t)-1 || end < start || lastx < 0)
> +	if (done || end == (xfs_fileoff_t)-1 || end < start)
>  		*rlen = 0;
>  	else
>  		*rlen = end - start + 1;
> @@ -5513,7 +5496,7 @@ xfs_bmse_merge(
>  	struct xfs_inode		*ip,
>  	int				whichfork,
>  	xfs_fileoff_t			shift,		/* shift fsb */
> -	int				*current_ext,	/* idx of gotp */
> +	struct xfs_iext_cursor		*icur,
>  	struct xfs_bmbt_irec		*got,		/* extent to shift */
>  	struct xfs_bmbt_irec		*left,		/* preceding extent */
>  	struct xfs_btree_cur		*cur,
> @@ -5568,10 +5551,10 @@ xfs_bmse_merge(
>  		return error;
>  
>  done:
> -	xfs_iext_remove(ip, *current_ext, 1, 0);
> -	--*current_ext;
> -	xfs_iext_update_extent(ip, xfs_bmap_fork_to_state(whichfork),
> -			*current_ext, &new);
> +	xfs_iext_remove(ip, icur, 1, 0);
> +	xfs_iext_prev(XFS_IFORK_PTR(ip, whichfork), icur);
> +	xfs_iext_update_extent(ip, xfs_bmap_fork_to_state(whichfork), icur,
> +			&new);
>  
>  	/* update reverse mapping. rmap functions merge the rmaps for us */
>  	error = xfs_rmap_unmap_extent(mp, dfops, ip, whichfork, got);
> @@ -5586,7 +5569,7 @@ static int
>  xfs_bmap_shift_update_extent(
>  	struct xfs_inode	*ip,
>  	int			whichfork,
> -	xfs_extnum_t		idx,
> +	struct xfs_iext_cursor	*icur,
>  	struct xfs_bmbt_irec	*got,
>  	struct xfs_btree_cur	*cur,
>  	int			*logflags,
> @@ -5614,7 +5597,8 @@ xfs_bmap_shift_update_extent(
>  		*logflags |= XFS_ILOG_DEXT;
>  	}
>  
> -	xfs_iext_update_extent(ip, xfs_bmap_fork_to_state(whichfork), idx, got);
> +	xfs_iext_update_extent(ip, xfs_bmap_fork_to_state(whichfork), icur,
> +			got);
>  
>  	/* update reverse mapping */
>  	error = xfs_rmap_unmap_extent(mp, dfops, ip, whichfork, &prev);
> @@ -5639,7 +5623,7 @@ xfs_bmap_collapse_extents(
>  	struct xfs_ifork	*ifp = XFS_IFORK_PTR(ip, whichfork);
>  	struct xfs_btree_cur	*cur = NULL;
>  	struct xfs_bmbt_irec	got, prev;
> -	xfs_extnum_t		current_ext;
> +	struct xfs_iext_cursor	icur;
>  	xfs_fileoff_t		new_startoff;
>  	int			error = 0;
>  	int			logflags = 0;
> @@ -5670,14 +5654,14 @@ xfs_bmap_collapse_extents(
>  		cur->bc_private.b.flags = 0;
>  	}
>  
> -	if (!xfs_iext_lookup_extent(ip, ifp, *next_fsb, &current_ext, &got)) {
> +	if (!xfs_iext_lookup_extent(ip, ifp, *next_fsb, &icur, &got)) {
>  		*done = true;
>  		goto del_cursor;
>  	}
>  	XFS_WANT_CORRUPTED_RETURN(mp, !isnullstartblock(got.br_startblock));
>  
>  	new_startoff = got.br_startoff - offset_shift_fsb;
> -	if (xfs_iext_get_extent(ifp, current_ext - 1, &prev)) {
> +	if (xfs_iext_peek_prev_extent(ifp, &icur, &prev)) {
>  		if (new_startoff < prev.br_startoff + prev.br_blockcount) {
>  			error = -EINVAL;
>  			goto del_cursor;
> @@ -5685,8 +5669,8 @@ xfs_bmap_collapse_extents(
>  
>  		if (xfs_bmse_can_merge(&prev, &got, offset_shift_fsb)) {
>  			error = xfs_bmse_merge(ip, whichfork, offset_shift_fsb,
> -					&current_ext, &got, &prev, cur,
> -					&logflags, dfops);
> +					&icur, &got, &prev, cur, &logflags,
> +					dfops);
>  			if (error)
>  				goto del_cursor;
>  			goto done;
> @@ -5698,15 +5682,15 @@ xfs_bmap_collapse_extents(
>  		}
>  	}
>  
> -	error = xfs_bmap_shift_update_extent(ip, whichfork, current_ext, &got,
> -			cur, &logflags, dfops, new_startoff);
> +	error = xfs_bmap_shift_update_extent(ip, whichfork, &icur, &got, cur,
> +			&logflags, dfops, new_startoff);
>  	if (error)
>  		goto del_cursor;
>  
>  done:
> -	if (!xfs_iext_get_extent(ifp, ++current_ext, &got)) {
> -		 *done = true;
> -		 goto del_cursor;
> +	if (!xfs_iext_next_extent(ifp, &icur, &got)) {
> +		*done = true;
> +		goto del_cursor;
>  	}
>  
>  	*next_fsb = got.br_startoff;
> @@ -5735,7 +5719,7 @@ xfs_bmap_insert_extents(
>  	struct xfs_ifork	*ifp = XFS_IFORK_PTR(ip, whichfork);
>  	struct xfs_btree_cur	*cur = NULL;
>  	struct xfs_bmbt_irec	got, next;
> -	xfs_extnum_t		current_ext;
> +	struct xfs_iext_cursor	icur;
>  	xfs_fileoff_t		new_startoff;
>  	int			error = 0;
>  	int			logflags = 0;
> @@ -5767,15 +5751,14 @@ xfs_bmap_insert_extents(
>  	}
>  
>  	if (*next_fsb == NULLFSBLOCK) {
> -		current_ext = xfs_iext_count(ifp) - 1;
> -		if (!xfs_iext_get_extent(ifp, current_ext, &got) ||
> +		xfs_iext_last(ifp, &icur);
> +		if (!xfs_iext_get_extent(ifp, &icur, &got) ||
>  		    stop_fsb > got.br_startoff) {
>  			*done = true;
>  			goto del_cursor;
>  		}
>  	} else {
> -		if (!xfs_iext_lookup_extent(ip, ifp, *next_fsb, &current_ext,
> -				&got)) {
> +		if (!xfs_iext_lookup_extent(ip, ifp, *next_fsb, &icur, &got)) {
>  			*done = true;
>  			goto del_cursor;
>  		}
> @@ -5788,7 +5771,7 @@ xfs_bmap_insert_extents(
>  	}
>  
>  	new_startoff = got.br_startoff + offset_shift_fsb;
> -	if (xfs_iext_get_extent(ifp, current_ext + 1, &next)) {
> +	if (xfs_iext_peek_next_extent(ifp, &icur, &next)) {
>  		if (new_startoff + got.br_blockcount > next.br_startoff) {
>  			error = -EINVAL;
>  			goto del_cursor;
> @@ -5804,12 +5787,12 @@ xfs_bmap_insert_extents(
>  			WARN_ON_ONCE(1);
>  	}
>  
> -	error = xfs_bmap_shift_update_extent(ip, whichfork, current_ext, &got,
> -			cur, &logflags, dfops, new_startoff);
> +	error = xfs_bmap_shift_update_extent(ip, whichfork, &icur, &got, cur,
> +			&logflags, dfops, new_startoff);
>  	if (error)
>  		goto del_cursor;
>  
> -	if (!xfs_iext_get_extent(ifp, --current_ext, &got) ||
> +	if (!xfs_iext_prev_extent(ifp, &icur, &got) ||
>  	    stop_fsb >= got.br_startoff + got.br_blockcount) {
>  		*done = true;
>  		goto del_cursor;
> @@ -5826,10 +5809,10 @@ xfs_bmap_insert_extents(
>  }
>  
>  /*
> - * Splits an extent into two extents at split_fsb block such that it is
> - * the first block of the current_ext. @current_ext is a target extent
> - * to be split. @split_fsb is a block where the extents is split.
> - * If split_fsb lies in a hole or the first block of extents, just return 0.
> + * Splits an extent into two extents at split_fsb block such that it is the
> + * first block of the current_ext. @ext is a target extent to be split.
> + * @split_fsb is a block where the extents is split.  If split_fsb lies in a
> + * hole or the first block of extents, just return 0.
>   */
>  STATIC int
>  xfs_bmap_split_extent_at(
> @@ -5846,7 +5829,7 @@ xfs_bmap_split_extent_at(
>  	struct xfs_mount		*mp = ip->i_mount;
>  	struct xfs_ifork		*ifp;
>  	xfs_fsblock_t			gotblkcnt; /* new block count for got */
> -	xfs_extnum_t			current_ext;
> +	struct xfs_iext_cursor		icur;
>  	int				error = 0;
>  	int				logflags = 0;
>  	int				i = 0;
> @@ -5874,7 +5857,7 @@ xfs_bmap_split_extent_at(
>  	/*
>  	 * If there are not extents, or split_fsb lies in a hole we are done.
>  	 */
> -	if (!xfs_iext_lookup_extent(ip, ifp, split_fsb, &current_ext, &got) ||
> +	if (!xfs_iext_lookup_extent(ip, ifp, split_fsb, &icur, &got) ||
>  	    got.br_startoff >= split_fsb)
>  		return 0;
>  
> @@ -5896,8 +5879,8 @@ xfs_bmap_split_extent_at(
>  	}
>  
>  	got.br_blockcount = gotblkcnt;
> -	xfs_iext_update_extent(ip, xfs_bmap_fork_to_state(whichfork),
> -			current_ext, &got);
> +	xfs_iext_update_extent(ip, xfs_bmap_fork_to_state(whichfork), &icur,
> +			&got);
>  
>  	logflags = XFS_ILOG_CORE;
>  	if (cur) {
> @@ -5908,8 +5891,8 @@ xfs_bmap_split_extent_at(
>  		logflags |= XFS_ILOG_DEXT;
>  
>  	/* Add new extent */
> -	current_ext++;
> -	xfs_iext_insert(ip, current_ext, 1, &new, 0);
> +	xfs_iext_next(ifp, &icur);
> +	xfs_iext_insert(ip, &icur, 1, &new, 0);
>  	XFS_IFORK_NEXT_SET(ip, whichfork,
>  			   XFS_IFORK_NEXTENTS(ip, whichfork) + 1);
>  
> diff --git a/fs/xfs/libxfs/xfs_bmap.h b/fs/xfs/libxfs/xfs_bmap.h
> index a8777682ba57..b6a395949d0c 100644
> --- a/fs/xfs/libxfs/xfs_bmap.h
> +++ b/fs/xfs/libxfs/xfs_bmap.h
> @@ -43,7 +43,7 @@ struct xfs_bmalloca {
>  	xfs_fsblock_t		blkno;	/* starting block of new extent */
>  
>  	struct xfs_btree_cur	*cur;	/* btree cursor */
> -	xfs_extnum_t		idx;	/* current extent index */
> +	struct xfs_iext_cursor	icur;	/* incore extent cursor */
>  	int			nallocs;/* number of extents alloc'd */
>  	int			logflags;/* flags for transaction logging */
>  
> @@ -216,10 +216,11 @@ int	xfs_bunmapi(struct xfs_trans *tp, struct xfs_inode *ip,
>  		xfs_extnum_t nexts, xfs_fsblock_t *firstblock,
>  		struct xfs_defer_ops *dfops, int *done);
>  int	xfs_bmap_del_extent_delay(struct xfs_inode *ip, int whichfork,
> -		xfs_extnum_t *idx, struct xfs_bmbt_irec *got,
> +		struct xfs_iext_cursor *cur, struct xfs_bmbt_irec *got,
> +		struct xfs_bmbt_irec *del);
> +void	xfs_bmap_del_extent_cow(struct xfs_inode *ip,
> +		struct xfs_iext_cursor *cur, struct xfs_bmbt_irec *got,
>  		struct xfs_bmbt_irec *del);
> -void	xfs_bmap_del_extent_cow(struct xfs_inode *ip, xfs_extnum_t *idx,
> -		struct xfs_bmbt_irec *got, struct xfs_bmbt_irec *del);
>  uint	xfs_default_attroffset(struct xfs_inode *ip);
>  int	xfs_bmap_collapse_extents(struct xfs_trans *tp, struct xfs_inode *ip,
>  		xfs_fileoff_t *next_fsb, xfs_fileoff_t offset_shift_fsb,
> @@ -232,7 +233,8 @@ int	xfs_bmap_insert_extents(struct xfs_trans *tp, struct xfs_inode *ip,
>  int	xfs_bmap_split_extent(struct xfs_inode *ip, xfs_fileoff_t split_offset);
>  int	xfs_bmapi_reserve_delalloc(struct xfs_inode *ip, int whichfork,
>  		xfs_fileoff_t off, xfs_filblks_t len, xfs_filblks_t prealloc,
> -		struct xfs_bmbt_irec *got, xfs_extnum_t *lastx, int eof);
> +		struct xfs_bmbt_irec *got, struct xfs_iext_cursor *cur,
> +		int eof);
>  
>  enum xfs_bmap_intent_type {
>  	XFS_BMAP_MAP = 1,
> diff --git a/fs/xfs/libxfs/xfs_inode_fork.c b/fs/xfs/libxfs/xfs_inode_fork.c
> index 7dd77b497fc2..1e28532ff551 100644
> --- a/fs/xfs/libxfs/xfs_inode_fork.c
> +++ b/fs/xfs/libxfs/xfs_inode_fork.c
> @@ -343,6 +343,7 @@ xfs_iformat_extents(
>  	int			state = xfs_bmap_fork_to_state(whichfork);
>  	int			nex = XFS_DFORK_NEXTENTS(dip, whichfork);
>  	int			size = nex * sizeof(xfs_bmbt_rec_t);
> +	struct xfs_iext_cursor	icur;
>  	struct xfs_bmbt_rec	*dp;
>  	int			i;
>  
> @@ -369,16 +370,21 @@ xfs_iformat_extents(
>  	ifp->if_bytes = size;
>  	if (size) {
>  		dp = (xfs_bmbt_rec_t *) XFS_DFORK_PTR(dip, whichfork);
> +
> +		xfs_iext_first(ifp, &icur);
>  		for (i = 0; i < nex; i++, dp++) {
>  			xfs_bmbt_rec_host_t *ep = xfs_iext_get_ext(ifp, i);
> +
>  			if (!xfs_bmbt_validate_extent(mp, whichfork, dp)) {
>  				XFS_ERROR_REPORT("xfs_iformat_extents(2)",
>  						 XFS_ERRLEVEL_LOW, mp);
>  				return -EFSCORRUPTED;
>  			}
> +
>  			ep->l0 = get_unaligned_be64(&dp->l0);
>  			ep->l1 = get_unaligned_be64(&dp->l1);
> -			trace_xfs_read_extent(ip, i, state, _THIS_IP_);
> +			trace_xfs_read_extent(ip, &icur, state, _THIS_IP_);
> +			xfs_iext_next(ifp, &icur);
>  		}
>  	}
>  	ifp->if_flags |= XFS_IFEXTENTS;
> @@ -739,17 +745,18 @@ xfs_iextents_copy(
>  {
>  	int			state = xfs_bmap_fork_to_state(whichfork);
>  	struct xfs_ifork	*ifp = XFS_IFORK_PTR(ip, whichfork);
> +	struct xfs_iext_cursor	icur;
>  	struct xfs_bmbt_irec	rec;
> -	int			copied = 0, i = 0;
> +	int			copied = 0;
>  
>  	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL | XFS_ILOCK_SHARED));
>  	ASSERT(ifp->if_bytes > 0);
>  
> -	while (xfs_iext_get_extent(ifp, i++, &rec)) {
> +	for_each_iext(ifp, &icur, &rec) {
>  		if (isnullstartblock(rec.br_startblock))
>  			continue;
>  		xfs_bmbt_disk_set_all(dp, &rec);
> -		trace_xfs_write_extent(ip, i, state, _RET_IP_);
> +		trace_xfs_write_extent(ip, &icur, state, _RET_IP_);
>  		ASSERT(xfs_bmbt_validate_extent(ip->i_mount, whichfork, dp));
>  		copied += sizeof(struct xfs_bmbt_rec);
>  		dp++;
> @@ -894,7 +901,7 @@ xfs_iext_state_to_fork(
>  void
>  xfs_iext_insert(
>  	xfs_inode_t	*ip,		/* incore inode pointer */
> -	xfs_extnum_t	idx,		/* starting index of new items */
> +	struct xfs_iext_cursor *cur,
>  	xfs_extnum_t	count,		/* number of inserted items */
>  	xfs_bmbt_irec_t	*new,		/* items to insert */
>  	int		state)		/* type of extent conversion */
> @@ -902,12 +909,12 @@ xfs_iext_insert(
>  	xfs_ifork_t	*ifp = xfs_iext_state_to_fork(ip, state);
>  	xfs_extnum_t	i;		/* extent record index */
>  
> -	trace_xfs_iext_insert(ip, idx, new, state, _RET_IP_);
> +	trace_xfs_iext_insert(ip, cur->idx, new, state, _RET_IP_);
>  
>  	ASSERT(ifp->if_flags & XFS_IFEXTENTS);
> -	xfs_iext_add(ifp, idx, count);
> -	for (i = idx; i < idx + count; i++, new++)
> -		xfs_bmbt_set_all(xfs_iext_get_ext(ifp, i), new);
> +	xfs_iext_add(ifp, cur->idx, count);
> +	for (i = 0; i < count; i++, new++)
> +		xfs_bmbt_set_all(xfs_iext_get_ext(ifp, cur->idx + i), new);
>  }
>  
>  /*
> @@ -1145,7 +1152,7 @@ xfs_iext_add_indirect_multi(
>  void
>  xfs_iext_remove(
>  	xfs_inode_t	*ip,		/* incore inode pointer */
> -	xfs_extnum_t	idx,		/* index to begin removing exts */
> +	struct xfs_iext_cursor *cur,
>  	int		ext_diff,	/* number of extents to remove */
>  	int		state)		/* type of extent conversion */
>  {
> @@ -1153,7 +1160,7 @@ xfs_iext_remove(
>  	xfs_extnum_t	nextents;	/* number of extents in file */
>  	int		new_size;	/* size of extents after removal */
>  
> -	trace_xfs_iext_remove(ip, idx, state, _RET_IP_);
> +	trace_xfs_iext_remove(ip, cur, state, _RET_IP_);
>  
>  	ASSERT(ext_diff > 0);
>  	nextents = xfs_iext_count(ifp);
> @@ -1162,11 +1169,11 @@ xfs_iext_remove(
>  	if (new_size == 0) {
>  		xfs_iext_destroy(ifp);
>  	} else if (ifp->if_flags & XFS_IFEXTIREC) {
> -		xfs_iext_remove_indirect(ifp, idx, ext_diff);
> +		xfs_iext_remove_indirect(ifp, cur->idx, ext_diff);
>  	} else if (ifp->if_real_bytes) {
> -		xfs_iext_remove_direct(ifp, idx, ext_diff);
> +		xfs_iext_remove_direct(ifp, cur->idx, ext_diff);
>  	} else {
> -		xfs_iext_remove_inline(ifp, idx, ext_diff);
> +		xfs_iext_remove_inline(ifp, cur->idx, ext_diff);
>  	}
>  	ifp->if_bytes = new_size;
>  }
> @@ -1913,26 +1920,26 @@ xfs_ifork_init_cow(
>   * Lookup the extent covering bno.
>   *
>   * If there is an extent covering bno return the extent index, and store the
> - * expanded extent structure in *gotp, and the extent index in *idx.
> + * expanded extent structure in *gotp, and the extent cursor in *cur.
>   * If there is no extent covering bno, but there is an extent after it (e.g.
> - * it lies in a hole) return that extent in *gotp and its index in *idx
> + * it lies in a hole) return that extent in *gotp and its cursor in *cur
>   * instead.
> - * If bno is beyond the last extent return false, and return the index after
> - * the last valid index in *idxp.
> + * If bno is beyond the last extent return false, and return an invalid
> + * cursor value.
>   */
>  bool
>  xfs_iext_lookup_extent(
>  	struct xfs_inode	*ip,
>  	struct xfs_ifork	*ifp,
>  	xfs_fileoff_t		bno,
> -	xfs_extnum_t		*idxp,
> +	struct xfs_iext_cursor	*cur,
>  	struct xfs_bmbt_irec	*gotp)
>  {
>  	struct xfs_bmbt_rec_host *ep;
>  
>  	XFS_STATS_INC(ip->i_mount, xs_look_exlist);
>  
> -	ep = xfs_iext_bno_to_ext(ifp, bno, idxp);
> +	ep = xfs_iext_bno_to_ext(ifp, bno, &cur->idx);
>  	if (!ep)
>  		return false;
>  	xfs_bmbt_get_all(ep, gotp);
> @@ -1948,31 +1955,31 @@ xfs_iext_lookup_extent_before(
>  	struct xfs_inode	*ip,
>  	struct xfs_ifork	*ifp,
>  	xfs_fileoff_t		*end,
> -	xfs_extnum_t		*idxp,
> +	struct xfs_iext_cursor	*cur,
>  	struct xfs_bmbt_irec	*gotp)
>  {
> -	if (xfs_iext_lookup_extent(ip, ifp, *end - 1, idxp, gotp) &&
> +	if (xfs_iext_lookup_extent(ip, ifp, *end - 1, cur, gotp) &&
>  	    gotp->br_startoff <= *end - 1)
>  		return true;
> -	if (!xfs_iext_get_extent(ifp, --*idxp, gotp))
> +	if (!xfs_iext_prev_extent(ifp, cur, gotp))
>  		return false;
>  	*end = gotp->br_startoff + gotp->br_blockcount;
>  	return true;
>  }
>  
>  /*
> - * Return true if there is an extent at index idx, and return the expanded
> - * extent structure at idx in that case.  Else return false.
> + * Return true if the cursor points at an extent and return the extent structure
> + * in gotp.  Else return false.
>   */
>  bool
>  xfs_iext_get_extent(
>  	struct xfs_ifork	*ifp,
> -	xfs_extnum_t		idx,
> +	struct xfs_iext_cursor	*cur,
>  	struct xfs_bmbt_irec	*gotp)
>  {
> -	if (idx < 0 || idx >= xfs_iext_count(ifp))
> +	if (cur->idx < 0 || cur->idx >= xfs_iext_count(ifp))
>  		return false;
> -	xfs_bmbt_get_all(xfs_iext_get_ext(ifp, idx), gotp);
> +	xfs_bmbt_get_all(xfs_iext_get_ext(ifp, cur->idx), gotp);
>  	return true;
>  }
>  
> @@ -1980,15 +1987,15 @@ void
>  xfs_iext_update_extent(
>  	struct xfs_inode	*ip,
>  	int			state,
> -	xfs_extnum_t		idx,
> +	struct xfs_iext_cursor	*cur,
>  	struct xfs_bmbt_irec	*gotp)
>  {
>  	struct xfs_ifork	*ifp = xfs_iext_state_to_fork(ip, state);
>  
> -	ASSERT(idx >= 0);
> -	ASSERT(idx < xfs_iext_count(ifp));
> +	ASSERT(cur->idx >= 0);
> +	ASSERT(cur->idx < xfs_iext_count(ifp));
>  
> -	trace_xfs_bmap_pre_update(ip, idx, state, _RET_IP_);
> -	xfs_bmbt_set_all(xfs_iext_get_ext(ifp, idx), gotp);
> -	trace_xfs_bmap_post_update(ip, idx, state, _RET_IP_);
> +	trace_xfs_bmap_pre_update(ip, cur, state, _RET_IP_);
> +	xfs_bmbt_set_all(xfs_iext_get_ext(ifp, cur->idx), gotp);
> +	trace_xfs_bmap_post_update(ip, cur, state, _RET_IP_);
>  }
> diff --git a/fs/xfs/libxfs/xfs_inode_fork.h b/fs/xfs/libxfs/xfs_inode_fork.h
> index 113fd42ec36d..7065544f446a 100644
> --- a/fs/xfs/libxfs/xfs_inode_fork.h
> +++ b/fs/xfs/libxfs/xfs_inode_fork.h
> @@ -151,12 +151,13 @@ void		xfs_init_local_fork(struct xfs_inode *, int, const void *, int);
>  struct xfs_bmbt_rec_host *
>  		xfs_iext_get_ext(struct xfs_ifork *, xfs_extnum_t);
>  xfs_extnum_t	xfs_iext_count(struct xfs_ifork *);
> -void		xfs_iext_insert(struct xfs_inode *, xfs_extnum_t, xfs_extnum_t,
> -				struct xfs_bmbt_irec *, int);
> +void		xfs_iext_insert(struct xfs_inode *, struct xfs_iext_cursor *cur,
> +			xfs_extnum_t, struct xfs_bmbt_irec *, int);
>  void		xfs_iext_add(struct xfs_ifork *, xfs_extnum_t, int);
>  void		xfs_iext_add_indirect_multi(struct xfs_ifork *, int,
>  					    xfs_extnum_t, int);
> -void		xfs_iext_remove(struct xfs_inode *, xfs_extnum_t, int, int);
> +void		xfs_iext_remove(struct xfs_inode *, struct xfs_iext_cursor *,
> +			int, int);
>  void		xfs_iext_remove_inline(struct xfs_ifork *, xfs_extnum_t, int);
>  void		xfs_iext_remove_direct(struct xfs_ifork *, xfs_extnum_t, int);
>  void		xfs_iext_remove_indirect(struct xfs_ifork *, xfs_extnum_t, int);
> @@ -182,15 +183,85 @@ void		xfs_iext_irec_update_extoffs(struct xfs_ifork *, int, int);
>  
>  bool		xfs_iext_lookup_extent(struct xfs_inode *ip,
>  			struct xfs_ifork *ifp, xfs_fileoff_t bno,
> -			xfs_extnum_t *idxp, struct xfs_bmbt_irec *gotp);
> +			struct xfs_iext_cursor *cur,
> +			struct xfs_bmbt_irec *gotp);
>  bool		xfs_iext_lookup_extent_before(struct xfs_inode *ip,
>  			struct xfs_ifork *ifp, xfs_fileoff_t *end,
> -			xfs_extnum_t *idxp, struct xfs_bmbt_irec *gotp);
> -
> -bool		xfs_iext_get_extent(struct xfs_ifork *ifp, xfs_extnum_t idx,
> +			struct xfs_iext_cursor *cur,
> +			struct xfs_bmbt_irec *gotp);
> +bool		xfs_iext_get_extent(struct xfs_ifork *ifp,
> +			struct xfs_iext_cursor *cur,
>  			struct xfs_bmbt_irec *gotp);
>  void		xfs_iext_update_extent(struct xfs_inode *ip, int state,
> -			xfs_extnum_t idx, struct xfs_bmbt_irec *gotp);
> +			struct xfs_iext_cursor *cur,
> +			struct xfs_bmbt_irec *gotp);
> +
> +static inline void xfs_iext_first(struct xfs_ifork *ifp,
> +		struct xfs_iext_cursor *cur)
> +{
> +	cur->idx = 0;
> +}
> +
> +static inline void xfs_iext_last(struct xfs_ifork *ifp,
> +		struct xfs_iext_cursor *cur)
> +{
> +	cur->idx = xfs_iext_count(ifp) - 1;
> +}
> +
> +static inline void xfs_iext_next(struct xfs_ifork *ifp,
> +		struct xfs_iext_cursor *cur)
> +{
> +	cur->idx++;
> +}
> +
> +static inline void xfs_iext_prev(struct xfs_ifork *ifp,
> +		struct xfs_iext_cursor *cur)
> +{
> +	cur->idx--;
> +}
> +
> +static inline bool xfs_iext_next_extent(struct xfs_ifork *ifp,
> +		struct xfs_iext_cursor *cur, struct xfs_bmbt_irec *gotp)
> +{
> +	xfs_iext_next(ifp, cur);
> +	return xfs_iext_get_extent(ifp, cur, gotp);
> +}
> +
> +static inline bool xfs_iext_prev_extent(struct xfs_ifork *ifp,
> +		struct xfs_iext_cursor *cur, struct xfs_bmbt_irec *gotp)
> +{
> +	xfs_iext_prev(ifp, cur);
> +	return xfs_iext_get_extent(ifp, cur, gotp);
> +}
> +
> +/*
> + * Return the extent after cur in gotp without updating the cursor.
> + */
> +static inline bool xfs_iext_peek_next_extent(struct xfs_ifork *ifp,
> +		struct xfs_iext_cursor *cur, struct xfs_bmbt_irec *gotp)
> +{
> +	struct xfs_iext_cursor ncur = *cur;
> +
> +	xfs_iext_next(ifp, &ncur);
> +	return xfs_iext_get_extent(ifp, &ncur, gotp);
> +}
> +
> +/*
> + * Return the extent before cur in gotp without updating the cursor.
> + */
> +static inline bool xfs_iext_peek_prev_extent(struct xfs_ifork *ifp,
> +		struct xfs_iext_cursor *cur, struct xfs_bmbt_irec *gotp)
> +{
> +	struct xfs_iext_cursor ncur = *cur;
> +
> +	xfs_iext_prev(ifp, &ncur);
> +	return xfs_iext_get_extent(ifp, &ncur, gotp);
> +}
> +
> +#define for_each_iext(ifp, ext, got)			\
> +	for (xfs_iext_first((ifp), (ext));		\
> +	     xfs_iext_get_extent((ifp), (ext), (got));	\
> +	     xfs_iext_next((ifp), (ext)))
>  
>  extern struct kmem_zone	*xfs_ifork_zone;
>  
> diff --git a/fs/xfs/libxfs/xfs_types.h b/fs/xfs/libxfs/xfs_types.h
> index f04dbfb2f50d..5da6382bdaf1 100644
> --- a/fs/xfs/libxfs/xfs_types.h
> +++ b/fs/xfs/libxfs/xfs_types.h
> @@ -142,5 +142,8 @@ typedef uint32_t	xfs_dqid_t;
>  #define	XFS_NBWORD	(1 << XFS_NBWORDLOG)
>  #define	XFS_WORDMASK	((1 << XFS_WORDLOG) - 1)
>  
> +struct xfs_iext_cursor {
> +	xfs_extnum_t		idx;
> +};
>  
>  #endif	/* __XFS_TYPES_H__ */
> diff --git a/fs/xfs/scrub/bmap.c b/fs/xfs/scrub/bmap.c
> index 3c17b182616f..be0bc11b6594 100644
> --- a/fs/xfs/scrub/bmap.c
> +++ b/fs/xfs/scrub/bmap.c
> @@ -237,7 +237,7 @@ xfs_scrub_bmap(
>  	struct xfs_inode		*ip = sc->ip;
>  	struct xfs_ifork		*ifp;
>  	xfs_fileoff_t			endoff;
> -	xfs_extnum_t			idx;
> +	struct xfs_iext_cursor		icur;
>  	bool				found;
>  	int				error = 0;
>  
> @@ -317,9 +317,9 @@ xfs_scrub_bmap(
>  	/* Scrub extent records. */
>  	info.lastoff = 0;
>  	ifp = XFS_IFORK_PTR(ip, whichfork);
> -	for (found = xfs_iext_lookup_extent(ip, ifp, 0, &idx, &irec);
> +	for (found = xfs_iext_lookup_extent(ip, ifp, 0, &icur, &irec);
>  	     found != 0;
> -	     found = xfs_iext_get_extent(ifp, ++idx, &irec)) {
> +	     found = xfs_iext_next_extent(ifp, &icur, &irec)) {
>  		if (xfs_scrub_should_terminate(sc, &error))
>  			break;
>  		if (isnullstartblock(irec.br_startblock))
> diff --git a/fs/xfs/scrub/dir.c b/fs/xfs/scrub/dir.c
> index c61362faed4a..73ac795aa6a5 100644
> --- a/fs/xfs/scrub/dir.c
> +++ b/fs/xfs/scrub/dir.c
> @@ -614,7 +614,7 @@ xfs_scrub_directory_blocks(
>  	xfs_fileoff_t			leaf_lblk;
>  	xfs_fileoff_t			free_lblk;
>  	xfs_fileoff_t			lblk;
> -	xfs_extnum_t			idx;
> +	struct xfs_iext_cursor		icur;
>  	xfs_dablk_t			dabno;
>  	bool				found;
>  	int				is_block = 0;
> @@ -639,7 +639,7 @@ xfs_scrub_directory_blocks(
>  		goto out;
>  
>  	/* Iterate all the data extents in the directory... */
> -	found = xfs_iext_lookup_extent(sc->ip, ifp, lblk, &idx, &got);
> +	found = xfs_iext_lookup_extent(sc->ip, ifp, lblk, &icur, &got);
>  	while (found) {
>  		/* Block directories only have a single block at offset 0. */
>  		if (is_block &&
> @@ -676,17 +676,17 @@ xfs_scrub_directory_blocks(
>  		}
>  		dabno = got.br_startoff + got.br_blockcount;
>  		lblk = roundup(dabno, args.geo->fsbcount);
> -		found = xfs_iext_lookup_extent(sc->ip, ifp, lblk, &idx, &got);
> +		found = xfs_iext_lookup_extent(sc->ip, ifp, lblk, &icur, &got);
>  	}
>  
>  	if (sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
>  		goto out;
>  
>  	/* Look for a leaf1 block, which has free info. */
> -	if (xfs_iext_lookup_extent(sc->ip, ifp, leaf_lblk, &idx, &got) &&
> +	if (xfs_iext_lookup_extent(sc->ip, ifp, leaf_lblk, &icur, &got) &&
>  	    got.br_startoff == leaf_lblk &&
>  	    got.br_blockcount == args.geo->fsbcount &&
> -	    !xfs_iext_get_extent(ifp, ++idx, &got)) {
> +	    !xfs_iext_next_extent(ifp, &icur, &got)) {
>  		if (is_block) {
>  			xfs_scrub_fblock_set_corrupt(sc, XFS_DATA_FORK, lblk);
>  			goto out;
> @@ -702,7 +702,7 @@ xfs_scrub_directory_blocks(
>  
>  	/* Scan for free blocks */
>  	lblk = free_lblk;
> -	found = xfs_iext_lookup_extent(sc->ip, ifp, lblk, &idx, &got);
> +	found = xfs_iext_lookup_extent(sc->ip, ifp, lblk, &icur, &got);
>  	while (found) {
>  		/*
>  		 * Dirs can't have blocks mapped above 2^32.
> @@ -740,7 +740,7 @@ xfs_scrub_directory_blocks(
>  		}
>  		dabno = got.br_startoff + got.br_blockcount;
>  		lblk = roundup(dabno, args.geo->fsbcount);
> -		found = xfs_iext_lookup_extent(sc->ip, ifp, lblk, &idx, &got);
> +		found = xfs_iext_lookup_extent(sc->ip, ifp, lblk, &icur, &got);
>  	}
>  out:
>  	return error;
> diff --git a/fs/xfs/xfs_bmap_util.c b/fs/xfs/xfs_bmap_util.c
> index 170b74c7f2d5..515eec004971 100644
> --- a/fs/xfs/xfs_bmap_util.c
> +++ b/fs/xfs/xfs_bmap_util.c
> @@ -229,15 +229,17 @@ xfs_bmap_count_leaves(
>  	struct xfs_ifork	*ifp,
>  	xfs_filblks_t		*count)
>  {
> +	struct xfs_iext_cursor	icur;
>  	struct xfs_bmbt_irec	got;
> -	xfs_extnum_t		numrecs = 0, i = 0;
> +	xfs_extnum_t		numrecs = 0;
>  
> -	while (xfs_iext_get_extent(ifp, i++, &got)) {
> +	for_each_iext(ifp, &icur, &got) {
>  		if (!isnullstartblock(got.br_startblock)) {
>  			*count += got.br_blockcount;
>  			numrecs++;
>  		}
>  	}
> +
>  	return numrecs;
>  }
>  
> @@ -525,7 +527,7 @@ xfs_getbmap(
>  	struct xfs_ifork	*ifp;
>  	struct xfs_bmbt_irec	got, rec;
>  	xfs_filblks_t		len;
> -	xfs_extnum_t		idx;
> +	struct xfs_iext_cursor	icur;
>  
>  	if (bmv->bmv_iflags & ~BMV_IF_VALID)
>  		return -EINVAL;
> @@ -629,7 +631,7 @@ xfs_getbmap(
>  			goto out_unlock_ilock;
>  	}
>  
> -	if (!xfs_iext_lookup_extent(ip, ifp, bno, &idx, &got)) {
> +	if (!xfs_iext_lookup_extent(ip, ifp, bno, &icur, &got)) {
>  		/*
>  		 * Report a whole-file hole if the delalloc flag is set to
>  		 * stay compatible with the old implementation.
> @@ -668,7 +670,7 @@ xfs_getbmap(
>  				goto out_unlock_ilock;
>  		} while (xfs_getbmap_next_rec(&rec, bno));
>  
> -		if (!xfs_iext_get_extent(ifp, ++idx, &got)) {
> +		if (!xfs_iext_next_extent(ifp, &icur, &got)) {
>  			xfs_fileoff_t	end = XFS_B_TO_FSB(mp, XFS_ISIZE(ip));
>  
>  			out[bmv->bmv_entries - 1].bmv_oflags |= BMV_OF_LAST;
> diff --git a/fs/xfs/xfs_dir2_readdir.c b/fs/xfs/xfs_dir2_readdir.c
> index 238e3650a9d2..0c58918bc0ad 100644
> --- a/fs/xfs/xfs_dir2_readdir.c
> +++ b/fs/xfs/xfs_dir2_readdir.c
> @@ -266,7 +266,7 @@ xfs_dir2_leaf_readbuf(
>  	xfs_dablk_t		next_ra;
>  	xfs_dablk_t		map_off;
>  	xfs_dablk_t		last_da;
> -	xfs_extnum_t		idx;
> +	struct xfs_iext_cursor	icur;
>  	int			ra_want;
>  	int			error = 0;
>  
> @@ -283,7 +283,7 @@ xfs_dir2_leaf_readbuf(
>  	 */
>  	last_da = xfs_dir2_byte_to_da(geo, XFS_DIR2_LEAF_OFFSET);
>  	map_off = xfs_dir2_db_to_da(geo, xfs_dir2_byte_to_db(geo, *cur_off));
> -	if (!xfs_iext_lookup_extent(dp, ifp, map_off, &idx, &map))
> +	if (!xfs_iext_lookup_extent(dp, ifp, map_off, &icur, &map))
>  		goto out;
>  	if (map.br_startoff >= last_da)
>  		goto out;
> @@ -311,7 +311,7 @@ xfs_dir2_leaf_readbuf(
>  	if (next_ra >= last_da)
>  		goto out_no_ra;
>  	if (map.br_blockcount < geo->fsbcount &&
> -	    !xfs_iext_get_extent(ifp, ++idx, &map))
> +	    !xfs_iext_next_extent(ifp, &icur, &map))
>  		goto out_no_ra;
>  	if (map.br_startoff >= last_da)
>  		goto out_no_ra;
> @@ -334,7 +334,7 @@ xfs_dir2_leaf_readbuf(
>  			ra_want -= geo->fsbcount;
>  			next_ra += geo->fsbcount;
>  		}
> -		if (!xfs_iext_get_extent(ifp, ++idx, &map)) {
> +		if (!xfs_iext_next_extent(ifp, &icur, &map)) {
>  			*ra_blk = last_da;
>  			break;
>  		}
> diff --git a/fs/xfs/xfs_dquot.c b/fs/xfs/xfs_dquot.c
> index cd82429d8df7..8338b894d54f 100644
> --- a/fs/xfs/xfs_dquot.c
> +++ b/fs/xfs/xfs_dquot.c
> @@ -703,7 +703,7 @@ xfs_dq_get_next_id(
>  	xfs_dqid_t		next_id = *id + 1; /* simple advance */
>  	uint			lock_flags;
>  	struct xfs_bmbt_irec	got;
> -	xfs_extnum_t		idx;
> +	struct xfs_iext_cursor	cur;
>  	xfs_fsblock_t		start;
>  	int			error = 0;
>  
> @@ -727,7 +727,7 @@ xfs_dq_get_next_id(
>  			return error;
>  	}
>  
> -	if (xfs_iext_lookup_extent(quotip, &quotip->i_df, start, &idx, &got)) {
> +	if (xfs_iext_lookup_extent(quotip, &quotip->i_df, start, &cur, &got)) {
>  		/* contiguous chunk, bump startoff for the id calculation */
>  		if (got.br_startoff < start)
>  			got.br_startoff = start;
> diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c
> index da0abc8a0725..ad48e2f24699 100644
> --- a/fs/xfs/xfs_iomap.c
> +++ b/fs/xfs/xfs_iomap.c
> @@ -390,7 +390,7 @@ xfs_iomap_prealloc_size(
>  	struct xfs_inode	*ip,
>  	loff_t			offset,
>  	loff_t			count,
> -	xfs_extnum_t		idx)
> +	struct xfs_iext_cursor	*icur)
>  {
>  	struct xfs_mount	*mp = ip->i_mount;
>  	struct xfs_ifork	*ifp = XFS_IFORK_PTR(ip, XFS_DATA_FORK);
> @@ -415,7 +415,7 @@ xfs_iomap_prealloc_size(
>  	 */
>  	if ((mp->m_flags & XFS_MOUNT_DFLT_IOSIZE) ||
>  	    XFS_ISIZE(ip) < XFS_FSB_TO_B(mp, mp->m_dalign) ||
> -	    !xfs_iext_get_extent(ifp, idx - 1, &prev) ||
> +	    !xfs_iext_peek_prev_extent(ifp, icur, &prev) ||
>  	    prev.br_startoff + prev.br_blockcount < offset_fsb)
>  		return mp->m_writeio_blocks;
>  
> @@ -533,7 +533,7 @@ xfs_file_iomap_begin_delay(
>  	xfs_fileoff_t		end_fsb;
>  	int			error = 0, eof = 0;
>  	struct xfs_bmbt_irec	got;
> -	xfs_extnum_t		idx;
> +	struct xfs_iext_cursor	icur;
>  	xfs_fsblock_t		prealloc_blocks = 0;
>  
>  	ASSERT(!XFS_IS_REALTIME_INODE(ip));
> @@ -558,7 +558,7 @@ xfs_file_iomap_begin_delay(
>  			goto out_unlock;
>  	}
>  
> -	eof = !xfs_iext_lookup_extent(ip, ifp, offset_fsb, &idx, &got);
> +	eof = !xfs_iext_lookup_extent(ip, ifp, offset_fsb, &icur, &got);
>  	if (!eof && got.br_startoff <= offset_fsb) {
>  		if (xfs_is_reflink_inode(ip)) {
>  			bool		shared;
> @@ -592,7 +592,8 @@ xfs_file_iomap_begin_delay(
>  	end_fsb = min(XFS_B_TO_FSB(mp, offset + count), maxbytes_fsb);
>  
>  	if (eof) {
> -		prealloc_blocks = xfs_iomap_prealloc_size(ip, offset, count, idx);
> +		prealloc_blocks = xfs_iomap_prealloc_size(ip, offset, count,
> +				&icur);
>  		if (prealloc_blocks) {
>  			xfs_extlen_t	align;
>  			xfs_off_t	end_offset;
> @@ -614,7 +615,8 @@ xfs_file_iomap_begin_delay(
>  
>  retry:
>  	error = xfs_bmapi_reserve_delalloc(ip, XFS_DATA_FORK, offset_fsb,
> -			end_fsb - offset_fsb, prealloc_blocks, &got, &idx, eof);
> +			end_fsb - offset_fsb, prealloc_blocks, &got, &icur,
> +			eof);
>  	switch (error) {
>  	case 0:
>  		break;
> diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c
> index 1205747e1409..d86c4378facf 100644
> --- a/fs/xfs/xfs_reflink.c
> +++ b/fs/xfs/xfs_reflink.c
> @@ -273,7 +273,7 @@ xfs_reflink_reserve_cow(
>  	struct xfs_bmbt_irec	got;
>  	int			error = 0;
>  	bool			eof = false, trimmed;
> -	xfs_extnum_t		idx;
> +	struct xfs_iext_cursor	icur;
>  
>  	/*
>  	 * Search the COW fork extent list first.  This serves two purposes:
> @@ -284,7 +284,7 @@ xfs_reflink_reserve_cow(
>  	 * tree.
>  	 */
>  
> -	if (!xfs_iext_lookup_extent(ip, ifp, imap->br_startoff, &idx, &got))
> +	if (!xfs_iext_lookup_extent(ip, ifp, imap->br_startoff, &icur, &got))
>  		eof = true;
>  	if (!eof && got.br_startoff <= imap->br_startoff) {
>  		trace_xfs_reflink_cow_found(ip, imap);
> @@ -312,7 +312,7 @@ xfs_reflink_reserve_cow(
>  		return error;
>  
>  	error = xfs_bmapi_reserve_delalloc(ip, XFS_COW_FORK, imap->br_startoff,
> -			imap->br_blockcount, 0, &got, &idx, eof);
> +			imap->br_blockcount, 0, &got, &icur, eof);
>  	if (error == -ENOSPC || error == -EDQUOT)
>  		trace_xfs_reflink_cow_enospc(ip, imap);
>  	if (error)
> @@ -359,16 +359,16 @@ xfs_reflink_convert_cow(
>  	struct xfs_ifork	*ifp = XFS_IFORK_PTR(ip, XFS_COW_FORK);
>  	xfs_fileoff_t		offset_fsb = XFS_B_TO_FSBT(mp, offset);
>  	xfs_fileoff_t		end_fsb = XFS_B_TO_FSB(mp, offset + count);
> -	xfs_extnum_t		idx;
> +	struct xfs_iext_cursor	icur;
>  	bool			found;
>  	int			error = 0;
>  
>  	xfs_ilock(ip, XFS_ILOCK_EXCL);
>  
>  	/* Convert all the extents to real from unwritten. */
> -	for (found = xfs_iext_lookup_extent(ip, ifp, offset_fsb, &idx, &got);
> +	for (found = xfs_iext_lookup_extent(ip, ifp, offset_fsb, &icur, &got);
>  	     found && got.br_startoff < end_fsb;
> -	     found = xfs_iext_get_extent(ifp, ++idx, &got)) {
> +	     found = xfs_iext_next_extent(ifp, &icur, &got)) {
>  		error = xfs_reflink_convert_cow_extent(ip, &got, offset_fsb,
>  				end_fsb - offset_fsb, &dfops);
>  		if (error)
> @@ -399,7 +399,7 @@ xfs_reflink_allocate_cow(
>  	bool			trimmed;
>  	xfs_filblks_t		resaligned;
>  	xfs_extlen_t		resblks = 0;
> -	xfs_extnum_t		idx;
> +	struct xfs_iext_cursor	icur;
>  
>  retry:
>  	ASSERT(xfs_is_reflink_inode(ip));
> @@ -409,7 +409,7 @@ xfs_reflink_allocate_cow(
>  	 * Even if the extent is not shared we might have a preallocation for
>  	 * it in the COW fork.  If so use it.
>  	 */
> -	if (xfs_iext_lookup_extent(ip, ip->i_cowfp, offset_fsb, &idx, &got) &&
> +	if (xfs_iext_lookup_extent(ip, ip->i_cowfp, offset_fsb, &icur, &got) &&
>  	    got.br_startoff <= offset_fsb) {
>  		*shared = true;
>  
> @@ -496,13 +496,13 @@ xfs_reflink_find_cow_mapping(
>  	struct xfs_ifork		*ifp = XFS_IFORK_PTR(ip, XFS_COW_FORK);
>  	xfs_fileoff_t			offset_fsb;
>  	struct xfs_bmbt_irec		got;
> -	xfs_extnum_t			idx;
> +	struct xfs_iext_cursor		icur;
>  
>  	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL | XFS_ILOCK_SHARED));
>  	ASSERT(xfs_is_reflink_inode(ip));
>  
>  	offset_fsb = XFS_B_TO_FSBT(ip->i_mount, offset);
> -	if (!xfs_iext_lookup_extent(ip, ifp, offset_fsb, &idx, &got))
> +	if (!xfs_iext_lookup_extent(ip, ifp, offset_fsb, &icur, &got))
>  		return false;
>  	if (got.br_startoff > offset_fsb)
>  		return false;
> @@ -524,18 +524,18 @@ xfs_reflink_trim_irec_to_next_cow(
>  {
>  	struct xfs_ifork		*ifp = XFS_IFORK_PTR(ip, XFS_COW_FORK);
>  	struct xfs_bmbt_irec		got;
> -	xfs_extnum_t			idx;
> +	struct xfs_iext_cursor		icur;
>  
>  	if (!xfs_is_reflink_inode(ip))
>  		return;
>  
>  	/* Find the extent in the CoW fork. */
> -	if (!xfs_iext_lookup_extent(ip, ifp, offset_fsb, &idx, &got))
> +	if (!xfs_iext_lookup_extent(ip, ifp, offset_fsb, &icur, &got))
>  		return;
>  
>  	/* This is the extent before; try sliding up one. */
>  	if (got.br_startoff < offset_fsb) {
> -		if (!xfs_iext_get_extent(ifp, idx + 1, &got))
> +		if (!xfs_iext_next_extent(ifp, &icur, &got))
>  			return;
>  	}
>  
> @@ -562,14 +562,14 @@ xfs_reflink_cancel_cow_blocks(
>  {
>  	struct xfs_ifork		*ifp = XFS_IFORK_PTR(ip, XFS_COW_FORK);
>  	struct xfs_bmbt_irec		got, del;
> -	xfs_extnum_t			idx;
> +	struct xfs_iext_cursor		icur;
>  	xfs_fsblock_t			firstfsb;
>  	struct xfs_defer_ops		dfops;
>  	int				error = 0;
>  
>  	if (!xfs_is_reflink_inode(ip))
>  		return 0;
> -	if (!xfs_iext_lookup_extent(ip, ifp, offset_fsb, &idx, &got))
> +	if (!xfs_iext_lookup_extent(ip, ifp, offset_fsb, &icur, &got))
>  		return 0;
>  
>  	while (got.br_startoff < end_fsb) {
> @@ -579,7 +579,7 @@ xfs_reflink_cancel_cow_blocks(
>  
>  		if (isnullstartblock(del.br_startblock)) {
>  			error = xfs_bmap_del_extent_delay(ip, XFS_COW_FORK,
> -					&idx, &got, &del);
> +					&icur, &got, &del);
>  			if (error)
>  				break;
>  		} else if (del.br_state == XFS_EXT_UNWRITTEN || cancel_real) {
> @@ -610,10 +610,10 @@ xfs_reflink_cancel_cow_blocks(
>  			}
>  
>  			/* Remove the mapping from the CoW fork. */
> -			xfs_bmap_del_extent_cow(ip, &idx, &got, &del);
> +			xfs_bmap_del_extent_cow(ip, &icur, &got, &del);
>  		}
>  
> -		if (!xfs_iext_get_extent(ifp, ++idx, &got))
> +		if (!xfs_iext_next_extent(ifp, &icur, &got))
>  			break;
>  	}
>  
> @@ -698,7 +698,7 @@ xfs_reflink_end_cow(
>  	int				error;
>  	unsigned int			resblks;
>  	xfs_filblks_t			rlen;
> -	xfs_extnum_t			idx;
> +	struct xfs_iext_cursor		icur;
>  
>  	trace_xfs_reflink_end_cow(ip, offset, count);
>  
> @@ -738,7 +738,7 @@ xfs_reflink_end_cow(
>  	 * left by the time I/O completes for the loser of the race.  In that
>  	 * case we are done.
>  	 */
> -	if (!xfs_iext_lookup_extent_before(ip, ifp, &end_fsb, &idx, &got))
> +	if (!xfs_iext_lookup_extent_before(ip, ifp, &end_fsb, &icur, &got))
>  		goto out_cancel;
>  
>  	/* Walk backwards until we're out of the I/O range... */
> @@ -746,9 +746,9 @@ xfs_reflink_end_cow(
>  		del = got;
>  		xfs_trim_extent(&del, offset_fsb, end_fsb - offset_fsb);
>  
> -		/* Extent delete may have bumped idx forward */
> +		/* Extent delete may have bumped ext forward */
>  		if (!del.br_blockcount) {
> -			idx--;
> +			xfs_iext_prev(ifp, &icur);
>  			goto next_extent;
>  		}
>  
> @@ -760,7 +760,7 @@ xfs_reflink_end_cow(
>  		 * allocated but have not yet been involved in a write.
>  		 */
>  		if (got.br_state == XFS_EXT_UNWRITTEN) {
> -			idx--;
> +			xfs_iext_prev(ifp, &icur);
>  			goto next_extent;
>  		}
>  
> @@ -791,14 +791,14 @@ xfs_reflink_end_cow(
>  			goto out_defer;
>  
>  		/* Remove the mapping from the CoW fork. */
> -		xfs_bmap_del_extent_cow(ip, &idx, &got, &del);
> +		xfs_bmap_del_extent_cow(ip, &icur, &got, &del);
>  
>  		xfs_defer_ijoin(&dfops, ip);
>  		error = xfs_defer_finish(&tp, &dfops);
>  		if (error)
>  			goto out_defer;
>  next_extent:
> -		if (!xfs_iext_get_extent(ifp, idx, &got))
> +		if (!xfs_iext_get_extent(ifp, &icur, &got))
>  			break;
>  	}
>  
> @@ -1428,7 +1428,7 @@ xfs_reflink_inode_has_shared_extents(
>  	xfs_extlen_t			aglen;
>  	xfs_agblock_t			rbno;
>  	xfs_extlen_t			rlen;
> -	xfs_extnum_t			idx;
> +	struct xfs_iext_cursor		icur;
>  	bool				found;
>  	int				error;
>  
> @@ -1440,7 +1440,7 @@ xfs_reflink_inode_has_shared_extents(
>  	}
>  
>  	*has_shared = false;
> -	found = xfs_iext_lookup_extent(ip, ifp, 0, &idx, &got);
> +	found = xfs_iext_lookup_extent(ip, ifp, 0, &icur, &got);
>  	while (found) {
>  		if (isnullstartblock(got.br_startblock) ||
>  		    got.br_state != XFS_EXT_NORM)
> @@ -1459,7 +1459,7 @@ xfs_reflink_inode_has_shared_extents(
>  			return 0;
>  		}
>  next:
> -		found = xfs_iext_get_extent(ifp, ++idx, &got);
> +		found = xfs_iext_next_extent(ifp, &icur, &got);
>  	}
>  
>  	return 0;
> diff --git a/fs/xfs/xfs_trace.h b/fs/xfs/xfs_trace.h
> index 665ef6cca90c..667bfce802cd 100644
> --- a/fs/xfs/xfs_trace.h
> +++ b/fs/xfs/xfs_trace.h
> @@ -258,9 +258,9 @@ TRACE_EVENT(xfs_iext_insert,
>  );
>  
>  DECLARE_EVENT_CLASS(xfs_bmap_class,
> -	TP_PROTO(struct xfs_inode *ip, xfs_extnum_t idx, int state,
> +	TP_PROTO(struct xfs_inode *ip, struct xfs_iext_cursor *cur, int state,
>  		 unsigned long caller_ip),
> -	TP_ARGS(ip, idx, state, caller_ip),
> +	TP_ARGS(ip, cur, state, caller_ip),
>  	TP_STRUCT__entry(
>  		__field(dev_t, dev)
>  		__field(xfs_ino_t, ino)
> @@ -277,10 +277,10 @@ DECLARE_EVENT_CLASS(xfs_bmap_class,
>  		struct xfs_bmbt_irec	r;
>  
>  		ifp = xfs_iext_state_to_fork(ip, state);
> -		xfs_iext_get_extent(ifp, idx, &r);
> +		xfs_iext_get_extent(ifp, cur, &r);
>  		__entry->dev = VFS_I(ip)->i_sb->s_dev;
>  		__entry->ino = ip->i_ino;
> -		__entry->idx = idx;
> +		__entry->idx = cur->idx;
>  		__entry->startoff = r.br_startoff;
>  		__entry->startblock = r.br_startblock;
>  		__entry->blockcount = r.br_blockcount;
> @@ -303,9 +303,9 @@ DECLARE_EVENT_CLASS(xfs_bmap_class,
>  
>  #define DEFINE_BMAP_EVENT(name) \
>  DEFINE_EVENT(xfs_bmap_class, name, \
> -	TP_PROTO(struct xfs_inode *ip, xfs_extnum_t idx, int state, \
> +	TP_PROTO(struct xfs_inode *ip, struct xfs_iext_cursor *cur, int state, \
>  		 unsigned long caller_ip), \
> -	TP_ARGS(ip, idx, state, caller_ip))
> +	TP_ARGS(ip, cur, state, caller_ip))
>  DEFINE_BMAP_EVENT(xfs_iext_remove);
>  DEFINE_BMAP_EVENT(xfs_bmap_pre_update);
>  DEFINE_BMAP_EVENT(xfs_bmap_post_update);
> -- 
> 2.14.2
> 
> --
> To unsubscribe from this list: send the line "unsubscribe linux-xfs" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

[PATCH 13/21] xfs: iterate backwards in xfs_reflink_cancel_cow_blocks

[Christoph Hellwig]

Match the iteration order for extent deletion in the truncate and
reflink I/O completion path.

This also happens to make implementing the new incore extent list
a lot easier.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 fs/xfs/xfs_reflink.c | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c
index d86c4378facf..cf976ed65260 100644
--- a/fs/xfs/xfs_reflink.c
+++ b/fs/xfs/xfs_reflink.c
@@ -569,12 +569,20 @@ xfs_reflink_cancel_cow_blocks(
 
 	if (!xfs_is_reflink_inode(ip))
 		return 0;
-	if (!xfs_iext_lookup_extent(ip, ifp, offset_fsb, &icur, &got))
+	if (!xfs_iext_lookup_extent_before(ip, ifp, &end_fsb, &icur, &got))
 		return 0;
 
-	while (got.br_startoff < end_fsb) {
+	/* Walk backwards until we're out of the I/O range... */
+	while (got.br_startoff + got.br_blockcount > offset_fsb) {
 		del = got;
 		xfs_trim_extent(&del, offset_fsb, end_fsb - offset_fsb);
+
+		/* Extent delete may have bumped ext forward */
+		if (!del.br_blockcount) {
+			xfs_iext_prev(ifp, &icur);
+			goto next_extent;
+		}
+
 		trace_xfs_reflink_cancel_cow(ip, &del);
 
 		if (isnullstartblock(del.br_startblock)) {
@@ -612,8 +620,8 @@ xfs_reflink_cancel_cow_blocks(
 			/* Remove the mapping from the CoW fork. */
 			xfs_bmap_del_extent_cow(ip, &icur, &got, &del);
 		}
-
-		if (!xfs_iext_next_extent(ifp, &icur, &got))
+next_extent:
+		if (!xfs_iext_get_extent(ifp, &icur, &got))
 			break;
 	}
 
-- 
2.14.2

Re: [PATCH 13/21] xfs: iterate backwards in xfs_reflink_cancel_cow_blocks

[Darrick J. Wong]

On Fri, Nov 03, 2017 at 05:45:31PM +0300, Christoph Hellwig wrote:
> Match the iteration order for extent deletion in the truncate and
> reflink I/O completion path.
> 
> This also happens to make implementing the new incore extent list
> a lot easier.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>

Looks ok,
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>

> ---
>  fs/xfs/xfs_reflink.c | 16 ++++++++++++----
>  1 file changed, 12 insertions(+), 4 deletions(-)
> 
> diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c
> index d86c4378facf..cf976ed65260 100644
> --- a/fs/xfs/xfs_reflink.c
> +++ b/fs/xfs/xfs_reflink.c
> @@ -569,12 +569,20 @@ xfs_reflink_cancel_cow_blocks(
>  
>  	if (!xfs_is_reflink_inode(ip))
>  		return 0;
> -	if (!xfs_iext_lookup_extent(ip, ifp, offset_fsb, &icur, &got))
> +	if (!xfs_iext_lookup_extent_before(ip, ifp, &end_fsb, &icur, &got))
>  		return 0;
>  
> -	while (got.br_startoff < end_fsb) {
> +	/* Walk backwards until we're out of the I/O range... */
> +	while (got.br_startoff + got.br_blockcount > offset_fsb) {
>  		del = got;
>  		xfs_trim_extent(&del, offset_fsb, end_fsb - offset_fsb);
> +
> +		/* Extent delete may have bumped ext forward */
> +		if (!del.br_blockcount) {
> +			xfs_iext_prev(ifp, &icur);
> +			goto next_extent;
> +		}
> +
>  		trace_xfs_reflink_cancel_cow(ip, &del);
>  
>  		if (isnullstartblock(del.br_startblock)) {
> @@ -612,8 +620,8 @@ xfs_reflink_cancel_cow_blocks(
>  			/* Remove the mapping from the CoW fork. */
>  			xfs_bmap_del_extent_cow(ip, &icur, &got, &del);
>  		}
> -
> -		if (!xfs_iext_next_extent(ifp, &icur, &got))
> +next_extent:
> +		if (!xfs_iext_get_extent(ifp, &icur, &got))
>  			break;
>  	}
>  
> -- 
> 2.14.2
> 
> --
> To unsubscribe from this list: send the line "unsubscribe linux-xfs" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

[PATCH 14/21] xfs: simplify xfs_reflink_convert_cow

[Christoph Hellwig]

Instead of looking up extents to convert and calling xfs_bmapi_write on
each of them just let xfs_bmapi_write handle the full range.  To make
this robust add a new XFS_BMAPI_CONVERT_ONLY that only converts ranges
and never allocates blocks.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 fs/xfs/libxfs/xfs_bmap.c |  3 ++-
 fs/xfs/libxfs/xfs_bmap.h |  6 +++++-
 fs/xfs/xfs_reflink.c     | 29 +++++++++++------------------
 3 files changed, 18 insertions(+), 20 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
index b08c4863c2af..8fcb186341ce 100644
--- a/fs/xfs/libxfs/xfs_bmap.c
+++ b/fs/xfs/libxfs/xfs_bmap.c
@@ -4331,7 +4331,8 @@ xfs_bmapi_write(
 		 * First, deal with the hole before the allocated space
 		 * that we found, if any.
 		 */
-		if (need_alloc || wasdelay) {
+		if ((need_alloc || wasdelay) &&
+		    !(flags & XFS_BMAPI_CONVERT_ONLY)) {
 			bma.eof = eof;
 			bma.conv = !!(flags & XFS_BMAPI_CONVERT);
 			bma.wasdel = wasdelay;
diff --git a/fs/xfs/libxfs/xfs_bmap.h b/fs/xfs/libxfs/xfs_bmap.h
index b6a395949d0c..eaf975eb35f8 100644
--- a/fs/xfs/libxfs/xfs_bmap.h
+++ b/fs/xfs/libxfs/xfs_bmap.h
@@ -113,6 +113,9 @@ struct xfs_extent_free_item
 /* Only convert delalloc space, don't allocate entirely new extents */
 #define XFS_BMAPI_DELALLOC	0x400
 
+/* Only convert unwritten extents, don't allocate new blocks */
+#define XFS_BMAPI_CONVERT_ONLY	0x800
+
 #define XFS_BMAPI_FLAGS \
 	{ XFS_BMAPI_ENTIRE,	"ENTIRE" }, \
 	{ XFS_BMAPI_METADATA,	"METADATA" }, \
@@ -124,7 +127,8 @@ struct xfs_extent_free_item
 	{ XFS_BMAPI_ZERO,	"ZERO" }, \
 	{ XFS_BMAPI_REMAP,	"REMAP" }, \
 	{ XFS_BMAPI_COWFORK,	"COWFORK" }, \
-	{ XFS_BMAPI_DELALLOC,	"DELALLOC" }
+	{ XFS_BMAPI_DELALLOC,	"DELALLOC" }, \
+	{ XFS_BMAPI_CONVERT_ONLY, "XFS_BMAPI_CONVERT_ONLY" }
 
 
 static inline int xfs_bmapi_aflag(int w)
diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c
index cf976ed65260..cc041a29eb70 100644
--- a/fs/xfs/xfs_reflink.c
+++ b/fs/xfs/xfs_reflink.c
@@ -353,29 +353,22 @@ xfs_reflink_convert_cow(
 	xfs_off_t		offset,
 	xfs_off_t		count)
 {
-	struct xfs_bmbt_irec	got;
-	struct xfs_defer_ops	dfops;
 	struct xfs_mount	*mp = ip->i_mount;
-	struct xfs_ifork	*ifp = XFS_IFORK_PTR(ip, XFS_COW_FORK);
 	xfs_fileoff_t		offset_fsb = XFS_B_TO_FSBT(mp, offset);
 	xfs_fileoff_t		end_fsb = XFS_B_TO_FSB(mp, offset + count);
-	struct xfs_iext_cursor	icur;
-	bool			found;
-	int			error = 0;
-
-	xfs_ilock(ip, XFS_ILOCK_EXCL);
+	xfs_filblks_t		count_fsb = end_fsb - offset_fsb;
+	struct xfs_bmbt_irec	imap;
+	struct xfs_defer_ops	dfops;
+	xfs_fsblock_t		first_block = NULLFSBLOCK;
+	int			nimaps = 1, error = 0;
 
-	/* Convert all the extents to real from unwritten. */
-	for (found = xfs_iext_lookup_extent(ip, ifp, offset_fsb, &icur, &got);
-	     found && got.br_startoff < end_fsb;
-	     found = xfs_iext_next_extent(ifp, &icur, &got)) {
-		error = xfs_reflink_convert_cow_extent(ip, &got, offset_fsb,
-				end_fsb - offset_fsb, &dfops);
-		if (error)
-			break;
-	}
+	ASSERT(count != 0);
 
-	/* Finish up. */
+	xfs_ilock(ip, XFS_ILOCK_EXCL);
+	error = xfs_bmapi_write(NULL, ip, offset_fsb, count_fsb,
+			XFS_BMAPI_COWFORK | XFS_BMAPI_CONVERT |
+			XFS_BMAPI_CONVERT_ONLY, &first_block, 0, &imap, &nimaps,
+			&dfops);
 	xfs_iunlock(ip, XFS_ILOCK_EXCL);
 	return error;
 }
-- 
2.14.2

Re: [PATCH 14/21] xfs: simplify xfs_reflink_convert_cow

[Darrick J. Wong]

On Fri, Nov 03, 2017 at 05:45:32PM +0300, Christoph Hellwig wrote:
> Instead of looking up extents to convert and calling xfs_bmapi_write on
> each of them just let xfs_bmapi_write handle the full range.  To make
> this robust add a new XFS_BMAPI_CONVERT_ONLY that only converts ranges
> and never allocates blocks.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>  fs/xfs/libxfs/xfs_bmap.c |  3 ++-
>  fs/xfs/libxfs/xfs_bmap.h |  6 +++++-
>  fs/xfs/xfs_reflink.c     | 29 +++++++++++------------------
>  3 files changed, 18 insertions(+), 20 deletions(-)
> 
> diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
> index b08c4863c2af..8fcb186341ce 100644
> --- a/fs/xfs/libxfs/xfs_bmap.c
> +++ b/fs/xfs/libxfs/xfs_bmap.c
> @@ -4331,7 +4331,8 @@ xfs_bmapi_write(
>  		 * First, deal with the hole before the allocated space
>  		 * that we found, if any.
>  		 */
> -		if (need_alloc || wasdelay) {
> +		if ((need_alloc || wasdelay) &&
> +		    !(flags & XFS_BMAPI_CONVERT_ONLY)) {
>  			bma.eof = eof;
>  			bma.conv = !!(flags & XFS_BMAPI_CONVERT);
>  			bma.wasdel = wasdelay;
> diff --git a/fs/xfs/libxfs/xfs_bmap.h b/fs/xfs/libxfs/xfs_bmap.h
> index b6a395949d0c..eaf975eb35f8 100644
> --- a/fs/xfs/libxfs/xfs_bmap.h
> +++ b/fs/xfs/libxfs/xfs_bmap.h
> @@ -113,6 +113,9 @@ struct xfs_extent_free_item
>  /* Only convert delalloc space, don't allocate entirely new extents */
>  #define XFS_BMAPI_DELALLOC	0x400
>  
> +/* Only convert unwritten extents, don't allocate new blocks */
> +#define XFS_BMAPI_CONVERT_ONLY	0x800
> +
>  #define XFS_BMAPI_FLAGS \
>  	{ XFS_BMAPI_ENTIRE,	"ENTIRE" }, \
>  	{ XFS_BMAPI_METADATA,	"METADATA" }, \
> @@ -124,7 +127,8 @@ struct xfs_extent_free_item
>  	{ XFS_BMAPI_ZERO,	"ZERO" }, \
>  	{ XFS_BMAPI_REMAP,	"REMAP" }, \
>  	{ XFS_BMAPI_COWFORK,	"COWFORK" }, \
> -	{ XFS_BMAPI_DELALLOC,	"DELALLOC" }
> +	{ XFS_BMAPI_DELALLOC,	"DELALLOC" }, \
> +	{ XFS_BMAPI_CONVERT_ONLY, "XFS_BMAPI_CONVERT_ONLY" }

"CONVERT_ONLY" to be consistent with the other flag strings?
I can fix this on the way in.

Otherwise,
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>

--D

>  
>  
>  static inline int xfs_bmapi_aflag(int w)
> diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c
> index cf976ed65260..cc041a29eb70 100644
> --- a/fs/xfs/xfs_reflink.c
> +++ b/fs/xfs/xfs_reflink.c
> @@ -353,29 +353,22 @@ xfs_reflink_convert_cow(
>  	xfs_off_t		offset,
>  	xfs_off_t		count)
>  {
> -	struct xfs_bmbt_irec	got;
> -	struct xfs_defer_ops	dfops;
>  	struct xfs_mount	*mp = ip->i_mount;
> -	struct xfs_ifork	*ifp = XFS_IFORK_PTR(ip, XFS_COW_FORK);
>  	xfs_fileoff_t		offset_fsb = XFS_B_TO_FSBT(mp, offset);
>  	xfs_fileoff_t		end_fsb = XFS_B_TO_FSB(mp, offset + count);
> -	struct xfs_iext_cursor	icur;
> -	bool			found;
> -	int			error = 0;
> -
> -	xfs_ilock(ip, XFS_ILOCK_EXCL);
> +	xfs_filblks_t		count_fsb = end_fsb - offset_fsb;
> +	struct xfs_bmbt_irec	imap;
> +	struct xfs_defer_ops	dfops;
> +	xfs_fsblock_t		first_block = NULLFSBLOCK;
> +	int			nimaps = 1, error = 0;
>  
> -	/* Convert all the extents to real from unwritten. */
> -	for (found = xfs_iext_lookup_extent(ip, ifp, offset_fsb, &icur, &got);
> -	     found && got.br_startoff < end_fsb;
> -	     found = xfs_iext_next_extent(ifp, &icur, &got)) {
> -		error = xfs_reflink_convert_cow_extent(ip, &got, offset_fsb,
> -				end_fsb - offset_fsb, &dfops);
> -		if (error)
> -			break;
> -	}
> +	ASSERT(count != 0);
>  
> -	/* Finish up. */
> +	xfs_ilock(ip, XFS_ILOCK_EXCL);
> +	error = xfs_bmapi_write(NULL, ip, offset_fsb, count_fsb,
> +			XFS_BMAPI_COWFORK | XFS_BMAPI_CONVERT |
> +			XFS_BMAPI_CONVERT_ONLY, &first_block, 0, &imap, &nimaps,
> +			&dfops);
>  	xfs_iunlock(ip, XFS_ILOCK_EXCL);
>  	return error;
>  }
> -- 
> 2.14.2
> 
> --
> To unsubscribe from this list: send the line "unsubscribe linux-xfs" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: [PATCH 14/21] xfs: simplify xfs_reflink_convert_cow

[Christoph Hellwig]

> >  	{ XFS_BMAPI_COWFORK,	"COWFORK" }, \
> > -	{ XFS_BMAPI_DELALLOC,	"DELALLOC" }
> > +	{ XFS_BMAPI_DELALLOC,	"DELALLOC" }, \
> > +	{ XFS_BMAPI_CONVERT_ONLY, "XFS_BMAPI_CONVERT_ONLY" }
> 
> "CONVERT_ONLY" to be consistent with the other flag strings?
> I can fix this on the way in.

Please do.  If I have to respin it either I'll also fix it up.

[PATCH 15/21] xfs: remove support for inlining data/extents into the inode fork

[Christoph Hellwig]

Supporting a small bit of data inside the inode fork blows up the fork size
a lot, removing the 32 bytes of inline data halves the effective size of
the inode fork (and it still has a lot of unused padding left), and the
performance of a single kmalloc doesn't show up compared to the size to read
an inode or create one.

It also simplifies the fork management code a lot.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 fs/xfs/libxfs/xfs_inode_fork.c | 185 +++--------------------------------------
 fs/xfs/libxfs/xfs_inode_fork.h |  11 ---
 fs/xfs/xfs_bmap_util.c         |  15 ----
 3 files changed, 13 insertions(+), 198 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_inode_fork.c b/fs/xfs/libxfs/xfs_inode_fork.c
index 1e28532ff551..1f888fcbd873 100644
--- a/fs/xfs/libxfs/xfs_inode_fork.c
+++ b/fs/xfs/libxfs/xfs_inode_fork.c
@@ -269,19 +269,14 @@ xfs_init_local_fork(
 	if (zero_terminate)
 		mem_size++;
 
-	if (size == 0)
-		ifp->if_u1.if_data = NULL;
-	else if (mem_size <= sizeof(ifp->if_u2.if_inline_data))
-		ifp->if_u1.if_data = ifp->if_u2.if_inline_data;
-	else {
+	if (size) {
 		real_size = roundup(mem_size, 4);
 		ifp->if_u1.if_data = kmem_alloc(real_size, KM_SLEEP | KM_NOFS);
-	}
-
-	if (size) {
 		memcpy(ifp->if_u1.if_data, data, size);
 		if (zero_terminate)
 			ifp->if_u1.if_data[size] = '\0';
+	} else {
+		ifp->if_u1.if_data = NULL;
 	}
 
 	ifp->if_bytes = size;
@@ -292,13 +287,6 @@ xfs_init_local_fork(
 
 /*
  * The file is in-lined in the on-disk inode.
- * If it fits into if_inline_data, then copy
- * it there, otherwise allocate a buffer for it
- * and copy the data there.  Either way, set
- * if_data to point at the data.
- * If we allocate a buffer for the data, make
- * sure that its size is a multiple of 4 and
- * record the real size in i_real_bytes.
  */
 STATIC int
 xfs_iformat_local(
@@ -328,9 +316,7 @@ xfs_iformat_local(
 
 /*
  * The file consists of a set of extents all of which fit into the on-disk
- * inode.  If there are few enough extents to fit into the if_inline_ext, then
- * copy them there.  Otherwise allocate a buffer for them and copy them into it.
- * Either way, set if_extents to point at the extents.
+ * inode.
  */
 STATIC int
 xfs_iformat_extents(
@@ -362,8 +348,6 @@ xfs_iformat_extents(
 	ifp->if_real_bytes = 0;
 	if (nex == 0)
 		ifp->if_u1.if_extents = NULL;
-	else if (nex <= XFS_INLINE_EXTS)
-		ifp->if_u1.if_extents = ifp->if_u2.if_inline_ext;
 	else
 		xfs_iext_add(ifp, 0, nex);
 
@@ -618,26 +602,9 @@ xfs_idata_realloc(
 	ASSERT(new_size >= 0);
 
 	if (new_size == 0) {
-		if (ifp->if_u1.if_data != ifp->if_u2.if_inline_data) {
-			kmem_free(ifp->if_u1.if_data);
-		}
+		kmem_free(ifp->if_u1.if_data);
 		ifp->if_u1.if_data = NULL;
 		real_size = 0;
-	} else if (new_size <= sizeof(ifp->if_u2.if_inline_data)) {
-		/*
-		 * If the valid extents/data can fit in if_inline_ext/data,
-		 * copy them from the malloc'd vector and free it.
-		 */
-		if (ifp->if_u1.if_data == NULL) {
-			ifp->if_u1.if_data = ifp->if_u2.if_inline_data;
-		} else if (ifp->if_u1.if_data != ifp->if_u2.if_inline_data) {
-			ASSERT(ifp->if_real_bytes != 0);
-			memcpy(ifp->if_u2.if_inline_data, ifp->if_u1.if_data,
-			      new_size);
-			kmem_free(ifp->if_u1.if_data);
-			ifp->if_u1.if_data = ifp->if_u2.if_inline_data;
-		}
-		real_size = 0;
 	} else {
 		/*
 		 * Stuck with malloc/realloc.
@@ -651,7 +618,7 @@ xfs_idata_realloc(
 			ASSERT(ifp->if_real_bytes == 0);
 			ifp->if_u1.if_data = kmem_alloc(real_size,
 							KM_SLEEP | KM_NOFS);
-		} else if (ifp->if_u1.if_data != ifp->if_u2.if_inline_data) {
+		} else {
 			/*
 			 * Only do the realloc if the underlying size
 			 * is really changing.
@@ -662,12 +629,6 @@ xfs_idata_realloc(
 							real_size,
 							KM_SLEEP | KM_NOFS);
 			}
-		} else {
-			ASSERT(ifp->if_real_bytes == 0);
-			ifp->if_u1.if_data = kmem_alloc(real_size,
-							KM_SLEEP | KM_NOFS);
-			memcpy(ifp->if_u1.if_data, ifp->if_u2.if_inline_data,
-				ifp->if_bytes);
 		}
 	}
 	ifp->if_real_bytes = real_size;
@@ -695,8 +656,7 @@ xfs_idestroy_fork(
 	 * so check and free it up if we do.
 	 */
 	if (XFS_IFORK_FORMAT(ip, whichfork) == XFS_DINODE_FMT_LOCAL) {
-		if ((ifp->if_u1.if_data != ifp->if_u2.if_inline_data) &&
-		    (ifp->if_u1.if_data != NULL)) {
+		if (ifp->if_u1.if_data != NULL) {
 			ASSERT(ifp->if_real_bytes != 0);
 			kmem_free(ifp->if_u1.if_data);
 			ifp->if_u1.if_data = NULL;
@@ -704,13 +664,11 @@ xfs_idestroy_fork(
 		}
 	} else if ((ifp->if_flags & XFS_IFEXTENTS) &&
 		   ((ifp->if_flags & XFS_IFEXTIREC) ||
-		    ((ifp->if_u1.if_extents != NULL) &&
-		     (ifp->if_u1.if_extents != ifp->if_u2.if_inline_ext)))) {
+		    (ifp->if_u1.if_extents != NULL))) {
 		ASSERT(ifp->if_real_bytes != 0);
 		xfs_iext_destroy(ifp);
 	}
-	ASSERT(ifp->if_u1.if_extents == NULL ||
-	       ifp->if_u1.if_extents == ifp->if_u2.if_inline_ext);
+	ASSERT(ifp->if_u1.if_extents == NULL);
 	ASSERT(ifp->if_real_bytes == 0);
 	if (whichfork == XFS_ATTR_FORK) {
 		kmem_zone_free(xfs_ifork_zone, ip->i_afp);
@@ -943,28 +901,14 @@ xfs_iext_add(
 	ASSERT((idx >= 0) && (idx <= nextents));
 	byte_diff = ext_diff * sizeof(xfs_bmbt_rec_t);
 	new_size = ifp->if_bytes + byte_diff;
+
 	/*
-	 * If the new number of extents (nextents + ext_diff)
-	 * fits inside the inode, then continue to use the inline
-	 * extent buffer.
-	 */
-	if (nextents + ext_diff <= XFS_INLINE_EXTS) {
-		if (idx < nextents) {
-			memmove(&ifp->if_u2.if_inline_ext[idx + ext_diff],
-				&ifp->if_u2.if_inline_ext[idx],
-				(nextents - idx) * sizeof(xfs_bmbt_rec_t));
-			memset(&ifp->if_u2.if_inline_ext[idx], 0, byte_diff);
-		}
-		ifp->if_u1.if_extents = ifp->if_u2.if_inline_ext;
-		ifp->if_real_bytes = 0;
-	}
-	/*
-	 * Otherwise use a linear (direct) extent list.
+	 * Use a linear (direct) extent list.
 	 * If the extents are currently inside the inode,
 	 * xfs_iext_realloc_direct will switch us from
 	 * inline to direct extent allocation mode.
 	 */
-	else if (nextents + ext_diff <= XFS_LINEAR_EXTS) {
+	if (nextents + ext_diff <= XFS_LINEAR_EXTS) {
 		xfs_iext_realloc_direct(ifp, new_size);
 		if (idx < nextents) {
 			memmove(&ifp->if_u1.if_extents[idx + ext_diff],
@@ -1172,43 +1116,10 @@ xfs_iext_remove(
 		xfs_iext_remove_indirect(ifp, cur->idx, ext_diff);
 	} else if (ifp->if_real_bytes) {
 		xfs_iext_remove_direct(ifp, cur->idx, ext_diff);
-	} else {
-		xfs_iext_remove_inline(ifp, cur->idx, ext_diff);
 	}
 	ifp->if_bytes = new_size;
 }
 
-/*
- * This removes ext_diff extents from the inline buffer, beginning
- * at extent index idx.
- */
-void
-xfs_iext_remove_inline(
-	xfs_ifork_t	*ifp,		/* inode fork pointer */
-	xfs_extnum_t	idx,		/* index to begin removing exts */
-	int		ext_diff)	/* number of extents to remove */
-{
-	int		nextents;	/* number of extents in file */
-
-	ASSERT(!(ifp->if_flags & XFS_IFEXTIREC));
-	ASSERT(idx < XFS_INLINE_EXTS);
-	nextents = xfs_iext_count(ifp);
-	ASSERT(((nextents - ext_diff) > 0) &&
-		(nextents - ext_diff) < XFS_INLINE_EXTS);
-
-	if (idx + ext_diff < nextents) {
-		memmove(&ifp->if_u2.if_inline_ext[idx],
-			&ifp->if_u2.if_inline_ext[idx + ext_diff],
-			(nextents - (idx + ext_diff)) *
-			 sizeof(xfs_bmbt_rec_t));
-		memset(&ifp->if_u2.if_inline_ext[nextents - ext_diff],
-			0, ext_diff * sizeof(xfs_bmbt_rec_t));
-	} else {
-		memset(&ifp->if_u2.if_inline_ext[idx], 0,
-			ext_diff * sizeof(xfs_bmbt_rec_t));
-	}
-}
-
 /*
  * This removes ext_diff extents from a linear (direct) extent list,
  * beginning at extent index idx. If the extents are being removed
@@ -1351,16 +1262,7 @@ xfs_iext_realloc_direct(
 	/* Free extent records */
 	if (new_size == 0) {
 		xfs_iext_destroy(ifp);
-	}
-	/* Resize direct extent list and zero any new bytes */
-	else if (ifp->if_real_bytes) {
-		/* Check if extents will fit inside the inode */
-		if (new_size <= XFS_INLINE_EXTS * sizeof(xfs_bmbt_rec_t)) {
-			xfs_iext_direct_to_inline(ifp, new_size /
-				(uint)sizeof(xfs_bmbt_rec_t));
-			ifp->if_bytes = new_size;
-			return;
-		}
+	} else {
 		if (!is_power_of_2(new_size)){
 			rnew_size = roundup_pow_of_two(new_size);
 		}
@@ -1375,63 +1277,10 @@ xfs_iext_realloc_direct(
 				rnew_size - ifp->if_real_bytes);
 		}
 	}
-	/* Switch from the inline extent buffer to a direct extent list */
-	else {
-		if (!is_power_of_2(new_size)) {
-			rnew_size = roundup_pow_of_two(new_size);
-		}
-		xfs_iext_inline_to_direct(ifp, rnew_size);
-	}
 	ifp->if_real_bytes = rnew_size;
 	ifp->if_bytes = new_size;
 }
 
-/*
- * Switch from linear (direct) extent records to inline buffer.
- */
-void
-xfs_iext_direct_to_inline(
-	xfs_ifork_t	*ifp,		/* inode fork pointer */
-	xfs_extnum_t	nextents)	/* number of extents in file */
-{
-	ASSERT(ifp->if_flags & XFS_IFEXTENTS);
-	ASSERT(nextents <= XFS_INLINE_EXTS);
-	/*
-	 * The inline buffer was zeroed when we switched
-	 * from inline to direct extent allocation mode,
-	 * so we don't need to clear it here.
-	 */
-	memcpy(ifp->if_u2.if_inline_ext, ifp->if_u1.if_extents,
-		nextents * sizeof(xfs_bmbt_rec_t));
-	kmem_free(ifp->if_u1.if_extents);
-	ifp->if_u1.if_extents = ifp->if_u2.if_inline_ext;
-	ifp->if_real_bytes = 0;
-}
-
-/*
- * Switch from inline buffer to linear (direct) extent records.
- * new_size should already be rounded up to the next power of 2
- * by the caller (when appropriate), so use new_size as it is.
- * However, since new_size may be rounded up, we can't update
- * if_bytes here. It is the caller's responsibility to update
- * if_bytes upon return.
- */
-void
-xfs_iext_inline_to_direct(
-	xfs_ifork_t	*ifp,		/* inode fork pointer */
-	int		new_size)	/* number of extents in file */
-{
-	ifp->if_u1.if_extents = kmem_alloc(new_size, KM_NOFS);
-	memset(ifp->if_u1.if_extents, 0, new_size);
-	if (ifp->if_bytes) {
-		memcpy(ifp->if_u1.if_extents, ifp->if_u2.if_inline_ext,
-			ifp->if_bytes);
-		memset(ifp->if_u2.if_inline_ext, 0, XFS_INLINE_EXTS *
-			sizeof(xfs_bmbt_rec_t));
-	}
-	ifp->if_real_bytes = new_size;
-}
-
 /*
  * Resize an extent indirection array to new_size bytes.
  */
@@ -1511,9 +1360,6 @@ xfs_iext_destroy(
 		xfs_iext_irec_remove_all(ifp);
 	} else if (ifp->if_real_bytes) {
 		kmem_free(ifp->if_u1.if_extents);
-	} else if (ifp->if_bytes) {
-		memset(ifp->if_u2.if_inline_ext, 0, XFS_INLINE_EXTS *
-			sizeof(xfs_bmbt_rec_t));
 	}
 	ifp->if_u1.if_extents = NULL;
 	ifp->if_real_bytes = 0;
@@ -1708,8 +1554,6 @@ xfs_iext_irec_init(
 
 	if (nextents == 0) {
 		ifp->if_u1.if_extents = kmem_alloc(XFS_IEXT_BUFSZ, KM_NOFS);
-	} else if (!ifp->if_real_bytes) {
-		xfs_iext_inline_to_direct(ifp, XFS_IEXT_BUFSZ);
 	} else if (ifp->if_real_bytes < XFS_IEXT_BUFSZ) {
 		xfs_iext_realloc_direct(ifp, XFS_IEXT_BUFSZ);
 	}
@@ -1829,9 +1673,6 @@ xfs_iext_irec_compact(
 
 	if (nextents == 0) {
 		xfs_iext_destroy(ifp);
-	} else if (nextents <= XFS_INLINE_EXTS) {
-		xfs_iext_indirect_to_direct(ifp);
-		xfs_iext_direct_to_inline(ifp, nextents);
 	} else if (nextents <= XFS_LINEAR_EXTS) {
 		xfs_iext_indirect_to_direct(ifp);
 	} else if (nextents < (nlists * XFS_LINEAR_EXTS) >> 1) {
diff --git a/fs/xfs/libxfs/xfs_inode_fork.h b/fs/xfs/libxfs/xfs_inode_fork.h
index 7065544f446a..cc7ca255ec98 100644
--- a/fs/xfs/libxfs/xfs_inode_fork.h
+++ b/fs/xfs/libxfs/xfs_inode_fork.h
@@ -51,8 +51,6 @@ typedef struct xfs_ext_irec {
  */
 #define	XFS_IEXT_BUFSZ		4096
 #define	XFS_LINEAR_EXTS		(XFS_IEXT_BUFSZ / (uint)sizeof(xfs_bmbt_rec_t))
-#define	XFS_INLINE_EXTS		2
-#define	XFS_INLINE_DATA		32
 typedef struct xfs_ifork {
 	int			if_bytes;	/* bytes in if_u1 */
 	int			if_real_bytes;	/* bytes allocated in if_u1 */
@@ -64,12 +62,6 @@ typedef struct xfs_ifork {
 		xfs_ext_irec_t	*if_ext_irec;	/* irec map file exts */
 		char		*if_data;	/* inline file data */
 	} if_u1;
-	union {
-		xfs_bmbt_rec_host_t if_inline_ext[XFS_INLINE_EXTS];
-						/* very small file extents */
-		char		if_inline_data[XFS_INLINE_DATA];
-						/* very small file data */
-	} if_u2;
 } xfs_ifork_t;
 
 /*
@@ -158,12 +150,9 @@ void		xfs_iext_add_indirect_multi(struct xfs_ifork *, int,
 					    xfs_extnum_t, int);
 void		xfs_iext_remove(struct xfs_inode *, struct xfs_iext_cursor *,
 			int, int);
-void		xfs_iext_remove_inline(struct xfs_ifork *, xfs_extnum_t, int);
 void		xfs_iext_remove_direct(struct xfs_ifork *, xfs_extnum_t, int);
 void		xfs_iext_remove_indirect(struct xfs_ifork *, xfs_extnum_t, int);
 void		xfs_iext_realloc_direct(struct xfs_ifork *, int);
-void		xfs_iext_direct_to_inline(struct xfs_ifork *, xfs_extnum_t);
-void		xfs_iext_inline_to_direct(struct xfs_ifork *, int);
 void		xfs_iext_destroy(struct xfs_ifork *);
 struct xfs_bmbt_rec_host *
 		xfs_iext_bno_to_ext(struct xfs_ifork *, xfs_fileoff_t, int *);
diff --git a/fs/xfs/xfs_bmap_util.c b/fs/xfs/xfs_bmap_util.c
index 515eec004971..893763cee691 100644
--- a/fs/xfs/xfs_bmap_util.c
+++ b/fs/xfs/xfs_bmap_util.c
@@ -1709,7 +1709,6 @@ xfs_swap_extent_forks(
 	xfs_filblks_t		aforkblks = 0;
 	xfs_filblks_t		taforkblks = 0;
 	xfs_extnum_t		junk;
-	xfs_extnum_t		nextents;
 	uint64_t		tmp;
 	int			error;
 
@@ -1784,13 +1783,6 @@ xfs_swap_extent_forks(
 
 	switch (ip->i_d.di_format) {
 	case XFS_DINODE_FMT_EXTENTS:
-		/*
-		 * If the extents fit in the inode, fix the pointer.  Otherwise
-		 * it's already NULL or pointing to the extent.
-		 */
-		nextents = xfs_iext_count(&ip->i_df);
-		if (nextents <= XFS_INLINE_EXTS)
-			ifp->if_u1.if_extents = ifp->if_u2.if_inline_ext;
 		(*src_log_flags) |= XFS_ILOG_DEXT;
 		break;
 	case XFS_DINODE_FMT_BTREE:
@@ -1802,13 +1794,6 @@ xfs_swap_extent_forks(
 
 	switch (tip->i_d.di_format) {
 	case XFS_DINODE_FMT_EXTENTS:
-		/*
-		 * If the extents fit in the inode, fix the pointer.  Otherwise
-		 * it's already NULL or pointing to the extent.
-		 */
-		nextents = xfs_iext_count(&tip->i_df);
-		if (nextents <= XFS_INLINE_EXTS)
-			tifp->if_u1.if_extents = tifp->if_u2.if_inline_ext;
 		(*target_log_flags) |= XFS_ILOG_DEXT;
 		break;
 	case XFS_DINODE_FMT_BTREE:
-- 
2.14.2

Re: [PATCH 15/21] xfs: remove support for inlining data/extents into the inode fork

[Darrick J. Wong]

On Fri, Nov 03, 2017 at 05:45:33PM +0300, Christoph Hellwig wrote:
> Supporting a small bit of data inside the inode fork blows up the fork size
> a lot, removing the 32 bytes of inline data halves the effective size of
> the inode fork (and it still has a lot of unused padding left), and the
> performance of a single kmalloc doesn't show up compared to the size to read
> an inode or create one.
> 
> It also simplifies the fork management code a lot.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>

Looks ok,
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>

> ---
>  fs/xfs/libxfs/xfs_inode_fork.c | 185 +++--------------------------------------
>  fs/xfs/libxfs/xfs_inode_fork.h |  11 ---
>  fs/xfs/xfs_bmap_util.c         |  15 ----
>  3 files changed, 13 insertions(+), 198 deletions(-)
> 
> diff --git a/fs/xfs/libxfs/xfs_inode_fork.c b/fs/xfs/libxfs/xfs_inode_fork.c
> index 1e28532ff551..1f888fcbd873 100644
> --- a/fs/xfs/libxfs/xfs_inode_fork.c
> +++ b/fs/xfs/libxfs/xfs_inode_fork.c
> @@ -269,19 +269,14 @@ xfs_init_local_fork(
>  	if (zero_terminate)
>  		mem_size++;
>  
> -	if (size == 0)
> -		ifp->if_u1.if_data = NULL;
> -	else if (mem_size <= sizeof(ifp->if_u2.if_inline_data))
> -		ifp->if_u1.if_data = ifp->if_u2.if_inline_data;
> -	else {
> +	if (size) {
>  		real_size = roundup(mem_size, 4);
>  		ifp->if_u1.if_data = kmem_alloc(real_size, KM_SLEEP | KM_NOFS);
> -	}
> -
> -	if (size) {
>  		memcpy(ifp->if_u1.if_data, data, size);
>  		if (zero_terminate)
>  			ifp->if_u1.if_data[size] = '\0';
> +	} else {
> +		ifp->if_u1.if_data = NULL;
>  	}
>  
>  	ifp->if_bytes = size;
> @@ -292,13 +287,6 @@ xfs_init_local_fork(
>  
>  /*
>   * The file is in-lined in the on-disk inode.
> - * If it fits into if_inline_data, then copy
> - * it there, otherwise allocate a buffer for it
> - * and copy the data there.  Either way, set
> - * if_data to point at the data.
> - * If we allocate a buffer for the data, make
> - * sure that its size is a multiple of 4 and
> - * record the real size in i_real_bytes.
>   */
>  STATIC int
>  xfs_iformat_local(
> @@ -328,9 +316,7 @@ xfs_iformat_local(
>  
>  /*
>   * The file consists of a set of extents all of which fit into the on-disk
> - * inode.  If there are few enough extents to fit into the if_inline_ext, then
> - * copy them there.  Otherwise allocate a buffer for them and copy them into it.
> - * Either way, set if_extents to point at the extents.
> + * inode.
>   */
>  STATIC int
>  xfs_iformat_extents(
> @@ -362,8 +348,6 @@ xfs_iformat_extents(
>  	ifp->if_real_bytes = 0;
>  	if (nex == 0)
>  		ifp->if_u1.if_extents = NULL;
> -	else if (nex <= XFS_INLINE_EXTS)
> -		ifp->if_u1.if_extents = ifp->if_u2.if_inline_ext;
>  	else
>  		xfs_iext_add(ifp, 0, nex);
>  
> @@ -618,26 +602,9 @@ xfs_idata_realloc(
>  	ASSERT(new_size >= 0);
>  
>  	if (new_size == 0) {
> -		if (ifp->if_u1.if_data != ifp->if_u2.if_inline_data) {
> -			kmem_free(ifp->if_u1.if_data);
> -		}
> +		kmem_free(ifp->if_u1.if_data);
>  		ifp->if_u1.if_data = NULL;
>  		real_size = 0;
> -	} else if (new_size <= sizeof(ifp->if_u2.if_inline_data)) {
> -		/*
> -		 * If the valid extents/data can fit in if_inline_ext/data,
> -		 * copy them from the malloc'd vector and free it.
> -		 */
> -		if (ifp->if_u1.if_data == NULL) {
> -			ifp->if_u1.if_data = ifp->if_u2.if_inline_data;
> -		} else if (ifp->if_u1.if_data != ifp->if_u2.if_inline_data) {
> -			ASSERT(ifp->if_real_bytes != 0);
> -			memcpy(ifp->if_u2.if_inline_data, ifp->if_u1.if_data,
> -			      new_size);
> -			kmem_free(ifp->if_u1.if_data);
> -			ifp->if_u1.if_data = ifp->if_u2.if_inline_data;
> -		}
> -		real_size = 0;
>  	} else {
>  		/*
>  		 * Stuck with malloc/realloc.
> @@ -651,7 +618,7 @@ xfs_idata_realloc(
>  			ASSERT(ifp->if_real_bytes == 0);
>  			ifp->if_u1.if_data = kmem_alloc(real_size,
>  							KM_SLEEP | KM_NOFS);
> -		} else if (ifp->if_u1.if_data != ifp->if_u2.if_inline_data) {
> +		} else {
>  			/*
>  			 * Only do the realloc if the underlying size
>  			 * is really changing.
> @@ -662,12 +629,6 @@ xfs_idata_realloc(
>  							real_size,
>  							KM_SLEEP | KM_NOFS);
>  			}
> -		} else {
> -			ASSERT(ifp->if_real_bytes == 0);
> -			ifp->if_u1.if_data = kmem_alloc(real_size,
> -							KM_SLEEP | KM_NOFS);
> -			memcpy(ifp->if_u1.if_data, ifp->if_u2.if_inline_data,
> -				ifp->if_bytes);
>  		}
>  	}
>  	ifp->if_real_bytes = real_size;
> @@ -695,8 +656,7 @@ xfs_idestroy_fork(
>  	 * so check and free it up if we do.
>  	 */
>  	if (XFS_IFORK_FORMAT(ip, whichfork) == XFS_DINODE_FMT_LOCAL) {
> -		if ((ifp->if_u1.if_data != ifp->if_u2.if_inline_data) &&
> -		    (ifp->if_u1.if_data != NULL)) {
> +		if (ifp->if_u1.if_data != NULL) {
>  			ASSERT(ifp->if_real_bytes != 0);
>  			kmem_free(ifp->if_u1.if_data);
>  			ifp->if_u1.if_data = NULL;
> @@ -704,13 +664,11 @@ xfs_idestroy_fork(
>  		}
>  	} else if ((ifp->if_flags & XFS_IFEXTENTS) &&
>  		   ((ifp->if_flags & XFS_IFEXTIREC) ||
> -		    ((ifp->if_u1.if_extents != NULL) &&
> -		     (ifp->if_u1.if_extents != ifp->if_u2.if_inline_ext)))) {
> +		    (ifp->if_u1.if_extents != NULL))) {
>  		ASSERT(ifp->if_real_bytes != 0);
>  		xfs_iext_destroy(ifp);
>  	}
> -	ASSERT(ifp->if_u1.if_extents == NULL ||
> -	       ifp->if_u1.if_extents == ifp->if_u2.if_inline_ext);
> +	ASSERT(ifp->if_u1.if_extents == NULL);
>  	ASSERT(ifp->if_real_bytes == 0);
>  	if (whichfork == XFS_ATTR_FORK) {
>  		kmem_zone_free(xfs_ifork_zone, ip->i_afp);
> @@ -943,28 +901,14 @@ xfs_iext_add(
>  	ASSERT((idx >= 0) && (idx <= nextents));
>  	byte_diff = ext_diff * sizeof(xfs_bmbt_rec_t);
>  	new_size = ifp->if_bytes + byte_diff;
> +
>  	/*
> -	 * If the new number of extents (nextents + ext_diff)
> -	 * fits inside the inode, then continue to use the inline
> -	 * extent buffer.
> -	 */
> -	if (nextents + ext_diff <= XFS_INLINE_EXTS) {
> -		if (idx < nextents) {
> -			memmove(&ifp->if_u2.if_inline_ext[idx + ext_diff],
> -				&ifp->if_u2.if_inline_ext[idx],
> -				(nextents - idx) * sizeof(xfs_bmbt_rec_t));
> -			memset(&ifp->if_u2.if_inline_ext[idx], 0, byte_diff);
> -		}
> -		ifp->if_u1.if_extents = ifp->if_u2.if_inline_ext;
> -		ifp->if_real_bytes = 0;
> -	}
> -	/*
> -	 * Otherwise use a linear (direct) extent list.
> +	 * Use a linear (direct) extent list.
>  	 * If the extents are currently inside the inode,
>  	 * xfs_iext_realloc_direct will switch us from
>  	 * inline to direct extent allocation mode.
>  	 */
> -	else if (nextents + ext_diff <= XFS_LINEAR_EXTS) {
> +	if (nextents + ext_diff <= XFS_LINEAR_EXTS) {
>  		xfs_iext_realloc_direct(ifp, new_size);
>  		if (idx < nextents) {
>  			memmove(&ifp->if_u1.if_extents[idx + ext_diff],
> @@ -1172,43 +1116,10 @@ xfs_iext_remove(
>  		xfs_iext_remove_indirect(ifp, cur->idx, ext_diff);
>  	} else if (ifp->if_real_bytes) {
>  		xfs_iext_remove_direct(ifp, cur->idx, ext_diff);
> -	} else {
> -		xfs_iext_remove_inline(ifp, cur->idx, ext_diff);
>  	}
>  	ifp->if_bytes = new_size;
>  }
>  
> -/*
> - * This removes ext_diff extents from the inline buffer, beginning
> - * at extent index idx.
> - */
> -void
> -xfs_iext_remove_inline(
> -	xfs_ifork_t	*ifp,		/* inode fork pointer */
> -	xfs_extnum_t	idx,		/* index to begin removing exts */
> -	int		ext_diff)	/* number of extents to remove */
> -{
> -	int		nextents;	/* number of extents in file */
> -
> -	ASSERT(!(ifp->if_flags & XFS_IFEXTIREC));
> -	ASSERT(idx < XFS_INLINE_EXTS);
> -	nextents = xfs_iext_count(ifp);
> -	ASSERT(((nextents - ext_diff) > 0) &&
> -		(nextents - ext_diff) < XFS_INLINE_EXTS);
> -
> -	if (idx + ext_diff < nextents) {
> -		memmove(&ifp->if_u2.if_inline_ext[idx],
> -			&ifp->if_u2.if_inline_ext[idx + ext_diff],
> -			(nextents - (idx + ext_diff)) *
> -			 sizeof(xfs_bmbt_rec_t));
> -		memset(&ifp->if_u2.if_inline_ext[nextents - ext_diff],
> -			0, ext_diff * sizeof(xfs_bmbt_rec_t));
> -	} else {
> -		memset(&ifp->if_u2.if_inline_ext[idx], 0,
> -			ext_diff * sizeof(xfs_bmbt_rec_t));
> -	}
> -}
> -
>  /*
>   * This removes ext_diff extents from a linear (direct) extent list,
>   * beginning at extent index idx. If the extents are being removed
> @@ -1351,16 +1262,7 @@ xfs_iext_realloc_direct(
>  	/* Free extent records */
>  	if (new_size == 0) {
>  		xfs_iext_destroy(ifp);
> -	}
> -	/* Resize direct extent list and zero any new bytes */
> -	else if (ifp->if_real_bytes) {
> -		/* Check if extents will fit inside the inode */
> -		if (new_size <= XFS_INLINE_EXTS * sizeof(xfs_bmbt_rec_t)) {
> -			xfs_iext_direct_to_inline(ifp, new_size /
> -				(uint)sizeof(xfs_bmbt_rec_t));
> -			ifp->if_bytes = new_size;
> -			return;
> -		}
> +	} else {
>  		if (!is_power_of_2(new_size)){
>  			rnew_size = roundup_pow_of_two(new_size);
>  		}
> @@ -1375,63 +1277,10 @@ xfs_iext_realloc_direct(
>  				rnew_size - ifp->if_real_bytes);
>  		}
>  	}
> -	/* Switch from the inline extent buffer to a direct extent list */
> -	else {
> -		if (!is_power_of_2(new_size)) {
> -			rnew_size = roundup_pow_of_two(new_size);
> -		}
> -		xfs_iext_inline_to_direct(ifp, rnew_size);
> -	}
>  	ifp->if_real_bytes = rnew_size;
>  	ifp->if_bytes = new_size;
>  }
>  
> -/*
> - * Switch from linear (direct) extent records to inline buffer.
> - */
> -void
> -xfs_iext_direct_to_inline(
> -	xfs_ifork_t	*ifp,		/* inode fork pointer */
> -	xfs_extnum_t	nextents)	/* number of extents in file */
> -{
> -	ASSERT(ifp->if_flags & XFS_IFEXTENTS);
> -	ASSERT(nextents <= XFS_INLINE_EXTS);
> -	/*
> -	 * The inline buffer was zeroed when we switched
> -	 * from inline to direct extent allocation mode,
> -	 * so we don't need to clear it here.
> -	 */
> -	memcpy(ifp->if_u2.if_inline_ext, ifp->if_u1.if_extents,
> -		nextents * sizeof(xfs_bmbt_rec_t));
> -	kmem_free(ifp->if_u1.if_extents);
> -	ifp->if_u1.if_extents = ifp->if_u2.if_inline_ext;
> -	ifp->if_real_bytes = 0;
> -}
> -
> -/*
> - * Switch from inline buffer to linear (direct) extent records.
> - * new_size should already be rounded up to the next power of 2
> - * by the caller (when appropriate), so use new_size as it is.
> - * However, since new_size may be rounded up, we can't update
> - * if_bytes here. It is the caller's responsibility to update
> - * if_bytes upon return.
> - */
> -void
> -xfs_iext_inline_to_direct(
> -	xfs_ifork_t	*ifp,		/* inode fork pointer */
> -	int		new_size)	/* number of extents in file */
> -{
> -	ifp->if_u1.if_extents = kmem_alloc(new_size, KM_NOFS);
> -	memset(ifp->if_u1.if_extents, 0, new_size);
> -	if (ifp->if_bytes) {
> -		memcpy(ifp->if_u1.if_extents, ifp->if_u2.if_inline_ext,
> -			ifp->if_bytes);
> -		memset(ifp->if_u2.if_inline_ext, 0, XFS_INLINE_EXTS *
> -			sizeof(xfs_bmbt_rec_t));
> -	}
> -	ifp->if_real_bytes = new_size;
> -}
> -
>  /*
>   * Resize an extent indirection array to new_size bytes.
>   */
> @@ -1511,9 +1360,6 @@ xfs_iext_destroy(
>  		xfs_iext_irec_remove_all(ifp);
>  	} else if (ifp->if_real_bytes) {
>  		kmem_free(ifp->if_u1.if_extents);
> -	} else if (ifp->if_bytes) {
> -		memset(ifp->if_u2.if_inline_ext, 0, XFS_INLINE_EXTS *
> -			sizeof(xfs_bmbt_rec_t));
>  	}
>  	ifp->if_u1.if_extents = NULL;
>  	ifp->if_real_bytes = 0;
> @@ -1708,8 +1554,6 @@ xfs_iext_irec_init(
>  
>  	if (nextents == 0) {
>  		ifp->if_u1.if_extents = kmem_alloc(XFS_IEXT_BUFSZ, KM_NOFS);
> -	} else if (!ifp->if_real_bytes) {
> -		xfs_iext_inline_to_direct(ifp, XFS_IEXT_BUFSZ);
>  	} else if (ifp->if_real_bytes < XFS_IEXT_BUFSZ) {
>  		xfs_iext_realloc_direct(ifp, XFS_IEXT_BUFSZ);
>  	}
> @@ -1829,9 +1673,6 @@ xfs_iext_irec_compact(
>  
>  	if (nextents == 0) {
>  		xfs_iext_destroy(ifp);
> -	} else if (nextents <= XFS_INLINE_EXTS) {
> -		xfs_iext_indirect_to_direct(ifp);
> -		xfs_iext_direct_to_inline(ifp, nextents);
>  	} else if (nextents <= XFS_LINEAR_EXTS) {
>  		xfs_iext_indirect_to_direct(ifp);
>  	} else if (nextents < (nlists * XFS_LINEAR_EXTS) >> 1) {
> diff --git a/fs/xfs/libxfs/xfs_inode_fork.h b/fs/xfs/libxfs/xfs_inode_fork.h
> index 7065544f446a..cc7ca255ec98 100644
> --- a/fs/xfs/libxfs/xfs_inode_fork.h
> +++ b/fs/xfs/libxfs/xfs_inode_fork.h
> @@ -51,8 +51,6 @@ typedef struct xfs_ext_irec {
>   */
>  #define	XFS_IEXT_BUFSZ		4096
>  #define	XFS_LINEAR_EXTS		(XFS_IEXT_BUFSZ / (uint)sizeof(xfs_bmbt_rec_t))
> -#define	XFS_INLINE_EXTS		2
> -#define	XFS_INLINE_DATA		32
>  typedef struct xfs_ifork {
>  	int			if_bytes;	/* bytes in if_u1 */
>  	int			if_real_bytes;	/* bytes allocated in if_u1 */
> @@ -64,12 +62,6 @@ typedef struct xfs_ifork {
>  		xfs_ext_irec_t	*if_ext_irec;	/* irec map file exts */
>  		char		*if_data;	/* inline file data */
>  	} if_u1;
> -	union {
> -		xfs_bmbt_rec_host_t if_inline_ext[XFS_INLINE_EXTS];
> -						/* very small file extents */
> -		char		if_inline_data[XFS_INLINE_DATA];
> -						/* very small file data */
> -	} if_u2;
>  } xfs_ifork_t;
>  
>  /*
> @@ -158,12 +150,9 @@ void		xfs_iext_add_indirect_multi(struct xfs_ifork *, int,
>  					    xfs_extnum_t, int);
>  void		xfs_iext_remove(struct xfs_inode *, struct xfs_iext_cursor *,
>  			int, int);
> -void		xfs_iext_remove_inline(struct xfs_ifork *, xfs_extnum_t, int);
>  void		xfs_iext_remove_direct(struct xfs_ifork *, xfs_extnum_t, int);
>  void		xfs_iext_remove_indirect(struct xfs_ifork *, xfs_extnum_t, int);
>  void		xfs_iext_realloc_direct(struct xfs_ifork *, int);
> -void		xfs_iext_direct_to_inline(struct xfs_ifork *, xfs_extnum_t);
> -void		xfs_iext_inline_to_direct(struct xfs_ifork *, int);
>  void		xfs_iext_destroy(struct xfs_ifork *);
>  struct xfs_bmbt_rec_host *
>  		xfs_iext_bno_to_ext(struct xfs_ifork *, xfs_fileoff_t, int *);
> diff --git a/fs/xfs/xfs_bmap_util.c b/fs/xfs/xfs_bmap_util.c
> index 515eec004971..893763cee691 100644
> --- a/fs/xfs/xfs_bmap_util.c
> +++ b/fs/xfs/xfs_bmap_util.c
> @@ -1709,7 +1709,6 @@ xfs_swap_extent_forks(
>  	xfs_filblks_t		aforkblks = 0;
>  	xfs_filblks_t		taforkblks = 0;
>  	xfs_extnum_t		junk;
> -	xfs_extnum_t		nextents;
>  	uint64_t		tmp;
>  	int			error;
>  
> @@ -1784,13 +1783,6 @@ xfs_swap_extent_forks(
>  
>  	switch (ip->i_d.di_format) {
>  	case XFS_DINODE_FMT_EXTENTS:
> -		/*
> -		 * If the extents fit in the inode, fix the pointer.  Otherwise
> -		 * it's already NULL or pointing to the extent.
> -		 */
> -		nextents = xfs_iext_count(&ip->i_df);
> -		if (nextents <= XFS_INLINE_EXTS)
> -			ifp->if_u1.if_extents = ifp->if_u2.if_inline_ext;
>  		(*src_log_flags) |= XFS_ILOG_DEXT;
>  		break;
>  	case XFS_DINODE_FMT_BTREE:
> @@ -1802,13 +1794,6 @@ xfs_swap_extent_forks(
>  
>  	switch (tip->i_d.di_format) {
>  	case XFS_DINODE_FMT_EXTENTS:
> -		/*
> -		 * If the extents fit in the inode, fix the pointer.  Otherwise
> -		 * it's already NULL or pointing to the extent.
> -		 */
> -		nextents = xfs_iext_count(&tip->i_df);
> -		if (nextents <= XFS_INLINE_EXTS)
> -			tifp->if_u1.if_extents = tifp->if_u2.if_inline_ext;
>  		(*target_log_flags) |= XFS_ILOG_DEXT;
>  		break;
>  	case XFS_DINODE_FMT_BTREE:
> -- 
> 2.14.2
> 
> --
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[PATCH 16/21] xfs: allow unaligned extent records in xfs_bmbt_disk_set_all

[Christoph Hellwig]

To make life a little simpler make xfs_bmbt_set_all unaligned access
aware so that we can use it directly on the destination buffer.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
---
 fs/xfs/libxfs/xfs_bmap_btree.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_bmap_btree.c b/fs/xfs/libxfs/xfs_bmap_btree.c
index 086e6fc8e4fc..89260972a0f6 100644
--- a/fs/xfs/libxfs/xfs_bmap_btree.c
+++ b/fs/xfs/libxfs/xfs_bmap_btree.c
@@ -199,14 +199,14 @@ xfs_bmbt_disk_set_all(
 	ASSERT(!(s->br_blockcount & xfs_mask64hi(64-BMBT_BLOCKCOUNT_BITLEN)));
 	ASSERT(!(s->br_startblock & xfs_mask64hi(64-BMBT_STARTBLOCK_BITLEN)));
 
-	r->l0 = cpu_to_be64(
+	put_unaligned_be64(
 		((xfs_bmbt_rec_base_t)extent_flag << 63) |
 		 ((xfs_bmbt_rec_base_t)s->br_startoff << 9) |
-		 ((xfs_bmbt_rec_base_t)s->br_startblock >> 43));
-	r->l1 = cpu_to_be64(
+		 ((xfs_bmbt_rec_base_t)s->br_startblock >> 43), &r->l0);
+	put_unaligned_be64(
 		((xfs_bmbt_rec_base_t)s->br_startblock << 21) |
 		 ((xfs_bmbt_rec_base_t)s->br_blockcount &
-		  (xfs_bmbt_rec_base_t)xfs_mask64lo(21)));
+		  (xfs_bmbt_rec_base_t)xfs_mask64lo(21)), &r->l1);
 }
 
 /*
-- 
2.14.2

[PATCH 17/21] xfs: use a b+tree for the in-core extent list

[Christoph Hellwig]

Replace the current linear list and the indirection array for the in-core
extent list with a b+tree to avoid the need for larger memory allocations
for the indirection array when lots of extents are present.  The current
extent list implementations leads to heavy pressure on the memory
allocator when modifying files with a high extent count, and can lead
to high latencies because of that.

The replacement is a b+tree with a few quirks.  The leaf nodes directly
store the extent record in two u64 values.  The encoding is a little bit
different from the existing in-core extent records so that the start
offset and length which are required for lookups can be retreived with
simple mask operations.  The inner nodes store a 64-bit key containing
the start offset in the first half of the node, and the pointers to the
next lower level in the second half.  In either case we walk the node
from the beginninig to the end and do a linear search, as that is more
efficient for the low number of cache lines touched during a search
(2 for the inner nodes, 4 for the leaf nodes) than a binary search.
We store termination markers (zero length for the leaf nodes, an
otherwise impossible high bit for the inner nodes) to terminate the key
list / records instead of storing a count to use the available cache
lines as efficiently as possible.

One quirk of the algorithm is that while we normally split a node half and
half like usual btree implementations we just spill over entries added at
the very end of the list to a new node on its own.  This means we get a
100% fill grade for the common cases of bulk inseration at reading an
inode into memory, and when only sequentially appending to a file.  The
downside is a slightly higher chance of splits on the first random
inserations.

Both insert and removal manually recurse into the lower levels, but
the bulk deletion of the whole tree is still implemented as a recursive
function call, although one limited by the overall depth and with very
little stack usage in every iteration.

For the first few extents we dynamically grow the list from a single
extent to the next powers of two until we have a first full leaf block
and that building the actual tree.

The code started out based on the generic lib/btree.c code from Joern
Engel based on earlier work from Peter Zijlstra, but has since been
rewritten beyond recognition.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 fs/xfs/Makefile                |    1 +
 fs/xfs/libxfs/xfs_bmap.c       |   20 +-
 fs/xfs/libxfs/xfs_bmap_btree.c |  103 +---
 fs/xfs/libxfs/xfs_bmap_btree.h |    7 +-
 fs/xfs/libxfs/xfs_format.h     |    4 -
 fs/xfs/libxfs/xfs_iext_tree.c  | 1035 ++++++++++++++++++++++++++++++++++++++++
 fs/xfs/libxfs/xfs_inode_fork.c | 1035 +---------------------------------------
 fs/xfs/libxfs/xfs_inode_fork.h |   84 +---
 fs/xfs/libxfs/xfs_types.h      |    3 +-
 fs/xfs/scrub/bmap.c            |    5 +-
 fs/xfs/xfs_inode.c             |    2 +-
 fs/xfs/xfs_inode_item.c        |    2 -
 fs/xfs/xfs_trace.h             |   51 +-
 13 files changed, 1093 insertions(+), 1259 deletions(-)
 create mode 100644 fs/xfs/libxfs/xfs_iext_tree.c

diff --git a/fs/xfs/Makefile b/fs/xfs/Makefile
index a2a5d046793d..7ceb41a9786a 100644
--- a/fs/xfs/Makefile
+++ b/fs/xfs/Makefile
@@ -49,6 +49,7 @@ xfs-y				+= $(addprefix libxfs/, \
 				   xfs_dquot_buf.o \
 				   xfs_ialloc.o \
 				   xfs_ialloc_btree.o \
+				   xfs_iext_tree.o \
 				   xfs_inode_fork.o \
 				   xfs_inode_buf.o \
 				   xfs_log_rlimit.o \
diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
index 8fcb186341ce..7d96e4d9fc91 100644
--- a/fs/xfs/libxfs/xfs_bmap.c
+++ b/fs/xfs/libxfs/xfs_bmap.c
@@ -806,6 +806,8 @@ xfs_bmap_local_to_extents_empty(
 	xfs_bmap_forkoff_reset(ip, whichfork);
 	ifp->if_flags &= ~XFS_IFINLINE;
 	ifp->if_flags |= XFS_IFEXTENTS;
+	ifp->if_u1.if_root = NULL;
+	ifp->if_height = 0;
 	XFS_IFORK_FMT_SET(ip, whichfork, XFS_DINODE_FMT_EXTENTS);
 }
 
@@ -847,8 +849,7 @@ xfs_bmap_local_to_extents(
 
 	flags = 0;
 	error = 0;
-	ASSERT((ifp->if_flags & (XFS_IFINLINE|XFS_IFEXTENTS|XFS_IFEXTIREC)) ==
-								XFS_IFINLINE);
+	ASSERT((ifp->if_flags & (XFS_IFINLINE|XFS_IFEXTENTS)) == XFS_IFINLINE);
 	memset(&args, 0, sizeof(args));
 	args.tp = tp;
 	args.mp = ip->i_mount;
@@ -892,6 +893,9 @@ xfs_bmap_local_to_extents(
 	xfs_bmap_local_to_extents_empty(ip, whichfork);
 	flags |= XFS_ILOG_CORE;
 
+	ifp->if_u1.if_root = NULL;
+	ifp->if_height = 0;
+
 	rec.br_startoff = 0;
 	rec.br_startblock = args.fsbno;
 	rec.br_blockcount = 1;
@@ -1178,6 +1182,7 @@ xfs_iread_extents(
 	xfs_extnum_t		nextents = XFS_IFORK_NEXTENTS(ip, whichfork);
 	struct xfs_btree_block	*block = ifp->if_broot;
 	struct xfs_iext_cursor	icur;
+	struct xfs_bmbt_irec	new;
 	xfs_fsblock_t		bno;
 	struct xfs_buf		*bp;
 	xfs_extnum_t		i, j;
@@ -1192,10 +1197,6 @@ xfs_iread_extents(
 		return -EFSCORRUPTED;
 	}
 
-	ifp->if_bytes = 0;
-	ifp->if_real_bytes = 0;
-	xfs_iext_add(ifp, 0, nextents);
-
 	/*
 	 * Root level must use BMAP_BROOT_PTR_ADDR macro to get ptr out.
 	 */
@@ -1259,16 +1260,15 @@ xfs_iread_extents(
 		 * Copy records into the extent records.
 		 */
 		frp = XFS_BMBT_REC_ADDR(mp, block, 1);
-		for (j = 0; j < num_recs; j++, i++, frp++) {
-			xfs_bmbt_rec_host_t *trp = xfs_iext_get_ext(ifp, i);
+		for (j = 0; j < num_recs; j++, frp++, i++) {
 			if (!xfs_bmbt_validate_extent(mp, whichfork, frp)) {
 				XFS_ERROR_REPORT("xfs_bmap_read_extents(2)",
 						 XFS_ERRLEVEL_LOW, mp);
 				error = -EFSCORRUPTED;
 				goto out_brelse;
 			}
-			trp->l0 = be64_to_cpu(frp->l0);
-			trp->l1 = be64_to_cpu(frp->l1);
+			xfs_bmbt_disk_get_all(frp, &new);
+			xfs_iext_insert(ip, &icur, 1, &new, state);
 			trace_xfs_read_extent(ip, &icur, state, _THIS_IP_);
 			xfs_iext_next(ifp, &icur);
 		}
diff --git a/fs/xfs/libxfs/xfs_bmap_btree.c b/fs/xfs/libxfs/xfs_bmap_btree.c
index 89260972a0f6..c10aecaaae44 100644
--- a/fs/xfs/libxfs/xfs_bmap_btree.c
+++ b/fs/xfs/libxfs/xfs_bmap_btree.c
@@ -71,73 +71,21 @@ xfs_bmdr_to_bmbt(
 	memcpy(tpp, fpp, sizeof(*fpp) * dmxr);
 }
 
-/*
- * Convert a compressed bmap extent record to an uncompressed form.
- * This code must be in sync with the routines xfs_bmbt_get_startoff,
- * xfs_bmbt_get_startblock and xfs_bmbt_get_blockcount.
- */
-STATIC void
-__xfs_bmbt_get_all(
-		uint64_t l0,
-		uint64_t l1,
-		xfs_bmbt_irec_t *s)
-{
-	int	ext_flag;
-	xfs_exntst_t st;
-
-	ext_flag = (int)(l0 >> (64 - BMBT_EXNTFLAG_BITLEN));
-	s->br_startoff = ((xfs_fileoff_t)l0 &
-			   xfs_mask64lo(64 - BMBT_EXNTFLAG_BITLEN)) >> 9;
-	s->br_startblock = (((xfs_fsblock_t)l0 & xfs_mask64lo(9)) << 43) |
-			   (((xfs_fsblock_t)l1) >> 21);
-	s->br_blockcount = (xfs_filblks_t)(l1 & xfs_mask64lo(21));
-	/* This is xfs_extent_state() in-line */
-	if (ext_flag) {
-		ASSERT(s->br_blockcount != 0);	/* saved for DMIG */
-		st = XFS_EXT_UNWRITTEN;
-	} else
-		st = XFS_EXT_NORM;
-	s->br_state = st;
-}
-
 void
-xfs_bmbt_get_all(
-	xfs_bmbt_rec_host_t *r,
-	xfs_bmbt_irec_t *s)
-{
-	__xfs_bmbt_get_all(r->l0, r->l1, s);
-}
-
-/*
- * Extract the blockcount field from an in memory bmap extent record.
- */
-xfs_filblks_t
-xfs_bmbt_get_blockcount(
-	xfs_bmbt_rec_host_t	*r)
-{
-	return (xfs_filblks_t)(r->l1 & xfs_mask64lo(21));
-}
-
-/*
- * Extract the startblock field from an in memory bmap extent record.
- */
-xfs_fsblock_t
-xfs_bmbt_get_startblock(
-	xfs_bmbt_rec_host_t	*r)
-{
-	return (((xfs_fsblock_t)r->l0 & xfs_mask64lo(9)) << 43) |
-	       (((xfs_fsblock_t)r->l1) >> 21);
-}
-
-/*
- * Extract the startoff field from an in memory bmap extent record.
- */
-xfs_fileoff_t
-xfs_bmbt_get_startoff(
-	xfs_bmbt_rec_host_t	*r)
-{
-	return ((xfs_fileoff_t)r->l0 &
-		 xfs_mask64lo(64 - BMBT_EXNTFLAG_BITLEN)) >> 9;
+xfs_bmbt_disk_get_all(
+	struct xfs_bmbt_rec	*rec,
+	struct xfs_bmbt_irec	*irec)
+{
+	uint64_t		l0 = get_unaligned_be64(&rec->l0);
+	uint64_t		l1 = get_unaligned_be64(&rec->l1);
+
+	irec->br_startoff = (l0 & xfs_mask64lo(64 - BMBT_EXNTFLAG_BITLEN)) >> 9;
+	irec->br_startblock = ((l0 & xfs_mask64lo(9)) << 43) | (l1 >> 21);
+	irec->br_blockcount = l1 & xfs_mask64lo(21);
+	if (l0 >> (64 - BMBT_EXNTFLAG_BITLEN))
+		irec->br_state = XFS_EXT_UNWRITTEN;
+	else
+		irec->br_state = XFS_EXT_NORM;
 }
 
 /*
@@ -161,29 +109,6 @@ xfs_bmbt_disk_get_startoff(
 		 xfs_mask64lo(64 - BMBT_EXNTFLAG_BITLEN)) >> 9;
 }
 
-/*
- * Set all the fields in a bmap extent record from the uncompressed form.
- */
-void
-xfs_bmbt_set_all(
-	struct xfs_bmbt_rec_host *r,
-	struct xfs_bmbt_irec	*s)
-{
-	int			extent_flag = (s->br_state != XFS_EXT_NORM);
-
-	ASSERT(s->br_state == XFS_EXT_NORM || s->br_state == XFS_EXT_UNWRITTEN);
-	ASSERT(!(s->br_startoff & xfs_mask64hi(64-BMBT_STARTOFF_BITLEN)));
-	ASSERT(!(s->br_blockcount & xfs_mask64hi(64-BMBT_BLOCKCOUNT_BITLEN)));
-	ASSERT(!(s->br_startblock & xfs_mask64hi(64-BMBT_STARTBLOCK_BITLEN)));
-
-	r->l0 = ((xfs_bmbt_rec_base_t)extent_flag << 63) |
-		 ((xfs_bmbt_rec_base_t)s->br_startoff << 9) |
-		 ((xfs_bmbt_rec_base_t)s->br_startblock >> 43);
-	r->l1 = ((xfs_bmbt_rec_base_t)s->br_startblock << 21) |
-		 ((xfs_bmbt_rec_base_t)s->br_blockcount &
-		  (xfs_bmbt_rec_base_t)xfs_mask64lo(21));
-}
-
 /*
  * Set all the fields in a bmap extent record from the uncompressed form.
  */
diff --git a/fs/xfs/libxfs/xfs_bmap_btree.h b/fs/xfs/libxfs/xfs_bmap_btree.h
index 2fbfe2a24b15..714bfbaf9b2d 100644
--- a/fs/xfs/libxfs/xfs_bmap_btree.h
+++ b/fs/xfs/libxfs/xfs_bmap_btree.h
@@ -98,16 +98,11 @@ struct xfs_trans;
  */
 extern void xfs_bmdr_to_bmbt(struct xfs_inode *, xfs_bmdr_block_t *, int,
 			struct xfs_btree_block *, int);
-extern void xfs_bmbt_get_all(xfs_bmbt_rec_host_t *r, xfs_bmbt_irec_t *s);
-extern xfs_filblks_t xfs_bmbt_get_blockcount(xfs_bmbt_rec_host_t *r);
-extern xfs_fsblock_t xfs_bmbt_get_startblock(xfs_bmbt_rec_host_t *r);
-extern xfs_fileoff_t xfs_bmbt_get_startoff(xfs_bmbt_rec_host_t *r);
 
 void xfs_bmbt_disk_set_all(struct xfs_bmbt_rec *r, struct xfs_bmbt_irec *s);
 extern xfs_filblks_t xfs_bmbt_disk_get_blockcount(xfs_bmbt_rec_t *r);
 extern xfs_fileoff_t xfs_bmbt_disk_get_startoff(xfs_bmbt_rec_t *r);
-
-extern void xfs_bmbt_set_all(xfs_bmbt_rec_host_t *r, xfs_bmbt_irec_t *s);
+extern void xfs_bmbt_disk_get_all(xfs_bmbt_rec_t *r, xfs_bmbt_irec_t *s);
 
 extern void xfs_bmbt_to_bmdr(struct xfs_mount *, struct xfs_btree_block *, int,
 			xfs_bmdr_block_t *, int);
diff --git a/fs/xfs/libxfs/xfs_format.h b/fs/xfs/libxfs/xfs_format.h
index 1e8c0b27f78b..fbe7d3c31345 100644
--- a/fs/xfs/libxfs/xfs_format.h
+++ b/fs/xfs/libxfs/xfs_format.h
@@ -1553,10 +1553,6 @@ typedef struct xfs_bmbt_rec {
 typedef uint64_t	xfs_bmbt_rec_base_t;	/* use this for casts */
 typedef xfs_bmbt_rec_t xfs_bmdr_rec_t;
 
-typedef struct xfs_bmbt_rec_host {
-	uint64_t		l0, l1;
-} xfs_bmbt_rec_host_t;
-
 /*
  * Values and macros for delayed-allocation startblock fields.
  */
diff --git a/fs/xfs/libxfs/xfs_iext_tree.c b/fs/xfs/libxfs/xfs_iext_tree.c
new file mode 100644
index 000000000000..8b6402d2d9b2
--- /dev/null
+++ b/fs/xfs/libxfs/xfs_iext_tree.c
@@ -0,0 +1,1035 @@
+/*
+ * Copyright (c) 2017 Christoph Hellwig.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ */
+
+#include <linux/cache.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include "xfs.h"
+#include "xfs_format.h"
+#include "xfs_bit.h"
+#include "xfs_log_format.h"
+#include "xfs_inode.h"
+#include "xfs_inode_fork.h"
+#include "xfs_trans_resv.h"
+#include "xfs_mount.h"
+#include "xfs_trace.h"
+
+/*
+ * In-core extent record layout:
+ *
+ * +-------+----------------------------+
+ * | 00:53 | all 54 bits of startoff    |
+ * | 54:63 | low 10 bits of startblock  |
+ * +-------+----------------------------+
+ * | 00:20 | all 21 bits of length      |
+ * |    21 | unwritten extent bit       |
+ * | 22:63 | high 42 bits of startblock |
+ * +-------+----------------------------+
+ */
+#define XFS_IEXT_STARTOFF_MASK		xfs_mask64lo(BMBT_STARTOFF_BITLEN)
+#define XFS_IEXT_LENGTH_MASK		xfs_mask64lo(BMBT_BLOCKCOUNT_BITLEN)
+#define XFS_IEXT_STARTBLOCK_MASK	xfs_mask64lo(BMBT_STARTBLOCK_BITLEN)
+
+struct xfs_iext_rec {
+	uint64_t			lo;
+	uint64_t			hi;
+};
+
+/*
+ * Given that the length can't be a zero, only an empty hi value indicates an
+ * unused record.
+ */
+static bool xfs_iext_rec_is_empty(struct xfs_iext_rec *rec)
+{
+	return rec->hi == 0;
+}
+
+static inline void xfs_iext_rec_clear(struct xfs_iext_rec *rec)
+{
+	rec->lo = 0;
+	rec->hi = 0;
+}
+
+static void
+xfs_iext_set(
+	struct xfs_iext_rec	*rec,
+	struct xfs_bmbt_irec	*irec)
+{
+	ASSERT((irec->br_startoff & ~XFS_IEXT_STARTOFF_MASK) == 0);
+	ASSERT((irec->br_blockcount & ~XFS_IEXT_LENGTH_MASK) == 0);
+	ASSERT((irec->br_startblock & ~XFS_IEXT_STARTBLOCK_MASK) == 0);
+
+	rec->lo = irec->br_startoff & XFS_IEXT_STARTOFF_MASK;
+	rec->hi = irec->br_blockcount & XFS_IEXT_LENGTH_MASK;
+
+	rec->lo |= (irec->br_startblock << 54);
+	rec->hi |= ((irec->br_startblock & ~xfs_mask64lo(10)) << (22 - 10));
+
+	if (irec->br_state == XFS_EXT_UNWRITTEN)
+		rec->hi |= (1 << 21);
+}
+
+static void
+xfs_iext_get(
+	struct xfs_bmbt_irec	*irec,
+	struct xfs_iext_rec	*rec)
+{
+	irec->br_startoff = rec->lo & XFS_IEXT_STARTOFF_MASK;
+	irec->br_blockcount = rec->hi & XFS_IEXT_LENGTH_MASK;
+
+	irec->br_startblock = rec->lo >> 54;
+	irec->br_startblock |= (rec->hi & xfs_mask64hi(42)) >> (22 - 10);
+
+	if (rec->hi & (1 << 21))
+		irec->br_state = XFS_EXT_UNWRITTEN;
+	else
+		irec->br_state = XFS_EXT_NORM;
+}
+
+enum {
+	NODE_SIZE	= 256,
+	KEYS_PER_NODE	= NODE_SIZE / (sizeof(uint64_t) + sizeof(void *)),
+	RECS_PER_LEAF	= (NODE_SIZE - (2 * sizeof(struct xfs_iext_leaf *))) /
+				sizeof(struct xfs_iext_rec),
+};
+
+/*
+ * In-core extent btree block layout:
+ *
+ * There are two types of blocks in the btree: leaf and inner (non-leaf) blocks.
+ *
+ * The leaf blocks are made up by %KEYS_PER_NODE extent records, which each
+ * contain the startoffset, blockcount, startblock and unwritten extent flag.
+ * See above for the exact format, followed by pointers to the previous and next
+ * leaf blocks (if there are any).
+ *
+ * The inner (non-leaf) blocks first contain KEYS_PER_NODE lookup keys, followed
+ * by an equal number of pointers to the btree blocks at the next lower level.
+ *
+ *		+-------+-------+-------+-------+-------+----------+----------+
+ * Leaf:	| rec 1 | rec 2 | rec 3 | rec 4 | rec N | prev-ptr | next-ptr |
+ *		+-------+-------+-------+-------+-------+----------+----------+
+ *
+ *		+-------+-------+-------+-------+-------+-------+------+-------+
+ * Inner:	| key 1 | key 2 | key 3 | key N | ptr 1 | ptr 2 | ptr3 | ptr N |
+ *		+-------+-------+-------+-------+-------+-------+------+-------+
+ */
+struct xfs_iext_node {
+	uint64_t		keys[KEYS_PER_NODE];
+#define XFS_IEXT_KEY_INVALID	(1ULL << 63)
+	void			*ptrs[KEYS_PER_NODE];
+};
+
+struct xfs_iext_leaf {
+	struct xfs_iext_rec	recs[RECS_PER_LEAF];
+	struct xfs_iext_leaf	*prev;
+	struct xfs_iext_leaf	*next;
+};
+
+inline xfs_extnum_t xfs_iext_count(struct xfs_ifork *ifp)
+{
+	return ifp->if_bytes / sizeof(struct xfs_iext_rec);
+}
+
+static inline int xfs_iext_max_recs(struct xfs_ifork *ifp)
+{
+	if (ifp->if_height == 1)
+		return xfs_iext_count(ifp);
+	return RECS_PER_LEAF;
+}
+
+static inline struct xfs_iext_rec *cur_rec(struct xfs_iext_cursor *cur)
+{
+	return &cur->leaf->recs[cur->pos];
+}
+
+static inline bool xfs_iext_valid(struct xfs_ifork *ifp,
+		struct xfs_iext_cursor *cur)
+{
+	if (!cur->leaf)
+		return false;
+	if (cur->pos < 0 || cur->pos >= xfs_iext_max_recs(ifp))
+		return false;
+	if (xfs_iext_rec_is_empty(cur_rec(cur)))
+		return false;
+	return true;
+}
+
+static void *
+xfs_iext_find_first_leaf(
+	struct xfs_ifork	*ifp)
+{
+	struct xfs_iext_node	*node = ifp->if_u1.if_root;
+	int			height;
+
+	if (!ifp->if_height)
+		return NULL;
+
+	for (height = ifp->if_height; height > 1; height--) {
+		node = node->ptrs[0];
+		ASSERT(node);
+	}
+
+	return node;
+}
+
+static void *
+xfs_iext_find_last_leaf(
+	struct xfs_ifork	*ifp)
+{
+	struct xfs_iext_node	*node = ifp->if_u1.if_root;
+	int			height, i;
+
+	if (!ifp->if_height)
+		return NULL;
+
+	for (height = ifp->if_height; height > 1; height--) {
+		for (i = 1; i < KEYS_PER_NODE; i++)
+			if (!node->ptrs[i])
+				break;
+		node = node->ptrs[i - 1];
+		ASSERT(node);
+	}
+
+	return node;
+}
+
+void
+xfs_iext_first(
+	struct xfs_ifork	*ifp,
+	struct xfs_iext_cursor	*cur)
+{
+	cur->pos = 0;
+	cur->leaf = xfs_iext_find_first_leaf(ifp);
+}
+
+void
+xfs_iext_last(
+	struct xfs_ifork	*ifp,
+	struct xfs_iext_cursor	*cur)
+{
+	int			i;
+
+	cur->leaf = xfs_iext_find_last_leaf(ifp);
+	if (!cur->leaf) {
+		cur->pos = 0;
+		return;
+	}
+
+	for (i = 1; i < xfs_iext_max_recs(ifp); i++) {
+		if (xfs_iext_rec_is_empty(&cur->leaf->recs[i]))
+			break;
+	}
+	cur->pos = i - 1;
+}
+
+void
+xfs_iext_next(
+	struct xfs_ifork	*ifp,
+	struct xfs_iext_cursor	*cur)
+{
+	if (!cur->leaf) {
+		ASSERT(cur->pos <= 0 || cur->pos >= RECS_PER_LEAF);
+		xfs_iext_first(ifp, cur);
+		return;
+	}
+
+	ASSERT(cur->pos >= 0);
+	ASSERT(cur->pos < xfs_iext_max_recs(ifp));
+
+	cur->pos++;
+	if (ifp->if_height > 1 && !xfs_iext_valid(ifp, cur) &&
+	    cur->leaf->next) {
+		cur->leaf = cur->leaf->next;
+		cur->pos = 0;
+	}
+}
+
+void
+xfs_iext_prev(
+	struct xfs_ifork	*ifp,
+	struct xfs_iext_cursor	*cur)
+{
+	if (!cur->leaf) {
+		ASSERT(cur->pos <= 0 || cur->pos >= RECS_PER_LEAF);
+		xfs_iext_last(ifp, cur);
+		return;
+	}
+
+	ASSERT(cur->pos >= 0);
+	ASSERT(cur->pos <= RECS_PER_LEAF);
+
+recurse:
+	do {
+		cur->pos--;
+		if (xfs_iext_valid(ifp, cur))
+			return;
+	} while (cur->pos > 0);
+
+	if (ifp->if_height > 1 && cur->leaf->prev) {
+		cur->leaf = cur->leaf->prev;
+		cur->pos = RECS_PER_LEAF;
+		goto recurse;
+	}
+}
+
+static inline int
+xfs_iext_key_cmp(
+	struct xfs_iext_node	*node,
+	int			n,
+	xfs_fileoff_t		offset)
+{
+	if (node->keys[n] > offset)
+		return 1;
+	if (node->keys[n] < offset)
+		return -1;
+	return 0;
+}
+
+static inline int
+xfs_iext_rec_cmp(
+	struct xfs_iext_rec	*rec,
+	xfs_fileoff_t		offset)
+{
+	uint64_t		rec_offset = rec->lo & XFS_IEXT_STARTOFF_MASK;
+	u32			rec_len = rec->hi & XFS_IEXT_LENGTH_MASK;
+
+	if (rec_offset > offset)
+		return 1;
+	if (rec_offset + rec_len <= offset)
+		return -1;
+	return 0;
+}
+
+static void *
+xfs_iext_find_level(
+	struct xfs_ifork	*ifp,
+	xfs_fileoff_t		offset,
+	int			level)
+{
+	struct xfs_iext_node	*node = ifp->if_u1.if_root;
+	int			height, i;
+
+	if (!ifp->if_height)
+		return NULL;
+
+	for (height = ifp->if_height; height > level; height--) {
+		for (i = 1; i < KEYS_PER_NODE; i++)
+			if (xfs_iext_key_cmp(node, i, offset) > 0)
+				break;
+
+		node = node->ptrs[i - 1];
+		if (!node)
+			break;
+	}
+
+	return node;
+}
+
+static int
+xfs_iext_node_pos(
+	struct xfs_iext_node	*node,
+	xfs_fileoff_t		offset)
+{
+	int			i;
+
+	for (i = 1; i < KEYS_PER_NODE; i++) {
+		if (xfs_iext_key_cmp(node, i, offset) > 0)
+			break;
+	}
+
+	return i - 1;
+}
+
+static int
+xfs_iext_node_insert_pos(
+	struct xfs_iext_node	*node,
+	xfs_fileoff_t		offset)
+{
+	int			i;
+
+	for (i = 0; i < KEYS_PER_NODE; i++) {
+		if (xfs_iext_key_cmp(node, i, offset) > 0)
+			return i;
+	}
+
+	return KEYS_PER_NODE;
+}
+
+static int
+xfs_iext_node_nr_entries(
+	struct xfs_iext_node	*node,
+	int			start)
+{
+	int			i;
+
+	for (i = start; i < KEYS_PER_NODE; i++) {
+		if (node->keys[i] == XFS_IEXT_KEY_INVALID)
+			break;
+	}
+
+	return i;
+}
+
+static int
+xfs_iext_leaf_nr_entries(
+	struct xfs_ifork	*ifp,
+	struct xfs_iext_leaf	*leaf,
+	int			start)
+{
+	int			i;
+
+	for (i = start; i < xfs_iext_max_recs(ifp); i++) {
+		if (xfs_iext_rec_is_empty(&leaf->recs[i]))
+			break;
+	}
+
+	return i;
+}
+
+static inline uint64_t
+xfs_iext_leaf_key(
+	struct xfs_iext_leaf	*leaf,
+	int			n)
+{
+	return leaf->recs[n].lo & XFS_IEXT_STARTOFF_MASK;
+}
+
+static void
+xfs_iext_grow(
+	struct xfs_ifork	*ifp)
+{
+	struct xfs_iext_node	*node = kmem_zalloc(NODE_SIZE, KM_NOFS);
+	int			i;
+
+	if (ifp->if_height == 1) {
+		struct xfs_iext_leaf *prev = ifp->if_u1.if_root;
+
+		node->keys[0] = xfs_iext_leaf_key(prev, 0);
+		node->ptrs[0] = prev;
+	} else  {
+		struct xfs_iext_node *prev = ifp->if_u1.if_root;
+
+		ASSERT(ifp->if_height > 1);
+
+		node->keys[0] = prev->keys[0];
+		node->ptrs[0] = prev;
+	}
+
+	for (i = 1; i < KEYS_PER_NODE; i++)
+		node->keys[i] = XFS_IEXT_KEY_INVALID;
+
+	ifp->if_u1.if_root = node;
+	ifp->if_height++;
+}
+
+static void
+xfs_iext_update_node(
+	struct xfs_ifork	*ifp,
+	xfs_fileoff_t		old_offset,
+	xfs_fileoff_t		new_offset,
+	int			level,
+	void			*ptr)
+{
+	struct xfs_iext_node	*node = ifp->if_u1.if_root;
+	int			height, i;
+
+	for (height = ifp->if_height; height > level; height--) {
+		for (i = 0; i < KEYS_PER_NODE; i++) {
+			if (i > 0 && xfs_iext_key_cmp(node, i, old_offset) > 0)
+				break;
+			if (node->keys[i] == old_offset)
+				node->keys[i] = new_offset;
+		}
+		node = node->ptrs[i - 1];
+		ASSERT(node);
+	}
+
+	ASSERT(node == ptr);
+}
+
+static struct xfs_iext_node *
+xfs_iext_split_node(
+	struct xfs_iext_node	**nodep,
+	int			*pos,
+	int			*nr_entries)
+{
+	struct xfs_iext_node	*node = *nodep;
+	struct xfs_iext_node	*new = kmem_zalloc(NODE_SIZE, KM_NOFS);
+	const int		nr_move = KEYS_PER_NODE / 2;
+	int			nr_keep = nr_move + (KEYS_PER_NODE & 1);
+	int			i = 0;
+
+	/* for sequential append operations just spill over into the new node */
+	if (*pos == KEYS_PER_NODE) {
+		*nodep = new;
+		*pos = 0;
+		*nr_entries = 0;
+		goto done;
+	}
+
+
+	for (i = 0; i < nr_move; i++) {
+		new->keys[i] = node->keys[nr_keep + i];
+		new->ptrs[i] = node->ptrs[nr_keep + i];
+
+		node->keys[nr_keep + i] = XFS_IEXT_KEY_INVALID;
+		node->ptrs[nr_keep + i] = NULL;
+	}
+
+	if (*pos >= nr_keep) {
+		*nodep = new;
+		*pos -= nr_keep;
+		*nr_entries = nr_move;
+	} else {
+		*nr_entries = nr_keep;
+	}
+done:
+	for (; i < KEYS_PER_NODE; i++)
+		new->keys[i] = XFS_IEXT_KEY_INVALID;
+	return new;
+}
+
+static void
+xfs_iext_insert_node(
+	struct xfs_ifork	*ifp,
+	uint64_t		offset,
+	void			*ptr,
+	int			level)
+{
+	struct xfs_iext_node	*node, *new;
+	int			i, pos, nr_entries;
+
+again:
+	if (ifp->if_height < level)
+		xfs_iext_grow(ifp);
+
+	new = NULL;
+	node = xfs_iext_find_level(ifp, offset, level);
+	pos = xfs_iext_node_insert_pos(node, offset);
+	nr_entries = xfs_iext_node_nr_entries(node, pos);
+
+	ASSERT(pos >= nr_entries || xfs_iext_key_cmp(node, pos, offset) != 0);
+	ASSERT(nr_entries <= KEYS_PER_NODE);
+
+	if (nr_entries == KEYS_PER_NODE)
+		new = xfs_iext_split_node(&node, &pos, &nr_entries);
+
+	if (node != new && pos == 0 && nr_entries > 0)
+		xfs_iext_update_node(ifp, node->keys[0], offset, level, node);
+
+	for (i = nr_entries; i > pos; i--) {
+		node->keys[i] = node->keys[i - 1];
+		node->ptrs[i] = node->ptrs[i - 1];
+	}
+	node->keys[pos] = offset;
+	node->ptrs[pos] = ptr;
+
+	if (new) {
+		offset = new->keys[0];
+		ptr = new;
+		level++;
+		goto again;
+	}
+}
+
+static struct xfs_iext_leaf *
+xfs_iext_split_leaf(
+	struct xfs_iext_cursor	*cur,
+	int			*nr_entries)
+{
+	struct xfs_iext_leaf	*leaf = cur->leaf;
+	struct xfs_iext_leaf	*new = kmem_zalloc(NODE_SIZE, KM_NOFS);
+	const int		nr_move = RECS_PER_LEAF / 2;
+	int			nr_keep = nr_move + (RECS_PER_LEAF & 1);
+	int			i;
+
+	/* for sequential append operations just spill over into the new node */
+	if (cur->pos == KEYS_PER_NODE) {
+		cur->leaf = new;
+		cur->pos = 0;
+		*nr_entries = 0;
+		goto done;
+	}
+
+	if (nr_keep & 1)
+		nr_keep++;
+
+	for (i = 0; i < nr_move; i++) {
+		new->recs[i] = leaf->recs[nr_keep + i];
+		xfs_iext_rec_clear(&leaf->recs[nr_keep + i]);
+	}
+
+	if (cur->pos >= nr_keep) {
+		cur->leaf = new;
+		cur->pos -= nr_keep;
+		*nr_entries = nr_move;
+	} else {
+		*nr_entries = nr_keep;
+	}
+done:
+	if (leaf->next)
+		leaf->next->prev = new;
+	new->next = leaf->next;
+	new->prev = leaf;
+	leaf->next = new;
+	return new;
+}
+
+static void
+xfs_iext_alloc_root(
+	struct xfs_ifork	*ifp,
+	struct xfs_iext_cursor	*cur)
+{
+	ASSERT(ifp->if_bytes == 0);
+
+	ifp->if_u1.if_root = kmem_zalloc(sizeof(struct xfs_iext_rec), KM_NOFS);
+	ifp->if_height = 1;
+
+	/* now that we have a node step into it */
+	cur->leaf = ifp->if_u1.if_root;
+	cur->pos = 0;
+}
+
+static void
+xfs_iext_realloc_root(
+	struct xfs_ifork	*ifp,
+	struct xfs_iext_cursor	*cur)
+{
+	size_t new_size = ifp->if_bytes + sizeof(struct xfs_iext_rec);
+	void *new;
+
+	/* account for the prev/next pointers */
+	if (new_size / sizeof(struct xfs_iext_rec) == RECS_PER_LEAF)
+		new_size = NODE_SIZE;
+
+	new = kmem_realloc(ifp->if_u1.if_root, new_size, KM_NOFS);
+	memset(new + ifp->if_bytes, 0, new_size - ifp->if_bytes);
+	ifp->if_u1.if_root = new;
+	cur->leaf = new;
+}
+
+static void
+__xfs_iext_insert(
+	struct xfs_ifork	*ifp,
+	struct xfs_iext_cursor	*cur,
+	struct xfs_bmbt_irec	*irec)
+{
+	xfs_fileoff_t		offset = irec->br_startoff;
+	struct xfs_iext_leaf	*new = NULL;
+	int			nr_entries, i;
+
+	if (ifp->if_height == 0)
+		xfs_iext_alloc_root(ifp, cur);
+	else if (ifp->if_height == 1)
+		xfs_iext_realloc_root(ifp, cur);
+
+	nr_entries = xfs_iext_leaf_nr_entries(ifp, cur->leaf, cur->pos);
+	ASSERT(nr_entries <= RECS_PER_LEAF);
+	ASSERT(cur->pos >= nr_entries ||
+	       xfs_iext_rec_cmp(cur_rec(cur), irec->br_startoff) != 0);
+
+	if (nr_entries == RECS_PER_LEAF)
+		new = xfs_iext_split_leaf(cur, &nr_entries);
+
+	if (cur->leaf != new && cur->pos == 0 && nr_entries > 0) {
+		xfs_iext_update_node(ifp, xfs_iext_leaf_key(cur->leaf, 0), offset, 1,
+				cur->leaf);
+	}
+
+	for (i = nr_entries; i > cur->pos; i--)
+		cur->leaf->recs[i] = cur->leaf->recs[i - 1];
+	xfs_iext_set(cur_rec(cur), irec);
+	ifp->if_bytes += sizeof(struct xfs_iext_rec);
+
+	if (new)
+		xfs_iext_insert_node(ifp, xfs_iext_leaf_key(new, 0), new, 2);
+}
+
+void
+xfs_iext_insert(
+	struct xfs_inode	*ip,
+	struct xfs_iext_cursor	*cur,
+	xfs_extnum_t		nr_extents,
+	struct xfs_bmbt_irec	*new,
+	int			state)
+{
+	struct xfs_ifork	*ifp = xfs_iext_state_to_fork(ip, state);
+	int			i;
+
+	ASSERT(nr_extents > 0);
+
+	for (i = nr_extents - 1; i >= 0; i--) {
+		__xfs_iext_insert(ifp, cur, new + i);
+		trace_xfs_iext_insert(ip, cur, state, _RET_IP_);
+	}
+}
+
+static struct xfs_iext_node *
+xfs_iext_rebalance_node(
+	struct xfs_iext_node	*parent,
+	int			*pos,
+	struct xfs_iext_node	*node,
+	int			nr_entries)
+{
+	if (nr_entries == 0)
+		return node;
+
+	if (*pos > 0) {
+		struct xfs_iext_node *prev = parent->ptrs[*pos - 1];
+		int nr_prev = xfs_iext_node_nr_entries(prev, 0), i;
+
+		if (nr_prev + nr_entries <= KEYS_PER_NODE) {
+			for (i = 0; i < nr_entries; i++) {
+				prev->keys[nr_prev + i] = node->keys[i];
+				prev->ptrs[nr_prev + i] = node->ptrs[i];
+			}
+			return node;
+		}
+	}
+
+	if (*pos + 1 < xfs_iext_node_nr_entries(parent, *pos)) {
+		struct xfs_iext_node *next = parent->ptrs[*pos + 1];
+		int nr_next = xfs_iext_node_nr_entries(next, 0), i;
+
+		if (nr_entries + nr_next <= KEYS_PER_NODE) {
+			for (i = 0; i < nr_next; i++) {
+				node->keys[nr_entries + i] = next->keys[i];
+				node->ptrs[nr_entries + i] = next->ptrs[i];
+			}
+
+			++*pos;
+			return next;
+		}
+	}
+
+	return NULL;
+}
+
+static void
+xfs_iext_remove_node(
+	struct xfs_ifork	*ifp,
+	xfs_fileoff_t		offset,
+	void			*victim)
+{
+	struct xfs_iext_node	*node, *parent;
+	int			level = 2, pos, nr_entries, i;
+
+	ASSERT(level <= ifp->if_height);
+	node = xfs_iext_find_level(ifp, offset, level);
+	pos = xfs_iext_node_pos(node, offset);
+again:
+	ASSERT(node->ptrs[pos]);
+	ASSERT(node->ptrs[pos] == victim);
+	kmem_free(victim);
+
+	nr_entries = xfs_iext_node_nr_entries(node, pos) - 1;
+	offset = node->keys[0];
+	for (i = pos; i < nr_entries; i++) {
+		node->keys[i] = node->keys[i + 1];
+		node->ptrs[i] = node->ptrs[i + 1];
+	}
+	node->keys[nr_entries] = XFS_IEXT_KEY_INVALID;
+	node->ptrs[nr_entries] = NULL;
+
+	if (pos == 0 && nr_entries > 0) {
+		xfs_iext_update_node(ifp, offset, node->keys[0], level,
+				node);
+		offset = node->keys[0];
+	}
+
+	if (nr_entries >= KEYS_PER_NODE / 2)
+		return;
+
+	if (level < ifp->if_height) {
+		level++;
+		parent = xfs_iext_find_level(ifp, offset, level);
+		pos = xfs_iext_node_pos(parent, offset);
+
+		ASSERT(pos != KEYS_PER_NODE);
+		ASSERT(parent->ptrs[pos] == node);
+
+		node = xfs_iext_rebalance_node(parent, &pos, node, nr_entries);
+		if (node) {
+			offset = node->keys[0];
+			victim = node;
+			node = parent;
+			goto again;
+		}
+	} else if (nr_entries == 1) {
+		ASSERT(node == ifp->if_u1.if_root);
+		ifp->if_u1.if_root = node->ptrs[0];
+		ifp->if_height--;
+		kmem_free(node);
+	}
+}
+
+static void
+xfs_iext_rebalance_leaf(
+	struct xfs_ifork	*ifp,
+	struct xfs_iext_cursor	*cur,
+	struct xfs_iext_leaf	*leaf,
+	xfs_fileoff_t		offset,
+	int			fill)
+{
+	if (leaf->prev) {
+		int nr_prev = xfs_iext_leaf_nr_entries(ifp, leaf->prev, 0), i;
+
+		if (nr_prev + fill <= RECS_PER_LEAF) {
+			for (i = 0; i < fill; i++)
+				leaf->prev->recs[nr_prev + i] = leaf->recs[i];
+
+			if (cur->leaf == leaf) {
+				cur->leaf = leaf->prev;
+				cur->pos += nr_prev;
+			}
+			goto remove_node;
+		}
+	}
+
+	if (leaf->next) {
+		int nr_next = xfs_iext_leaf_nr_entries(ifp, leaf->next, 0), i;
+
+		if (fill + nr_next <= RECS_PER_LEAF) {
+			for (i = 0; i < nr_next; i++)
+				leaf->recs[fill + i] = leaf->next->recs[i];
+
+			if (cur->leaf == leaf->next) {
+				cur->leaf = leaf;
+				cur->pos += fill;
+			}
+
+			offset = xfs_iext_leaf_key(leaf->next, 0);
+			leaf = leaf->next;
+			goto remove_node;
+		}
+	}
+
+	return;
+remove_node:
+	if (leaf->prev)
+		leaf->prev->next = leaf->next;
+	if (leaf->next)
+		leaf->next->prev = leaf->prev;
+	xfs_iext_remove_node(ifp, offset, leaf);
+}
+
+static void
+xfs_iext_free_last_leaf(
+	struct xfs_ifork	*ifp)
+{
+	ifp->if_u1.if_root = NULL;
+	ifp->if_height--;
+	kmem_free(ifp->if_u1.if_root);
+}
+
+static void
+__xfs_iext_remove(
+	struct xfs_ifork	*ifp,
+	struct xfs_iext_cursor	*cur)
+{
+	struct xfs_iext_leaf	*leaf = cur->leaf;
+	xfs_fileoff_t		offset = xfs_iext_leaf_key(leaf, 0);
+	int			i, nr_entries;
+
+	ASSERT(ifp->if_height > 0);
+	ASSERT(ifp->if_u1.if_root != NULL);
+	ASSERT(xfs_iext_valid(ifp, cur));
+
+	nr_entries = xfs_iext_leaf_nr_entries(ifp, leaf, cur->pos) - 1;
+	for (i = cur->pos; i < nr_entries; i++)
+		leaf->recs[i] = leaf->recs[i + 1];
+	xfs_iext_rec_clear(&leaf->recs[nr_entries]);
+	ifp->if_bytes -= sizeof(struct xfs_iext_rec);
+
+	if (cur->pos == 0 && nr_entries > 0) {
+		xfs_iext_update_node(ifp, offset, xfs_iext_leaf_key(leaf, 0), 1,
+				leaf);
+		offset = xfs_iext_leaf_key(leaf, 0);
+	} else if (cur->pos == nr_entries) {
+		if (ifp->if_height > 1 && leaf->next)
+			cur->leaf = leaf->next;
+		else
+			cur->leaf = NULL;
+		cur->pos = 0;
+	}
+
+	if (nr_entries >= RECS_PER_LEAF / 2)
+		return;
+
+	if (ifp->if_height > 1)
+		xfs_iext_rebalance_leaf(ifp, cur, leaf, offset, nr_entries);
+	else if (nr_entries == 0)
+		xfs_iext_free_last_leaf(ifp);
+}
+
+void
+xfs_iext_remove(
+	struct xfs_inode	*ip,
+	struct xfs_iext_cursor	*cur,
+	int			nr_extents,
+	int			state)
+{
+	struct xfs_ifork	*ifp = xfs_iext_state_to_fork(ip, state);
+	int			i;
+
+	ASSERT(nr_extents > 0);
+
+	for (i = 0; i < nr_extents; i++) {
+		trace_xfs_iext_remove(ip, cur, state, _RET_IP_);
+		__xfs_iext_remove(ifp, cur);
+	}
+}
+
+/*
+ * Lookup the extent covering bno.
+ *
+ * If there is an extent covering bno return the extent index, and store the
+ * expanded extent structure in *gotp, and the extent cursor in *cur.
+ * If there is no extent covering bno, but there is an extent after it (e.g.
+ * it lies in a hole) return that extent in *gotp and its cursor in *cur
+ * instead.
+ * If bno is beyond the last extent return false, and return an invalid
+ * cursor value.
+ */
+bool
+xfs_iext_lookup_extent(
+	struct xfs_inode	*ip,
+	struct xfs_ifork	*ifp,
+	xfs_fileoff_t		offset,
+	struct xfs_iext_cursor	*cur,
+	struct xfs_bmbt_irec	*gotp)
+{
+	XFS_STATS_INC(ip->i_mount, xs_look_exlist);
+
+	cur->leaf = xfs_iext_find_level(ifp, offset, 1);
+	if (!cur->leaf) {
+		cur->pos = 0;
+		return false;
+	}
+
+	for (cur->pos = 0; cur->pos < xfs_iext_max_recs(ifp); cur->pos++) {
+		struct xfs_iext_rec *rec = cur_rec(cur);
+
+		if (xfs_iext_rec_is_empty(rec))
+			break;
+		if (xfs_iext_rec_cmp(rec, offset) >= 0)
+			goto found;
+	}
+
+	/* Try looking in the next node for an entry > offset */
+	if (ifp->if_height == 1 || !cur->leaf->next)
+		return false;
+	cur->leaf = cur->leaf->next;
+	cur->pos = 0;
+	if (!xfs_iext_valid(ifp, cur))
+		return false;
+found:
+	xfs_iext_get(gotp, cur_rec(cur));
+	return true;
+}
+
+/*
+ * Returns the last extent before end, and if this extent doesn't cover
+ * end, update end to the end of the extent.
+ */
+bool
+xfs_iext_lookup_extent_before(
+	struct xfs_inode	*ip,
+	struct xfs_ifork	*ifp,
+	xfs_fileoff_t		*end,
+	struct xfs_iext_cursor	*cur,
+	struct xfs_bmbt_irec	*gotp)
+{
+	/* could be optimized to not even look up the next on a match.. */
+	if (xfs_iext_lookup_extent(ip, ifp, *end - 1, cur, gotp) &&
+	    gotp->br_startoff <= *end - 1)
+		return true;
+	if (!xfs_iext_prev_extent(ifp, cur, gotp))
+		return false;
+	*end = gotp->br_startoff + gotp->br_blockcount;
+	return true;
+}
+
+void
+xfs_iext_update_extent(
+	struct xfs_inode	*ip,
+	int			state,
+	struct xfs_iext_cursor	*cur,
+	struct xfs_bmbt_irec	*new)
+{
+	struct xfs_ifork	*ifp = xfs_iext_state_to_fork(ip, state);
+
+	if (cur->pos == 0) {
+		struct xfs_bmbt_irec	old;
+
+		xfs_iext_get(&old, cur_rec(cur));
+		if (new->br_startoff != old.br_startoff) {
+			xfs_iext_update_node(ifp, old.br_startoff,
+					new->br_startoff, 1, cur->leaf);
+		}
+	}
+
+	trace_xfs_bmap_pre_update(ip, cur, state, _RET_IP_);
+	xfs_iext_set(cur_rec(cur), new);
+	trace_xfs_bmap_post_update(ip, cur, state, _RET_IP_);
+}
+
+/*
+ * Return true if the cursor points at an extent and return the extent structure
+ * in gotp.  Else return false.
+ */
+bool
+xfs_iext_get_extent(
+	struct xfs_ifork	*ifp,
+	struct xfs_iext_cursor	*cur,
+	struct xfs_bmbt_irec	*gotp)
+{
+	if (!xfs_iext_valid(ifp, cur))
+		return false;
+	xfs_iext_get(gotp, cur_rec(cur));
+	return true;
+}
+
+/*
+ * This is a recursive function, because of that we need to be extremely
+ * careful with stack usage.
+ */
+static void
+xfs_iext_destroy_node(
+	struct xfs_iext_node	*node,
+	int			level)
+{
+	int			i;
+
+	if (level > 1) {
+		for (i = 0; i < KEYS_PER_NODE; i++) {
+			if (node->keys[i] == XFS_IEXT_KEY_INVALID)
+				break;
+			xfs_iext_destroy_node(node->ptrs[i], level - 1);
+		}
+	}
+
+	kmem_free(node);
+}
+
+void
+xfs_iext_destroy(
+	struct xfs_ifork	*ifp)
+{
+	xfs_iext_destroy_node(ifp->if_u1.if_root, ifp->if_height);
+
+	ifp->if_bytes = 0;
+	ifp->if_height = 0;
+	ifp->if_u1.if_root = NULL;
+}
diff --git a/fs/xfs/libxfs/xfs_inode_fork.c b/fs/xfs/libxfs/xfs_inode_fork.c
index 1f888fcbd873..1839202133ba 100644
--- a/fs/xfs/libxfs/xfs_inode_fork.c
+++ b/fs/xfs/libxfs/xfs_inode_fork.c
@@ -331,6 +331,7 @@ xfs_iformat_extents(
 	int			size = nex * sizeof(xfs_bmbt_rec_t);
 	struct xfs_iext_cursor	icur;
 	struct xfs_bmbt_rec	*dp;
+	struct xfs_bmbt_irec	new;
 	int			i;
 
 	/*
@@ -346,27 +347,22 @@ xfs_iformat_extents(
 	}
 
 	ifp->if_real_bytes = 0;
-	if (nex == 0)
-		ifp->if_u1.if_extents = NULL;
-	else
-		xfs_iext_add(ifp, 0, nex);
-
-	ifp->if_bytes = size;
+	ifp->if_bytes = 0;
+	ifp->if_u1.if_root = NULL;
+	ifp->if_height = 0;
 	if (size) {
 		dp = (xfs_bmbt_rec_t *) XFS_DFORK_PTR(dip, whichfork);
 
 		xfs_iext_first(ifp, &icur);
 		for (i = 0; i < nex; i++, dp++) {
-			xfs_bmbt_rec_host_t *ep = xfs_iext_get_ext(ifp, i);
-
 			if (!xfs_bmbt_validate_extent(mp, whichfork, dp)) {
 				XFS_ERROR_REPORT("xfs_iformat_extents(2)",
 						 XFS_ERRLEVEL_LOW, mp);
 				return -EFSCORRUPTED;
 			}
 
-			ep->l0 = get_unaligned_be64(&dp->l0);
-			ep->l1 = get_unaligned_be64(&dp->l1);
+			xfs_bmbt_disk_get_all(dp, &new);
+			xfs_iext_insert(ip, &icur, 1, &new, state);
 			trace_xfs_read_extent(ip, &icur, state, _THIS_IP_);
 			xfs_iext_next(ifp, &icur);
 		}
@@ -435,6 +431,10 @@ xfs_iformat_btree(
 	ifp->if_flags &= ~XFS_IFEXTENTS;
 	ifp->if_flags |= XFS_IFBROOT;
 
+	ifp->if_real_bytes = 0;
+	ifp->if_bytes = 0;
+	ifp->if_u1.if_root = NULL;
+	ifp->if_height = 0;
 	return 0;
 }
 
@@ -662,14 +662,12 @@ xfs_idestroy_fork(
 			ifp->if_u1.if_data = NULL;
 			ifp->if_real_bytes = 0;
 		}
-	} else if ((ifp->if_flags & XFS_IFEXTENTS) &&
-		   ((ifp->if_flags & XFS_IFEXTIREC) ||
-		    (ifp->if_u1.if_extents != NULL))) {
-		ASSERT(ifp->if_real_bytes != 0);
+	} else if ((ifp->if_flags & XFS_IFEXTENTS) && ifp->if_height) {
 		xfs_iext_destroy(ifp);
 	}
-	ASSERT(ifp->if_u1.if_extents == NULL);
+
 	ASSERT(ifp->if_real_bytes == 0);
+
 	if (whichfork == XFS_ATTR_FORK) {
 		kmem_zone_free(xfs_ifork_zone, ip->i_afp);
 		ip->i_afp = NULL;
@@ -679,13 +677,6 @@ xfs_idestroy_fork(
 	}
 }
 
-/* Count number of incore extents based on if_bytes */
-xfs_extnum_t
-xfs_iext_count(struct xfs_ifork *ifp)
-{
-	return ifp->if_bytes / (uint)sizeof(xfs_bmbt_rec_t);
-}
-
 /*
  * Convert in-core extents to on-disk form
  *
@@ -780,7 +771,6 @@ xfs_iflush_fork(
 		       !(iip->ili_fields & extflag[whichfork]));
 		if ((iip->ili_fields & extflag[whichfork]) &&
 		    (ifp->if_bytes > 0)) {
-			ASSERT(xfs_iext_get_ext(ifp, 0));
 			ASSERT(XFS_IFORK_NEXTENTS(ip, whichfork) > 0);
 			(void)xfs_iextents_copy(ip, (xfs_bmbt_rec_t *)cp,
 				whichfork);
@@ -812,33 +802,6 @@ xfs_iflush_fork(
 	}
 }
 
-/*
- * Return a pointer to the extent record at file index idx.
- */
-xfs_bmbt_rec_host_t *
-xfs_iext_get_ext(
-	xfs_ifork_t	*ifp,		/* inode fork pointer */
-	xfs_extnum_t	idx)		/* index of target extent */
-{
-	ASSERT(idx >= 0);
-	ASSERT(idx < xfs_iext_count(ifp));
-
-	if ((ifp->if_flags & XFS_IFEXTIREC) && (idx == 0)) {
-		return ifp->if_u1.if_ext_irec->er_extbuf;
-	} else if (ifp->if_flags & XFS_IFEXTIREC) {
-		xfs_ext_irec_t	*erp;		/* irec pointer */
-		int		erp_idx = 0;	/* irec index */
-		xfs_extnum_t	page_idx = idx;	/* ext index in target list */
-
-		erp = xfs_iext_idx_to_irec(ifp, &page_idx, &erp_idx, 0);
-		return &erp->er_extbuf[page_idx];
-	} else if (ifp->if_bytes) {
-		return &ifp->if_u1.if_extents[idx];
-	} else {
-		return NULL;
-	}
-}
-
 /* Convert bmap state flags to an inode fork. */
 struct xfs_ifork *
 xfs_iext_state_to_fork(
@@ -852,894 +815,6 @@ xfs_iext_state_to_fork(
 	return &ip->i_df;
 }
 
-/*
- * Insert new item(s) into the extent records for incore inode
- * fork 'ifp'.  'count' new items are inserted at index 'idx'.
- */
-void
-xfs_iext_insert(
-	xfs_inode_t	*ip,		/* incore inode pointer */
-	struct xfs_iext_cursor *cur,
-	xfs_extnum_t	count,		/* number of inserted items */
-	xfs_bmbt_irec_t	*new,		/* items to insert */
-	int		state)		/* type of extent conversion */
-{
-	xfs_ifork_t	*ifp = xfs_iext_state_to_fork(ip, state);
-	xfs_extnum_t	i;		/* extent record index */
-
-	trace_xfs_iext_insert(ip, cur->idx, new, state, _RET_IP_);
-
-	ASSERT(ifp->if_flags & XFS_IFEXTENTS);
-	xfs_iext_add(ifp, cur->idx, count);
-	for (i = 0; i < count; i++, new++)
-		xfs_bmbt_set_all(xfs_iext_get_ext(ifp, cur->idx + i), new);
-}
-
-/*
- * This is called when the amount of space required for incore file
- * extents needs to be increased. The ext_diff parameter stores the
- * number of new extents being added and the idx parameter contains
- * the extent index where the new extents will be added. If the new
- * extents are being appended, then we just need to (re)allocate and
- * initialize the space. Otherwise, if the new extents are being
- * inserted into the middle of the existing entries, a bit more work
- * is required to make room for the new extents to be inserted. The
- * caller is responsible for filling in the new extent entries upon
- * return.
- */
-void
-xfs_iext_add(
-	xfs_ifork_t	*ifp,		/* inode fork pointer */
-	xfs_extnum_t	idx,		/* index to begin adding exts */
-	int		ext_diff)	/* number of extents to add */
-{
-	int		byte_diff;	/* new bytes being added */
-	int		new_size;	/* size of extents after adding */
-	xfs_extnum_t	nextents;	/* number of extents in file */
-
-	nextents = xfs_iext_count(ifp);
-	ASSERT((idx >= 0) && (idx <= nextents));
-	byte_diff = ext_diff * sizeof(xfs_bmbt_rec_t);
-	new_size = ifp->if_bytes + byte_diff;
-
-	/*
-	 * Use a linear (direct) extent list.
-	 * If the extents are currently inside the inode,
-	 * xfs_iext_realloc_direct will switch us from
-	 * inline to direct extent allocation mode.
-	 */
-	if (nextents + ext_diff <= XFS_LINEAR_EXTS) {
-		xfs_iext_realloc_direct(ifp, new_size);
-		if (idx < nextents) {
-			memmove(&ifp->if_u1.if_extents[idx + ext_diff],
-				&ifp->if_u1.if_extents[idx],
-				(nextents - idx) * sizeof(xfs_bmbt_rec_t));
-			memset(&ifp->if_u1.if_extents[idx], 0, byte_diff);
-		}
-	}
-	/* Indirection array */
-	else {
-		xfs_ext_irec_t	*erp;
-		int		erp_idx = 0;
-		int		page_idx = idx;
-
-		ASSERT(nextents + ext_diff > XFS_LINEAR_EXTS);
-		if (ifp->if_flags & XFS_IFEXTIREC) {
-			erp = xfs_iext_idx_to_irec(ifp, &page_idx, &erp_idx, 1);
-		} else {
-			xfs_iext_irec_init(ifp);
-			ASSERT(ifp->if_flags & XFS_IFEXTIREC);
-			erp = ifp->if_u1.if_ext_irec;
-		}
-		/* Extents fit in target extent page */
-		if (erp && erp->er_extcount + ext_diff <= XFS_LINEAR_EXTS) {
-			if (page_idx < erp->er_extcount) {
-				memmove(&erp->er_extbuf[page_idx + ext_diff],
-					&erp->er_extbuf[page_idx],
-					(erp->er_extcount - page_idx) *
-					sizeof(xfs_bmbt_rec_t));
-				memset(&erp->er_extbuf[page_idx], 0, byte_diff);
-			}
-			erp->er_extcount += ext_diff;
-			xfs_iext_irec_update_extoffs(ifp, erp_idx + 1, ext_diff);
-		}
-		/* Insert a new extent page */
-		else if (erp) {
-			xfs_iext_add_indirect_multi(ifp,
-				erp_idx, page_idx, ext_diff);
-		}
-		/*
-		 * If extent(s) are being appended to the last page in
-		 * the indirection array and the new extent(s) don't fit
-		 * in the page, then erp is NULL and erp_idx is set to
-		 * the next index needed in the indirection array.
-		 */
-		else {
-			uint	count = ext_diff;
-
-			while (count) {
-				erp = xfs_iext_irec_new(ifp, erp_idx);
-				erp->er_extcount = min(count, XFS_LINEAR_EXTS);
-				count -= erp->er_extcount;
-				if (count)
-					erp_idx++;
-			}
-		}
-	}
-	ifp->if_bytes = new_size;
-}
-
-/*
- * This is called when incore extents are being added to the indirection
- * array and the new extents do not fit in the target extent list. The
- * erp_idx parameter contains the irec index for the target extent list
- * in the indirection array, and the idx parameter contains the extent
- * index within the list. The number of extents being added is stored
- * in the count parameter.
- *
- *    |-------|   |-------|
- *    |       |   |       |    idx - number of extents before idx
- *    |  idx  |   | count |
- *    |       |   |       |    count - number of extents being inserted at idx
- *    |-------|   |-------|
- *    | count |   | nex2  |    nex2 - number of extents after idx + count
- *    |-------|   |-------|
- */
-void
-xfs_iext_add_indirect_multi(
-	xfs_ifork_t	*ifp,			/* inode fork pointer */
-	int		erp_idx,		/* target extent irec index */
-	xfs_extnum_t	idx,			/* index within target list */
-	int		count)			/* new extents being added */
-{
-	int		byte_diff;		/* new bytes being added */
-	xfs_ext_irec_t	*erp;			/* pointer to irec entry */
-	xfs_extnum_t	ext_diff;		/* number of extents to add */
-	xfs_extnum_t	ext_cnt;		/* new extents still needed */
-	xfs_extnum_t	nex2;			/* extents after idx + count */
-	xfs_bmbt_rec_t	*nex2_ep = NULL;	/* temp list for nex2 extents */
-	int		nlists;			/* number of irec's (lists) */
-
-	ASSERT(ifp->if_flags & XFS_IFEXTIREC);
-	erp = &ifp->if_u1.if_ext_irec[erp_idx];
-	nex2 = erp->er_extcount - idx;
-	nlists = ifp->if_real_bytes / XFS_IEXT_BUFSZ;
-
-	/*
-	 * Save second part of target extent list
-	 * (all extents past */
-	if (nex2) {
-		byte_diff = nex2 * sizeof(xfs_bmbt_rec_t);
-		nex2_ep = (xfs_bmbt_rec_t *) kmem_alloc(byte_diff, KM_NOFS);
-		memmove(nex2_ep, &erp->er_extbuf[idx], byte_diff);
-		erp->er_extcount -= nex2;
-		xfs_iext_irec_update_extoffs(ifp, erp_idx + 1, -nex2);
-		memset(&erp->er_extbuf[idx], 0, byte_diff);
-	}
-
-	/*
-	 * Add the new extents to the end of the target
-	 * list, then allocate new irec record(s) and
-	 * extent buffer(s) as needed to store the rest
-	 * of the new extents.
-	 */
-	ext_cnt = count;
-	ext_diff = MIN(ext_cnt, (int)XFS_LINEAR_EXTS - erp->er_extcount);
-	if (ext_diff) {
-		erp->er_extcount += ext_diff;
-		xfs_iext_irec_update_extoffs(ifp, erp_idx + 1, ext_diff);
-		ext_cnt -= ext_diff;
-	}
-	while (ext_cnt) {
-		erp_idx++;
-		erp = xfs_iext_irec_new(ifp, erp_idx);
-		ext_diff = MIN(ext_cnt, (int)XFS_LINEAR_EXTS);
-		erp->er_extcount = ext_diff;
-		xfs_iext_irec_update_extoffs(ifp, erp_idx + 1, ext_diff);
-		ext_cnt -= ext_diff;
-	}
-
-	/* Add nex2 extents back to indirection array */
-	if (nex2) {
-		xfs_extnum_t	ext_avail;
-		int		i;
-
-		byte_diff = nex2 * sizeof(xfs_bmbt_rec_t);
-		ext_avail = XFS_LINEAR_EXTS - erp->er_extcount;
-		i = 0;
-		/*
-		 * If nex2 extents fit in the current page, append
-		 * nex2_ep after the new extents.
-		 */
-		if (nex2 <= ext_avail) {
-			i = erp->er_extcount;
-		}
-		/*
-		 * Otherwise, check if space is available in the
-		 * next page.
-		 */
-		else if ((erp_idx < nlists - 1) &&
-			 (nex2 <= (ext_avail = XFS_LINEAR_EXTS -
-			  ifp->if_u1.if_ext_irec[erp_idx+1].er_extcount))) {
-			erp_idx++;
-			erp++;
-			/* Create a hole for nex2 extents */
-			memmove(&erp->er_extbuf[nex2], erp->er_extbuf,
-				erp->er_extcount * sizeof(xfs_bmbt_rec_t));
-		}
-		/*
-		 * Final choice, create a new extent page for
-		 * nex2 extents.
-		 */
-		else {
-			erp_idx++;
-			erp = xfs_iext_irec_new(ifp, erp_idx);
-		}
-		memmove(&erp->er_extbuf[i], nex2_ep, byte_diff);
-		kmem_free(nex2_ep);
-		erp->er_extcount += nex2;
-		xfs_iext_irec_update_extoffs(ifp, erp_idx + 1, nex2);
-	}
-}
-
-/*
- * This is called when the amount of space required for incore file
- * extents needs to be decreased. The ext_diff parameter stores the
- * number of extents to be removed and the idx parameter contains
- * the extent index where the extents will be removed from.
- *
- * If the amount of space needed has decreased below the linear
- * limit, XFS_IEXT_BUFSZ, then switch to using the contiguous
- * extent array.  Otherwise, use kmem_realloc() to adjust the
- * size to what is needed.
- */
-void
-xfs_iext_remove(
-	xfs_inode_t	*ip,		/* incore inode pointer */
-	struct xfs_iext_cursor *cur,
-	int		ext_diff,	/* number of extents to remove */
-	int		state)		/* type of extent conversion */
-{
-	xfs_ifork_t	*ifp = xfs_iext_state_to_fork(ip, state);
-	xfs_extnum_t	nextents;	/* number of extents in file */
-	int		new_size;	/* size of extents after removal */
-
-	trace_xfs_iext_remove(ip, cur, state, _RET_IP_);
-
-	ASSERT(ext_diff > 0);
-	nextents = xfs_iext_count(ifp);
-	new_size = (nextents - ext_diff) * sizeof(xfs_bmbt_rec_t);
-
-	if (new_size == 0) {
-		xfs_iext_destroy(ifp);
-	} else if (ifp->if_flags & XFS_IFEXTIREC) {
-		xfs_iext_remove_indirect(ifp, cur->idx, ext_diff);
-	} else if (ifp->if_real_bytes) {
-		xfs_iext_remove_direct(ifp, cur->idx, ext_diff);
-	}
-	ifp->if_bytes = new_size;
-}
-
-/*
- * This removes ext_diff extents from a linear (direct) extent list,
- * beginning at extent index idx. If the extents are being removed
- * from the end of the list (ie. truncate) then we just need to re-
- * allocate the list to remove the extra space. Otherwise, if the
- * extents are being removed from the middle of the existing extent
- * entries, then we first need to move the extent records beginning
- * at idx + ext_diff up in the list to overwrite the records being
- * removed, then remove the extra space via kmem_realloc.
- */
-void
-xfs_iext_remove_direct(
-	xfs_ifork_t	*ifp,		/* inode fork pointer */
-	xfs_extnum_t	idx,		/* index to begin removing exts */
-	int		ext_diff)	/* number of extents to remove */
-{
-	xfs_extnum_t	nextents;	/* number of extents in file */
-	int		new_size;	/* size of extents after removal */
-
-	ASSERT(!(ifp->if_flags & XFS_IFEXTIREC));
-	new_size = ifp->if_bytes -
-		(ext_diff * sizeof(xfs_bmbt_rec_t));
-	nextents = xfs_iext_count(ifp);
-
-	if (new_size == 0) {
-		xfs_iext_destroy(ifp);
-		return;
-	}
-	/* Move extents up in the list (if needed) */
-	if (idx + ext_diff < nextents) {
-		memmove(&ifp->if_u1.if_extents[idx],
-			&ifp->if_u1.if_extents[idx + ext_diff],
-			(nextents - (idx + ext_diff)) *
-			 sizeof(xfs_bmbt_rec_t));
-	}
-	memset(&ifp->if_u1.if_extents[nextents - ext_diff],
-		0, ext_diff * sizeof(xfs_bmbt_rec_t));
-	/*
-	 * Reallocate the direct extent list. If the extents
-	 * will fit inside the inode then xfs_iext_realloc_direct
-	 * will switch from direct to inline extent allocation
-	 * mode for us.
-	 */
-	xfs_iext_realloc_direct(ifp, new_size);
-	ifp->if_bytes = new_size;
-}
-
-/*
- * This is called when incore extents are being removed from the
- * indirection array and the extents being removed span multiple extent
- * buffers. The idx parameter contains the file extent index where we
- * want to begin removing extents, and the count parameter contains
- * how many extents need to be removed.
- *
- *    |-------|   |-------|
- *    | nex1  |   |       |    nex1 - number of extents before idx
- *    |-------|   | count |
- *    |       |   |       |    count - number of extents being removed at idx
- *    | count |   |-------|
- *    |       |   | nex2  |    nex2 - number of extents after idx + count
- *    |-------|   |-------|
- */
-void
-xfs_iext_remove_indirect(
-	xfs_ifork_t	*ifp,		/* inode fork pointer */
-	xfs_extnum_t	idx,		/* index to begin removing extents */
-	int		count)		/* number of extents to remove */
-{
-	xfs_ext_irec_t	*erp;		/* indirection array pointer */
-	int		erp_idx = 0;	/* indirection array index */
-	xfs_extnum_t	ext_cnt;	/* extents left to remove */
-	xfs_extnum_t	ext_diff;	/* extents to remove in current list */
-	xfs_extnum_t	nex1;		/* number of extents before idx */
-	xfs_extnum_t	nex2;		/* extents after idx + count */
-	int		page_idx = idx;	/* index in target extent list */
-
-	ASSERT(ifp->if_flags & XFS_IFEXTIREC);
-	erp = xfs_iext_idx_to_irec(ifp,  &page_idx, &erp_idx, 0);
-	ASSERT(erp != NULL);
-	nex1 = page_idx;
-	ext_cnt = count;
-	while (ext_cnt) {
-		nex2 = MAX((erp->er_extcount - (nex1 + ext_cnt)), 0);
-		ext_diff = MIN(ext_cnt, (erp->er_extcount - nex1));
-		/*
-		 * Check for deletion of entire list;
-		 * xfs_iext_irec_remove() updates extent offsets.
-		 */
-		if (ext_diff == erp->er_extcount) {
-			xfs_iext_irec_remove(ifp, erp_idx);
-			ext_cnt -= ext_diff;
-			nex1 = 0;
-			if (ext_cnt) {
-				ASSERT(erp_idx < ifp->if_real_bytes /
-					XFS_IEXT_BUFSZ);
-				erp = &ifp->if_u1.if_ext_irec[erp_idx];
-				nex1 = 0;
-				continue;
-			} else {
-				break;
-			}
-		}
-		/* Move extents up (if needed) */
-		if (nex2) {
-			memmove(&erp->er_extbuf[nex1],
-				&erp->er_extbuf[nex1 + ext_diff],
-				nex2 * sizeof(xfs_bmbt_rec_t));
-		}
-		/* Zero out rest of page */
-		memset(&erp->er_extbuf[nex1 + nex2], 0, (XFS_IEXT_BUFSZ -
-			((nex1 + nex2) * sizeof(xfs_bmbt_rec_t))));
-		/* Update remaining counters */
-		erp->er_extcount -= ext_diff;
-		xfs_iext_irec_update_extoffs(ifp, erp_idx + 1, -ext_diff);
-		ext_cnt -= ext_diff;
-		nex1 = 0;
-		erp_idx++;
-		erp++;
-	}
-	ifp->if_bytes -= count * sizeof(xfs_bmbt_rec_t);
-	xfs_iext_irec_compact(ifp);
-}
-
-/*
- * Create, destroy, or resize a linear (direct) block of extents.
- */
-void
-xfs_iext_realloc_direct(
-	xfs_ifork_t	*ifp,		/* inode fork pointer */
-	int		new_size)	/* new size of extents after adding */
-{
-	int		rnew_size;	/* real new size of extents */
-
-	rnew_size = new_size;
-
-	ASSERT(!(ifp->if_flags & XFS_IFEXTIREC) ||
-		((new_size >= 0) && (new_size <= XFS_IEXT_BUFSZ) &&
-		 (new_size != ifp->if_real_bytes)));
-
-	/* Free extent records */
-	if (new_size == 0) {
-		xfs_iext_destroy(ifp);
-	} else {
-		if (!is_power_of_2(new_size)){
-			rnew_size = roundup_pow_of_two(new_size);
-		}
-		if (rnew_size != ifp->if_real_bytes) {
-			ifp->if_u1.if_extents =
-				kmem_realloc(ifp->if_u1.if_extents,
-						rnew_size, KM_NOFS);
-		}
-		if (rnew_size > ifp->if_real_bytes) {
-			memset(&ifp->if_u1.if_extents[ifp->if_bytes /
-				(uint)sizeof(xfs_bmbt_rec_t)], 0,
-				rnew_size - ifp->if_real_bytes);
-		}
-	}
-	ifp->if_real_bytes = rnew_size;
-	ifp->if_bytes = new_size;
-}
-
-/*
- * Resize an extent indirection array to new_size bytes.
- */
-STATIC void
-xfs_iext_realloc_indirect(
-	xfs_ifork_t	*ifp,		/* inode fork pointer */
-	int		new_size)	/* new indirection array size */
-{
-	ASSERT(ifp->if_flags & XFS_IFEXTIREC);
-	ASSERT(ifp->if_real_bytes);
-	ASSERT((new_size >= 0) &&
-	       (new_size != ((ifp->if_real_bytes / XFS_IEXT_BUFSZ) *
-			     sizeof(xfs_ext_irec_t))));
-	if (new_size == 0) {
-		xfs_iext_destroy(ifp);
-	} else {
-		ifp->if_u1.if_ext_irec =
-			kmem_realloc(ifp->if_u1.if_ext_irec, new_size, KM_NOFS);
-	}
-}
-
-/*
- * Switch from indirection array to linear (direct) extent allocations.
- */
-STATIC void
-xfs_iext_indirect_to_direct(
-	 xfs_ifork_t	*ifp)		/* inode fork pointer */
-{
-	xfs_bmbt_rec_host_t *ep;	/* extent record pointer */
-	xfs_extnum_t	nextents;	/* number of extents in file */
-	int		size;		/* size of file extents */
-
-	ASSERT(ifp->if_flags & XFS_IFEXTIREC);
-	nextents = xfs_iext_count(ifp);
-	ASSERT(nextents <= XFS_LINEAR_EXTS);
-	size = nextents * sizeof(xfs_bmbt_rec_t);
-
-	xfs_iext_irec_compact_pages(ifp);
-	ASSERT(ifp->if_real_bytes == XFS_IEXT_BUFSZ);
-
-	ep = ifp->if_u1.if_ext_irec->er_extbuf;
-	kmem_free(ifp->if_u1.if_ext_irec);
-	ifp->if_flags &= ~XFS_IFEXTIREC;
-	ifp->if_u1.if_extents = ep;
-	ifp->if_bytes = size;
-	if (nextents < XFS_LINEAR_EXTS) {
-		xfs_iext_realloc_direct(ifp, size);
-	}
-}
-
-/*
- * Remove all records from the indirection array.
- */
-STATIC void
-xfs_iext_irec_remove_all(
-	struct xfs_ifork *ifp)
-{
-	int		nlists;
-	int		i;
-
-	ASSERT(ifp->if_flags & XFS_IFEXTIREC);
-	nlists = ifp->if_real_bytes / XFS_IEXT_BUFSZ;
-	for (i = 0; i < nlists; i++)
-		kmem_free(ifp->if_u1.if_ext_irec[i].er_extbuf);
-	kmem_free(ifp->if_u1.if_ext_irec);
-	ifp->if_flags &= ~XFS_IFEXTIREC;
-}
-
-/*
- * Free incore file extents.
- */
-void
-xfs_iext_destroy(
-	xfs_ifork_t	*ifp)		/* inode fork pointer */
-{
-	if (ifp->if_flags & XFS_IFEXTIREC) {
-		xfs_iext_irec_remove_all(ifp);
-	} else if (ifp->if_real_bytes) {
-		kmem_free(ifp->if_u1.if_extents);
-	}
-	ifp->if_u1.if_extents = NULL;
-	ifp->if_real_bytes = 0;
-	ifp->if_bytes = 0;
-}
-
-/*
- * Return a pointer to the extent record for file system block bno.
- */
-xfs_bmbt_rec_host_t *			/* pointer to found extent record */
-xfs_iext_bno_to_ext(
-	xfs_ifork_t	*ifp,		/* inode fork pointer */
-	xfs_fileoff_t	bno,		/* block number to search for */
-	xfs_extnum_t	*idxp)		/* index of target extent */
-{
-	xfs_bmbt_rec_host_t *base;	/* pointer to first extent */
-	xfs_filblks_t	blockcount = 0;	/* number of blocks in extent */
-	xfs_bmbt_rec_host_t *ep = NULL;	/* pointer to target extent */
-	xfs_ext_irec_t	*erp = NULL;	/* indirection array pointer */
-	int		high;		/* upper boundary in search */
-	xfs_extnum_t	idx = 0;	/* index of target extent */
-	int		low;		/* lower boundary in search */
-	xfs_extnum_t	nextents;	/* number of file extents */
-	xfs_fileoff_t	startoff = 0;	/* start offset of extent */
-
-	nextents = xfs_iext_count(ifp);
-	if (nextents == 0) {
-		*idxp = 0;
-		return NULL;
-	}
-	low = 0;
-	if (ifp->if_flags & XFS_IFEXTIREC) {
-		/* Find target extent list */
-		int	erp_idx = 0;
-		erp = xfs_iext_bno_to_irec(ifp, bno, &erp_idx);
-		base = erp->er_extbuf;
-		high = erp->er_extcount - 1;
-	} else {
-		base = ifp->if_u1.if_extents;
-		high = nextents - 1;
-	}
-	/* Binary search extent records */
-	while (low <= high) {
-		idx = (low + high) >> 1;
-		ep = base + idx;
-		startoff = xfs_bmbt_get_startoff(ep);
-		blockcount = xfs_bmbt_get_blockcount(ep);
-		if (bno < startoff) {
-			high = idx - 1;
-		} else if (bno >= startoff + blockcount) {
-			low = idx + 1;
-		} else {
-			/* Convert back to file-based extent index */
-			if (ifp->if_flags & XFS_IFEXTIREC) {
-				idx += erp->er_extoff;
-			}
-			*idxp = idx;
-			return ep;
-		}
-	}
-	/* Convert back to file-based extent index */
-	if (ifp->if_flags & XFS_IFEXTIREC) {
-		idx += erp->er_extoff;
-	}
-	if (bno >= startoff + blockcount) {
-		if (++idx == nextents) {
-			ep = NULL;
-		} else {
-			ep = xfs_iext_get_ext(ifp, idx);
-		}
-	}
-	*idxp = idx;
-	return ep;
-}
-
-/*
- * Return a pointer to the indirection array entry containing the
- * extent record for filesystem block bno. Store the index of the
- * target irec in *erp_idxp.
- */
-xfs_ext_irec_t *			/* pointer to found extent record */
-xfs_iext_bno_to_irec(
-	xfs_ifork_t	*ifp,		/* inode fork pointer */
-	xfs_fileoff_t	bno,		/* block number to search for */
-	int		*erp_idxp)	/* irec index of target ext list */
-{
-	xfs_ext_irec_t	*erp = NULL;	/* indirection array pointer */
-	xfs_ext_irec_t	*erp_next;	/* next indirection array entry */
-	int		erp_idx;	/* indirection array index */
-	int		nlists;		/* number of extent irec's (lists) */
-	int		high;		/* binary search upper limit */
-	int		low;		/* binary search lower limit */
-
-	ASSERT(ifp->if_flags & XFS_IFEXTIREC);
-	nlists = ifp->if_real_bytes / XFS_IEXT_BUFSZ;
-	erp_idx = 0;
-	low = 0;
-	high = nlists - 1;
-	while (low <= high) {
-		erp_idx = (low + high) >> 1;
-		erp = &ifp->if_u1.if_ext_irec[erp_idx];
-		erp_next = erp_idx < nlists - 1 ? erp + 1 : NULL;
-		if (bno < xfs_bmbt_get_startoff(erp->er_extbuf)) {
-			high = erp_idx - 1;
-		} else if (erp_next && bno >=
-			   xfs_bmbt_get_startoff(erp_next->er_extbuf)) {
-			low = erp_idx + 1;
-		} else {
-			break;
-		}
-	}
-	*erp_idxp = erp_idx;
-	return erp;
-}
-
-/*
- * Return a pointer to the indirection array entry containing the
- * extent record at file extent index *idxp. Store the index of the
- * target irec in *erp_idxp and store the page index of the target
- * extent record in *idxp.
- */
-xfs_ext_irec_t *
-xfs_iext_idx_to_irec(
-	xfs_ifork_t	*ifp,		/* inode fork pointer */
-	xfs_extnum_t	*idxp,		/* extent index (file -> page) */
-	int		*erp_idxp,	/* pointer to target irec */
-	int		realloc)	/* new bytes were just added */
-{
-	xfs_ext_irec_t	*prev;		/* pointer to previous irec */
-	xfs_ext_irec_t	*erp = NULL;	/* pointer to current irec */
-	int		erp_idx;	/* indirection array index */
-	int		nlists;		/* number of irec's (ex lists) */
-	int		high;		/* binary search upper limit */
-	int		low;		/* binary search lower limit */
-	xfs_extnum_t	page_idx = *idxp; /* extent index in target list */
-
-	ASSERT(ifp->if_flags & XFS_IFEXTIREC);
-	ASSERT(page_idx >= 0);
-	ASSERT(page_idx <= xfs_iext_count(ifp));
-	ASSERT(page_idx < xfs_iext_count(ifp) || realloc);
-
-	nlists = ifp->if_real_bytes / XFS_IEXT_BUFSZ;
-	erp_idx = 0;
-	low = 0;
-	high = nlists - 1;
-
-	/* Binary search extent irec's */
-	while (low <= high) {
-		erp_idx = (low + high) >> 1;
-		erp = &ifp->if_u1.if_ext_irec[erp_idx];
-		prev = erp_idx > 0 ? erp - 1 : NULL;
-		if (page_idx < erp->er_extoff || (page_idx == erp->er_extoff &&
-		     realloc && prev && prev->er_extcount < XFS_LINEAR_EXTS)) {
-			high = erp_idx - 1;
-		} else if (page_idx > erp->er_extoff + erp->er_extcount ||
-			   (page_idx == erp->er_extoff + erp->er_extcount &&
-			    !realloc)) {
-			low = erp_idx + 1;
-		} else if (page_idx == erp->er_extoff + erp->er_extcount &&
-			   erp->er_extcount == XFS_LINEAR_EXTS) {
-			ASSERT(realloc);
-			page_idx = 0;
-			erp_idx++;
-			erp = erp_idx < nlists ? erp + 1 : NULL;
-			break;
-		} else {
-			page_idx -= erp->er_extoff;
-			break;
-		}
-	}
-	*idxp = page_idx;
-	*erp_idxp = erp_idx;
-	return erp;
-}
-
-/*
- * Allocate and initialize an indirection array once the space needed
- * for incore extents increases above XFS_IEXT_BUFSZ.
- */
-void
-xfs_iext_irec_init(
-	xfs_ifork_t	*ifp)		/* inode fork pointer */
-{
-	xfs_ext_irec_t	*erp;		/* indirection array pointer */
-	xfs_extnum_t	nextents;	/* number of extents in file */
-
-	ASSERT(!(ifp->if_flags & XFS_IFEXTIREC));
-	nextents = xfs_iext_count(ifp);
-	ASSERT(nextents <= XFS_LINEAR_EXTS);
-
-	erp = kmem_alloc(sizeof(xfs_ext_irec_t), KM_NOFS);
-
-	if (nextents == 0) {
-		ifp->if_u1.if_extents = kmem_alloc(XFS_IEXT_BUFSZ, KM_NOFS);
-	} else if (ifp->if_real_bytes < XFS_IEXT_BUFSZ) {
-		xfs_iext_realloc_direct(ifp, XFS_IEXT_BUFSZ);
-	}
-	erp->er_extbuf = ifp->if_u1.if_extents;
-	erp->er_extcount = nextents;
-	erp->er_extoff = 0;
-
-	ifp->if_flags |= XFS_IFEXTIREC;
-	ifp->if_real_bytes = XFS_IEXT_BUFSZ;
-	ifp->if_bytes = nextents * sizeof(xfs_bmbt_rec_t);
-	ifp->if_u1.if_ext_irec = erp;
-
-	return;
-}
-
-/*
- * Allocate and initialize a new entry in the indirection array.
- */
-xfs_ext_irec_t *
-xfs_iext_irec_new(
-	xfs_ifork_t	*ifp,		/* inode fork pointer */
-	int		erp_idx)	/* index for new irec */
-{
-	xfs_ext_irec_t	*erp;		/* indirection array pointer */
-	int		i;		/* loop counter */
-	int		nlists;		/* number of irec's (ex lists) */
-
-	ASSERT(ifp->if_flags & XFS_IFEXTIREC);
-	nlists = ifp->if_real_bytes / XFS_IEXT_BUFSZ;
-
-	/* Resize indirection array */
-	xfs_iext_realloc_indirect(ifp, ++nlists *
-				  sizeof(xfs_ext_irec_t));
-	/*
-	 * Move records down in the array so the
-	 * new page can use erp_idx.
-	 */
-	erp = ifp->if_u1.if_ext_irec;
-	for (i = nlists - 1; i > erp_idx; i--) {
-		memmove(&erp[i], &erp[i-1], sizeof(xfs_ext_irec_t));
-	}
-	ASSERT(i == erp_idx);
-
-	/* Initialize new extent record */
-	erp = ifp->if_u1.if_ext_irec;
-	erp[erp_idx].er_extbuf = kmem_alloc(XFS_IEXT_BUFSZ, KM_NOFS);
-	ifp->if_real_bytes = nlists * XFS_IEXT_BUFSZ;
-	memset(erp[erp_idx].er_extbuf, 0, XFS_IEXT_BUFSZ);
-	erp[erp_idx].er_extcount = 0;
-	erp[erp_idx].er_extoff = erp_idx > 0 ?
-		erp[erp_idx-1].er_extoff + erp[erp_idx-1].er_extcount : 0;
-	return (&erp[erp_idx]);
-}
-
-/*
- * Remove a record from the indirection array.
- */
-void
-xfs_iext_irec_remove(
-	xfs_ifork_t	*ifp,		/* inode fork pointer */
-	int		erp_idx)	/* irec index to remove */
-{
-	xfs_ext_irec_t	*erp;		/* indirection array pointer */
-	int		i;		/* loop counter */
-	int		nlists;		/* number of irec's (ex lists) */
-
-	ASSERT(ifp->if_flags & XFS_IFEXTIREC);
-	nlists = ifp->if_real_bytes / XFS_IEXT_BUFSZ;
-	erp = &ifp->if_u1.if_ext_irec[erp_idx];
-	if (erp->er_extbuf) {
-		xfs_iext_irec_update_extoffs(ifp, erp_idx + 1,
-			-erp->er_extcount);
-		kmem_free(erp->er_extbuf);
-	}
-	/* Compact extent records */
-	erp = ifp->if_u1.if_ext_irec;
-	for (i = erp_idx; i < nlists - 1; i++) {
-		memmove(&erp[i], &erp[i+1], sizeof(xfs_ext_irec_t));
-	}
-	/*
-	 * Manually free the last extent record from the indirection
-	 * array.  A call to xfs_iext_realloc_indirect() with a size
-	 * of zero would result in a call to xfs_iext_destroy() which
-	 * would in turn call this function again, creating a nasty
-	 * infinite loop.
-	 */
-	if (--nlists) {
-		xfs_iext_realloc_indirect(ifp,
-			nlists * sizeof(xfs_ext_irec_t));
-	} else {
-		kmem_free(ifp->if_u1.if_ext_irec);
-	}
-	ifp->if_real_bytes = nlists * XFS_IEXT_BUFSZ;
-}
-
-/*
- * This is called to clean up large amounts of unused memory allocated
- * by the indirection array.  Before compacting anything though, verify
- * that the indirection array is still needed and switch back to the
- * linear extent list (or even the inline buffer) if possible.  The
- * compaction policy is as follows:
- *
- *    Full Compaction: Extents fit into a single page (or inline buffer)
- * Partial Compaction: Extents occupy less than 50% of allocated space
- *      No Compaction: Extents occupy at least 50% of allocated space
- */
-void
-xfs_iext_irec_compact(
-	xfs_ifork_t	*ifp)		/* inode fork pointer */
-{
-	xfs_extnum_t	nextents;	/* number of extents in file */
-	int		nlists;		/* number of irec's (ex lists) */
-
-	ASSERT(ifp->if_flags & XFS_IFEXTIREC);
-	nlists = ifp->if_real_bytes / XFS_IEXT_BUFSZ;
-	nextents = xfs_iext_count(ifp);
-
-	if (nextents == 0) {
-		xfs_iext_destroy(ifp);
-	} else if (nextents <= XFS_LINEAR_EXTS) {
-		xfs_iext_indirect_to_direct(ifp);
-	} else if (nextents < (nlists * XFS_LINEAR_EXTS) >> 1) {
-		xfs_iext_irec_compact_pages(ifp);
-	}
-}
-
-/*
- * Combine extents from neighboring extent pages.
- */
-void
-xfs_iext_irec_compact_pages(
-	xfs_ifork_t	*ifp)		/* inode fork pointer */
-{
-	xfs_ext_irec_t	*erp, *erp_next;/* pointers to irec entries */
-	int		erp_idx = 0;	/* indirection array index */
-	int		nlists;		/* number of irec's (ex lists) */
-
-	ASSERT(ifp->if_flags & XFS_IFEXTIREC);
-	nlists = ifp->if_real_bytes / XFS_IEXT_BUFSZ;
-	while (erp_idx < nlists - 1) {
-		erp = &ifp->if_u1.if_ext_irec[erp_idx];
-		erp_next = erp + 1;
-		if (erp_next->er_extcount <=
-		    (XFS_LINEAR_EXTS - erp->er_extcount)) {
-			memcpy(&erp->er_extbuf[erp->er_extcount],
-				erp_next->er_extbuf, erp_next->er_extcount *
-				sizeof(xfs_bmbt_rec_t));
-			erp->er_extcount += erp_next->er_extcount;
-			/*
-			 * Free page before removing extent record
-			 * so er_extoffs don't get modified in
-			 * xfs_iext_irec_remove.
-			 */
-			kmem_free(erp_next->er_extbuf);
-			erp_next->er_extbuf = NULL;
-			xfs_iext_irec_remove(ifp, erp_idx + 1);
-			nlists = ifp->if_real_bytes / XFS_IEXT_BUFSZ;
-		} else {
-			erp_idx++;
-		}
-	}
-}
-
-/*
- * This is called to update the er_extoff field in the indirection
- * array when extents have been added or removed from one of the
- * extent lists. erp_idx contains the irec index to begin updating
- * at and ext_diff contains the number of extents that were added
- * or removed.
- */
-void
-xfs_iext_irec_update_extoffs(
-	xfs_ifork_t	*ifp,		/* inode fork pointer */
-	int		erp_idx,	/* irec index to update */
-	int		ext_diff)	/* number of new extents */
-{
-	int		i;		/* loop counter */
-	int		nlists;		/* number of irec's (ex lists */
-
-	ASSERT(ifp->if_flags & XFS_IFEXTIREC);
-	nlists = ifp->if_real_bytes / XFS_IEXT_BUFSZ;
-	for (i = erp_idx; i < nlists; i++) {
-		ifp->if_u1.if_ext_irec[i].er_extoff += ext_diff;
-	}
-}
-
 /*
  * Initialize an inode's copy-on-write fork.
  */
@@ -1756,87 +831,3 @@ xfs_ifork_init_cow(
 	ip->i_cformat = XFS_DINODE_FMT_EXTENTS;
 	ip->i_cnextents = 0;
 }
-
-/*
- * Lookup the extent covering bno.
- *
- * If there is an extent covering bno return the extent index, and store the
- * expanded extent structure in *gotp, and the extent cursor in *cur.
- * If there is no extent covering bno, but there is an extent after it (e.g.
- * it lies in a hole) return that extent in *gotp and its cursor in *cur
- * instead.
- * If bno is beyond the last extent return false, and return an invalid
- * cursor value.
- */
-bool
-xfs_iext_lookup_extent(
-	struct xfs_inode	*ip,
-	struct xfs_ifork	*ifp,
-	xfs_fileoff_t		bno,
-	struct xfs_iext_cursor	*cur,
-	struct xfs_bmbt_irec	*gotp)
-{
-	struct xfs_bmbt_rec_host *ep;
-
-	XFS_STATS_INC(ip->i_mount, xs_look_exlist);
-
-	ep = xfs_iext_bno_to_ext(ifp, bno, &cur->idx);
-	if (!ep)
-		return false;
-	xfs_bmbt_get_all(ep, gotp);
-	return true;
-}
-
-/*
- * Returns the last extent before end, and if this extent doesn't cover
- * end, update end to the end of the extent.
- */
-bool
-xfs_iext_lookup_extent_before(
-	struct xfs_inode	*ip,
-	struct xfs_ifork	*ifp,
-	xfs_fileoff_t		*end,
-	struct xfs_iext_cursor	*cur,
-	struct xfs_bmbt_irec	*gotp)
-{
-	if (xfs_iext_lookup_extent(ip, ifp, *end - 1, cur, gotp) &&
-	    gotp->br_startoff <= *end - 1)
-		return true;
-	if (!xfs_iext_prev_extent(ifp, cur, gotp))
-		return false;
-	*end = gotp->br_startoff + gotp->br_blockcount;
-	return true;
-}
-
-/*
- * Return true if the cursor points at an extent and return the extent structure
- * in gotp.  Else return false.
- */
-bool
-xfs_iext_get_extent(
-	struct xfs_ifork	*ifp,
-	struct xfs_iext_cursor	*cur,
-	struct xfs_bmbt_irec	*gotp)
-{
-	if (cur->idx < 0 || cur->idx >= xfs_iext_count(ifp))
-		return false;
-	xfs_bmbt_get_all(xfs_iext_get_ext(ifp, cur->idx), gotp);
-	return true;
-}
-
-void
-xfs_iext_update_extent(
-	struct xfs_inode	*ip,
-	int			state,
-	struct xfs_iext_cursor	*cur,
-	struct xfs_bmbt_irec	*gotp)
-{
-	struct xfs_ifork	*ifp = xfs_iext_state_to_fork(ip, state);
-
-	ASSERT(cur->idx >= 0);
-	ASSERT(cur->idx < xfs_iext_count(ifp));
-
-	trace_xfs_bmap_pre_update(ip, cur, state, _RET_IP_);
-	xfs_bmbt_set_all(xfs_iext_get_ext(ifp, cur->idx), gotp);
-	trace_xfs_bmap_post_update(ip, cur, state, _RET_IP_);
-}
diff --git a/fs/xfs/libxfs/xfs_inode_fork.h b/fs/xfs/libxfs/xfs_inode_fork.h
index cc7ca255ec98..7fda248e32ab 100644
--- a/fs/xfs/libxfs/xfs_inode_fork.h
+++ b/fs/xfs/libxfs/xfs_inode_fork.h
@@ -21,45 +21,18 @@
 struct xfs_inode_log_item;
 struct xfs_dinode;
 
-/*
- * The following xfs_ext_irec_t struct introduces a second (top) level
- * to the in-core extent allocation scheme. These structs are allocated
- * in a contiguous block, creating an indirection array where each entry
- * (irec) contains a pointer to a buffer of in-core extent records which
- * it manages. Each extent buffer is 4k in size, since 4k is the system
- * page size on Linux i386 and systems with larger page sizes don't seem
- * to gain much, if anything, by using their native page size as the
- * extent buffer size. Also, using 4k extent buffers everywhere provides
- * a consistent interface for CXFS across different platforms.
- *
- * There is currently no limit on the number of irec's (extent lists)
- * allowed, so heavily fragmented files may require an indirection array
- * which spans multiple system pages of memory. The number of extents
- * which would require this amount of contiguous memory is very large
- * and should not cause problems in the foreseeable future. However,
- * if the memory needed for the contiguous array ever becomes a problem,
- * it is possible that a third level of indirection may be required.
- */
-typedef struct xfs_ext_irec {
-	xfs_bmbt_rec_host_t *er_extbuf;	/* block of extent records */
-	xfs_extnum_t	er_extoff;	/* extent offset in file */
-	xfs_extnum_t	er_extcount;	/* number of extents in page/block */
-} xfs_ext_irec_t;
-
 /*
  * File incore extent information, present for each of data & attr forks.
  */
-#define	XFS_IEXT_BUFSZ		4096
-#define	XFS_LINEAR_EXTS		(XFS_IEXT_BUFSZ / (uint)sizeof(xfs_bmbt_rec_t))
 typedef struct xfs_ifork {
 	int			if_bytes;	/* bytes in if_u1 */
 	int			if_real_bytes;	/* bytes allocated in if_u1 */
 	struct xfs_btree_block	*if_broot;	/* file's incore btree root */
 	short			if_broot_bytes;	/* bytes allocated for root */
 	unsigned char		if_flags;	/* per-fork flags */
+	int			if_height;	/* height of the extent tree */
 	union {
-		xfs_bmbt_rec_host_t *if_extents;/* linear map file exts */
-		xfs_ext_irec_t	*if_ext_irec;	/* irec map file exts */
+		void		*if_root;	/* extent tree root */
 		char		*if_data;	/* inline file data */
 	} if_u1;
 } xfs_ifork_t;
@@ -70,7 +43,6 @@ typedef struct xfs_ifork {
 #define	XFS_IFINLINE	0x01	/* Inline data is read in */
 #define	XFS_IFEXTENTS	0x02	/* All extent pointers are read in */
 #define	XFS_IFBROOT	0x04	/* i_broot points to the bmap b-tree root */
-#define	XFS_IFEXTIREC	0x08	/* Indirection array of extent blocks */
 
 /*
  * Fork handling.
@@ -140,35 +112,12 @@ int		xfs_iextents_copy(struct xfs_inode *, struct xfs_bmbt_rec *,
 				  int);
 void		xfs_init_local_fork(struct xfs_inode *, int, const void *, int);
 
-struct xfs_bmbt_rec_host *
-		xfs_iext_get_ext(struct xfs_ifork *, xfs_extnum_t);
-xfs_extnum_t	xfs_iext_count(struct xfs_ifork *);
+xfs_extnum_t	xfs_iext_count(struct xfs_ifork *ifp);
 void		xfs_iext_insert(struct xfs_inode *, struct xfs_iext_cursor *cur,
 			xfs_extnum_t, struct xfs_bmbt_irec *, int);
-void		xfs_iext_add(struct xfs_ifork *, xfs_extnum_t, int);
-void		xfs_iext_add_indirect_multi(struct xfs_ifork *, int,
-					    xfs_extnum_t, int);
 void		xfs_iext_remove(struct xfs_inode *, struct xfs_iext_cursor *,
 			int, int);
-void		xfs_iext_remove_direct(struct xfs_ifork *, xfs_extnum_t, int);
-void		xfs_iext_remove_indirect(struct xfs_ifork *, xfs_extnum_t, int);
-void		xfs_iext_realloc_direct(struct xfs_ifork *, int);
 void		xfs_iext_destroy(struct xfs_ifork *);
-struct xfs_bmbt_rec_host *
-		xfs_iext_bno_to_ext(struct xfs_ifork *, xfs_fileoff_t, int *);
-struct xfs_ext_irec *
-		xfs_iext_bno_to_irec(struct xfs_ifork *, xfs_fileoff_t, int *);
-struct xfs_ext_irec *
-		xfs_iext_idx_to_irec(struct xfs_ifork *, xfs_extnum_t *, int *,
-				     int);
-void		xfs_iext_irec_init(struct xfs_ifork *);
-struct xfs_ext_irec *
-		xfs_iext_irec_new(struct xfs_ifork *, int);
-void		xfs_iext_irec_remove(struct xfs_ifork *, int);
-void		xfs_iext_irec_compact(struct xfs_ifork *);
-void		xfs_iext_irec_compact_pages(struct xfs_ifork *);
-void		xfs_iext_irec_compact_full(struct xfs_ifork *);
-void		xfs_iext_irec_update_extoffs(struct xfs_ifork *, int, int);
 
 bool		xfs_iext_lookup_extent(struct xfs_inode *ip,
 			struct xfs_ifork *ifp, xfs_fileoff_t bno,
@@ -185,29 +134,10 @@ void		xfs_iext_update_extent(struct xfs_inode *ip, int state,
 			struct xfs_iext_cursor *cur,
 			struct xfs_bmbt_irec *gotp);
 
-static inline void xfs_iext_first(struct xfs_ifork *ifp,
-		struct xfs_iext_cursor *cur)
-{
-	cur->idx = 0;
-}
-
-static inline void xfs_iext_last(struct xfs_ifork *ifp,
-		struct xfs_iext_cursor *cur)
-{
-	cur->idx = xfs_iext_count(ifp) - 1;
-}
-
-static inline void xfs_iext_next(struct xfs_ifork *ifp,
-		struct xfs_iext_cursor *cur)
-{
-	cur->idx++;
-}
-
-static inline void xfs_iext_prev(struct xfs_ifork *ifp,
-		struct xfs_iext_cursor *cur)
-{
-	cur->idx--;
-}
+void		xfs_iext_first(struct xfs_ifork *, struct xfs_iext_cursor *);
+void		xfs_iext_last(struct xfs_ifork *, struct xfs_iext_cursor *);
+void		xfs_iext_next(struct xfs_ifork *, struct xfs_iext_cursor *);
+void		xfs_iext_prev(struct xfs_ifork *, struct xfs_iext_cursor *);
 
 static inline bool xfs_iext_next_extent(struct xfs_ifork *ifp,
 		struct xfs_iext_cursor *cur, struct xfs_bmbt_irec *gotp)
diff --git a/fs/xfs/libxfs/xfs_types.h b/fs/xfs/libxfs/xfs_types.h
index 5da6382bdaf1..983878019097 100644
--- a/fs/xfs/libxfs/xfs_types.h
+++ b/fs/xfs/libxfs/xfs_types.h
@@ -143,7 +143,8 @@ typedef uint32_t	xfs_dqid_t;
 #define	XFS_WORDMASK	((1 << XFS_WORDLOG) - 1)
 
 struct xfs_iext_cursor {
-	xfs_extnum_t		idx;
+	struct xfs_iext_leaf	*leaf;
+	int			pos;
 };
 
 #endif	/* __XFS_TYPES_H__ */
diff --git a/fs/xfs/scrub/bmap.c b/fs/xfs/scrub/bmap.c
index be0bc11b6594..39fb2a537aea 100644
--- a/fs/xfs/scrub/bmap.c
+++ b/fs/xfs/scrub/bmap.c
@@ -168,7 +168,6 @@ xfs_scrub_bmapbt_rec(
 	struct xfs_scrub_btree		*bs,
 	union xfs_btree_rec		*rec)
 {
-	struct xfs_bmbt_rec_host	ihost;
 	struct xfs_bmbt_irec		irec;
 	struct xfs_scrub_bmap_info	*info = bs->private;
 	struct xfs_inode		*ip = bs->cur->bc_private.b.ip;
@@ -193,9 +192,7 @@ xfs_scrub_bmapbt_rec(
 	}
 
 	/* Set up the in-core record and scrub it. */
-	ihost.l0 = be64_to_cpu(rec->bmbt.l0);
-	ihost.l1 = be64_to_cpu(rec->bmbt.l1);
-	xfs_bmbt_get_all(&ihost, &irec);
+	xfs_bmbt_disk_get_all(&rec->bmbt, &irec);
 	return xfs_scrub_bmap_extent(ip, bs->cur, info, &irec);
 }
 
diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
index 02497828e993..edd98353fbeb 100644
--- a/fs/xfs/xfs_inode.c
+++ b/fs/xfs/xfs_inode.c
@@ -934,7 +934,7 @@ xfs_ialloc(
 		ip->i_d.di_format = XFS_DINODE_FMT_EXTENTS;
 		ip->i_df.if_flags = XFS_IFEXTENTS;
 		ip->i_df.if_bytes = ip->i_df.if_real_bytes = 0;
-		ip->i_df.if_u1.if_extents = NULL;
+		ip->i_df.if_u1.if_root = NULL;
 		break;
 	default:
 		ASSERT(0);
diff --git a/fs/xfs/xfs_inode_item.c b/fs/xfs/xfs_inode_item.c
index eb6f4f7c9520..6ee5c3bf19ad 100644
--- a/fs/xfs/xfs_inode_item.c
+++ b/fs/xfs/xfs_inode_item.c
@@ -162,7 +162,6 @@ xfs_inode_item_format_data_fork(
 		    ip->i_df.if_bytes > 0) {
 			struct xfs_bmbt_rec *p;
 
-			ASSERT(ip->i_df.if_u1.if_extents != NULL);
 			ASSERT(xfs_iext_count(&ip->i_df) > 0);
 
 			p = xlog_prepare_iovec(lv, vecp, XLOG_REG_TYPE_IEXT);
@@ -252,7 +251,6 @@ xfs_inode_item_format_attr_fork(
 
 			ASSERT(xfs_iext_count(ip->i_afp) ==
 				ip->i_d.di_anextents);
-			ASSERT(ip->i_afp->if_u1.if_extents != NULL);
 
 			p = xlog_prepare_iovec(lv, vecp, XLOG_REG_TYPE_IATTR_EXT);
 			data_bytes = xfs_iextents_copy(ip, p, XFS_ATTR_FORK);
diff --git a/fs/xfs/xfs_trace.h b/fs/xfs/xfs_trace.h
index 667bfce802cd..515ba042d75c 100644
--- a/fs/xfs/xfs_trace.h
+++ b/fs/xfs/xfs_trace.h
@@ -218,45 +218,6 @@ TRACE_EVENT(xfs_attr_list_node_descend,
 		   __entry->bt_before)
 );
 
-TRACE_EVENT(xfs_iext_insert,
-	TP_PROTO(struct xfs_inode *ip, xfs_extnum_t idx,
-		 struct xfs_bmbt_irec *r, int state, unsigned long caller_ip),
-	TP_ARGS(ip, idx, r, state, caller_ip),
-	TP_STRUCT__entry(
-		__field(dev_t, dev)
-		__field(xfs_ino_t, ino)
-		__field(xfs_extnum_t, idx)
-		__field(xfs_fileoff_t, startoff)
-		__field(xfs_fsblock_t, startblock)
-		__field(xfs_filblks_t, blockcount)
-		__field(xfs_exntst_t, state)
-		__field(int, bmap_state)
-		__field(unsigned long, caller_ip)
-	),
-	TP_fast_assign(
-		__entry->dev = VFS_I(ip)->i_sb->s_dev;
-		__entry->ino = ip->i_ino;
-		__entry->idx = idx;
-		__entry->startoff = r->br_startoff;
-		__entry->startblock = r->br_startblock;
-		__entry->blockcount = r->br_blockcount;
-		__entry->state = r->br_state;
-		__entry->bmap_state = state;
-		__entry->caller_ip = caller_ip;
-	),
-	TP_printk("dev %d:%d ino 0x%llx state %s idx %ld "
-		  "offset %lld block %lld count %lld flag %d caller %ps",
-		  MAJOR(__entry->dev), MINOR(__entry->dev),
-		  __entry->ino,
-		  __print_flags(__entry->bmap_state, "|", XFS_BMAP_EXT_FLAGS),
-		  (long)__entry->idx,
-		  __entry->startoff,
-		  (int64_t)__entry->startblock,
-		  __entry->blockcount,
-		  __entry->state,
-		  (char *)__entry->caller_ip)
-);
-
 DECLARE_EVENT_CLASS(xfs_bmap_class,
 	TP_PROTO(struct xfs_inode *ip, struct xfs_iext_cursor *cur, int state,
 		 unsigned long caller_ip),
@@ -264,7 +225,8 @@ DECLARE_EVENT_CLASS(xfs_bmap_class,
 	TP_STRUCT__entry(
 		__field(dev_t, dev)
 		__field(xfs_ino_t, ino)
-		__field(xfs_extnum_t, idx)
+		__field(void *, leaf);
+		__field(int, pos);
 		__field(xfs_fileoff_t, startoff)
 		__field(xfs_fsblock_t, startblock)
 		__field(xfs_filblks_t, blockcount)
@@ -280,7 +242,8 @@ DECLARE_EVENT_CLASS(xfs_bmap_class,
 		xfs_iext_get_extent(ifp, cur, &r);
 		__entry->dev = VFS_I(ip)->i_sb->s_dev;
 		__entry->ino = ip->i_ino;
-		__entry->idx = cur->idx;
+		__entry->leaf = cur->leaf;
+		__entry->pos = cur->pos;
 		__entry->startoff = r.br_startoff;
 		__entry->startblock = r.br_startblock;
 		__entry->blockcount = r.br_blockcount;
@@ -288,12 +251,13 @@ DECLARE_EVENT_CLASS(xfs_bmap_class,
 		__entry->bmap_state = state;
 		__entry->caller_ip = caller_ip;
 	),
-	TP_printk("dev %d:%d ino 0x%llx state %s idx %ld "
+	TP_printk("dev %d:%d ino 0x%llx state %s cur 0x%p/%d "
 		  "offset %lld block %lld count %lld flag %d caller %ps",
 		  MAJOR(__entry->dev), MINOR(__entry->dev),
 		  __entry->ino,
 		  __print_flags(__entry->bmap_state, "|", XFS_BMAP_EXT_FLAGS),
-		  (long)__entry->idx,
+		  __entry->leaf,
+		  __entry->pos,
 		  __entry->startoff,
 		  (int64_t)__entry->startblock,
 		  __entry->blockcount,
@@ -306,6 +270,7 @@ DEFINE_EVENT(xfs_bmap_class, name, \
 	TP_PROTO(struct xfs_inode *ip, struct xfs_iext_cursor *cur, int state, \
 		 unsigned long caller_ip), \
 	TP_ARGS(ip, cur, state, caller_ip))
+DEFINE_BMAP_EVENT(xfs_iext_insert);
 DEFINE_BMAP_EVENT(xfs_iext_remove);
 DEFINE_BMAP_EVENT(xfs_bmap_pre_update);
 DEFINE_BMAP_EVENT(xfs_bmap_post_update);
-- 
2.14.2

Re: [PATCH 17/21] xfs: use a b+tree for the in-core extent list

[Darrick J. Wong]

On Fri, Nov 03, 2017 at 05:45:35PM +0300, Christoph Hellwig wrote:
> Replace the current linear list and the indirection array for the in-core
> extent list with a b+tree to avoid the need for larger memory allocations
> for the indirection array when lots of extents are present.  The current
> extent list implementations leads to heavy pressure on the memory
> allocator when modifying files with a high extent count, and can lead
> to high latencies because of that.
> 
> The replacement is a b+tree with a few quirks.  The leaf nodes directly
> store the extent record in two u64 values.  The encoding is a little bit
> different from the existing in-core extent records so that the start
> offset and length which are required for lookups can be retreived with
> simple mask operations.  The inner nodes store a 64-bit key containing
> the start offset in the first half of the node, and the pointers to the
> next lower level in the second half.  In either case we walk the node
> from the beginninig to the end and do a linear search, as that is more
> efficient for the low number of cache lines touched during a search
> (2 for the inner nodes, 4 for the leaf nodes) than a binary search.
> We store termination markers (zero length for the leaf nodes, an
> otherwise impossible high bit for the inner nodes) to terminate the key
> list / records instead of storing a count to use the available cache
> lines as efficiently as possible.
> 
> One quirk of the algorithm is that while we normally split a node half and
> half like usual btree implementations we just spill over entries added at
> the very end of the list to a new node on its own.  This means we get a
> 100% fill grade for the common cases of bulk inseration at reading an
> inode into memory, and when only sequentially appending to a file.  The
> downside is a slightly higher chance of splits on the first random
> inserations.
> 
> Both insert and removal manually recurse into the lower levels, but
> the bulk deletion of the whole tree is still implemented as a recursive
> function call, although one limited by the overall depth and with very
> little stack usage in every iteration.
> 
> For the first few extents we dynamically grow the list from a single
> extent to the next powers of two until we have a first full leaf block
> and that building the actual tree.
> 
> The code started out based on the generic lib/btree.c code from Joern
> Engel based on earlier work from Peter Zijlstra, but has since been
> rewritten beyond recognition.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---

Looks good enough to (re)test,
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>

--D

>  fs/xfs/Makefile                |    1 +
>  fs/xfs/libxfs/xfs_bmap.c       |   20 +-
>  fs/xfs/libxfs/xfs_bmap_btree.c |  103 +---
>  fs/xfs/libxfs/xfs_bmap_btree.h |    7 +-
>  fs/xfs/libxfs/xfs_format.h     |    4 -
>  fs/xfs/libxfs/xfs_iext_tree.c  | 1035 ++++++++++++++++++++++++++++++++++++++++
>  fs/xfs/libxfs/xfs_inode_fork.c | 1035 +---------------------------------------
>  fs/xfs/libxfs/xfs_inode_fork.h |   84 +---
>  fs/xfs/libxfs/xfs_types.h      |    3 +-
>  fs/xfs/scrub/bmap.c            |    5 +-
>  fs/xfs/xfs_inode.c             |    2 +-
>  fs/xfs/xfs_inode_item.c        |    2 -
>  fs/xfs/xfs_trace.h             |   51 +-
>  13 files changed, 1093 insertions(+), 1259 deletions(-)
>  create mode 100644 fs/xfs/libxfs/xfs_iext_tree.c
> 
> diff --git a/fs/xfs/Makefile b/fs/xfs/Makefile
> index a2a5d046793d..7ceb41a9786a 100644
> --- a/fs/xfs/Makefile
> +++ b/fs/xfs/Makefile
> @@ -49,6 +49,7 @@ xfs-y				+= $(addprefix libxfs/, \
>  				   xfs_dquot_buf.o \
>  				   xfs_ialloc.o \
>  				   xfs_ialloc_btree.o \
> +				   xfs_iext_tree.o \
>  				   xfs_inode_fork.o \
>  				   xfs_inode_buf.o \
>  				   xfs_log_rlimit.o \
> diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
> index 8fcb186341ce..7d96e4d9fc91 100644
> --- a/fs/xfs/libxfs/xfs_bmap.c
> +++ b/fs/xfs/libxfs/xfs_bmap.c
> @@ -806,6 +806,8 @@ xfs_bmap_local_to_extents_empty(
>  	xfs_bmap_forkoff_reset(ip, whichfork);
>  	ifp->if_flags &= ~XFS_IFINLINE;
>  	ifp->if_flags |= XFS_IFEXTENTS;
> +	ifp->if_u1.if_root = NULL;
> +	ifp->if_height = 0;
>  	XFS_IFORK_FMT_SET(ip, whichfork, XFS_DINODE_FMT_EXTENTS);
>  }
>  
> @@ -847,8 +849,7 @@ xfs_bmap_local_to_extents(
>  
>  	flags = 0;
>  	error = 0;
> -	ASSERT((ifp->if_flags & (XFS_IFINLINE|XFS_IFEXTENTS|XFS_IFEXTIREC)) ==
> -								XFS_IFINLINE);
> +	ASSERT((ifp->if_flags & (XFS_IFINLINE|XFS_IFEXTENTS)) == XFS_IFINLINE);
>  	memset(&args, 0, sizeof(args));
>  	args.tp = tp;
>  	args.mp = ip->i_mount;
> @@ -892,6 +893,9 @@ xfs_bmap_local_to_extents(
>  	xfs_bmap_local_to_extents_empty(ip, whichfork);
>  	flags |= XFS_ILOG_CORE;
>  
> +	ifp->if_u1.if_root = NULL;
> +	ifp->if_height = 0;
> +
>  	rec.br_startoff = 0;
>  	rec.br_startblock = args.fsbno;
>  	rec.br_blockcount = 1;
> @@ -1178,6 +1182,7 @@ xfs_iread_extents(
>  	xfs_extnum_t		nextents = XFS_IFORK_NEXTENTS(ip, whichfork);
>  	struct xfs_btree_block	*block = ifp->if_broot;
>  	struct xfs_iext_cursor	icur;
> +	struct xfs_bmbt_irec	new;
>  	xfs_fsblock_t		bno;
>  	struct xfs_buf		*bp;
>  	xfs_extnum_t		i, j;
> @@ -1192,10 +1197,6 @@ xfs_iread_extents(
>  		return -EFSCORRUPTED;
>  	}
>  
> -	ifp->if_bytes = 0;
> -	ifp->if_real_bytes = 0;
> -	xfs_iext_add(ifp, 0, nextents);
> -
>  	/*
>  	 * Root level must use BMAP_BROOT_PTR_ADDR macro to get ptr out.
>  	 */
> @@ -1259,16 +1260,15 @@ xfs_iread_extents(
>  		 * Copy records into the extent records.
>  		 */
>  		frp = XFS_BMBT_REC_ADDR(mp, block, 1);
> -		for (j = 0; j < num_recs; j++, i++, frp++) {
> -			xfs_bmbt_rec_host_t *trp = xfs_iext_get_ext(ifp, i);
> +		for (j = 0; j < num_recs; j++, frp++, i++) {
>  			if (!xfs_bmbt_validate_extent(mp, whichfork, frp)) {
>  				XFS_ERROR_REPORT("xfs_bmap_read_extents(2)",
>  						 XFS_ERRLEVEL_LOW, mp);
>  				error = -EFSCORRUPTED;
>  				goto out_brelse;
>  			}
> -			trp->l0 = be64_to_cpu(frp->l0);
> -			trp->l1 = be64_to_cpu(frp->l1);
> +			xfs_bmbt_disk_get_all(frp, &new);
> +			xfs_iext_insert(ip, &icur, 1, &new, state);
>  			trace_xfs_read_extent(ip, &icur, state, _THIS_IP_);
>  			xfs_iext_next(ifp, &icur);
>  		}
> diff --git a/fs/xfs/libxfs/xfs_bmap_btree.c b/fs/xfs/libxfs/xfs_bmap_btree.c
> index 89260972a0f6..c10aecaaae44 100644
> --- a/fs/xfs/libxfs/xfs_bmap_btree.c
> +++ b/fs/xfs/libxfs/xfs_bmap_btree.c
> @@ -71,73 +71,21 @@ xfs_bmdr_to_bmbt(
>  	memcpy(tpp, fpp, sizeof(*fpp) * dmxr);
>  }
>  
> -/*
> - * Convert a compressed bmap extent record to an uncompressed form.
> - * This code must be in sync with the routines xfs_bmbt_get_startoff,
> - * xfs_bmbt_get_startblock and xfs_bmbt_get_blockcount.
> - */
> -STATIC void
> -__xfs_bmbt_get_all(
> -		uint64_t l0,
> -		uint64_t l1,
> -		xfs_bmbt_irec_t *s)
> -{
> -	int	ext_flag;
> -	xfs_exntst_t st;
> -
> -	ext_flag = (int)(l0 >> (64 - BMBT_EXNTFLAG_BITLEN));
> -	s->br_startoff = ((xfs_fileoff_t)l0 &
> -			   xfs_mask64lo(64 - BMBT_EXNTFLAG_BITLEN)) >> 9;
> -	s->br_startblock = (((xfs_fsblock_t)l0 & xfs_mask64lo(9)) << 43) |
> -			   (((xfs_fsblock_t)l1) >> 21);
> -	s->br_blockcount = (xfs_filblks_t)(l1 & xfs_mask64lo(21));
> -	/* This is xfs_extent_state() in-line */
> -	if (ext_flag) {
> -		ASSERT(s->br_blockcount != 0);	/* saved for DMIG */
> -		st = XFS_EXT_UNWRITTEN;
> -	} else
> -		st = XFS_EXT_NORM;
> -	s->br_state = st;
> -}
> -
>  void
> -xfs_bmbt_get_all(
> -	xfs_bmbt_rec_host_t *r,
> -	xfs_bmbt_irec_t *s)
> -{
> -	__xfs_bmbt_get_all(r->l0, r->l1, s);
> -}
> -
> -/*
> - * Extract the blockcount field from an in memory bmap extent record.
> - */
> -xfs_filblks_t
> -xfs_bmbt_get_blockcount(
> -	xfs_bmbt_rec_host_t	*r)
> -{
> -	return (xfs_filblks_t)(r->l1 & xfs_mask64lo(21));
> -}
> -
> -/*
> - * Extract the startblock field from an in memory bmap extent record.
> - */
> -xfs_fsblock_t
> -xfs_bmbt_get_startblock(
> -	xfs_bmbt_rec_host_t	*r)
> -{
> -	return (((xfs_fsblock_t)r->l0 & xfs_mask64lo(9)) << 43) |
> -	       (((xfs_fsblock_t)r->l1) >> 21);
> -}
> -
> -/*
> - * Extract the startoff field from an in memory bmap extent record.
> - */
> -xfs_fileoff_t
> -xfs_bmbt_get_startoff(
> -	xfs_bmbt_rec_host_t	*r)
> -{
> -	return ((xfs_fileoff_t)r->l0 &
> -		 xfs_mask64lo(64 - BMBT_EXNTFLAG_BITLEN)) >> 9;
> +xfs_bmbt_disk_get_all(
> +	struct xfs_bmbt_rec	*rec,
> +	struct xfs_bmbt_irec	*irec)
> +{
> +	uint64_t		l0 = get_unaligned_be64(&rec->l0);
> +	uint64_t		l1 = get_unaligned_be64(&rec->l1);
> +
> +	irec->br_startoff = (l0 & xfs_mask64lo(64 - BMBT_EXNTFLAG_BITLEN)) >> 9;
> +	irec->br_startblock = ((l0 & xfs_mask64lo(9)) << 43) | (l1 >> 21);
> +	irec->br_blockcount = l1 & xfs_mask64lo(21);
> +	if (l0 >> (64 - BMBT_EXNTFLAG_BITLEN))
> +		irec->br_state = XFS_EXT_UNWRITTEN;
> +	else
> +		irec->br_state = XFS_EXT_NORM;
>  }
>  
>  /*
> @@ -161,29 +109,6 @@ xfs_bmbt_disk_get_startoff(
>  		 xfs_mask64lo(64 - BMBT_EXNTFLAG_BITLEN)) >> 9;
>  }
>  
> -/*
> - * Set all the fields in a bmap extent record from the uncompressed form.
> - */
> -void
> -xfs_bmbt_set_all(
> -	struct xfs_bmbt_rec_host *r,
> -	struct xfs_bmbt_irec	*s)
> -{
> -	int			extent_flag = (s->br_state != XFS_EXT_NORM);
> -
> -	ASSERT(s->br_state == XFS_EXT_NORM || s->br_state == XFS_EXT_UNWRITTEN);
> -	ASSERT(!(s->br_startoff & xfs_mask64hi(64-BMBT_STARTOFF_BITLEN)));
> -	ASSERT(!(s->br_blockcount & xfs_mask64hi(64-BMBT_BLOCKCOUNT_BITLEN)));
> -	ASSERT(!(s->br_startblock & xfs_mask64hi(64-BMBT_STARTBLOCK_BITLEN)));
> -
> -	r->l0 = ((xfs_bmbt_rec_base_t)extent_flag << 63) |
> -		 ((xfs_bmbt_rec_base_t)s->br_startoff << 9) |
> -		 ((xfs_bmbt_rec_base_t)s->br_startblock >> 43);
> -	r->l1 = ((xfs_bmbt_rec_base_t)s->br_startblock << 21) |
> -		 ((xfs_bmbt_rec_base_t)s->br_blockcount &
> -		  (xfs_bmbt_rec_base_t)xfs_mask64lo(21));
> -}
> -
>  /*
>   * Set all the fields in a bmap extent record from the uncompressed form.
>   */
> diff --git a/fs/xfs/libxfs/xfs_bmap_btree.h b/fs/xfs/libxfs/xfs_bmap_btree.h
> index 2fbfe2a24b15..714bfbaf9b2d 100644
> --- a/fs/xfs/libxfs/xfs_bmap_btree.h
> +++ b/fs/xfs/libxfs/xfs_bmap_btree.h
> @@ -98,16 +98,11 @@ struct xfs_trans;
>   */
>  extern void xfs_bmdr_to_bmbt(struct xfs_inode *, xfs_bmdr_block_t *, int,
>  			struct xfs_btree_block *, int);
> -extern void xfs_bmbt_get_all(xfs_bmbt_rec_host_t *r, xfs_bmbt_irec_t *s);
> -extern xfs_filblks_t xfs_bmbt_get_blockcount(xfs_bmbt_rec_host_t *r);
> -extern xfs_fsblock_t xfs_bmbt_get_startblock(xfs_bmbt_rec_host_t *r);
> -extern xfs_fileoff_t xfs_bmbt_get_startoff(xfs_bmbt_rec_host_t *r);
>  
>  void xfs_bmbt_disk_set_all(struct xfs_bmbt_rec *r, struct xfs_bmbt_irec *s);
>  extern xfs_filblks_t xfs_bmbt_disk_get_blockcount(xfs_bmbt_rec_t *r);
>  extern xfs_fileoff_t xfs_bmbt_disk_get_startoff(xfs_bmbt_rec_t *r);
> -
> -extern void xfs_bmbt_set_all(xfs_bmbt_rec_host_t *r, xfs_bmbt_irec_t *s);
> +extern void xfs_bmbt_disk_get_all(xfs_bmbt_rec_t *r, xfs_bmbt_irec_t *s);
>  
>  extern void xfs_bmbt_to_bmdr(struct xfs_mount *, struct xfs_btree_block *, int,
>  			xfs_bmdr_block_t *, int);
> diff --git a/fs/xfs/libxfs/xfs_format.h b/fs/xfs/libxfs/xfs_format.h
> index 1e8c0b27f78b..fbe7d3c31345 100644
> --- a/fs/xfs/libxfs/xfs_format.h
> +++ b/fs/xfs/libxfs/xfs_format.h
> @@ -1553,10 +1553,6 @@ typedef struct xfs_bmbt_rec {
>  typedef uint64_t	xfs_bmbt_rec_base_t;	/* use this for casts */
>  typedef xfs_bmbt_rec_t xfs_bmdr_rec_t;
>  
> -typedef struct xfs_bmbt_rec_host {
> -	uint64_t		l0, l1;
> -} xfs_bmbt_rec_host_t;
> -
>  /*
>   * Values and macros for delayed-allocation startblock fields.
>   */
> diff --git a/fs/xfs/libxfs/xfs_iext_tree.c b/fs/xfs/libxfs/xfs_iext_tree.c
> new file mode 100644
> index 000000000000..8b6402d2d9b2
> --- /dev/null
> +++ b/fs/xfs/libxfs/xfs_iext_tree.c
> @@ -0,0 +1,1035 @@
> +/*
> + * Copyright (c) 2017 Christoph Hellwig.
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms and conditions of the GNU General Public License,
> + * version 2, as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope it will be useful, but WITHOUT
> + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
> + * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
> + * more details.
> + */
> +
> +#include <linux/cache.h>
> +#include <linux/kernel.h>
> +#include <linux/slab.h>
> +#include "xfs.h"
> +#include "xfs_format.h"
> +#include "xfs_bit.h"
> +#include "xfs_log_format.h"
> +#include "xfs_inode.h"
> +#include "xfs_inode_fork.h"
> +#include "xfs_trans_resv.h"
> +#include "xfs_mount.h"
> +#include "xfs_trace.h"
> +
> +/*
> + * In-core extent record layout:
> + *
> + * +-------+----------------------------+
> + * | 00:53 | all 54 bits of startoff    |
> + * | 54:63 | low 10 bits of startblock  |
> + * +-------+----------------------------+
> + * | 00:20 | all 21 bits of length      |
> + * |    21 | unwritten extent bit       |
> + * | 22:63 | high 42 bits of startblock |
> + * +-------+----------------------------+
> + */
> +#define XFS_IEXT_STARTOFF_MASK		xfs_mask64lo(BMBT_STARTOFF_BITLEN)
> +#define XFS_IEXT_LENGTH_MASK		xfs_mask64lo(BMBT_BLOCKCOUNT_BITLEN)
> +#define XFS_IEXT_STARTBLOCK_MASK	xfs_mask64lo(BMBT_STARTBLOCK_BITLEN)
> +
> +struct xfs_iext_rec {
> +	uint64_t			lo;
> +	uint64_t			hi;
> +};
> +
> +/*
> + * Given that the length can't be a zero, only an empty hi value indicates an
> + * unused record.
> + */
> +static bool xfs_iext_rec_is_empty(struct xfs_iext_rec *rec)
> +{
> +	return rec->hi == 0;
> +}
> +
> +static inline void xfs_iext_rec_clear(struct xfs_iext_rec *rec)
> +{
> +	rec->lo = 0;
> +	rec->hi = 0;
> +}
> +
> +static void
> +xfs_iext_set(
> +	struct xfs_iext_rec	*rec,
> +	struct xfs_bmbt_irec	*irec)
> +{
> +	ASSERT((irec->br_startoff & ~XFS_IEXT_STARTOFF_MASK) == 0);
> +	ASSERT((irec->br_blockcount & ~XFS_IEXT_LENGTH_MASK) == 0);
> +	ASSERT((irec->br_startblock & ~XFS_IEXT_STARTBLOCK_MASK) == 0);
> +
> +	rec->lo = irec->br_startoff & XFS_IEXT_STARTOFF_MASK;
> +	rec->hi = irec->br_blockcount & XFS_IEXT_LENGTH_MASK;
> +
> +	rec->lo |= (irec->br_startblock << 54);
> +	rec->hi |= ((irec->br_startblock & ~xfs_mask64lo(10)) << (22 - 10));
> +
> +	if (irec->br_state == XFS_EXT_UNWRITTEN)
> +		rec->hi |= (1 << 21);
> +}
> +
> +static void
> +xfs_iext_get(
> +	struct xfs_bmbt_irec	*irec,
> +	struct xfs_iext_rec	*rec)
> +{
> +	irec->br_startoff = rec->lo & XFS_IEXT_STARTOFF_MASK;
> +	irec->br_blockcount = rec->hi & XFS_IEXT_LENGTH_MASK;
> +
> +	irec->br_startblock = rec->lo >> 54;
> +	irec->br_startblock |= (rec->hi & xfs_mask64hi(42)) >> (22 - 10);
> +
> +	if (rec->hi & (1 << 21))
> +		irec->br_state = XFS_EXT_UNWRITTEN;
> +	else
> +		irec->br_state = XFS_EXT_NORM;
> +}
> +
> +enum {
> +	NODE_SIZE	= 256,
> +	KEYS_PER_NODE	= NODE_SIZE / (sizeof(uint64_t) + sizeof(void *)),
> +	RECS_PER_LEAF	= (NODE_SIZE - (2 * sizeof(struct xfs_iext_leaf *))) /
> +				sizeof(struct xfs_iext_rec),
> +};
> +
> +/*
> + * In-core extent btree block layout:
> + *
> + * There are two types of blocks in the btree: leaf and inner (non-leaf) blocks.
> + *
> + * The leaf blocks are made up by %KEYS_PER_NODE extent records, which each
> + * contain the startoffset, blockcount, startblock and unwritten extent flag.
> + * See above for the exact format, followed by pointers to the previous and next
> + * leaf blocks (if there are any).
> + *
> + * The inner (non-leaf) blocks first contain KEYS_PER_NODE lookup keys, followed
> + * by an equal number of pointers to the btree blocks at the next lower level.
> + *
> + *		+-------+-------+-------+-------+-------+----------+----------+
> + * Leaf:	| rec 1 | rec 2 | rec 3 | rec 4 | rec N | prev-ptr | next-ptr |
> + *		+-------+-------+-------+-------+-------+----------+----------+
> + *
> + *		+-------+-------+-------+-------+-------+-------+------+-------+
> + * Inner:	| key 1 | key 2 | key 3 | key N | ptr 1 | ptr 2 | ptr3 | ptr N |
> + *		+-------+-------+-------+-------+-------+-------+------+-------+
> + */
> +struct xfs_iext_node {
> +	uint64_t		keys[KEYS_PER_NODE];
> +#define XFS_IEXT_KEY_INVALID	(1ULL << 63)
> +	void			*ptrs[KEYS_PER_NODE];
> +};
> +
> +struct xfs_iext_leaf {
> +	struct xfs_iext_rec	recs[RECS_PER_LEAF];
> +	struct xfs_iext_leaf	*prev;
> +	struct xfs_iext_leaf	*next;
> +};
> +
> +inline xfs_extnum_t xfs_iext_count(struct xfs_ifork *ifp)
> +{
> +	return ifp->if_bytes / sizeof(struct xfs_iext_rec);
> +}
> +
> +static inline int xfs_iext_max_recs(struct xfs_ifork *ifp)
> +{
> +	if (ifp->if_height == 1)
> +		return xfs_iext_count(ifp);
> +	return RECS_PER_LEAF;
> +}
> +
> +static inline struct xfs_iext_rec *cur_rec(struct xfs_iext_cursor *cur)
> +{
> +	return &cur->leaf->recs[cur->pos];
> +}
> +
> +static inline bool xfs_iext_valid(struct xfs_ifork *ifp,
> +		struct xfs_iext_cursor *cur)
> +{
> +	if (!cur->leaf)
> +		return false;
> +	if (cur->pos < 0 || cur->pos >= xfs_iext_max_recs(ifp))
> +		return false;
> +	if (xfs_iext_rec_is_empty(cur_rec(cur)))
> +		return false;
> +	return true;
> +}
> +
> +static void *
> +xfs_iext_find_first_leaf(
> +	struct xfs_ifork	*ifp)
> +{
> +	struct xfs_iext_node	*node = ifp->if_u1.if_root;
> +	int			height;
> +
> +	if (!ifp->if_height)
> +		return NULL;
> +
> +	for (height = ifp->if_height; height > 1; height--) {
> +		node = node->ptrs[0];
> +		ASSERT(node);
> +	}
> +
> +	return node;
> +}
> +
> +static void *
> +xfs_iext_find_last_leaf(
> +	struct xfs_ifork	*ifp)
> +{
> +	struct xfs_iext_node	*node = ifp->if_u1.if_root;
> +	int			height, i;
> +
> +	if (!ifp->if_height)
> +		return NULL;
> +
> +	for (height = ifp->if_height; height > 1; height--) {
> +		for (i = 1; i < KEYS_PER_NODE; i++)
> +			if (!node->ptrs[i])
> +				break;
> +		node = node->ptrs[i - 1];
> +		ASSERT(node);
> +	}
> +
> +	return node;
> +}
> +
> +void
> +xfs_iext_first(
> +	struct xfs_ifork	*ifp,
> +	struct xfs_iext_cursor	*cur)
> +{
> +	cur->pos = 0;
> +	cur->leaf = xfs_iext_find_first_leaf(ifp);
> +}
> +
> +void
> +xfs_iext_last(
> +	struct xfs_ifork	*ifp,
> +	struct xfs_iext_cursor	*cur)
> +{
> +	int			i;
> +
> +	cur->leaf = xfs_iext_find_last_leaf(ifp);
> +	if (!cur->leaf) {
> +		cur->pos = 0;
> +		return;
> +	}
> +
> +	for (i = 1; i < xfs_iext_max_recs(ifp); i++) {
> +		if (xfs_iext_rec_is_empty(&cur->leaf->recs[i]))
> +			break;
> +	}
> +	cur->pos = i - 1;
> +}
> +
> +void
> +xfs_iext_next(
> +	struct xfs_ifork	*ifp,
> +	struct xfs_iext_cursor	*cur)
> +{
> +	if (!cur->leaf) {
> +		ASSERT(cur->pos <= 0 || cur->pos >= RECS_PER_LEAF);
> +		xfs_iext_first(ifp, cur);
> +		return;
> +	}
> +
> +	ASSERT(cur->pos >= 0);
> +	ASSERT(cur->pos < xfs_iext_max_recs(ifp));
> +
> +	cur->pos++;
> +	if (ifp->if_height > 1 && !xfs_iext_valid(ifp, cur) &&
> +	    cur->leaf->next) {
> +		cur->leaf = cur->leaf->next;
> +		cur->pos = 0;
> +	}
> +}
> +
> +void
> +xfs_iext_prev(
> +	struct xfs_ifork	*ifp,
> +	struct xfs_iext_cursor	*cur)
> +{
> +	if (!cur->leaf) {
> +		ASSERT(cur->pos <= 0 || cur->pos >= RECS_PER_LEAF);
> +		xfs_iext_last(ifp, cur);
> +		return;
> +	}
> +
> +	ASSERT(cur->pos >= 0);
> +	ASSERT(cur->pos <= RECS_PER_LEAF);
> +
> +recurse:
> +	do {
> +		cur->pos--;
> +		if (xfs_iext_valid(ifp, cur))
> +			return;
> +	} while (cur->pos > 0);
> +
> +	if (ifp->if_height > 1 && cur->leaf->prev) {
> +		cur->leaf = cur->leaf->prev;
> +		cur->pos = RECS_PER_LEAF;
> +		goto recurse;
> +	}
> +}
> +
> +static inline int
> +xfs_iext_key_cmp(
> +	struct xfs_iext_node	*node,
> +	int			n,
> +	xfs_fileoff_t		offset)
> +{
> +	if (node->keys[n] > offset)
> +		return 1;
> +	if (node->keys[n] < offset)
> +		return -1;
> +	return 0;
> +}
> +
> +static inline int
> +xfs_iext_rec_cmp(
> +	struct xfs_iext_rec	*rec,
> +	xfs_fileoff_t		offset)
> +{
> +	uint64_t		rec_offset = rec->lo & XFS_IEXT_STARTOFF_MASK;
> +	u32			rec_len = rec->hi & XFS_IEXT_LENGTH_MASK;
> +
> +	if (rec_offset > offset)
> +		return 1;
> +	if (rec_offset + rec_len <= offset)
> +		return -1;
> +	return 0;
> +}
> +
> +static void *
> +xfs_iext_find_level(
> +	struct xfs_ifork	*ifp,
> +	xfs_fileoff_t		offset,
> +	int			level)
> +{
> +	struct xfs_iext_node	*node = ifp->if_u1.if_root;
> +	int			height, i;
> +
> +	if (!ifp->if_height)
> +		return NULL;
> +
> +	for (height = ifp->if_height; height > level; height--) {
> +		for (i = 1; i < KEYS_PER_NODE; i++)
> +			if (xfs_iext_key_cmp(node, i, offset) > 0)
> +				break;
> +
> +		node = node->ptrs[i - 1];
> +		if (!node)
> +			break;
> +	}
> +
> +	return node;
> +}
> +
> +static int
> +xfs_iext_node_pos(
> +	struct xfs_iext_node	*node,
> +	xfs_fileoff_t		offset)
> +{
> +	int			i;
> +
> +	for (i = 1; i < KEYS_PER_NODE; i++) {
> +		if (xfs_iext_key_cmp(node, i, offset) > 0)
> +			break;
> +	}
> +
> +	return i - 1;
> +}
> +
> +static int
> +xfs_iext_node_insert_pos(
> +	struct xfs_iext_node	*node,
> +	xfs_fileoff_t		offset)
> +{
> +	int			i;
> +
> +	for (i = 0; i < KEYS_PER_NODE; i++) {
> +		if (xfs_iext_key_cmp(node, i, offset) > 0)
> +			return i;
> +	}
> +
> +	return KEYS_PER_NODE;
> +}
> +
> +static int
> +xfs_iext_node_nr_entries(
> +	struct xfs_iext_node	*node,
> +	int			start)
> +{
> +	int			i;
> +
> +	for (i = start; i < KEYS_PER_NODE; i++) {
> +		if (node->keys[i] == XFS_IEXT_KEY_INVALID)
> +			break;
> +	}
> +
> +	return i;
> +}
> +
> +static int
> +xfs_iext_leaf_nr_entries(
> +	struct xfs_ifork	*ifp,
> +	struct xfs_iext_leaf	*leaf,
> +	int			start)
> +{
> +	int			i;
> +
> +	for (i = start; i < xfs_iext_max_recs(ifp); i++) {
> +		if (xfs_iext_rec_is_empty(&leaf->recs[i]))
> +			break;
> +	}
> +
> +	return i;
> +}
> +
> +static inline uint64_t
> +xfs_iext_leaf_key(
> +	struct xfs_iext_leaf	*leaf,
> +	int			n)
> +{
> +	return leaf->recs[n].lo & XFS_IEXT_STARTOFF_MASK;
> +}
> +
> +static void
> +xfs_iext_grow(
> +	struct xfs_ifork	*ifp)
> +{
> +	struct xfs_iext_node	*node = kmem_zalloc(NODE_SIZE, KM_NOFS);
> +	int			i;
> +
> +	if (ifp->if_height == 1) {
> +		struct xfs_iext_leaf *prev = ifp->if_u1.if_root;
> +
> +		node->keys[0] = xfs_iext_leaf_key(prev, 0);
> +		node->ptrs[0] = prev;
> +	} else  {
> +		struct xfs_iext_node *prev = ifp->if_u1.if_root;
> +
> +		ASSERT(ifp->if_height > 1);
> +
> +		node->keys[0] = prev->keys[0];
> +		node->ptrs[0] = prev;
> +	}
> +
> +	for (i = 1; i < KEYS_PER_NODE; i++)
> +		node->keys[i] = XFS_IEXT_KEY_INVALID;
> +
> +	ifp->if_u1.if_root = node;
> +	ifp->if_height++;
> +}
> +
> +static void
> +xfs_iext_update_node(
> +	struct xfs_ifork	*ifp,
> +	xfs_fileoff_t		old_offset,
> +	xfs_fileoff_t		new_offset,
> +	int			level,
> +	void			*ptr)
> +{
> +	struct xfs_iext_node	*node = ifp->if_u1.if_root;
> +	int			height, i;
> +
> +	for (height = ifp->if_height; height > level; height--) {
> +		for (i = 0; i < KEYS_PER_NODE; i++) {
> +			if (i > 0 && xfs_iext_key_cmp(node, i, old_offset) > 0)
> +				break;
> +			if (node->keys[i] == old_offset)
> +				node->keys[i] = new_offset;
> +		}
> +		node = node->ptrs[i - 1];
> +		ASSERT(node);
> +	}
> +
> +	ASSERT(node == ptr);
> +}
> +
> +static struct xfs_iext_node *
> +xfs_iext_split_node(
> +	struct xfs_iext_node	**nodep,
> +	int			*pos,
> +	int			*nr_entries)
> +{
> +	struct xfs_iext_node	*node = *nodep;
> +	struct xfs_iext_node	*new = kmem_zalloc(NODE_SIZE, KM_NOFS);
> +	const int		nr_move = KEYS_PER_NODE / 2;
> +	int			nr_keep = nr_move + (KEYS_PER_NODE & 1);
> +	int			i = 0;
> +
> +	/* for sequential append operations just spill over into the new node */
> +	if (*pos == KEYS_PER_NODE) {
> +		*nodep = new;
> +		*pos = 0;
> +		*nr_entries = 0;
> +		goto done;
> +	}
> +
> +
> +	for (i = 0; i < nr_move; i++) {
> +		new->keys[i] = node->keys[nr_keep + i];
> +		new->ptrs[i] = node->ptrs[nr_keep + i];
> +
> +		node->keys[nr_keep + i] = XFS_IEXT_KEY_INVALID;
> +		node->ptrs[nr_keep + i] = NULL;
> +	}
> +
> +	if (*pos >= nr_keep) {
> +		*nodep = new;
> +		*pos -= nr_keep;
> +		*nr_entries = nr_move;
> +	} else {
> +		*nr_entries = nr_keep;
> +	}
> +done:
> +	for (; i < KEYS_PER_NODE; i++)
> +		new->keys[i] = XFS_IEXT_KEY_INVALID;
> +	return new;
> +}
> +
> +static void
> +xfs_iext_insert_node(
> +	struct xfs_ifork	*ifp,
> +	uint64_t		offset,
> +	void			*ptr,
> +	int			level)
> +{
> +	struct xfs_iext_node	*node, *new;
> +	int			i, pos, nr_entries;
> +
> +again:
> +	if (ifp->if_height < level)
> +		xfs_iext_grow(ifp);
> +
> +	new = NULL;
> +	node = xfs_iext_find_level(ifp, offset, level);
> +	pos = xfs_iext_node_insert_pos(node, offset);
> +	nr_entries = xfs_iext_node_nr_entries(node, pos);
> +
> +	ASSERT(pos >= nr_entries || xfs_iext_key_cmp(node, pos, offset) != 0);
> +	ASSERT(nr_entries <= KEYS_PER_NODE);
> +
> +	if (nr_entries == KEYS_PER_NODE)
> +		new = xfs_iext_split_node(&node, &pos, &nr_entries);
> +
> +	if (node != new && pos == 0 && nr_entries > 0)
> +		xfs_iext_update_node(ifp, node->keys[0], offset, level, node);
> +
> +	for (i = nr_entries; i > pos; i--) {
> +		node->keys[i] = node->keys[i - 1];
> +		node->ptrs[i] = node->ptrs[i - 1];
> +	}
> +	node->keys[pos] = offset;
> +	node->ptrs[pos] = ptr;
> +
> +	if (new) {
> +		offset = new->keys[0];
> +		ptr = new;
> +		level++;
> +		goto again;
> +	}
> +}
> +
> +static struct xfs_iext_leaf *
> +xfs_iext_split_leaf(
> +	struct xfs_iext_cursor	*cur,
> +	int			*nr_entries)
> +{
> +	struct xfs_iext_leaf	*leaf = cur->leaf;
> +	struct xfs_iext_leaf	*new = kmem_zalloc(NODE_SIZE, KM_NOFS);
> +	const int		nr_move = RECS_PER_LEAF / 2;
> +	int			nr_keep = nr_move + (RECS_PER_LEAF & 1);
> +	int			i;
> +
> +	/* for sequential append operations just spill over into the new node */
> +	if (cur->pos == KEYS_PER_NODE) {
> +		cur->leaf = new;
> +		cur->pos = 0;
> +		*nr_entries = 0;
> +		goto done;
> +	}
> +
> +	if (nr_keep & 1)
> +		nr_keep++;
> +
> +	for (i = 0; i < nr_move; i++) {
> +		new->recs[i] = leaf->recs[nr_keep + i];
> +		xfs_iext_rec_clear(&leaf->recs[nr_keep + i]);
> +	}
> +
> +	if (cur->pos >= nr_keep) {
> +		cur->leaf = new;
> +		cur->pos -= nr_keep;
> +		*nr_entries = nr_move;
> +	} else {
> +		*nr_entries = nr_keep;
> +	}
> +done:
> +	if (leaf->next)
> +		leaf->next->prev = new;
> +	new->next = leaf->next;
> +	new->prev = leaf;
> +	leaf->next = new;
> +	return new;
> +}
> +
> +static void
> +xfs_iext_alloc_root(
> +	struct xfs_ifork	*ifp,
> +	struct xfs_iext_cursor	*cur)
> +{
> +	ASSERT(ifp->if_bytes == 0);
> +
> +	ifp->if_u1.if_root = kmem_zalloc(sizeof(struct xfs_iext_rec), KM_NOFS);
> +	ifp->if_height = 1;
> +
> +	/* now that we have a node step into it */
> +	cur->leaf = ifp->if_u1.if_root;
> +	cur->pos = 0;
> +}
> +
> +static void
> +xfs_iext_realloc_root(
> +	struct xfs_ifork	*ifp,
> +	struct xfs_iext_cursor	*cur)
> +{
> +	size_t new_size = ifp->if_bytes + sizeof(struct xfs_iext_rec);
> +	void *new;
> +
> +	/* account for the prev/next pointers */
> +	if (new_size / sizeof(struct xfs_iext_rec) == RECS_PER_LEAF)
> +		new_size = NODE_SIZE;
> +
> +	new = kmem_realloc(ifp->if_u1.if_root, new_size, KM_NOFS);
> +	memset(new + ifp->if_bytes, 0, new_size - ifp->if_bytes);
> +	ifp->if_u1.if_root = new;
> +	cur->leaf = new;
> +}
> +
> +static void
> +__xfs_iext_insert(
> +	struct xfs_ifork	*ifp,
> +	struct xfs_iext_cursor	*cur,
> +	struct xfs_bmbt_irec	*irec)
> +{
> +	xfs_fileoff_t		offset = irec->br_startoff;
> +	struct xfs_iext_leaf	*new = NULL;
> +	int			nr_entries, i;
> +
> +	if (ifp->if_height == 0)
> +		xfs_iext_alloc_root(ifp, cur);
> +	else if (ifp->if_height == 1)
> +		xfs_iext_realloc_root(ifp, cur);
> +
> +	nr_entries = xfs_iext_leaf_nr_entries(ifp, cur->leaf, cur->pos);
> +	ASSERT(nr_entries <= RECS_PER_LEAF);
> +	ASSERT(cur->pos >= nr_entries ||
> +	       xfs_iext_rec_cmp(cur_rec(cur), irec->br_startoff) != 0);
> +
> +	if (nr_entries == RECS_PER_LEAF)
> +		new = xfs_iext_split_leaf(cur, &nr_entries);
> +
> +	if (cur->leaf != new && cur->pos == 0 && nr_entries > 0) {
> +		xfs_iext_update_node(ifp, xfs_iext_leaf_key(cur->leaf, 0), offset, 1,
> +				cur->leaf);
> +	}
> +
> +	for (i = nr_entries; i > cur->pos; i--)
> +		cur->leaf->recs[i] = cur->leaf->recs[i - 1];
> +	xfs_iext_set(cur_rec(cur), irec);
> +	ifp->if_bytes += sizeof(struct xfs_iext_rec);
> +
> +	if (new)
> +		xfs_iext_insert_node(ifp, xfs_iext_leaf_key(new, 0), new, 2);
> +}
> +
> +void
> +xfs_iext_insert(
> +	struct xfs_inode	*ip,
> +	struct xfs_iext_cursor	*cur,
> +	xfs_extnum_t		nr_extents,
> +	struct xfs_bmbt_irec	*new,
> +	int			state)
> +{
> +	struct xfs_ifork	*ifp = xfs_iext_state_to_fork(ip, state);
> +	int			i;
> +
> +	ASSERT(nr_extents > 0);
> +
> +	for (i = nr_extents - 1; i >= 0; i--) {
> +		__xfs_iext_insert(ifp, cur, new + i);
> +		trace_xfs_iext_insert(ip, cur, state, _RET_IP_);
> +	}
> +}
> +
> +static struct xfs_iext_node *
> +xfs_iext_rebalance_node(
> +	struct xfs_iext_node	*parent,
> +	int			*pos,
> +	struct xfs_iext_node	*node,
> +	int			nr_entries)
> +{
> +	if (nr_entries == 0)
> +		return node;
> +
> +	if (*pos > 0) {
> +		struct xfs_iext_node *prev = parent->ptrs[*pos - 1];
> +		int nr_prev = xfs_iext_node_nr_entries(prev, 0), i;
> +
> +		if (nr_prev + nr_entries <= KEYS_PER_NODE) {
> +			for (i = 0; i < nr_entries; i++) {
> +				prev->keys[nr_prev + i] = node->keys[i];
> +				prev->ptrs[nr_prev + i] = node->ptrs[i];
> +			}
> +			return node;
> +		}
> +	}
> +
> +	if (*pos + 1 < xfs_iext_node_nr_entries(parent, *pos)) {
> +		struct xfs_iext_node *next = parent->ptrs[*pos + 1];
> +		int nr_next = xfs_iext_node_nr_entries(next, 0), i;
> +
> +		if (nr_entries + nr_next <= KEYS_PER_NODE) {
> +			for (i = 0; i < nr_next; i++) {
> +				node->keys[nr_entries + i] = next->keys[i];
> +				node->ptrs[nr_entries + i] = next->ptrs[i];
> +			}
> +
> +			++*pos;
> +			return next;
> +		}
> +	}
> +
> +	return NULL;
> +}
> +
> +static void
> +xfs_iext_remove_node(
> +	struct xfs_ifork	*ifp,
> +	xfs_fileoff_t		offset,
> +	void			*victim)
> +{
> +	struct xfs_iext_node	*node, *parent;
> +	int			level = 2, pos, nr_entries, i;
> +
> +	ASSERT(level <= ifp->if_height);
> +	node = xfs_iext_find_level(ifp, offset, level);
> +	pos = xfs_iext_node_pos(node, offset);
> +again:
> +	ASSERT(node->ptrs[pos]);
> +	ASSERT(node->ptrs[pos] == victim);
> +	kmem_free(victim);
> +
> +	nr_entries = xfs_iext_node_nr_entries(node, pos) - 1;
> +	offset = node->keys[0];
> +	for (i = pos; i < nr_entries; i++) {
> +		node->keys[i] = node->keys[i + 1];
> +		node->ptrs[i] = node->ptrs[i + 1];
> +	}
> +	node->keys[nr_entries] = XFS_IEXT_KEY_INVALID;
> +	node->ptrs[nr_entries] = NULL;
> +
> +	if (pos == 0 && nr_entries > 0) {
> +		xfs_iext_update_node(ifp, offset, node->keys[0], level,
> +				node);
> +		offset = node->keys[0];
> +	}
> +
> +	if (nr_entries >= KEYS_PER_NODE / 2)
> +		return;
> +
> +	if (level < ifp->if_height) {
> +		level++;
> +		parent = xfs_iext_find_level(ifp, offset, level);
> +		pos = xfs_iext_node_pos(parent, offset);
> +
> +		ASSERT(pos != KEYS_PER_NODE);
> +		ASSERT(parent->ptrs[pos] == node);
> +
> +		node = xfs_iext_rebalance_node(parent, &pos, node, nr_entries);
> +		if (node) {
> +			offset = node->keys[0];
> +			victim = node;
> +			node = parent;
> +			goto again;
> +		}
> +	} else if (nr_entries == 1) {
> +		ASSERT(node == ifp->if_u1.if_root);
> +		ifp->if_u1.if_root = node->ptrs[0];
> +		ifp->if_height--;
> +		kmem_free(node);
> +	}
> +}
> +
> +static void
> +xfs_iext_rebalance_leaf(
> +	struct xfs_ifork	*ifp,
> +	struct xfs_iext_cursor	*cur,
> +	struct xfs_iext_leaf	*leaf,
> +	xfs_fileoff_t		offset,
> +	int			fill)
> +{
> +	if (leaf->prev) {
> +		int nr_prev = xfs_iext_leaf_nr_entries(ifp, leaf->prev, 0), i;
> +
> +		if (nr_prev + fill <= RECS_PER_LEAF) {
> +			for (i = 0; i < fill; i++)
> +				leaf->prev->recs[nr_prev + i] = leaf->recs[i];
> +
> +			if (cur->leaf == leaf) {
> +				cur->leaf = leaf->prev;
> +				cur->pos += nr_prev;
> +			}
> +			goto remove_node;
> +		}
> +	}
> +
> +	if (leaf->next) {
> +		int nr_next = xfs_iext_leaf_nr_entries(ifp, leaf->next, 0), i;
> +
> +		if (fill + nr_next <= RECS_PER_LEAF) {
> +			for (i = 0; i < nr_next; i++)
> +				leaf->recs[fill + i] = leaf->next->recs[i];
> +
> +			if (cur->leaf == leaf->next) {
> +				cur->leaf = leaf;
> +				cur->pos += fill;
> +			}
> +
> +			offset = xfs_iext_leaf_key(leaf->next, 0);
> +			leaf = leaf->next;
> +			goto remove_node;
> +		}
> +	}
> +
> +	return;
> +remove_node:
> +	if (leaf->prev)
> +		leaf->prev->next = leaf->next;
> +	if (leaf->next)
> +		leaf->next->prev = leaf->prev;
> +	xfs_iext_remove_node(ifp, offset, leaf);
> +}
> +
> +static void
> +xfs_iext_free_last_leaf(
> +	struct xfs_ifork	*ifp)
> +{
> +	ifp->if_u1.if_root = NULL;
> +	ifp->if_height--;
> +	kmem_free(ifp->if_u1.if_root);
> +}
> +
> +static void
> +__xfs_iext_remove(
> +	struct xfs_ifork	*ifp,
> +	struct xfs_iext_cursor	*cur)
> +{
> +	struct xfs_iext_leaf	*leaf = cur->leaf;
> +	xfs_fileoff_t		offset = xfs_iext_leaf_key(leaf, 0);
> +	int			i, nr_entries;
> +
> +	ASSERT(ifp->if_height > 0);
> +	ASSERT(ifp->if_u1.if_root != NULL);
> +	ASSERT(xfs_iext_valid(ifp, cur));
> +
> +	nr_entries = xfs_iext_leaf_nr_entries(ifp, leaf, cur->pos) - 1;
> +	for (i = cur->pos; i < nr_entries; i++)
> +		leaf->recs[i] = leaf->recs[i + 1];
> +	xfs_iext_rec_clear(&leaf->recs[nr_entries]);
> +	ifp->if_bytes -= sizeof(struct xfs_iext_rec);
> +
> +	if (cur->pos == 0 && nr_entries > 0) {
> +		xfs_iext_update_node(ifp, offset, xfs_iext_leaf_key(leaf, 0), 1,
> +				leaf);
> +		offset = xfs_iext_leaf_key(leaf, 0);
> +	} else if (cur->pos == nr_entries) {
> +		if (ifp->if_height > 1 && leaf->next)
> +			cur->leaf = leaf->next;
> +		else
> +			cur->leaf = NULL;
> +		cur->pos = 0;
> +	}
> +
> +	if (nr_entries >= RECS_PER_LEAF / 2)
> +		return;
> +
> +	if (ifp->if_height > 1)
> +		xfs_iext_rebalance_leaf(ifp, cur, leaf, offset, nr_entries);
> +	else if (nr_entries == 0)
> +		xfs_iext_free_last_leaf(ifp);
> +}
> +
> +void
> +xfs_iext_remove(
> +	struct xfs_inode	*ip,
> +	struct xfs_iext_cursor	*cur,
> +	int			nr_extents,
> +	int			state)
> +{
> +	struct xfs_ifork	*ifp = xfs_iext_state_to_fork(ip, state);
> +	int			i;
> +
> +	ASSERT(nr_extents > 0);
> +
> +	for (i = 0; i < nr_extents; i++) {
> +		trace_xfs_iext_remove(ip, cur, state, _RET_IP_);
> +		__xfs_iext_remove(ifp, cur);
> +	}
> +}
> +
> +/*
> + * Lookup the extent covering bno.
> + *
> + * If there is an extent covering bno return the extent index, and store the
> + * expanded extent structure in *gotp, and the extent cursor in *cur.
> + * If there is no extent covering bno, but there is an extent after it (e.g.
> + * it lies in a hole) return that extent in *gotp and its cursor in *cur
> + * instead.
> + * If bno is beyond the last extent return false, and return an invalid
> + * cursor value.
> + */
> +bool
> +xfs_iext_lookup_extent(
> +	struct xfs_inode	*ip,
> +	struct xfs_ifork	*ifp,
> +	xfs_fileoff_t		offset,
> +	struct xfs_iext_cursor	*cur,
> +	struct xfs_bmbt_irec	*gotp)
> +{
> +	XFS_STATS_INC(ip->i_mount, xs_look_exlist);
> +
> +	cur->leaf = xfs_iext_find_level(ifp, offset, 1);
> +	if (!cur->leaf) {
> +		cur->pos = 0;
> +		return false;
> +	}
> +
> +	for (cur->pos = 0; cur->pos < xfs_iext_max_recs(ifp); cur->pos++) {
> +		struct xfs_iext_rec *rec = cur_rec(cur);
> +
> +		if (xfs_iext_rec_is_empty(rec))
> +			break;
> +		if (xfs_iext_rec_cmp(rec, offset) >= 0)
> +			goto found;
> +	}
> +
> +	/* Try looking in the next node for an entry > offset */
> +	if (ifp->if_height == 1 || !cur->leaf->next)
> +		return false;
> +	cur->leaf = cur->leaf->next;
> +	cur->pos = 0;
> +	if (!xfs_iext_valid(ifp, cur))
> +		return false;
> +found:
> +	xfs_iext_get(gotp, cur_rec(cur));
> +	return true;
> +}
> +
> +/*
> + * Returns the last extent before end, and if this extent doesn't cover
> + * end, update end to the end of the extent.
> + */
> +bool
> +xfs_iext_lookup_extent_before(
> +	struct xfs_inode	*ip,
> +	struct xfs_ifork	*ifp,
> +	xfs_fileoff_t		*end,
> +	struct xfs_iext_cursor	*cur,
> +	struct xfs_bmbt_irec	*gotp)
> +{
> +	/* could be optimized to not even look up the next on a match.. */
> +	if (xfs_iext_lookup_extent(ip, ifp, *end - 1, cur, gotp) &&
> +	    gotp->br_startoff <= *end - 1)
> +		return true;
> +	if (!xfs_iext_prev_extent(ifp, cur, gotp))
> +		return false;
> +	*end = gotp->br_startoff + gotp->br_blockcount;
> +	return true;
> +}
> +
> +void
> +xfs_iext_update_extent(
> +	struct xfs_inode	*ip,
> +	int			state,
> +	struct xfs_iext_cursor	*cur,
> +	struct xfs_bmbt_irec	*new)
> +{
> +	struct xfs_ifork	*ifp = xfs_iext_state_to_fork(ip, state);
> +
> +	if (cur->pos == 0) {
> +		struct xfs_bmbt_irec	old;
> +
> +		xfs_iext_get(&old, cur_rec(cur));
> +		if (new->br_startoff != old.br_startoff) {
> +			xfs_iext_update_node(ifp, old.br_startoff,
> +					new->br_startoff, 1, cur->leaf);
> +		}
> +	}
> +
> +	trace_xfs_bmap_pre_update(ip, cur, state, _RET_IP_);
> +	xfs_iext_set(cur_rec(cur), new);
> +	trace_xfs_bmap_post_update(ip, cur, state, _RET_IP_);
> +}
> +
> +/*
> + * Return true if the cursor points at an extent and return the extent structure
> + * in gotp.  Else return false.
> + */
> +bool
> +xfs_iext_get_extent(
> +	struct xfs_ifork	*ifp,
> +	struct xfs_iext_cursor	*cur,
> +	struct xfs_bmbt_irec	*gotp)
> +{
> +	if (!xfs_iext_valid(ifp, cur))
> +		return false;
> +	xfs_iext_get(gotp, cur_rec(cur));
> +	return true;
> +}
> +
> +/*
> + * This is a recursive function, because of that we need to be extremely
> + * careful with stack usage.
> + */
> +static void
> +xfs_iext_destroy_node(
> +	struct xfs_iext_node	*node,
> +	int			level)
> +{
> +	int			i;
> +
> +	if (level > 1) {
> +		for (i = 0; i < KEYS_PER_NODE; i++) {
> +			if (node->keys[i] == XFS_IEXT_KEY_INVALID)
> +				break;
> +			xfs_iext_destroy_node(node->ptrs[i], level - 1);
> +		}
> +	}
> +
> +	kmem_free(node);
> +}
> +
> +void
> +xfs_iext_destroy(
> +	struct xfs_ifork	*ifp)
> +{
> +	xfs_iext_destroy_node(ifp->if_u1.if_root, ifp->if_height);
> +
> +	ifp->if_bytes = 0;
> +	ifp->if_height = 0;
> +	ifp->if_u1.if_root = NULL;
> +}
> diff --git a/fs/xfs/libxfs/xfs_inode_fork.c b/fs/xfs/libxfs/xfs_inode_fork.c
> index 1f888fcbd873..1839202133ba 100644
> --- a/fs/xfs/libxfs/xfs_inode_fork.c
> +++ b/fs/xfs/libxfs/xfs_inode_fork.c
> @@ -331,6 +331,7 @@ xfs_iformat_extents(
>  	int			size = nex * sizeof(xfs_bmbt_rec_t);
>  	struct xfs_iext_cursor	icur;
>  	struct xfs_bmbt_rec	*dp;
> +	struct xfs_bmbt_irec	new;
>  	int			i;
>  
>  	/*
> @@ -346,27 +347,22 @@ xfs_iformat_extents(
>  	}
>  
>  	ifp->if_real_bytes = 0;
> -	if (nex == 0)
> -		ifp->if_u1.if_extents = NULL;
> -	else
> -		xfs_iext_add(ifp, 0, nex);
> -
> -	ifp->if_bytes = size;
> +	ifp->if_bytes = 0;
> +	ifp->if_u1.if_root = NULL;
> +	ifp->if_height = 0;
>  	if (size) {
>  		dp = (xfs_bmbt_rec_t *) XFS_DFORK_PTR(dip, whichfork);
>  
>  		xfs_iext_first(ifp, &icur);
>  		for (i = 0; i < nex; i++, dp++) {
> -			xfs_bmbt_rec_host_t *ep = xfs_iext_get_ext(ifp, i);
> -
>  			if (!xfs_bmbt_validate_extent(mp, whichfork, dp)) {
>  				XFS_ERROR_REPORT("xfs_iformat_extents(2)",
>  						 XFS_ERRLEVEL_LOW, mp);
>  				return -EFSCORRUPTED;
>  			}
>  
> -			ep->l0 = get_unaligned_be64(&dp->l0);
> -			ep->l1 = get_unaligned_be64(&dp->l1);
> +			xfs_bmbt_disk_get_all(dp, &new);
> +			xfs_iext_insert(ip, &icur, 1, &new, state);
>  			trace_xfs_read_extent(ip, &icur, state, _THIS_IP_);
>  			xfs_iext_next(ifp, &icur);
>  		}
> @@ -435,6 +431,10 @@ xfs_iformat_btree(
>  	ifp->if_flags &= ~XFS_IFEXTENTS;
>  	ifp->if_flags |= XFS_IFBROOT;
>  
> +	ifp->if_real_bytes = 0;
> +	ifp->if_bytes = 0;
> +	ifp->if_u1.if_root = NULL;
> +	ifp->if_height = 0;
>  	return 0;
>  }
>  
> @@ -662,14 +662,12 @@ xfs_idestroy_fork(
>  			ifp->if_u1.if_data = NULL;
>  			ifp->if_real_bytes = 0;
>  		}
> -	} else if ((ifp->if_flags & XFS_IFEXTENTS) &&
> -		   ((ifp->if_flags & XFS_IFEXTIREC) ||
> -		    (ifp->if_u1.if_extents != NULL))) {
> -		ASSERT(ifp->if_real_bytes != 0);
> +	} else if ((ifp->if_flags & XFS_IFEXTENTS) && ifp->if_height) {
>  		xfs_iext_destroy(ifp);
>  	}
> -	ASSERT(ifp->if_u1.if_extents == NULL);
> +
>  	ASSERT(ifp->if_real_bytes == 0);
> +
>  	if (whichfork == XFS_ATTR_FORK) {
>  		kmem_zone_free(xfs_ifork_zone, ip->i_afp);
>  		ip->i_afp = NULL;
> @@ -679,13 +677,6 @@ xfs_idestroy_fork(
>  	}
>  }
>  
> -/* Count number of incore extents based on if_bytes */
> -xfs_extnum_t
> -xfs_iext_count(struct xfs_ifork *ifp)
> -{
> -	return ifp->if_bytes / (uint)sizeof(xfs_bmbt_rec_t);
> -}
> -
>  /*
>   * Convert in-core extents to on-disk form
>   *
> @@ -780,7 +771,6 @@ xfs_iflush_fork(
>  		       !(iip->ili_fields & extflag[whichfork]));
>  		if ((iip->ili_fields & extflag[whichfork]) &&
>  		    (ifp->if_bytes > 0)) {
> -			ASSERT(xfs_iext_get_ext(ifp, 0));
>  			ASSERT(XFS_IFORK_NEXTENTS(ip, whichfork) > 0);
>  			(void)xfs_iextents_copy(ip, (xfs_bmbt_rec_t *)cp,
>  				whichfork);
> @@ -812,33 +802,6 @@ xfs_iflush_fork(
>  	}
>  }
>  
> -/*
> - * Return a pointer to the extent record at file index idx.
> - */
> -xfs_bmbt_rec_host_t *
> -xfs_iext_get_ext(
> -	xfs_ifork_t	*ifp,		/* inode fork pointer */
> -	xfs_extnum_t	idx)		/* index of target extent */
> -{
> -	ASSERT(idx >= 0);
> -	ASSERT(idx < xfs_iext_count(ifp));
> -
> -	if ((ifp->if_flags & XFS_IFEXTIREC) && (idx == 0)) {
> -		return ifp->if_u1.if_ext_irec->er_extbuf;
> -	} else if (ifp->if_flags & XFS_IFEXTIREC) {
> -		xfs_ext_irec_t	*erp;		/* irec pointer */
> -		int		erp_idx = 0;	/* irec index */
> -		xfs_extnum_t	page_idx = idx;	/* ext index in target list */
> -
> -		erp = xfs_iext_idx_to_irec(ifp, &page_idx, &erp_idx, 0);
> -		return &erp->er_extbuf[page_idx];
> -	} else if (ifp->if_bytes) {
> -		return &ifp->if_u1.if_extents[idx];
> -	} else {
> -		return NULL;
> -	}
> -}
> -
>  /* Convert bmap state flags to an inode fork. */
>  struct xfs_ifork *
>  xfs_iext_state_to_fork(
> @@ -852,894 +815,6 @@ xfs_iext_state_to_fork(
>  	return &ip->i_df;
>  }
>  
> -/*
> - * Insert new item(s) into the extent records for incore inode
> - * fork 'ifp'.  'count' new items are inserted at index 'idx'.
> - */
> -void
> -xfs_iext_insert(
> -	xfs_inode_t	*ip,		/* incore inode pointer */
> -	struct xfs_iext_cursor *cur,
> -	xfs_extnum_t	count,		/* number of inserted items */
> -	xfs_bmbt_irec_t	*new,		/* items to insert */
> -	int		state)		/* type of extent conversion */
> -{
> -	xfs_ifork_t	*ifp = xfs_iext_state_to_fork(ip, state);
> -	xfs_extnum_t	i;		/* extent record index */
> -
> -	trace_xfs_iext_insert(ip, cur->idx, new, state, _RET_IP_);
> -
> -	ASSERT(ifp->if_flags & XFS_IFEXTENTS);
> -	xfs_iext_add(ifp, cur->idx, count);
> -	for (i = 0; i < count; i++, new++)
> -		xfs_bmbt_set_all(xfs_iext_get_ext(ifp, cur->idx + i), new);
> -}
> -
> -/*
> - * This is called when the amount of space required for incore file
> - * extents needs to be increased. The ext_diff parameter stores the
> - * number of new extents being added and the idx parameter contains
> - * the extent index where the new extents will be added. If the new
> - * extents are being appended, then we just need to (re)allocate and
> - * initialize the space. Otherwise, if the new extents are being
> - * inserted into the middle of the existing entries, a bit more work
> - * is required to make room for the new extents to be inserted. The
> - * caller is responsible for filling in the new extent entries upon
> - * return.
> - */
> -void
> -xfs_iext_add(
> -	xfs_ifork_t	*ifp,		/* inode fork pointer */
> -	xfs_extnum_t	idx,		/* index to begin adding exts */
> -	int		ext_diff)	/* number of extents to add */
> -{
> -	int		byte_diff;	/* new bytes being added */
> -	int		new_size;	/* size of extents after adding */
> -	xfs_extnum_t	nextents;	/* number of extents in file */
> -
> -	nextents = xfs_iext_count(ifp);
> -	ASSERT((idx >= 0) && (idx <= nextents));
> -	byte_diff = ext_diff * sizeof(xfs_bmbt_rec_t);
> -	new_size = ifp->if_bytes + byte_diff;
> -
> -	/*
> -	 * Use a linear (direct) extent list.
> -	 * If the extents are currently inside the inode,
> -	 * xfs_iext_realloc_direct will switch us from
> -	 * inline to direct extent allocation mode.
> -	 */
> -	if (nextents + ext_diff <= XFS_LINEAR_EXTS) {
> -		xfs_iext_realloc_direct(ifp, new_size);
> -		if (idx < nextents) {
> -			memmove(&ifp->if_u1.if_extents[idx + ext_diff],
> -				&ifp->if_u1.if_extents[idx],
> -				(nextents - idx) * sizeof(xfs_bmbt_rec_t));
> -			memset(&ifp->if_u1.if_extents[idx], 0, byte_diff);
> -		}
> -	}
> -	/* Indirection array */
> -	else {
> -		xfs_ext_irec_t	*erp;
> -		int		erp_idx = 0;
> -		int		page_idx = idx;
> -
> -		ASSERT(nextents + ext_diff > XFS_LINEAR_EXTS);
> -		if (ifp->if_flags & XFS_IFEXTIREC) {
> -			erp = xfs_iext_idx_to_irec(ifp, &page_idx, &erp_idx, 1);
> -		} else {
> -			xfs_iext_irec_init(ifp);
> -			ASSERT(ifp->if_flags & XFS_IFEXTIREC);
> -			erp = ifp->if_u1.if_ext_irec;
> -		}
> -		/* Extents fit in target extent page */
> -		if (erp && erp->er_extcount + ext_diff <= XFS_LINEAR_EXTS) {
> -			if (page_idx < erp->er_extcount) {
> -				memmove(&erp->er_extbuf[page_idx + ext_diff],
> -					&erp->er_extbuf[page_idx],
> -					(erp->er_extcount - page_idx) *
> -					sizeof(xfs_bmbt_rec_t));
> -				memset(&erp->er_extbuf[page_idx], 0, byte_diff);
> -			}
> -			erp->er_extcount += ext_diff;
> -			xfs_iext_irec_update_extoffs(ifp, erp_idx + 1, ext_diff);
> -		}
> -		/* Insert a new extent page */
> -		else if (erp) {
> -			xfs_iext_add_indirect_multi(ifp,
> -				erp_idx, page_idx, ext_diff);
> -		}
> -		/*
> -		 * If extent(s) are being appended to the last page in
> -		 * the indirection array and the new extent(s) don't fit
> -		 * in the page, then erp is NULL and erp_idx is set to
> -		 * the next index needed in the indirection array.
> -		 */
> -		else {
> -			uint	count = ext_diff;
> -
> -			while (count) {
> -				erp = xfs_iext_irec_new(ifp, erp_idx);
> -				erp->er_extcount = min(count, XFS_LINEAR_EXTS);
> -				count -= erp->er_extcount;
> -				if (count)
> -					erp_idx++;
> -			}
> -		}
> -	}
> -	ifp->if_bytes = new_size;
> -}
> -
> -/*
> - * This is called when incore extents are being added to the indirection
> - * array and the new extents do not fit in the target extent list. The
> - * erp_idx parameter contains the irec index for the target extent list
> - * in the indirection array, and the idx parameter contains the extent
> - * index within the list. The number of extents being added is stored
> - * in the count parameter.
> - *
> - *    |-------|   |-------|
> - *    |       |   |       |    idx - number of extents before idx
> - *    |  idx  |   | count |
> - *    |       |   |       |    count - number of extents being inserted at idx
> - *    |-------|   |-------|
> - *    | count |   | nex2  |    nex2 - number of extents after idx + count
> - *    |-------|   |-------|
> - */
> -void
> -xfs_iext_add_indirect_multi(
> -	xfs_ifork_t	*ifp,			/* inode fork pointer */
> -	int		erp_idx,		/* target extent irec index */
> -	xfs_extnum_t	idx,			/* index within target list */
> -	int		count)			/* new extents being added */
> -{
> -	int		byte_diff;		/* new bytes being added */
> -	xfs_ext_irec_t	*erp;			/* pointer to irec entry */
> -	xfs_extnum_t	ext_diff;		/* number of extents to add */
> -	xfs_extnum_t	ext_cnt;		/* new extents still needed */
> -	xfs_extnum_t	nex2;			/* extents after idx + count */
> -	xfs_bmbt_rec_t	*nex2_ep = NULL;	/* temp list for nex2 extents */
> -	int		nlists;			/* number of irec's (lists) */
> -
> -	ASSERT(ifp->if_flags & XFS_IFEXTIREC);
> -	erp = &ifp->if_u1.if_ext_irec[erp_idx];
> -	nex2 = erp->er_extcount - idx;
> -	nlists = ifp->if_real_bytes / XFS_IEXT_BUFSZ;
> -
> -	/*
> -	 * Save second part of target extent list
> -	 * (all extents past */
> -	if (nex2) {
> -		byte_diff = nex2 * sizeof(xfs_bmbt_rec_t);
> -		nex2_ep = (xfs_bmbt_rec_t *) kmem_alloc(byte_diff, KM_NOFS);
> -		memmove(nex2_ep, &erp->er_extbuf[idx], byte_diff);
> -		erp->er_extcount -= nex2;
> -		xfs_iext_irec_update_extoffs(ifp, erp_idx + 1, -nex2);
> -		memset(&erp->er_extbuf[idx], 0, byte_diff);
> -	}
> -
> -	/*
> -	 * Add the new extents to the end of the target
> -	 * list, then allocate new irec record(s) and
> -	 * extent buffer(s) as needed to store the rest
> -	 * of the new extents.
> -	 */
> -	ext_cnt = count;
> -	ext_diff = MIN(ext_cnt, (int)XFS_LINEAR_EXTS - erp->er_extcount);
> -	if (ext_diff) {
> -		erp->er_extcount += ext_diff;
> -		xfs_iext_irec_update_extoffs(ifp, erp_idx + 1, ext_diff);
> -		ext_cnt -= ext_diff;
> -	}
> -	while (ext_cnt) {
> -		erp_idx++;
> -		erp = xfs_iext_irec_new(ifp, erp_idx);
> -		ext_diff = MIN(ext_cnt, (int)XFS_LINEAR_EXTS);
> -		erp->er_extcount = ext_diff;
> -		xfs_iext_irec_update_extoffs(ifp, erp_idx + 1, ext_diff);
> -		ext_cnt -= ext_diff;
> -	}
> -
> -	/* Add nex2 extents back to indirection array */
> -	if (nex2) {
> -		xfs_extnum_t	ext_avail;
> -		int		i;
> -
> -		byte_diff = nex2 * sizeof(xfs_bmbt_rec_t);
> -		ext_avail = XFS_LINEAR_EXTS - erp->er_extcount;
> -		i = 0;
> -		/*
> -		 * If nex2 extents fit in the current page, append
> -		 * nex2_ep after the new extents.
> -		 */
> -		if (nex2 <= ext_avail) {
> -			i = erp->er_extcount;
> -		}
> -		/*
> -		 * Otherwise, check if space is available in the
> -		 * next page.
> -		 */
> -		else if ((erp_idx < nlists - 1) &&
> -			 (nex2 <= (ext_avail = XFS_LINEAR_EXTS -
> -			  ifp->if_u1.if_ext_irec[erp_idx+1].er_extcount))) {
> -			erp_idx++;
> -			erp++;
> -			/* Create a hole for nex2 extents */
> -			memmove(&erp->er_extbuf[nex2], erp->er_extbuf,
> -				erp->er_extcount * sizeof(xfs_bmbt_rec_t));
> -		}
> -		/*
> -		 * Final choice, create a new extent page for
> -		 * nex2 extents.
> -		 */
> -		else {
> -			erp_idx++;
> -			erp = xfs_iext_irec_new(ifp, erp_idx);
> -		}
> -		memmove(&erp->er_extbuf[i], nex2_ep, byte_diff);
> -		kmem_free(nex2_ep);
> -		erp->er_extcount += nex2;
> -		xfs_iext_irec_update_extoffs(ifp, erp_idx + 1, nex2);
> -	}
> -}
> -
> -/*
> - * This is called when the amount of space required for incore file
> - * extents needs to be decreased. The ext_diff parameter stores the
> - * number of extents to be removed and the idx parameter contains
> - * the extent index where the extents will be removed from.
> - *
> - * If the amount of space needed has decreased below the linear
> - * limit, XFS_IEXT_BUFSZ, then switch to using the contiguous
> - * extent array.  Otherwise, use kmem_realloc() to adjust the
> - * size to what is needed.
> - */
> -void
> -xfs_iext_remove(
> -	xfs_inode_t	*ip,		/* incore inode pointer */
> -	struct xfs_iext_cursor *cur,
> -	int		ext_diff,	/* number of extents to remove */
> -	int		state)		/* type of extent conversion */
> -{
> -	xfs_ifork_t	*ifp = xfs_iext_state_to_fork(ip, state);
> -	xfs_extnum_t	nextents;	/* number of extents in file */
> -	int		new_size;	/* size of extents after removal */
> -
> -	trace_xfs_iext_remove(ip, cur, state, _RET_IP_);
> -
> -	ASSERT(ext_diff > 0);
> -	nextents = xfs_iext_count(ifp);
> -	new_size = (nextents - ext_diff) * sizeof(xfs_bmbt_rec_t);
> -
> -	if (new_size == 0) {
> -		xfs_iext_destroy(ifp);
> -	} else if (ifp->if_flags & XFS_IFEXTIREC) {
> -		xfs_iext_remove_indirect(ifp, cur->idx, ext_diff);
> -	} else if (ifp->if_real_bytes) {
> -		xfs_iext_remove_direct(ifp, cur->idx, ext_diff);
> -	}
> -	ifp->if_bytes = new_size;
> -}
> -
> -/*
> - * This removes ext_diff extents from a linear (direct) extent list,
> - * beginning at extent index idx. If the extents are being removed
> - * from the end of the list (ie. truncate) then we just need to re-
> - * allocate the list to remove the extra space. Otherwise, if the
> - * extents are being removed from the middle of the existing extent
> - * entries, then we first need to move the extent records beginning
> - * at idx + ext_diff up in the list to overwrite the records being
> - * removed, then remove the extra space via kmem_realloc.
> - */
> -void
> -xfs_iext_remove_direct(
> -	xfs_ifork_t	*ifp,		/* inode fork pointer */
> -	xfs_extnum_t	idx,		/* index to begin removing exts */
> -	int		ext_diff)	/* number of extents to remove */
> -{
> -	xfs_extnum_t	nextents;	/* number of extents in file */
> -	int		new_size;	/* size of extents after removal */
> -
> -	ASSERT(!(ifp->if_flags & XFS_IFEXTIREC));
> -	new_size = ifp->if_bytes -
> -		(ext_diff * sizeof(xfs_bmbt_rec_t));
> -	nextents = xfs_iext_count(ifp);
> -
> -	if (new_size == 0) {
> -		xfs_iext_destroy(ifp);
> -		return;
> -	}
> -	/* Move extents up in the list (if needed) */
> -	if (idx + ext_diff < nextents) {
> -		memmove(&ifp->if_u1.if_extents[idx],
> -			&ifp->if_u1.if_extents[idx + ext_diff],
> -			(nextents - (idx + ext_diff)) *
> -			 sizeof(xfs_bmbt_rec_t));
> -	}
> -	memset(&ifp->if_u1.if_extents[nextents - ext_diff],
> -		0, ext_diff * sizeof(xfs_bmbt_rec_t));
> -	/*
> -	 * Reallocate the direct extent list. If the extents
> -	 * will fit inside the inode then xfs_iext_realloc_direct
> -	 * will switch from direct to inline extent allocation
> -	 * mode for us.
> -	 */
> -	xfs_iext_realloc_direct(ifp, new_size);
> -	ifp->if_bytes = new_size;
> -}
> -
> -/*
> - * This is called when incore extents are being removed from the
> - * indirection array and the extents being removed span multiple extent
> - * buffers. The idx parameter contains the file extent index where we
> - * want to begin removing extents, and the count parameter contains
> - * how many extents need to be removed.
> - *
> - *    |-------|   |-------|
> - *    | nex1  |   |       |    nex1 - number of extents before idx
> - *    |-------|   | count |
> - *    |       |   |       |    count - number of extents being removed at idx
> - *    | count |   |-------|
> - *    |       |   | nex2  |    nex2 - number of extents after idx + count
> - *    |-------|   |-------|
> - */
> -void
> -xfs_iext_remove_indirect(
> -	xfs_ifork_t	*ifp,		/* inode fork pointer */
> -	xfs_extnum_t	idx,		/* index to begin removing extents */
> -	int		count)		/* number of extents to remove */
> -{
> -	xfs_ext_irec_t	*erp;		/* indirection array pointer */
> -	int		erp_idx = 0;	/* indirection array index */
> -	xfs_extnum_t	ext_cnt;	/* extents left to remove */
> -	xfs_extnum_t	ext_diff;	/* extents to remove in current list */
> -	xfs_extnum_t	nex1;		/* number of extents before idx */
> -	xfs_extnum_t	nex2;		/* extents after idx + count */
> -	int		page_idx = idx;	/* index in target extent list */
> -
> -	ASSERT(ifp->if_flags & XFS_IFEXTIREC);
> -	erp = xfs_iext_idx_to_irec(ifp,  &page_idx, &erp_idx, 0);
> -	ASSERT(erp != NULL);
> -	nex1 = page_idx;
> -	ext_cnt = count;
> -	while (ext_cnt) {
> -		nex2 = MAX((erp->er_extcount - (nex1 + ext_cnt)), 0);
> -		ext_diff = MIN(ext_cnt, (erp->er_extcount - nex1));
> -		/*
> -		 * Check for deletion of entire list;
> -		 * xfs_iext_irec_remove() updates extent offsets.
> -		 */
> -		if (ext_diff == erp->er_extcount) {
> -			xfs_iext_irec_remove(ifp, erp_idx);
> -			ext_cnt -= ext_diff;
> -			nex1 = 0;
> -			if (ext_cnt) {
> -				ASSERT(erp_idx < ifp->if_real_bytes /
> -					XFS_IEXT_BUFSZ);
> -				erp = &ifp->if_u1.if_ext_irec[erp_idx];
> -				nex1 = 0;
> -				continue;
> -			} else {
> -				break;
> -			}
> -		}
> -		/* Move extents up (if needed) */
> -		if (nex2) {
> -			memmove(&erp->er_extbuf[nex1],
> -				&erp->er_extbuf[nex1 + ext_diff],
> -				nex2 * sizeof(xfs_bmbt_rec_t));
> -		}
> -		/* Zero out rest of page */
> -		memset(&erp->er_extbuf[nex1 + nex2], 0, (XFS_IEXT_BUFSZ -
> -			((nex1 + nex2) * sizeof(xfs_bmbt_rec_t))));
> -		/* Update remaining counters */
> -		erp->er_extcount -= ext_diff;
> -		xfs_iext_irec_update_extoffs(ifp, erp_idx + 1, -ext_diff);
> -		ext_cnt -= ext_diff;
> -		nex1 = 0;
> -		erp_idx++;
> -		erp++;
> -	}
> -	ifp->if_bytes -= count * sizeof(xfs_bmbt_rec_t);
> -	xfs_iext_irec_compact(ifp);
> -}
> -
> -/*
> - * Create, destroy, or resize a linear (direct) block of extents.
> - */
> -void
> -xfs_iext_realloc_direct(
> -	xfs_ifork_t	*ifp,		/* inode fork pointer */
> -	int		new_size)	/* new size of extents after adding */
> -{
> -	int		rnew_size;	/* real new size of extents */
> -
> -	rnew_size = new_size;
> -
> -	ASSERT(!(ifp->if_flags & XFS_IFEXTIREC) ||
> -		((new_size >= 0) && (new_size <= XFS_IEXT_BUFSZ) &&
> -		 (new_size != ifp->if_real_bytes)));
> -
> -	/* Free extent records */
> -	if (new_size == 0) {
> -		xfs_iext_destroy(ifp);
> -	} else {
> -		if (!is_power_of_2(new_size)){
> -			rnew_size = roundup_pow_of_two(new_size);
> -		}
> -		if (rnew_size != ifp->if_real_bytes) {
> -			ifp->if_u1.if_extents =
> -				kmem_realloc(ifp->if_u1.if_extents,
> -						rnew_size, KM_NOFS);
> -		}
> -		if (rnew_size > ifp->if_real_bytes) {
> -			memset(&ifp->if_u1.if_extents[ifp->if_bytes /
> -				(uint)sizeof(xfs_bmbt_rec_t)], 0,
> -				rnew_size - ifp->if_real_bytes);
> -		}
> -	}
> -	ifp->if_real_bytes = rnew_size;
> -	ifp->if_bytes = new_size;
> -}
> -
> -/*
> - * Resize an extent indirection array to new_size bytes.
> - */
> -STATIC void
> -xfs_iext_realloc_indirect(
> -	xfs_ifork_t	*ifp,		/* inode fork pointer */
> -	int		new_size)	/* new indirection array size */
> -{
> -	ASSERT(ifp->if_flags & XFS_IFEXTIREC);
> -	ASSERT(ifp->if_real_bytes);
> -	ASSERT((new_size >= 0) &&
> -	       (new_size != ((ifp->if_real_bytes / XFS_IEXT_BUFSZ) *
> -			     sizeof(xfs_ext_irec_t))));
> -	if (new_size == 0) {
> -		xfs_iext_destroy(ifp);
> -	} else {
> -		ifp->if_u1.if_ext_irec =
> -			kmem_realloc(ifp->if_u1.if_ext_irec, new_size, KM_NOFS);
> -	}
> -}
> -
> -/*
> - * Switch from indirection array to linear (direct) extent allocations.
> - */
> -STATIC void
> -xfs_iext_indirect_to_direct(
> -	 xfs_ifork_t	*ifp)		/* inode fork pointer */
> -{
> -	xfs_bmbt_rec_host_t *ep;	/* extent record pointer */
> -	xfs_extnum_t	nextents;	/* number of extents in file */
> -	int		size;		/* size of file extents */
> -
> -	ASSERT(ifp->if_flags & XFS_IFEXTIREC);
> -	nextents = xfs_iext_count(ifp);
> -	ASSERT(nextents <= XFS_LINEAR_EXTS);
> -	size = nextents * sizeof(xfs_bmbt_rec_t);
> -
> -	xfs_iext_irec_compact_pages(ifp);
> -	ASSERT(ifp->if_real_bytes == XFS_IEXT_BUFSZ);
> -
> -	ep = ifp->if_u1.if_ext_irec->er_extbuf;
> -	kmem_free(ifp->if_u1.if_ext_irec);
> -	ifp->if_flags &= ~XFS_IFEXTIREC;
> -	ifp->if_u1.if_extents = ep;
> -	ifp->if_bytes = size;
> -	if (nextents < XFS_LINEAR_EXTS) {
> -		xfs_iext_realloc_direct(ifp, size);
> -	}
> -}
> -
> -/*
> - * Remove all records from the indirection array.
> - */
> -STATIC void
> -xfs_iext_irec_remove_all(
> -	struct xfs_ifork *ifp)
> -{
> -	int		nlists;
> -	int		i;
> -
> -	ASSERT(ifp->if_flags & XFS_IFEXTIREC);
> -	nlists = ifp->if_real_bytes / XFS_IEXT_BUFSZ;
> -	for (i = 0; i < nlists; i++)
> -		kmem_free(ifp->if_u1.if_ext_irec[i].er_extbuf);
> -	kmem_free(ifp->if_u1.if_ext_irec);
> -	ifp->if_flags &= ~XFS_IFEXTIREC;
> -}
> -
> -/*
> - * Free incore file extents.
> - */
> -void
> -xfs_iext_destroy(
> -	xfs_ifork_t	*ifp)		/* inode fork pointer */
> -{
> -	if (ifp->if_flags & XFS_IFEXTIREC) {
> -		xfs_iext_irec_remove_all(ifp);
> -	} else if (ifp->if_real_bytes) {
> -		kmem_free(ifp->if_u1.if_extents);
> -	}
> -	ifp->if_u1.if_extents = NULL;
> -	ifp->if_real_bytes = 0;
> -	ifp->if_bytes = 0;
> -}
> -
> -/*
> - * Return a pointer to the extent record for file system block bno.
> - */
> -xfs_bmbt_rec_host_t *			/* pointer to found extent record */
> -xfs_iext_bno_to_ext(
> -	xfs_ifork_t	*ifp,		/* inode fork pointer */
> -	xfs_fileoff_t	bno,		/* block number to search for */
> -	xfs_extnum_t	*idxp)		/* index of target extent */
> -{
> -	xfs_bmbt_rec_host_t *base;	/* pointer to first extent */
> -	xfs_filblks_t	blockcount = 0;	/* number of blocks in extent */
> -	xfs_bmbt_rec_host_t *ep = NULL;	/* pointer to target extent */
> -	xfs_ext_irec_t	*erp = NULL;	/* indirection array pointer */
> -	int		high;		/* upper boundary in search */
> -	xfs_extnum_t	idx = 0;	/* index of target extent */
> -	int		low;		/* lower boundary in search */
> -	xfs_extnum_t	nextents;	/* number of file extents */
> -	xfs_fileoff_t	startoff = 0;	/* start offset of extent */
> -
> -	nextents = xfs_iext_count(ifp);
> -	if (nextents == 0) {
> -		*idxp = 0;
> -		return NULL;
> -	}
> -	low = 0;
> -	if (ifp->if_flags & XFS_IFEXTIREC) {
> -		/* Find target extent list */
> -		int	erp_idx = 0;
> -		erp = xfs_iext_bno_to_irec(ifp, bno, &erp_idx);
> -		base = erp->er_extbuf;
> -		high = erp->er_extcount - 1;
> -	} else {
> -		base = ifp->if_u1.if_extents;
> -		high = nextents - 1;
> -	}
> -	/* Binary search extent records */
> -	while (low <= high) {
> -		idx = (low + high) >> 1;
> -		ep = base + idx;
> -		startoff = xfs_bmbt_get_startoff(ep);
> -		blockcount = xfs_bmbt_get_blockcount(ep);
> -		if (bno < startoff) {
> -			high = idx - 1;
> -		} else if (bno >= startoff + blockcount) {
> -			low = idx + 1;
> -		} else {
> -			/* Convert back to file-based extent index */
> -			if (ifp->if_flags & XFS_IFEXTIREC) {
> -				idx += erp->er_extoff;
> -			}
> -			*idxp = idx;
> -			return ep;
> -		}
> -	}
> -	/* Convert back to file-based extent index */
> -	if (ifp->if_flags & XFS_IFEXTIREC) {
> -		idx += erp->er_extoff;
> -	}
> -	if (bno >= startoff + blockcount) {
> -		if (++idx == nextents) {
> -			ep = NULL;
> -		} else {
> -			ep = xfs_iext_get_ext(ifp, idx);
> -		}
> -	}
> -	*idxp = idx;
> -	return ep;
> -}
> -
> -/*
> - * Return a pointer to the indirection array entry containing the
> - * extent record for filesystem block bno. Store the index of the
> - * target irec in *erp_idxp.
> - */
> -xfs_ext_irec_t *			/* pointer to found extent record */
> -xfs_iext_bno_to_irec(
> -	xfs_ifork_t	*ifp,		/* inode fork pointer */
> -	xfs_fileoff_t	bno,		/* block number to search for */
> -	int		*erp_idxp)	/* irec index of target ext list */
> -{
> -	xfs_ext_irec_t	*erp = NULL;	/* indirection array pointer */
> -	xfs_ext_irec_t	*erp_next;	/* next indirection array entry */
> -	int		erp_idx;	/* indirection array index */
> -	int		nlists;		/* number of extent irec's (lists) */
> -	int		high;		/* binary search upper limit */
> -	int		low;		/* binary search lower limit */
> -
> -	ASSERT(ifp->if_flags & XFS_IFEXTIREC);
> -	nlists = ifp->if_real_bytes / XFS_IEXT_BUFSZ;
> -	erp_idx = 0;
> -	low = 0;
> -	high = nlists - 1;
> -	while (low <= high) {
> -		erp_idx = (low + high) >> 1;
> -		erp = &ifp->if_u1.if_ext_irec[erp_idx];
> -		erp_next = erp_idx < nlists - 1 ? erp + 1 : NULL;
> -		if (bno < xfs_bmbt_get_startoff(erp->er_extbuf)) {
> -			high = erp_idx - 1;
> -		} else if (erp_next && bno >=
> -			   xfs_bmbt_get_startoff(erp_next->er_extbuf)) {
> -			low = erp_idx + 1;
> -		} else {
> -			break;
> -		}
> -	}
> -	*erp_idxp = erp_idx;
> -	return erp;
> -}
> -
> -/*
> - * Return a pointer to the indirection array entry containing the
> - * extent record at file extent index *idxp. Store the index of the
> - * target irec in *erp_idxp and store the page index of the target
> - * extent record in *idxp.
> - */
> -xfs_ext_irec_t *
> -xfs_iext_idx_to_irec(
> -	xfs_ifork_t	*ifp,		/* inode fork pointer */
> -	xfs_extnum_t	*idxp,		/* extent index (file -> page) */
> -	int		*erp_idxp,	/* pointer to target irec */
> -	int		realloc)	/* new bytes were just added */
> -{
> -	xfs_ext_irec_t	*prev;		/* pointer to previous irec */
> -	xfs_ext_irec_t	*erp = NULL;	/* pointer to current irec */
> -	int		erp_idx;	/* indirection array index */
> -	int		nlists;		/* number of irec's (ex lists) */
> -	int		high;		/* binary search upper limit */
> -	int		low;		/* binary search lower limit */
> -	xfs_extnum_t	page_idx = *idxp; /* extent index in target list */
> -
> -	ASSERT(ifp->if_flags & XFS_IFEXTIREC);
> -	ASSERT(page_idx >= 0);
> -	ASSERT(page_idx <= xfs_iext_count(ifp));
> -	ASSERT(page_idx < xfs_iext_count(ifp) || realloc);
> -
> -	nlists = ifp->if_real_bytes / XFS_IEXT_BUFSZ;
> -	erp_idx = 0;
> -	low = 0;
> -	high = nlists - 1;
> -
> -	/* Binary search extent irec's */
> -	while (low <= high) {
> -		erp_idx = (low + high) >> 1;
> -		erp = &ifp->if_u1.if_ext_irec[erp_idx];
> -		prev = erp_idx > 0 ? erp - 1 : NULL;
> -		if (page_idx < erp->er_extoff || (page_idx == erp->er_extoff &&
> -		     realloc && prev && prev->er_extcount < XFS_LINEAR_EXTS)) {
> -			high = erp_idx - 1;
> -		} else if (page_idx > erp->er_extoff + erp->er_extcount ||
> -			   (page_idx == erp->er_extoff + erp->er_extcount &&
> -			    !realloc)) {
> -			low = erp_idx + 1;
> -		} else if (page_idx == erp->er_extoff + erp->er_extcount &&
> -			   erp->er_extcount == XFS_LINEAR_EXTS) {
> -			ASSERT(realloc);
> -			page_idx = 0;
> -			erp_idx++;
> -			erp = erp_idx < nlists ? erp + 1 : NULL;
> -			break;
> -		} else {
> -			page_idx -= erp->er_extoff;
> -			break;
> -		}
> -	}
> -	*idxp = page_idx;
> -	*erp_idxp = erp_idx;
> -	return erp;
> -}
> -
> -/*
> - * Allocate and initialize an indirection array once the space needed
> - * for incore extents increases above XFS_IEXT_BUFSZ.
> - */
> -void
> -xfs_iext_irec_init(
> -	xfs_ifork_t	*ifp)		/* inode fork pointer */
> -{
> -	xfs_ext_irec_t	*erp;		/* indirection array pointer */
> -	xfs_extnum_t	nextents;	/* number of extents in file */
> -
> -	ASSERT(!(ifp->if_flags & XFS_IFEXTIREC));
> -	nextents = xfs_iext_count(ifp);
> -	ASSERT(nextents <= XFS_LINEAR_EXTS);
> -
> -	erp = kmem_alloc(sizeof(xfs_ext_irec_t), KM_NOFS);
> -
> -	if (nextents == 0) {
> -		ifp->if_u1.if_extents = kmem_alloc(XFS_IEXT_BUFSZ, KM_NOFS);
> -	} else if (ifp->if_real_bytes < XFS_IEXT_BUFSZ) {
> -		xfs_iext_realloc_direct(ifp, XFS_IEXT_BUFSZ);
> -	}
> -	erp->er_extbuf = ifp->if_u1.if_extents;
> -	erp->er_extcount = nextents;
> -	erp->er_extoff = 0;
> -
> -	ifp->if_flags |= XFS_IFEXTIREC;
> -	ifp->if_real_bytes = XFS_IEXT_BUFSZ;
> -	ifp->if_bytes = nextents * sizeof(xfs_bmbt_rec_t);
> -	ifp->if_u1.if_ext_irec = erp;
> -
> -	return;
> -}
> -
> -/*
> - * Allocate and initialize a new entry in the indirection array.
> - */
> -xfs_ext_irec_t *
> -xfs_iext_irec_new(
> -	xfs_ifork_t	*ifp,		/* inode fork pointer */
> -	int		erp_idx)	/* index for new irec */
> -{
> -	xfs_ext_irec_t	*erp;		/* indirection array pointer */
> -	int		i;		/* loop counter */
> -	int		nlists;		/* number of irec's (ex lists) */
> -
> -	ASSERT(ifp->if_flags & XFS_IFEXTIREC);
> -	nlists = ifp->if_real_bytes / XFS_IEXT_BUFSZ;
> -
> -	/* Resize indirection array */
> -	xfs_iext_realloc_indirect(ifp, ++nlists *
> -				  sizeof(xfs_ext_irec_t));
> -	/*
> -	 * Move records down in the array so the
> -	 * new page can use erp_idx.
> -	 */
> -	erp = ifp->if_u1.if_ext_irec;
> -	for (i = nlists - 1; i > erp_idx; i--) {
> -		memmove(&erp[i], &erp[i-1], sizeof(xfs_ext_irec_t));
> -	}
> -	ASSERT(i == erp_idx);
> -
> -	/* Initialize new extent record */
> -	erp = ifp->if_u1.if_ext_irec;
> -	erp[erp_idx].er_extbuf = kmem_alloc(XFS_IEXT_BUFSZ, KM_NOFS);
> -	ifp->if_real_bytes = nlists * XFS_IEXT_BUFSZ;
> -	memset(erp[erp_idx].er_extbuf, 0, XFS_IEXT_BUFSZ);
> -	erp[erp_idx].er_extcount = 0;
> -	erp[erp_idx].er_extoff = erp_idx > 0 ?
> -		erp[erp_idx-1].er_extoff + erp[erp_idx-1].er_extcount : 0;
> -	return (&erp[erp_idx]);
> -}
> -
> -/*
> - * Remove a record from the indirection array.
> - */
> -void
> -xfs_iext_irec_remove(
> -	xfs_ifork_t	*ifp,		/* inode fork pointer */
> -	int		erp_idx)	/* irec index to remove */
> -{
> -	xfs_ext_irec_t	*erp;		/* indirection array pointer */
> -	int		i;		/* loop counter */
> -	int		nlists;		/* number of irec's (ex lists) */
> -
> -	ASSERT(ifp->if_flags & XFS_IFEXTIREC);
> -	nlists = ifp->if_real_bytes / XFS_IEXT_BUFSZ;
> -	erp = &ifp->if_u1.if_ext_irec[erp_idx];
> -	if (erp->er_extbuf) {
> -		xfs_iext_irec_update_extoffs(ifp, erp_idx + 1,
> -			-erp->er_extcount);
> -		kmem_free(erp->er_extbuf);
> -	}
> -	/* Compact extent records */
> -	erp = ifp->if_u1.if_ext_irec;
> -	for (i = erp_idx; i < nlists - 1; i++) {
> -		memmove(&erp[i], &erp[i+1], sizeof(xfs_ext_irec_t));
> -	}
> -	/*
> -	 * Manually free the last extent record from the indirection
> -	 * array.  A call to xfs_iext_realloc_indirect() with a size
> -	 * of zero would result in a call to xfs_iext_destroy() which
> -	 * would in turn call this function again, creating a nasty
> -	 * infinite loop.
> -	 */
> -	if (--nlists) {
> -		xfs_iext_realloc_indirect(ifp,
> -			nlists * sizeof(xfs_ext_irec_t));
> -	} else {
> -		kmem_free(ifp->if_u1.if_ext_irec);
> -	}
> -	ifp->if_real_bytes = nlists * XFS_IEXT_BUFSZ;
> -}
> -
> -/*
> - * This is called to clean up large amounts of unused memory allocated
> - * by the indirection array.  Before compacting anything though, verify
> - * that the indirection array is still needed and switch back to the
> - * linear extent list (or even the inline buffer) if possible.  The
> - * compaction policy is as follows:
> - *
> - *    Full Compaction: Extents fit into a single page (or inline buffer)
> - * Partial Compaction: Extents occupy less than 50% of allocated space
> - *      No Compaction: Extents occupy at least 50% of allocated space
> - */
> -void
> -xfs_iext_irec_compact(
> -	xfs_ifork_t	*ifp)		/* inode fork pointer */
> -{
> -	xfs_extnum_t	nextents;	/* number of extents in file */
> -	int		nlists;		/* number of irec's (ex lists) */
> -
> -	ASSERT(ifp->if_flags & XFS_IFEXTIREC);
> -	nlists = ifp->if_real_bytes / XFS_IEXT_BUFSZ;
> -	nextents = xfs_iext_count(ifp);
> -
> -	if (nextents == 0) {
> -		xfs_iext_destroy(ifp);
> -	} else if (nextents <= XFS_LINEAR_EXTS) {
> -		xfs_iext_indirect_to_direct(ifp);
> -	} else if (nextents < (nlists * XFS_LINEAR_EXTS) >> 1) {
> -		xfs_iext_irec_compact_pages(ifp);
> -	}
> -}
> -
> -/*
> - * Combine extents from neighboring extent pages.
> - */
> -void
> -xfs_iext_irec_compact_pages(
> -	xfs_ifork_t	*ifp)		/* inode fork pointer */
> -{
> -	xfs_ext_irec_t	*erp, *erp_next;/* pointers to irec entries */
> -	int		erp_idx = 0;	/* indirection array index */
> -	int		nlists;		/* number of irec's (ex lists) */
> -
> -	ASSERT(ifp->if_flags & XFS_IFEXTIREC);
> -	nlists = ifp->if_real_bytes / XFS_IEXT_BUFSZ;
> -	while (erp_idx < nlists - 1) {
> -		erp = &ifp->if_u1.if_ext_irec[erp_idx];
> -		erp_next = erp + 1;
> -		if (erp_next->er_extcount <=
> -		    (XFS_LINEAR_EXTS - erp->er_extcount)) {
> -			memcpy(&erp->er_extbuf[erp->er_extcount],
> -				erp_next->er_extbuf, erp_next->er_extcount *
> -				sizeof(xfs_bmbt_rec_t));
> -			erp->er_extcount += erp_next->er_extcount;
> -			/*
> -			 * Free page before removing extent record
> -			 * so er_extoffs don't get modified in
> -			 * xfs_iext_irec_remove.
> -			 */
> -			kmem_free(erp_next->er_extbuf);
> -			erp_next->er_extbuf = NULL;
> -			xfs_iext_irec_remove(ifp, erp_idx + 1);
> -			nlists = ifp->if_real_bytes / XFS_IEXT_BUFSZ;
> -		} else {
> -			erp_idx++;
> -		}
> -	}
> -}
> -
> -/*
> - * This is called to update the er_extoff field in the indirection
> - * array when extents have been added or removed from one of the
> - * extent lists. erp_idx contains the irec index to begin updating
> - * at and ext_diff contains the number of extents that were added
> - * or removed.
> - */
> -void
> -xfs_iext_irec_update_extoffs(
> -	xfs_ifork_t	*ifp,		/* inode fork pointer */
> -	int		erp_idx,	/* irec index to update */
> -	int		ext_diff)	/* number of new extents */
> -{
> -	int		i;		/* loop counter */
> -	int		nlists;		/* number of irec's (ex lists */
> -
> -	ASSERT(ifp->if_flags & XFS_IFEXTIREC);
> -	nlists = ifp->if_real_bytes / XFS_IEXT_BUFSZ;
> -	for (i = erp_idx; i < nlists; i++) {
> -		ifp->if_u1.if_ext_irec[i].er_extoff += ext_diff;
> -	}
> -}
> -
>  /*
>   * Initialize an inode's copy-on-write fork.
>   */
> @@ -1756,87 +831,3 @@ xfs_ifork_init_cow(
>  	ip->i_cformat = XFS_DINODE_FMT_EXTENTS;
>  	ip->i_cnextents = 0;
>  }
> -
> -/*
> - * Lookup the extent covering bno.
> - *
> - * If there is an extent covering bno return the extent index, and store the
> - * expanded extent structure in *gotp, and the extent cursor in *cur.
> - * If there is no extent covering bno, but there is an extent after it (e.g.
> - * it lies in a hole) return that extent in *gotp and its cursor in *cur
> - * instead.
> - * If bno is beyond the last extent return false, and return an invalid
> - * cursor value.
> - */
> -bool
> -xfs_iext_lookup_extent(
> -	struct xfs_inode	*ip,
> -	struct xfs_ifork	*ifp,
> -	xfs_fileoff_t		bno,
> -	struct xfs_iext_cursor	*cur,
> -	struct xfs_bmbt_irec	*gotp)
> -{
> -	struct xfs_bmbt_rec_host *ep;
> -
> -	XFS_STATS_INC(ip->i_mount, xs_look_exlist);
> -
> -	ep = xfs_iext_bno_to_ext(ifp, bno, &cur->idx);
> -	if (!ep)
> -		return false;
> -	xfs_bmbt_get_all(ep, gotp);
> -	return true;
> -}
> -
> -/*
> - * Returns the last extent before end, and if this extent doesn't cover
> - * end, update end to the end of the extent.
> - */
> -bool
> -xfs_iext_lookup_extent_before(
> -	struct xfs_inode	*ip,
> -	struct xfs_ifork	*ifp,
> -	xfs_fileoff_t		*end,
> -	struct xfs_iext_cursor	*cur,
> -	struct xfs_bmbt_irec	*gotp)
> -{
> -	if (xfs_iext_lookup_extent(ip, ifp, *end - 1, cur, gotp) &&
> -	    gotp->br_startoff <= *end - 1)
> -		return true;
> -	if (!xfs_iext_prev_extent(ifp, cur, gotp))
> -		return false;
> -	*end = gotp->br_startoff + gotp->br_blockcount;
> -	return true;
> -}
> -
> -/*
> - * Return true if the cursor points at an extent and return the extent structure
> - * in gotp.  Else return false.
> - */
> -bool
> -xfs_iext_get_extent(
> -	struct xfs_ifork	*ifp,
> -	struct xfs_iext_cursor	*cur,
> -	struct xfs_bmbt_irec	*gotp)
> -{
> -	if (cur->idx < 0 || cur->idx >= xfs_iext_count(ifp))
> -		return false;
> -	xfs_bmbt_get_all(xfs_iext_get_ext(ifp, cur->idx), gotp);
> -	return true;
> -}
> -
> -void
> -xfs_iext_update_extent(
> -	struct xfs_inode	*ip,
> -	int			state,
> -	struct xfs_iext_cursor	*cur,
> -	struct xfs_bmbt_irec	*gotp)
> -{
> -	struct xfs_ifork	*ifp = xfs_iext_state_to_fork(ip, state);
> -
> -	ASSERT(cur->idx >= 0);
> -	ASSERT(cur->idx < xfs_iext_count(ifp));
> -
> -	trace_xfs_bmap_pre_update(ip, cur, state, _RET_IP_);
> -	xfs_bmbt_set_all(xfs_iext_get_ext(ifp, cur->idx), gotp);
> -	trace_xfs_bmap_post_update(ip, cur, state, _RET_IP_);
> -}
> diff --git a/fs/xfs/libxfs/xfs_inode_fork.h b/fs/xfs/libxfs/xfs_inode_fork.h
> index cc7ca255ec98..7fda248e32ab 100644
> --- a/fs/xfs/libxfs/xfs_inode_fork.h
> +++ b/fs/xfs/libxfs/xfs_inode_fork.h
> @@ -21,45 +21,18 @@
>  struct xfs_inode_log_item;
>  struct xfs_dinode;
>  
> -/*
> - * The following xfs_ext_irec_t struct introduces a second (top) level
> - * to the in-core extent allocation scheme. These structs are allocated
> - * in a contiguous block, creating an indirection array where each entry
> - * (irec) contains a pointer to a buffer of in-core extent records which
> - * it manages. Each extent buffer is 4k in size, since 4k is the system
> - * page size on Linux i386 and systems with larger page sizes don't seem
> - * to gain much, if anything, by using their native page size as the
> - * extent buffer size. Also, using 4k extent buffers everywhere provides
> - * a consistent interface for CXFS across different platforms.
> - *
> - * There is currently no limit on the number of irec's (extent lists)
> - * allowed, so heavily fragmented files may require an indirection array
> - * which spans multiple system pages of memory. The number of extents
> - * which would require this amount of contiguous memory is very large
> - * and should not cause problems in the foreseeable future. However,
> - * if the memory needed for the contiguous array ever becomes a problem,
> - * it is possible that a third level of indirection may be required.
> - */
> -typedef struct xfs_ext_irec {
> -	xfs_bmbt_rec_host_t *er_extbuf;	/* block of extent records */
> -	xfs_extnum_t	er_extoff;	/* extent offset in file */
> -	xfs_extnum_t	er_extcount;	/* number of extents in page/block */
> -} xfs_ext_irec_t;
> -
>  /*
>   * File incore extent information, present for each of data & attr forks.
>   */
> -#define	XFS_IEXT_BUFSZ		4096
> -#define	XFS_LINEAR_EXTS		(XFS_IEXT_BUFSZ / (uint)sizeof(xfs_bmbt_rec_t))
>  typedef struct xfs_ifork {
>  	int			if_bytes;	/* bytes in if_u1 */
>  	int			if_real_bytes;	/* bytes allocated in if_u1 */
>  	struct xfs_btree_block	*if_broot;	/* file's incore btree root */
>  	short			if_broot_bytes;	/* bytes allocated for root */
>  	unsigned char		if_flags;	/* per-fork flags */
> +	int			if_height;	/* height of the extent tree */
>  	union {
> -		xfs_bmbt_rec_host_t *if_extents;/* linear map file exts */
> -		xfs_ext_irec_t	*if_ext_irec;	/* irec map file exts */
> +		void		*if_root;	/* extent tree root */
>  		char		*if_data;	/* inline file data */
>  	} if_u1;
>  } xfs_ifork_t;
> @@ -70,7 +43,6 @@ typedef struct xfs_ifork {
>  #define	XFS_IFINLINE	0x01	/* Inline data is read in */
>  #define	XFS_IFEXTENTS	0x02	/* All extent pointers are read in */
>  #define	XFS_IFBROOT	0x04	/* i_broot points to the bmap b-tree root */
> -#define	XFS_IFEXTIREC	0x08	/* Indirection array of extent blocks */
>  
>  /*
>   * Fork handling.
> @@ -140,35 +112,12 @@ int		xfs_iextents_copy(struct xfs_inode *, struct xfs_bmbt_rec *,
>  				  int);
>  void		xfs_init_local_fork(struct xfs_inode *, int, const void *, int);
>  
> -struct xfs_bmbt_rec_host *
> -		xfs_iext_get_ext(struct xfs_ifork *, xfs_extnum_t);
> -xfs_extnum_t	xfs_iext_count(struct xfs_ifork *);
> +xfs_extnum_t	xfs_iext_count(struct xfs_ifork *ifp);
>  void		xfs_iext_insert(struct xfs_inode *, struct xfs_iext_cursor *cur,
>  			xfs_extnum_t, struct xfs_bmbt_irec *, int);
> -void		xfs_iext_add(struct xfs_ifork *, xfs_extnum_t, int);
> -void		xfs_iext_add_indirect_multi(struct xfs_ifork *, int,
> -					    xfs_extnum_t, int);
>  void		xfs_iext_remove(struct xfs_inode *, struct xfs_iext_cursor *,
>  			int, int);
> -void		xfs_iext_remove_direct(struct xfs_ifork *, xfs_extnum_t, int);
> -void		xfs_iext_remove_indirect(struct xfs_ifork *, xfs_extnum_t, int);
> -void		xfs_iext_realloc_direct(struct xfs_ifork *, int);
>  void		xfs_iext_destroy(struct xfs_ifork *);
> -struct xfs_bmbt_rec_host *
> -		xfs_iext_bno_to_ext(struct xfs_ifork *, xfs_fileoff_t, int *);
> -struct xfs_ext_irec *
> -		xfs_iext_bno_to_irec(struct xfs_ifork *, xfs_fileoff_t, int *);
> -struct xfs_ext_irec *
> -		xfs_iext_idx_to_irec(struct xfs_ifork *, xfs_extnum_t *, int *,
> -				     int);
> -void		xfs_iext_irec_init(struct xfs_ifork *);
> -struct xfs_ext_irec *
> -		xfs_iext_irec_new(struct xfs_ifork *, int);
> -void		xfs_iext_irec_remove(struct xfs_ifork *, int);
> -void		xfs_iext_irec_compact(struct xfs_ifork *);
> -void		xfs_iext_irec_compact_pages(struct xfs_ifork *);
> -void		xfs_iext_irec_compact_full(struct xfs_ifork *);
> -void		xfs_iext_irec_update_extoffs(struct xfs_ifork *, int, int);
>  
>  bool		xfs_iext_lookup_extent(struct xfs_inode *ip,
>  			struct xfs_ifork *ifp, xfs_fileoff_t bno,
> @@ -185,29 +134,10 @@ void		xfs_iext_update_extent(struct xfs_inode *ip, int state,
>  			struct xfs_iext_cursor *cur,
>  			struct xfs_bmbt_irec *gotp);
>  
> -static inline void xfs_iext_first(struct xfs_ifork *ifp,
> -		struct xfs_iext_cursor *cur)
> -{
> -	cur->idx = 0;
> -}
> -
> -static inline void xfs_iext_last(struct xfs_ifork *ifp,
> -		struct xfs_iext_cursor *cur)
> -{
> -	cur->idx = xfs_iext_count(ifp) - 1;
> -}
> -
> -static inline void xfs_iext_next(struct xfs_ifork *ifp,
> -		struct xfs_iext_cursor *cur)
> -{
> -	cur->idx++;
> -}
> -
> -static inline void xfs_iext_prev(struct xfs_ifork *ifp,
> -		struct xfs_iext_cursor *cur)
> -{
> -	cur->idx--;
> -}
> +void		xfs_iext_first(struct xfs_ifork *, struct xfs_iext_cursor *);
> +void		xfs_iext_last(struct xfs_ifork *, struct xfs_iext_cursor *);
> +void		xfs_iext_next(struct xfs_ifork *, struct xfs_iext_cursor *);
> +void		xfs_iext_prev(struct xfs_ifork *, struct xfs_iext_cursor *);
>  
>  static inline bool xfs_iext_next_extent(struct xfs_ifork *ifp,
>  		struct xfs_iext_cursor *cur, struct xfs_bmbt_irec *gotp)
> diff --git a/fs/xfs/libxfs/xfs_types.h b/fs/xfs/libxfs/xfs_types.h
> index 5da6382bdaf1..983878019097 100644
> --- a/fs/xfs/libxfs/xfs_types.h
> +++ b/fs/xfs/libxfs/xfs_types.h
> @@ -143,7 +143,8 @@ typedef uint32_t	xfs_dqid_t;
>  #define	XFS_WORDMASK	((1 << XFS_WORDLOG) - 1)
>  
>  struct xfs_iext_cursor {
> -	xfs_extnum_t		idx;
> +	struct xfs_iext_leaf	*leaf;
> +	int			pos;
>  };
>  
>  #endif	/* __XFS_TYPES_H__ */
> diff --git a/fs/xfs/scrub/bmap.c b/fs/xfs/scrub/bmap.c
> index be0bc11b6594..39fb2a537aea 100644
> --- a/fs/xfs/scrub/bmap.c
> +++ b/fs/xfs/scrub/bmap.c
> @@ -168,7 +168,6 @@ xfs_scrub_bmapbt_rec(
>  	struct xfs_scrub_btree		*bs,
>  	union xfs_btree_rec		*rec)
>  {
> -	struct xfs_bmbt_rec_host	ihost;
>  	struct xfs_bmbt_irec		irec;
>  	struct xfs_scrub_bmap_info	*info = bs->private;
>  	struct xfs_inode		*ip = bs->cur->bc_private.b.ip;
> @@ -193,9 +192,7 @@ xfs_scrub_bmapbt_rec(
>  	}
>  
>  	/* Set up the in-core record and scrub it. */
> -	ihost.l0 = be64_to_cpu(rec->bmbt.l0);
> -	ihost.l1 = be64_to_cpu(rec->bmbt.l1);
> -	xfs_bmbt_get_all(&ihost, &irec);
> +	xfs_bmbt_disk_get_all(&rec->bmbt, &irec);
>  	return xfs_scrub_bmap_extent(ip, bs->cur, info, &irec);
>  }
>  
> diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
> index 02497828e993..edd98353fbeb 100644
> --- a/fs/xfs/xfs_inode.c
> +++ b/fs/xfs/xfs_inode.c
> @@ -934,7 +934,7 @@ xfs_ialloc(
>  		ip->i_d.di_format = XFS_DINODE_FMT_EXTENTS;
>  		ip->i_df.if_flags = XFS_IFEXTENTS;
>  		ip->i_df.if_bytes = ip->i_df.if_real_bytes = 0;
> -		ip->i_df.if_u1.if_extents = NULL;
> +		ip->i_df.if_u1.if_root = NULL;
>  		break;
>  	default:
>  		ASSERT(0);
> diff --git a/fs/xfs/xfs_inode_item.c b/fs/xfs/xfs_inode_item.c
> index eb6f4f7c9520..6ee5c3bf19ad 100644
> --- a/fs/xfs/xfs_inode_item.c
> +++ b/fs/xfs/xfs_inode_item.c
> @@ -162,7 +162,6 @@ xfs_inode_item_format_data_fork(
>  		    ip->i_df.if_bytes > 0) {
>  			struct xfs_bmbt_rec *p;
>  
> -			ASSERT(ip->i_df.if_u1.if_extents != NULL);
>  			ASSERT(xfs_iext_count(&ip->i_df) > 0);
>  
>  			p = xlog_prepare_iovec(lv, vecp, XLOG_REG_TYPE_IEXT);
> @@ -252,7 +251,6 @@ xfs_inode_item_format_attr_fork(
>  
>  			ASSERT(xfs_iext_count(ip->i_afp) ==
>  				ip->i_d.di_anextents);
> -			ASSERT(ip->i_afp->if_u1.if_extents != NULL);
>  
>  			p = xlog_prepare_iovec(lv, vecp, XLOG_REG_TYPE_IATTR_EXT);
>  			data_bytes = xfs_iextents_copy(ip, p, XFS_ATTR_FORK);
> diff --git a/fs/xfs/xfs_trace.h b/fs/xfs/xfs_trace.h
> index 667bfce802cd..515ba042d75c 100644
> --- a/fs/xfs/xfs_trace.h
> +++ b/fs/xfs/xfs_trace.h
> @@ -218,45 +218,6 @@ TRACE_EVENT(xfs_attr_list_node_descend,
>  		   __entry->bt_before)
>  );
>  
> -TRACE_EVENT(xfs_iext_insert,
> -	TP_PROTO(struct xfs_inode *ip, xfs_extnum_t idx,
> -		 struct xfs_bmbt_irec *r, int state, unsigned long caller_ip),
> -	TP_ARGS(ip, idx, r, state, caller_ip),
> -	TP_STRUCT__entry(
> -		__field(dev_t, dev)
> -		__field(xfs_ino_t, ino)
> -		__field(xfs_extnum_t, idx)
> -		__field(xfs_fileoff_t, startoff)
> -		__field(xfs_fsblock_t, startblock)
> -		__field(xfs_filblks_t, blockcount)
> -		__field(xfs_exntst_t, state)
> -		__field(int, bmap_state)
> -		__field(unsigned long, caller_ip)
> -	),
> -	TP_fast_assign(
> -		__entry->dev = VFS_I(ip)->i_sb->s_dev;
> -		__entry->ino = ip->i_ino;
> -		__entry->idx = idx;
> -		__entry->startoff = r->br_startoff;
> -		__entry->startblock = r->br_startblock;
> -		__entry->blockcount = r->br_blockcount;
> -		__entry->state = r->br_state;
> -		__entry->bmap_state = state;
> -		__entry->caller_ip = caller_ip;
> -	),
> -	TP_printk("dev %d:%d ino 0x%llx state %s idx %ld "
> -		  "offset %lld block %lld count %lld flag %d caller %ps",
> -		  MAJOR(__entry->dev), MINOR(__entry->dev),
> -		  __entry->ino,
> -		  __print_flags(__entry->bmap_state, "|", XFS_BMAP_EXT_FLAGS),
> -		  (long)__entry->idx,
> -		  __entry->startoff,
> -		  (int64_t)__entry->startblock,
> -		  __entry->blockcount,
> -		  __entry->state,
> -		  (char *)__entry->caller_ip)
> -);
> -
>  DECLARE_EVENT_CLASS(xfs_bmap_class,
>  	TP_PROTO(struct xfs_inode *ip, struct xfs_iext_cursor *cur, int state,
>  		 unsigned long caller_ip),
> @@ -264,7 +225,8 @@ DECLARE_EVENT_CLASS(xfs_bmap_class,
>  	TP_STRUCT__entry(
>  		__field(dev_t, dev)
>  		__field(xfs_ino_t, ino)
> -		__field(xfs_extnum_t, idx)
> +		__field(void *, leaf);
> +		__field(int, pos);
>  		__field(xfs_fileoff_t, startoff)
>  		__field(xfs_fsblock_t, startblock)
>  		__field(xfs_filblks_t, blockcount)
> @@ -280,7 +242,8 @@ DECLARE_EVENT_CLASS(xfs_bmap_class,
>  		xfs_iext_get_extent(ifp, cur, &r);
>  		__entry->dev = VFS_I(ip)->i_sb->s_dev;
>  		__entry->ino = ip->i_ino;
> -		__entry->idx = cur->idx;
> +		__entry->leaf = cur->leaf;
> +		__entry->pos = cur->pos;
>  		__entry->startoff = r.br_startoff;
>  		__entry->startblock = r.br_startblock;
>  		__entry->blockcount = r.br_blockcount;
> @@ -288,12 +251,13 @@ DECLARE_EVENT_CLASS(xfs_bmap_class,
>  		__entry->bmap_state = state;
>  		__entry->caller_ip = caller_ip;
>  	),
> -	TP_printk("dev %d:%d ino 0x%llx state %s idx %ld "
> +	TP_printk("dev %d:%d ino 0x%llx state %s cur 0x%p/%d "
>  		  "offset %lld block %lld count %lld flag %d caller %ps",
>  		  MAJOR(__entry->dev), MINOR(__entry->dev),
>  		  __entry->ino,
>  		  __print_flags(__entry->bmap_state, "|", XFS_BMAP_EXT_FLAGS),
> -		  (long)__entry->idx,
> +		  __entry->leaf,
> +		  __entry->pos,
>  		  __entry->startoff,
>  		  (int64_t)__entry->startblock,
>  		  __entry->blockcount,
> @@ -306,6 +270,7 @@ DEFINE_EVENT(xfs_bmap_class, name, \
>  	TP_PROTO(struct xfs_inode *ip, struct xfs_iext_cursor *cur, int state, \
>  		 unsigned long caller_ip), \
>  	TP_ARGS(ip, cur, state, caller_ip))
> +DEFINE_BMAP_EVENT(xfs_iext_insert);
>  DEFINE_BMAP_EVENT(xfs_iext_remove);
>  DEFINE_BMAP_EVENT(xfs_bmap_pre_update);
>  DEFINE_BMAP_EVENT(xfs_bmap_post_update);
> -- 
> 2.14.2
> 
> --
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Re: [PATCH 17/21] xfs: use a b+tree for the in-core extent list

[Brian Foster]

On Fri, Nov 03, 2017 at 05:45:35PM +0300, Christoph Hellwig wrote:
> Replace the current linear list and the indirection array for the in-core
> extent list with a b+tree to avoid the need for larger memory allocations
> for the indirection array when lots of extents are present.  The current
> extent list implementations leads to heavy pressure on the memory
> allocator when modifying files with a high extent count, and can lead
> to high latencies because of that.
> 
> The replacement is a b+tree with a few quirks.  The leaf nodes directly
> store the extent record in two u64 values.  The encoding is a little bit
> different from the existing in-core extent records so that the start
> offset and length which are required for lookups can be retreived with
> simple mask operations.  The inner nodes store a 64-bit key containing
> the start offset in the first half of the node, and the pointers to the
> next lower level in the second half.  In either case we walk the node
> from the beginninig to the end and do a linear search, as that is more
> efficient for the low number of cache lines touched during a search
> (2 for the inner nodes, 4 for the leaf nodes) than a binary search.
> We store termination markers (zero length for the leaf nodes, an
> otherwise impossible high bit for the inner nodes) to terminate the key
> list / records instead of storing a count to use the available cache
> lines as efficiently as possible.
> 
> One quirk of the algorithm is that while we normally split a node half and
> half like usual btree implementations we just spill over entries added at
> the very end of the list to a new node on its own.  This means we get a
> 100% fill grade for the common cases of bulk inseration at reading an
> inode into memory, and when only sequentially appending to a file.  The
> downside is a slightly higher chance of splits on the first random
> inserations.
> 
> Both insert and removal manually recurse into the lower levels, but
> the bulk deletion of the whole tree is still implemented as a recursive
> function call, although one limited by the overall depth and with very
> little stack usage in every iteration.
> 
> For the first few extents we dynamically grow the list from a single
> extent to the next powers of two until we have a first full leaf block
> and that building the actual tree.
> 
> The code started out based on the generic lib/btree.c code from Joern
> Engel based on earlier work from Peter Zijlstra, but has since been
> rewritten beyond recognition.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---

I notice this was actually already merged. Sorry for being slow, I've
been rather distracted this week. I hadn't got through all of this, but
here's the comments I have through most of it..

>  fs/xfs/Makefile                |    1 +
>  fs/xfs/libxfs/xfs_bmap.c       |   20 +-
>  fs/xfs/libxfs/xfs_bmap_btree.c |  103 +---
>  fs/xfs/libxfs/xfs_bmap_btree.h |    7 +-
>  fs/xfs/libxfs/xfs_format.h     |    4 -
>  fs/xfs/libxfs/xfs_iext_tree.c  | 1035 ++++++++++++++++++++++++++++++++++++++++
>  fs/xfs/libxfs/xfs_inode_fork.c | 1035 +---------------------------------------
>  fs/xfs/libxfs/xfs_inode_fork.h |   84 +---
>  fs/xfs/libxfs/xfs_types.h      |    3 +-
>  fs/xfs/scrub/bmap.c            |    5 +-
>  fs/xfs/xfs_inode.c             |    2 +-
>  fs/xfs/xfs_inode_item.c        |    2 -
>  fs/xfs/xfs_trace.h             |   51 +-
>  13 files changed, 1093 insertions(+), 1259 deletions(-)
>  create mode 100644 fs/xfs/libxfs/xfs_iext_tree.c
> 
...
> diff --git a/fs/xfs/libxfs/xfs_iext_tree.c b/fs/xfs/libxfs/xfs_iext_tree.c
> new file mode 100644
> index 000000000000..8b6402d2d9b2
> --- /dev/null
> +++ b/fs/xfs/libxfs/xfs_iext_tree.c
> @@ -0,0 +1,1035 @@
...
> +static void
> +xfs_iext_update_node(
> +	struct xfs_ifork	*ifp,
> +	xfs_fileoff_t		old_offset,
> +	xfs_fileoff_t		new_offset,
> +	int			level,
> +	void			*ptr)
> +{
> +	struct xfs_iext_node	*node = ifp->if_u1.if_root;
> +	int			height, i;
> +
> +	for (height = ifp->if_height; height > level; height--) {
> +		for (i = 0; i < KEYS_PER_NODE; i++) {
> +			if (i > 0 && xfs_iext_key_cmp(node, i, old_offset) > 0)
> +				break;
> +			if (node->keys[i] == old_offset)
> +				node->keys[i] = new_offset;

The logic seems a bit convoluted. Is this not the same as something like
the following:

                        if (xfs_iext_key_cmp(node, i, old_offset) == 0) {
                                node->keys[i] = new_offset;
                                node = node->ptrs[i];
                                break;
                        }

(and kill the node assignment below)..?

> +		}
> +		node = node->ptrs[i - 1];
> +		ASSERT(node);
> +	}

Hmm, so we walk the tree from the top and update any references to a
particular key. I'm wondering why we wouldn't/couldn't do something a
bit more efficient (and cautious) like walk from the leaf up using the
find_level bits, then stop once we update a key that is not a zero
index..?

I guess find_level() itself has to do a top-down walk each go around
since we don't have any up-pointers, so maybe that answers my question.
;) Perhaps a more robust cursor could help us optimize some of these
cases in the future without bloating the tree, if warranted.

> +
> +	ASSERT(node == ptr);
> +}
> +
...
> +static struct xfs_iext_leaf *
> +xfs_iext_split_leaf(
> +	struct xfs_iext_cursor	*cur,
> +	int			*nr_entries)
> +{
> +	struct xfs_iext_leaf	*leaf = cur->leaf;
> +	struct xfs_iext_leaf	*new = kmem_zalloc(NODE_SIZE, KM_NOFS);
> +	const int		nr_move = RECS_PER_LEAF / 2;
> +	int			nr_keep = nr_move + (RECS_PER_LEAF & 1);
> +	int			i;
> +
> +	/* for sequential append operations just spill over into the new node */
> +	if (cur->pos == KEYS_PER_NODE) {
> +		cur->leaf = new;
> +		cur->pos = 0;
> +		*nr_entries = 0;
> +		goto done;
> +	}

Hmm, this is called when nr_entries is RECS_PER_LEAF, which is currently
15. KEYS_PER_NODE is currently 16, so when will the above ever occur?
Wouldn't cur->pos point to 15 on a sequential append?

> +
> +	if (nr_keep & 1)
> +		nr_keep++;
> +

This also seems superfluous. nr_move is RECS_PER_LEAF/2 and so matches
the parity of RECS_PER_LEAF. nr_keep is nr_move plus 1 iff RECS_PER_LEAF
is odd, which looks like it means nr_keep is always even. Am I missing
some other case..?

> +	for (i = 0; i < nr_move; i++) {
> +		new->recs[i] = leaf->recs[nr_keep + i];
> +		xfs_iext_rec_clear(&leaf->recs[nr_keep + i]);
> +	}
> +
> +	if (cur->pos >= nr_keep) {
> +		cur->leaf = new;
> +		cur->pos -= nr_keep;
> +		*nr_entries = nr_move;
> +	} else {
> +		*nr_entries = nr_keep;
> +	}
> +done:
> +	if (leaf->next)
> +		leaf->next->prev = new;
> +	new->next = leaf->next;
> +	new->prev = leaf;
> +	leaf->next = new;
> +	return new;
> +}
> +
...
> +
> +static void
> +xfs_iext_realloc_root(
> +	struct xfs_ifork	*ifp,
> +	struct xfs_iext_cursor	*cur)
> +{
> +	size_t new_size = ifp->if_bytes + sizeof(struct xfs_iext_rec);
> +	void *new;
> +
> +	/* account for the prev/next pointers */
> +	if (new_size / sizeof(struct xfs_iext_rec) == RECS_PER_LEAF)
> +		new_size = NODE_SIZE;
> +
> +	new = kmem_realloc(ifp->if_u1.if_root, new_size, KM_NOFS);
> +	memset(new + ifp->if_bytes, 0, new_size - ifp->if_bytes);
> +	ifp->if_u1.if_root = new;
> +	cur->leaf = new;

I don't think it's an immediate problem, but this look like a bit of a
landmine because of how we update to the node size. The first time that
we bump up to NODE_SIZE it looks like we zero everything properly. We
call this again however in the case where the leaf would need to be
split. The new_size doesn't change and so I suspect the realloc doesn't
do anything, but we still zero over the last part of the structure as if
it were going to be a new record.

> +}
> +
> +static void
> +__xfs_iext_insert(
> +	struct xfs_ifork	*ifp,
> +	struct xfs_iext_cursor	*cur,
> +	struct xfs_bmbt_irec	*irec)
> +{
> +	xfs_fileoff_t		offset = irec->br_startoff;
> +	struct xfs_iext_leaf	*new = NULL;
> +	int			nr_entries, i;
> +
> +	if (ifp->if_height == 0)
> +		xfs_iext_alloc_root(ifp, cur);
> +	else if (ifp->if_height == 1)
> +		xfs_iext_realloc_root(ifp, cur);
> +
> +	nr_entries = xfs_iext_leaf_nr_entries(ifp, cur->leaf, cur->pos);
> +	ASSERT(nr_entries <= RECS_PER_LEAF);
> +	ASSERT(cur->pos >= nr_entries ||
> +	       xfs_iext_rec_cmp(cur_rec(cur), irec->br_startoff) != 0);
> +
> +	if (nr_entries == RECS_PER_LEAF)
> +		new = xfs_iext_split_leaf(cur, &nr_entries);
> +

A comment would be nice here since the function names are a bit vague
(to me). I.e., point out we're updating the keys up the tree unless
we've added a new node, since a new node hasn't been added to the tree
yet.

> +	if (cur->leaf != new && cur->pos == 0 && nr_entries > 0) {
> +		xfs_iext_update_node(ifp, xfs_iext_leaf_key(cur->leaf, 0), offset, 1,
> +				cur->leaf);
> +	}
> +
> +	for (i = nr_entries; i > cur->pos; i--)
> +		cur->leaf->recs[i] = cur->leaf->recs[i - 1];
> +	xfs_iext_set(cur_rec(cur), irec);
> +	ifp->if_bytes += sizeof(struct xfs_iext_rec);
> +
> +	if (new)
> +		xfs_iext_insert_node(ifp, xfs_iext_leaf_key(new, 0), new, 2);
> +}
> +
...
> +
> +static void
> +xfs_iext_remove_node(
> +	struct xfs_ifork	*ifp,
> +	xfs_fileoff_t		offset,
> +	void			*victim)
> +{
> +	struct xfs_iext_node	*node, *parent;
> +	int			level = 2, pos, nr_entries, i;
> +
> +	ASSERT(level <= ifp->if_height);
> +	node = xfs_iext_find_level(ifp, offset, level);
> +	pos = xfs_iext_node_pos(node, offset);
> +again:
> +	ASSERT(node->ptrs[pos]);
> +	ASSERT(node->ptrs[pos] == victim);
> +	kmem_free(victim);
> +
> +	nr_entries = xfs_iext_node_nr_entries(node, pos) - 1;
> +	offset = node->keys[0];
> +	for (i = pos; i < nr_entries; i++) {
> +		node->keys[i] = node->keys[i + 1];
> +		node->ptrs[i] = node->ptrs[i + 1];
> +	}
> +	node->keys[nr_entries] = XFS_IEXT_KEY_INVALID;
> +	node->ptrs[nr_entries] = NULL;
> +
> +	if (pos == 0 && nr_entries > 0) {
> +		xfs_iext_update_node(ifp, offset, node->keys[0], level,
> +				node);
> +		offset = node->keys[0];
> +	}
> +
> +	if (nr_entries >= KEYS_PER_NODE / 2)
> +		return;
> +
> +	if (level < ifp->if_height) {
> +		level++;
> +		parent = xfs_iext_find_level(ifp, offset, level);
> +		pos = xfs_iext_node_pos(parent, offset);
> +
> +		ASSERT(pos != KEYS_PER_NODE);
> +		ASSERT(parent->ptrs[pos] == node);
> +
> +		node = xfs_iext_rebalance_node(parent, &pos, node, nr_entries);
> +		if (node) {
> +			offset = node->keys[0];

It doesn't look like there is any need to update offset here. It will be
overwritten above.

> +			victim = node;
> +			node = parent;
> +			goto again;
> +		}
> +	} else if (nr_entries == 1) {
> +		ASSERT(node == ifp->if_u1.if_root);
> +		ifp->if_u1.if_root = node->ptrs[0];
> +		ifp->if_height--;
> +		kmem_free(node);
> +	}
> +}
> +

These lower level rebalance functions could really use some comments.
It's easy to lose track of the current state of things, for example, why
we pass leaf separate from cursor...

> +static void
> +xfs_iext_rebalance_leaf(
> +	struct xfs_ifork	*ifp,
> +	struct xfs_iext_cursor	*cur,
> +	struct xfs_iext_leaf	*leaf,
> +	xfs_fileoff_t		offset,
> +	int			fill)
> +{
> +	if (leaf->prev) {
> +		int nr_prev = xfs_iext_leaf_nr_entries(ifp, leaf->prev, 0), i;
> +

... and then why we do things like remove the current node vs. the next
node in the below hunks. I'm guessing that is to easily preserve record
order by always filling backwards, and perhaps implicitly avoid the need
for key updates as part of the rebalance itself..?

> +		if (nr_prev + fill <= RECS_PER_LEAF) {
> +			for (i = 0; i < fill; i++)
> +				leaf->prev->recs[nr_prev + i] = leaf->recs[i];
> +
> +			if (cur->leaf == leaf) {
> +				cur->leaf = leaf->prev;
> +				cur->pos += nr_prev;
> +			}
> +			goto remove_node;
> +		}
> +	}
> +
> +	if (leaf->next) {
> +		int nr_next = xfs_iext_leaf_nr_entries(ifp, leaf->next, 0), i;
> +
> +		if (fill + nr_next <= RECS_PER_LEAF) {
> +			for (i = 0; i < nr_next; i++)
> +				leaf->recs[fill + i] = leaf->next->recs[i];
> +
> +			if (cur->leaf == leaf->next) {
> +				cur->leaf = leaf;
> +				cur->pos += fill;
> +			}
> +
> +			offset = xfs_iext_leaf_key(leaf->next, 0);
> +			leaf = leaf->next;

If fill happens to be 0 [1] because we've emptied the first leaf in the
tree, we end up here where we copy all of the records from the next leaf
to the empty leaf. We therefore update recs[0] of the empty leaf, set
'offset' to the key of the next and proceed to delete that next leaf.

The node remove below would then remove the keys up the tree based on
next, but where would we have updated the key of the reference to the
current leaf that we've just updated with a new index 0? Unless I'm
missing where that happens, it looks like we could end up with a busted
tree.

[1] Note that I'm not sure how possible this is atm if the sequential
append spillover logic is actually broken. That aside... at least with
that kind of logic in place, it seems you'd be able to fill up two
leaves sequentially, then remove all of the records from the first
without ever triggering a rebalance (until fill == 0) because the next
leaf is already full.

Even if I'm missing something here and/or with the spillover logic and
this is not a problem, I'd really like to see some DEBUG code attached
to this that validates the integrity of the tree every so often (after
certain operations, for example).

Brian

> +			goto remove_node;
> +		}
> +	}
> +
> +	return;
> +remove_node:
> +	if (leaf->prev)
> +		leaf->prev->next = leaf->next;
> +	if (leaf->next)
> +		leaf->next->prev = leaf->prev;
> +	xfs_iext_remove_node(ifp, offset, leaf);
> +}
> +
...
> -- 
> 2.14.2
> 
> --
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Re: [PATCH 17/21] xfs: use a b+tree for the in-core extent list

[Christoph Hellwig]

On Wed, Nov 08, 2017 at 08:50:33AM -0500, Brian Foster wrote:
> > +	for (height = ifp->if_height; height > level; height--) {
> > +		for (i = 0; i < KEYS_PER_NODE; i++) {
> > +			if (i > 0 && xfs_iext_key_cmp(node, i, old_offset) > 0)
> > +				break;
> > +			if (node->keys[i] == old_offset)
> > +				node->keys[i] = new_offset;
> 
> The logic seems a bit convoluted. Is this not the same as something like
> the following:
> 
>                         if (xfs_iext_key_cmp(node, i, old_offset) == 0) {
>                                 node->keys[i] = new_offset;
>                                 node = node->ptrs[i];
>                                 break;
>                         }
> 
> (and kill the node assignment below)..?

No.  The big difference is that we need to handle non-exact matches.
Not every possible offset exists at the lower levels - we need to grab
the previous pointer as soon as a key is larger than the offset to deal
with offsets that are inside the next node, and not the first one.

> Hmm, so we walk the tree from the top and update any references to a
> particular key. I'm wondering why we wouldn't/couldn't do something a
> bit more efficient (and cautious) like walk from the leaf up using the
> find_level bits, then stop once we update a key that is not a zero
> index..?
> 
> I guess find_level() itself has to do a top-down walk each go around
> since we don't have any up-pointers, so maybe that answers my question.
> ;)

Yes.  Your above suggestion was my first naive implementation until
I noticed it is very ineffcient.

> Perhaps a more robust cursor could help us optimize some of these
> cases in the future without bloating the tree, if warranted.

Such a cursor would have to track a node + offset for each level,
so we couldn't easily keep it on the stack and would have to introduce
a memory allocation.

> > +static struct xfs_iext_leaf *
> > +xfs_iext_split_leaf(
> > +	struct xfs_iext_cursor	*cur,
> > +	int			*nr_entries)
> > +{
> > +	struct xfs_iext_leaf	*leaf = cur->leaf;
> > +	struct xfs_iext_leaf	*new = kmem_zalloc(NODE_SIZE, KM_NOFS);
> > +	const int		nr_move = RECS_PER_LEAF / 2;
> > +	int			nr_keep = nr_move + (RECS_PER_LEAF & 1);
> > +	int			i;
> > +
> > +	/* for sequential append operations just spill over into the new node */
> > +	if (cur->pos == KEYS_PER_NODE) {
> > +		cur->leaf = new;
> > +		cur->pos = 0;
> > +		*nr_entries = 0;
> > +		goto done;
> > +	}
> 
> Hmm, this is called when nr_entries is RECS_PER_LEAF, which is currently
> 15. KEYS_PER_NODE is currently 16, so when will the above ever occur?
> Wouldn't cur->pos point to 15 on a sequential append?

This should actually be RECS_PER_LEAF..

> > +	if (nr_keep & 1)
> > +		nr_keep++;
> > +
> 
> This also seems superfluous. nr_move is RECS_PER_LEAF/2 and so matches
> the parity of RECS_PER_LEAF. nr_keep is nr_move plus 1 iff RECS_PER_LEAF
> is odd, which looks like it means nr_keep is always even. Am I missing
> some other case..?

Yes, this should be dropped.  I'm pretty sure I got this right before,
I suspect I got some mismerge here when cleaning up the patch series.

> > +	size_t new_size = ifp->if_bytes + sizeof(struct xfs_iext_rec);
> > +	void *new;
> > +
> > +	/* account for the prev/next pointers */
> > +	if (new_size / sizeof(struct xfs_iext_rec) == RECS_PER_LEAF)
> > +		new_size = NODE_SIZE;
> > +
> > +	new = kmem_realloc(ifp->if_u1.if_root, new_size, KM_NOFS);
> > +	memset(new + ifp->if_bytes, 0, new_size - ifp->if_bytes);
> > +	ifp->if_u1.if_root = new;
> > +	cur->leaf = new;
> 
> I don't think it's an immediate problem, but this look like a bit of a
> landmine because of how we update to the node size. The first time that
> we bump up to NODE_SIZE it looks like we zero everything properly. We
> call this again however in the case where the leaf would need to be
> split. The new_size doesn't change and so I suspect the realloc doesn't
> do anything, but we still zero over the last part of the structure as if
> it were going to be a new record.

It will zero the next/prev pointers again which is pointless, but also
harmless because we don't use the next/prev pointers for  a single-level
tree.  I'll see if I can avoid it somehow.

> A comment would be nice here since the function names are a bit vague
> (to me). I.e., point out we're updating the keys up the tree unless
> we've added a new node, since a new node hasn't been added to the tree
> yet.

Ok.

> > +		node = xfs_iext_rebalance_node(parent, &pos, node, nr_entries);
> > +		if (node) {
> > +			offset = node->keys[0];
> 
> It doesn't look like there is any need to update offset here. It will be
> overwritten above.

Indeed, fixed.

> > +	} else if (nr_entries == 1) {
> > +		ASSERT(node == ifp->if_u1.if_root);
> > +		ifp->if_u1.if_root = node->ptrs[0];
> > +		ifp->if_height--;
> > +		kmem_free(node);
> > +	}
> > +}
> > +
> 
> These lower level rebalance functions could really use some comments.
> It's easy to lose track of the current state of things, for example, why
> we pass leaf separate from cursor...
> 
> > +static void
> > +xfs_iext_rebalance_leaf(
> > +	struct xfs_ifork	*ifp,
> > +	struct xfs_iext_cursor	*cur,
> > +	struct xfs_iext_leaf	*leaf,
> > +	xfs_fileoff_t		offset,
> > +	int			fill)
> > +{
> > +	if (leaf->prev) {
> > +		int nr_prev = xfs_iext_leaf_nr_entries(ifp, leaf->prev, 0), i;
> > +
> 
> ... and then why we do things like remove the current node vs. the next
> node in the below hunks. I'm guessing that is to easily preserve record
> order by always filling backwards, and perhaps implicitly avoid the need
> for key updates as part of the rebalance itself..?

Mostly for the latter.  Preserving the order would be doable even
without that.

> > +	if (leaf->next) {
> > +		int nr_next = xfs_iext_leaf_nr_entries(ifp, leaf->next, 0), i;
> > +
> > +		if (fill + nr_next <= RECS_PER_LEAF) {
> > +			for (i = 0; i < nr_next; i++)
> > +				leaf->recs[fill + i] = leaf->next->recs[i];
> > +
> > +			if (cur->leaf == leaf->next) {
> > +				cur->leaf = leaf;
> > +				cur->pos += fill;
> > +			}
> > +
> > +			offset = xfs_iext_leaf_key(leaf->next, 0);
> > +			leaf = leaf->next;
> 
> If fill happens to be 0 [1] because we've emptied the first leaf in the
> tree, we end up here where we copy all of the records from the next leaf
> to the empty leaf. We therefore update recs[0] of the empty leaf, set
> 'offset' to the key of the next and proceed to delete that next leaf.

Yeah, we can handle it the same way as for the lower levels.  Note that
you don't need the sequential insert logic to trigger it - just fill
up at least three nodes entirely after they are split and delete all th
e entries in the middle one then.  This might even be doable with an
xfstest.

[PATCH 18/21] xfs: remove the nr_extents argument to xfs_iext_insert

[Christoph Hellwig]

We only have two places that insert 2 extents at the same time, so unroll
the loop there.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
---
 fs/xfs/libxfs/xfs_bmap.c       | 31 ++++++++++++++++---------------
 fs/xfs/libxfs/xfs_iext_tree.c  | 31 ++++++++-----------------------
 fs/xfs/libxfs/xfs_inode_fork.c |  2 +-
 fs/xfs/libxfs/xfs_inode_fork.h |  2 +-
 4 files changed, 26 insertions(+), 40 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
index 7d96e4d9fc91..c12620f57de5 100644
--- a/fs/xfs/libxfs/xfs_bmap.c
+++ b/fs/xfs/libxfs/xfs_bmap.c
@@ -901,7 +901,7 @@ xfs_bmap_local_to_extents(
 	rec.br_blockcount = 1;
 	rec.br_state = XFS_EXT_NORM;
 	xfs_iext_first(ifp, &icur);
-	xfs_iext_insert(ip, &icur, 1, &rec, 0);
+	xfs_iext_insert(ip, &icur, &rec, 0);
 
 	XFS_IFORK_NEXT_SET(ip, whichfork, 1);
 	ip->i_d.di_nblocks = 1;
@@ -1268,7 +1268,7 @@ xfs_iread_extents(
 				goto out_brelse;
 			}
 			xfs_bmbt_disk_get_all(frp, &new);
-			xfs_iext_insert(ip, &icur, 1, &new, state);
+			xfs_iext_insert(ip, &icur, &new, state);
 			trace_xfs_read_extent(ip, &icur, state, _THIS_IP_);
 			xfs_iext_next(ifp, &icur);
 		}
@@ -1824,7 +1824,7 @@ xfs_bmap_add_extent_delay_real(
 		PREV.br_blockcount = temp;
 		PREV.br_startblock = nullstartblock(da_new);
 		xfs_iext_next(ifp, &bma->icur);
-		xfs_iext_insert(bma->ip, &bma->icur, 1, &PREV, state);
+		xfs_iext_insert(bma->ip, &bma->icur, &PREV, state);
 		xfs_iext_prev(ifp, &bma->icur);
 		break;
 
@@ -1900,7 +1900,7 @@ xfs_bmap_add_extent_delay_real(
 
 		PREV.br_startblock = nullstartblock(da_new);
 		PREV.br_blockcount = temp;
-		xfs_iext_insert(bma->ip, &bma->icur, 1, &PREV, state);
+		xfs_iext_insert(bma->ip, &bma->icur, &PREV, state);
 		xfs_iext_next(ifp, &bma->icur);
 		break;
 
@@ -1946,9 +1946,9 @@ xfs_bmap_add_extent_delay_real(
 					PREV.br_blockcount));
 		xfs_iext_update_extent(bma->ip, state, &bma->icur, &PREV);
 
-		/* insert LEFT (r[0]) and RIGHT (r[1]) at the same time */
 		xfs_iext_next(ifp, &bma->icur);
-		xfs_iext_insert(bma->ip, &bma->icur, 2, &LEFT, state);
+		xfs_iext_insert(bma->ip, &bma->icur, &RIGHT, state);
+		xfs_iext_insert(bma->ip, &bma->icur, &LEFT, state);
 		(*nextents)++;
 
 		if (bma->cur == NULL)
@@ -2312,7 +2312,7 @@ xfs_bmap_add_extent_unwritten_real(
 		PREV.br_blockcount -= new->br_blockcount;
 
 		xfs_iext_update_extent(ip, state, icur, &PREV);
-		xfs_iext_insert(ip, icur, 1, new, state);
+		xfs_iext_insert(ip, icur, new, state);
 		XFS_IFORK_NEXT_SET(ip, whichfork,
 				XFS_IFORK_NEXTENTS(ip, whichfork) + 1);
 		if (cur == NULL)
@@ -2379,7 +2379,7 @@ xfs_bmap_add_extent_unwritten_real(
 
 		xfs_iext_update_extent(ip, state, icur, &PREV);
 		xfs_iext_next(ifp, icur);
-		xfs_iext_insert(ip, icur, 1, new, state);
+		xfs_iext_insert(ip, icur, new, state);
 
 		XFS_IFORK_NEXT_SET(ip, whichfork,
 				XFS_IFORK_NEXTENTS(ip, whichfork) + 1);
@@ -2422,7 +2422,8 @@ xfs_bmap_add_extent_unwritten_real(
 
 		xfs_iext_update_extent(ip, state, icur, &PREV);
 		xfs_iext_next(ifp, icur);
-		xfs_iext_insert(ip, icur, 2, &r[0], state);
+		xfs_iext_insert(ip, icur, &r[1], state);
+		xfs_iext_insert(ip, icur, &r[0], state);
 
 		XFS_IFORK_NEXT_SET(ip, whichfork,
 				XFS_IFORK_NEXTENTS(ip, whichfork) + 2);
@@ -2630,7 +2631,7 @@ xfs_bmap_add_extent_hole_delay(
 		 * Insert a new entry.
 		 */
 		oldlen = newlen = 0;
-		xfs_iext_insert(ip, icur, 1, new, state);
+		xfs_iext_insert(ip, icur, new, state);
 		break;
 	}
 	if (oldlen != newlen) {
@@ -2814,7 +2815,7 @@ xfs_bmap_add_extent_hole_real(
 		 * real allocation.
 		 * Insert a new entry.
 		 */
-		xfs_iext_insert(ip, icur, 1, new, state);
+		xfs_iext_insert(ip, icur, new, state);
 		XFS_IFORK_NEXT_SET(ip, whichfork,
 			XFS_IFORK_NEXTENTS(ip, whichfork) + 1);
 		if (cur == NULL) {
@@ -4737,7 +4738,7 @@ xfs_bmap_del_extent_delay(
 
 		xfs_iext_update_extent(ip, state, icur, got);
 		xfs_iext_next(ifp, icur);
-		xfs_iext_insert(ip, icur, 1, &new, state);
+		xfs_iext_insert(ip, icur, &new, state);
 
 		da_new = got_indlen + new_indlen - stolen;
 		del->br_blockcount -= stolen;
@@ -4818,7 +4819,7 @@ xfs_bmap_del_extent_cow(
 
 		xfs_iext_update_extent(ip, state, icur, got);
 		xfs_iext_next(ifp, icur);
-		xfs_iext_insert(ip, icur, 1, &new, state);
+		xfs_iext_insert(ip, icur, &new, state);
 		break;
 	}
 }
@@ -5031,7 +5032,7 @@ xfs_bmap_del_extent_real(
 		XFS_IFORK_NEXT_SET(ip, whichfork,
 			XFS_IFORK_NEXTENTS(ip, whichfork) + 1);
 		xfs_iext_next(ifp, icur);
-		xfs_iext_insert(ip, icur, 1, &new, state);
+		xfs_iext_insert(ip, icur, &new, state);
 		break;
 	}
 
@@ -5893,7 +5894,7 @@ xfs_bmap_split_extent_at(
 
 	/* Add new extent */
 	xfs_iext_next(ifp, &icur);
-	xfs_iext_insert(ip, &icur, 1, &new, 0);
+	xfs_iext_insert(ip, &icur, &new, 0);
 	XFS_IFORK_NEXT_SET(ip, whichfork,
 			   XFS_IFORK_NEXTENTS(ip, whichfork) + 1);
 
diff --git a/fs/xfs/libxfs/xfs_iext_tree.c b/fs/xfs/libxfs/xfs_iext_tree.c
index 8b6402d2d9b2..da3b6d727748 100644
--- a/fs/xfs/libxfs/xfs_iext_tree.c
+++ b/fs/xfs/libxfs/xfs_iext_tree.c
@@ -619,16 +619,20 @@ xfs_iext_realloc_root(
 	cur->leaf = new;
 }
 
-static void
-__xfs_iext_insert(
-	struct xfs_ifork	*ifp,
+void
+xfs_iext_insert(
+	struct xfs_inode	*ip,
 	struct xfs_iext_cursor	*cur,
-	struct xfs_bmbt_irec	*irec)
+	struct xfs_bmbt_irec	*irec,
+	int			state)
 {
+	struct xfs_ifork	*ifp = xfs_iext_state_to_fork(ip, state);
 	xfs_fileoff_t		offset = irec->br_startoff;
 	struct xfs_iext_leaf	*new = NULL;
 	int			nr_entries, i;
 
+	trace_xfs_iext_insert(ip, cur, state, _RET_IP_);
+
 	if (ifp->if_height == 0)
 		xfs_iext_alloc_root(ifp, cur);
 	else if (ifp->if_height == 1)
@@ -656,25 +660,6 @@ __xfs_iext_insert(
 		xfs_iext_insert_node(ifp, xfs_iext_leaf_key(new, 0), new, 2);
 }
 
-void
-xfs_iext_insert(
-	struct xfs_inode	*ip,
-	struct xfs_iext_cursor	*cur,
-	xfs_extnum_t		nr_extents,
-	struct xfs_bmbt_irec	*new,
-	int			state)
-{
-	struct xfs_ifork	*ifp = xfs_iext_state_to_fork(ip, state);
-	int			i;
-
-	ASSERT(nr_extents > 0);
-
-	for (i = nr_extents - 1; i >= 0; i--) {
-		__xfs_iext_insert(ifp, cur, new + i);
-		trace_xfs_iext_insert(ip, cur, state, _RET_IP_);
-	}
-}
-
 static struct xfs_iext_node *
 xfs_iext_rebalance_node(
 	struct xfs_iext_node	*parent,
diff --git a/fs/xfs/libxfs/xfs_inode_fork.c b/fs/xfs/libxfs/xfs_inode_fork.c
index 1839202133ba..71901ee2e35c 100644
--- a/fs/xfs/libxfs/xfs_inode_fork.c
+++ b/fs/xfs/libxfs/xfs_inode_fork.c
@@ -362,7 +362,7 @@ xfs_iformat_extents(
 			}
 
 			xfs_bmbt_disk_get_all(dp, &new);
-			xfs_iext_insert(ip, &icur, 1, &new, state);
+			xfs_iext_insert(ip, &icur, &new, state);
 			trace_xfs_read_extent(ip, &icur, state, _THIS_IP_);
 			xfs_iext_next(ifp, &icur);
 		}
diff --git a/fs/xfs/libxfs/xfs_inode_fork.h b/fs/xfs/libxfs/xfs_inode_fork.h
index 7fda248e32ab..4859db42fef8 100644
--- a/fs/xfs/libxfs/xfs_inode_fork.h
+++ b/fs/xfs/libxfs/xfs_inode_fork.h
@@ -114,7 +114,7 @@ void		xfs_init_local_fork(struct xfs_inode *, int, const void *, int);
 
 xfs_extnum_t	xfs_iext_count(struct xfs_ifork *ifp);
 void		xfs_iext_insert(struct xfs_inode *, struct xfs_iext_cursor *cur,
-			xfs_extnum_t, struct xfs_bmbt_irec *, int);
+			struct xfs_bmbt_irec *, int);
 void		xfs_iext_remove(struct xfs_inode *, struct xfs_iext_cursor *,
 			int, int);
 void		xfs_iext_destroy(struct xfs_ifork *);
-- 
2.14.2

[PATCH 19/21] xfs: remove the nr_extents argument to xfs_iext_remove

[Christoph Hellwig]

We only have two places that remove 2 extents at the same time, so unroll
the loop there.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
---
 fs/xfs/libxfs/xfs_bmap.c       | 26 ++++++++++++++------------
 fs/xfs/libxfs/xfs_iext_tree.c  | 30 ++++++++----------------------
 fs/xfs/libxfs/xfs_inode_fork.h |  2 +-
 3 files changed, 23 insertions(+), 35 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
index c12620f57de5..57c974fea3a9 100644
--- a/fs/xfs/libxfs/xfs_bmap.c
+++ b/fs/xfs/libxfs/xfs_bmap.c
@@ -1645,7 +1645,8 @@ xfs_bmap_add_extent_delay_real(
 		 */
 		LEFT.br_blockcount += PREV.br_blockcount + RIGHT.br_blockcount;
 
-		xfs_iext_remove(bma->ip, &bma->icur, 2, state);
+		xfs_iext_remove(bma->ip, &bma->icur, state);
+		xfs_iext_remove(bma->ip, &bma->icur, state);
 		xfs_iext_prev(ifp, &bma->icur);
 		xfs_iext_update_extent(bma->ip, state, &bma->icur, &LEFT);
 		(*nextents)--;
@@ -1680,7 +1681,7 @@ xfs_bmap_add_extent_delay_real(
 		old = LEFT;
 		LEFT.br_blockcount += PREV.br_blockcount;
 
-		xfs_iext_remove(bma->ip, &bma->icur, 1, state);
+		xfs_iext_remove(bma->ip, &bma->icur, state);
 		xfs_iext_prev(ifp, &bma->icur);
 		xfs_iext_update_extent(bma->ip, state, &bma->icur, &LEFT);
 
@@ -1707,7 +1708,7 @@ xfs_bmap_add_extent_delay_real(
 		PREV.br_blockcount += RIGHT.br_blockcount;
 
 		xfs_iext_next(ifp, &bma->icur);
-		xfs_iext_remove(bma->ip, &bma->icur, 1, state);
+		xfs_iext_remove(bma->ip, &bma->icur, state);
 		xfs_iext_prev(ifp, &bma->icur);
 		xfs_iext_update_extent(bma->ip, state, &bma->icur, &PREV);
 
@@ -2144,7 +2145,8 @@ xfs_bmap_add_extent_unwritten_real(
 		 */
 		LEFT.br_blockcount += PREV.br_blockcount + RIGHT.br_blockcount;
 
-		xfs_iext_remove(ip, icur, 2, state);
+		xfs_iext_remove(ip, icur, state);
+		xfs_iext_remove(ip, icur, state);
 		xfs_iext_prev(ifp, icur);
 		xfs_iext_update_extent(ip, state, icur, &LEFT);
 		XFS_IFORK_NEXT_SET(ip, whichfork,
@@ -2182,7 +2184,7 @@ xfs_bmap_add_extent_unwritten_real(
 		 */
 		LEFT.br_blockcount += PREV.br_blockcount;
 
-		xfs_iext_remove(ip, icur, 1, state);
+		xfs_iext_remove(ip, icur, state);
 		xfs_iext_prev(ifp, icur);
 		xfs_iext_update_extent(ip, state, icur, &LEFT);
 		XFS_IFORK_NEXT_SET(ip, whichfork,
@@ -2216,7 +2218,7 @@ xfs_bmap_add_extent_unwritten_real(
 		PREV.br_state = new->br_state;
 
 		xfs_iext_next(ifp, icur);
-		xfs_iext_remove(ip, icur, 1, state);
+		xfs_iext_remove(ip, icur, state);
 		xfs_iext_prev(ifp, icur);
 		xfs_iext_update_extent(ip, state, icur, &PREV);
 
@@ -2583,7 +2585,7 @@ xfs_bmap_add_extent_hole_delay(
 		left.br_startblock = nullstartblock(newlen);
 		left.br_blockcount = temp;
 
-		xfs_iext_remove(ip, icur, 1, state);
+		xfs_iext_remove(ip, icur, state);
 		xfs_iext_prev(ifp, icur);
 		xfs_iext_update_extent(ip, state, icur, &left);
 		break;
@@ -2728,7 +2730,7 @@ xfs_bmap_add_extent_hole_real(
 		 */
 		left.br_blockcount += new->br_blockcount + right.br_blockcount;
 
-		xfs_iext_remove(ip, icur, 1, state);
+		xfs_iext_remove(ip, icur, state);
 		xfs_iext_prev(ifp, icur);
 		xfs_iext_update_extent(ip, state, icur, &left);
 
@@ -4686,7 +4688,7 @@ xfs_bmap_del_extent_delay(
 		/*
 		 * Matches the whole extent.  Delete the entry.
 		 */
-		xfs_iext_remove(ip, icur, 1, state);
+		xfs_iext_remove(ip, icur, state);
 		xfs_iext_prev(ifp, icur);
 		break;
 	case BMAP_LEFT_FILLING:
@@ -4787,7 +4789,7 @@ xfs_bmap_del_extent_cow(
 		/*
 		 * Matches the whole extent.  Delete the entry.
 		 */
-		xfs_iext_remove(ip, icur, 1, state);
+		xfs_iext_remove(ip, icur, state);
 		xfs_iext_prev(ifp, icur);
 		break;
 	case BMAP_LEFT_FILLING:
@@ -4927,7 +4929,7 @@ xfs_bmap_del_extent_real(
 		/*
 		 * Matches the whole extent.  Delete the entry.
 		 */
-		xfs_iext_remove(ip, icur, 1, state);
+		xfs_iext_remove(ip, icur, state);
 		xfs_iext_prev(ifp, icur);
 		XFS_IFORK_NEXT_SET(ip, whichfork,
 			XFS_IFORK_NEXTENTS(ip, whichfork) - 1);
@@ -5553,7 +5555,7 @@ xfs_bmse_merge(
 		return error;
 
 done:
-	xfs_iext_remove(ip, icur, 1, 0);
+	xfs_iext_remove(ip, icur, 0);
 	xfs_iext_prev(XFS_IFORK_PTR(ip, whichfork), icur);
 	xfs_iext_update_extent(ip, xfs_bmap_fork_to_state(whichfork), icur,
 			&new);
diff --git a/fs/xfs/libxfs/xfs_iext_tree.c b/fs/xfs/libxfs/xfs_iext_tree.c
index da3b6d727748..a35c4e51fedc 100644
--- a/fs/xfs/libxfs/xfs_iext_tree.c
+++ b/fs/xfs/libxfs/xfs_iext_tree.c
@@ -818,15 +818,19 @@ xfs_iext_free_last_leaf(
 	kmem_free(ifp->if_u1.if_root);
 }
 
-static void
-__xfs_iext_remove(
-	struct xfs_ifork	*ifp,
-	struct xfs_iext_cursor	*cur)
+void
+xfs_iext_remove(
+	struct xfs_inode	*ip,
+	struct xfs_iext_cursor	*cur,
+	int			state)
 {
+	struct xfs_ifork	*ifp = xfs_iext_state_to_fork(ip, state);
 	struct xfs_iext_leaf	*leaf = cur->leaf;
 	xfs_fileoff_t		offset = xfs_iext_leaf_key(leaf, 0);
 	int			i, nr_entries;
 
+	trace_xfs_iext_remove(ip, cur, state, _RET_IP_);
+
 	ASSERT(ifp->if_height > 0);
 	ASSERT(ifp->if_u1.if_root != NULL);
 	ASSERT(xfs_iext_valid(ifp, cur));
@@ -858,24 +862,6 @@ __xfs_iext_remove(
 		xfs_iext_free_last_leaf(ifp);
 }
 
-void
-xfs_iext_remove(
-	struct xfs_inode	*ip,
-	struct xfs_iext_cursor	*cur,
-	int			nr_extents,
-	int			state)
-{
-	struct xfs_ifork	*ifp = xfs_iext_state_to_fork(ip, state);
-	int			i;
-
-	ASSERT(nr_extents > 0);
-
-	for (i = 0; i < nr_extents; i++) {
-		trace_xfs_iext_remove(ip, cur, state, _RET_IP_);
-		__xfs_iext_remove(ifp, cur);
-	}
-}
-
 /*
  * Lookup the extent covering bno.
  *
diff --git a/fs/xfs/libxfs/xfs_inode_fork.h b/fs/xfs/libxfs/xfs_inode_fork.h
index 4859db42fef8..98e46c6666a5 100644
--- a/fs/xfs/libxfs/xfs_inode_fork.h
+++ b/fs/xfs/libxfs/xfs_inode_fork.h
@@ -116,7 +116,7 @@ xfs_extnum_t	xfs_iext_count(struct xfs_ifork *ifp);
 void		xfs_iext_insert(struct xfs_inode *, struct xfs_iext_cursor *cur,
 			struct xfs_bmbt_irec *, int);
 void		xfs_iext_remove(struct xfs_inode *, struct xfs_iext_cursor *,
-			int, int);
+			int);
 void		xfs_iext_destroy(struct xfs_ifork *);
 
 bool		xfs_iext_lookup_extent(struct xfs_inode *ip,
-- 
2.14.2

[PATCH 20/21] xfs: pass struct xfs_bmbt_irec to xfs_bmbt_validate_extent

[Christoph Hellwig]

This removed an unaligned load per extent, as well as the manual poking
into the on-disk extent format.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 fs/xfs/libxfs/xfs_bmap.c       | 4 ++--
 fs/xfs/libxfs/xfs_bmap_btree.h | 4 ++--
 fs/xfs/libxfs/xfs_inode_fork.c | 6 +++---
 3 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
index 57c974fea3a9..4e0e10472434 100644
--- a/fs/xfs/libxfs/xfs_bmap.c
+++ b/fs/xfs/libxfs/xfs_bmap.c
@@ -1261,13 +1261,13 @@ xfs_iread_extents(
 		 */
 		frp = XFS_BMBT_REC_ADDR(mp, block, 1);
 		for (j = 0; j < num_recs; j++, frp++, i++) {
-			if (!xfs_bmbt_validate_extent(mp, whichfork, frp)) {
+			xfs_bmbt_disk_get_all(frp, &new);
+			if (!xfs_bmbt_validate_extent(mp, whichfork, &new)) {
 				XFS_ERROR_REPORT("xfs_bmap_read_extents(2)",
 						 XFS_ERRLEVEL_LOW, mp);
 				error = -EFSCORRUPTED;
 				goto out_brelse;
 			}
-			xfs_bmbt_disk_get_all(frp, &new);
 			xfs_iext_insert(ip, &icur, &new, state);
 			trace_xfs_read_extent(ip, &icur, state, _THIS_IP_);
 			xfs_iext_next(ifp, &icur);
diff --git a/fs/xfs/libxfs/xfs_bmap_btree.h b/fs/xfs/libxfs/xfs_bmap_btree.h
index 714bfbaf9b2d..135b8c56d23e 100644
--- a/fs/xfs/libxfs/xfs_bmap_btree.h
+++ b/fs/xfs/libxfs/xfs_bmap_btree.h
@@ -122,9 +122,9 @@ extern struct xfs_btree_cur *xfs_bmbt_init_cursor(struct xfs_mount *,
  * Check that the extent does not contain an invalid unwritten extent flag.
  */
 static inline bool xfs_bmbt_validate_extent(struct xfs_mount *mp, int whichfork,
-		struct xfs_bmbt_rec *ep)
+		struct xfs_bmbt_irec *irec)
 {
-	if (get_unaligned_be64(&ep->l0) >> (64 - BMBT_EXNTFLAG_BITLEN) == 0)
+	if (irec->br_state == XFS_EXT_NORM)
 		return true;
 	if (whichfork == XFS_DATA_FORK &&
 	    xfs_sb_version_hasextflgbit(&mp->m_sb))
diff --git a/fs/xfs/libxfs/xfs_inode_fork.c b/fs/xfs/libxfs/xfs_inode_fork.c
index 71901ee2e35c..9ff7e33accd5 100644
--- a/fs/xfs/libxfs/xfs_inode_fork.c
+++ b/fs/xfs/libxfs/xfs_inode_fork.c
@@ -355,13 +355,13 @@ xfs_iformat_extents(
 
 		xfs_iext_first(ifp, &icur);
 		for (i = 0; i < nex; i++, dp++) {
-			if (!xfs_bmbt_validate_extent(mp, whichfork, dp)) {
+			xfs_bmbt_disk_get_all(dp, &new);
+			if (!xfs_bmbt_validate_extent(mp, whichfork, &new)) {
 				XFS_ERROR_REPORT("xfs_iformat_extents(2)",
 						 XFS_ERRLEVEL_LOW, mp);
 				return -EFSCORRUPTED;
 			}
 
-			xfs_bmbt_disk_get_all(dp, &new);
 			xfs_iext_insert(ip, &icur, &new, state);
 			trace_xfs_read_extent(ip, &icur, state, _THIS_IP_);
 			xfs_iext_next(ifp, &icur);
@@ -704,9 +704,9 @@ xfs_iextents_copy(
 	for_each_iext(ifp, &icur, &rec) {
 		if (isnullstartblock(rec.br_startblock))
 			continue;
+		ASSERT(xfs_bmbt_validate_extent(ip->i_mount, whichfork, &rec));
 		xfs_bmbt_disk_set_all(dp, &rec);
 		trace_xfs_write_extent(ip, &icur, state, _RET_IP_);
-		ASSERT(xfs_bmbt_validate_extent(ip->i_mount, whichfork, dp));
 		copied += sizeof(struct xfs_bmbt_rec);
 		dp++;
 	}
-- 
2.14.2

Re: [PATCH 20/21] xfs: pass struct xfs_bmbt_irec to xfs_bmbt_validate_extent

[Darrick J. Wong]

On Fri, Nov 03, 2017 at 05:45:38PM +0300, Christoph Hellwig wrote:
> This removed an unaligned load per extent, as well as the manual poking
> into the on-disk extent format.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>

Looks ok,
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>

> ---
>  fs/xfs/libxfs/xfs_bmap.c       | 4 ++--
>  fs/xfs/libxfs/xfs_bmap_btree.h | 4 ++--
>  fs/xfs/libxfs/xfs_inode_fork.c | 6 +++---
>  3 files changed, 7 insertions(+), 7 deletions(-)
> 
> diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
> index 57c974fea3a9..4e0e10472434 100644
> --- a/fs/xfs/libxfs/xfs_bmap.c
> +++ b/fs/xfs/libxfs/xfs_bmap.c
> @@ -1261,13 +1261,13 @@ xfs_iread_extents(
>  		 */
>  		frp = XFS_BMBT_REC_ADDR(mp, block, 1);
>  		for (j = 0; j < num_recs; j++, frp++, i++) {
> -			if (!xfs_bmbt_validate_extent(mp, whichfork, frp)) {
> +			xfs_bmbt_disk_get_all(frp, &new);
> +			if (!xfs_bmbt_validate_extent(mp, whichfork, &new)) {
>  				XFS_ERROR_REPORT("xfs_bmap_read_extents(2)",
>  						 XFS_ERRLEVEL_LOW, mp);
>  				error = -EFSCORRUPTED;
>  				goto out_brelse;
>  			}
> -			xfs_bmbt_disk_get_all(frp, &new);
>  			xfs_iext_insert(ip, &icur, &new, state);
>  			trace_xfs_read_extent(ip, &icur, state, _THIS_IP_);
>  			xfs_iext_next(ifp, &icur);
> diff --git a/fs/xfs/libxfs/xfs_bmap_btree.h b/fs/xfs/libxfs/xfs_bmap_btree.h
> index 714bfbaf9b2d..135b8c56d23e 100644
> --- a/fs/xfs/libxfs/xfs_bmap_btree.h
> +++ b/fs/xfs/libxfs/xfs_bmap_btree.h
> @@ -122,9 +122,9 @@ extern struct xfs_btree_cur *xfs_bmbt_init_cursor(struct xfs_mount *,
>   * Check that the extent does not contain an invalid unwritten extent flag.
>   */
>  static inline bool xfs_bmbt_validate_extent(struct xfs_mount *mp, int whichfork,
> -		struct xfs_bmbt_rec *ep)
> +		struct xfs_bmbt_irec *irec)
>  {
> -	if (get_unaligned_be64(&ep->l0) >> (64 - BMBT_EXNTFLAG_BITLEN) == 0)
> +	if (irec->br_state == XFS_EXT_NORM)
>  		return true;
>  	if (whichfork == XFS_DATA_FORK &&
>  	    xfs_sb_version_hasextflgbit(&mp->m_sb))
> diff --git a/fs/xfs/libxfs/xfs_inode_fork.c b/fs/xfs/libxfs/xfs_inode_fork.c
> index 71901ee2e35c..9ff7e33accd5 100644
> --- a/fs/xfs/libxfs/xfs_inode_fork.c
> +++ b/fs/xfs/libxfs/xfs_inode_fork.c
> @@ -355,13 +355,13 @@ xfs_iformat_extents(
>  
>  		xfs_iext_first(ifp, &icur);
>  		for (i = 0; i < nex; i++, dp++) {
> -			if (!xfs_bmbt_validate_extent(mp, whichfork, dp)) {
> +			xfs_bmbt_disk_get_all(dp, &new);
> +			if (!xfs_bmbt_validate_extent(mp, whichfork, &new)) {
>  				XFS_ERROR_REPORT("xfs_iformat_extents(2)",
>  						 XFS_ERRLEVEL_LOW, mp);
>  				return -EFSCORRUPTED;
>  			}
>  
> -			xfs_bmbt_disk_get_all(dp, &new);
>  			xfs_iext_insert(ip, &icur, &new, state);
>  			trace_xfs_read_extent(ip, &icur, state, _THIS_IP_);
>  			xfs_iext_next(ifp, &icur);
> @@ -704,9 +704,9 @@ xfs_iextents_copy(
>  	for_each_iext(ifp, &icur, &rec) {
>  		if (isnullstartblock(rec.br_startblock))
>  			continue;
> +		ASSERT(xfs_bmbt_validate_extent(ip->i_mount, whichfork, &rec));
>  		xfs_bmbt_disk_set_all(dp, &rec);
>  		trace_xfs_write_extent(ip, &icur, state, _RET_IP_);
> -		ASSERT(xfs_bmbt_validate_extent(ip->i_mount, whichfork, dp));
>  		copied += sizeof(struct xfs_bmbt_rec);
>  		dp++;
>  	}
> -- 
> 2.14.2
> 
> --
> To unsubscribe from this list: send the line "unsubscribe linux-xfs" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

[PATCH 21/21] xfs: move xfs_bmbt_irec and xfs_exntst_t to xfs_types.h

[Christoph Hellwig]

Neither defines an on-disk format, so move them out of xfs_format.h.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 fs/xfs/libxfs/xfs_format.h | 18 ------------------
 fs/xfs/libxfs/xfs_types.h  | 12 ++++++++++++
 2 files changed, 12 insertions(+), 18 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_format.h b/fs/xfs/libxfs/xfs_format.h
index fbe7d3c31345..2e047e76db2f 100644
--- a/fs/xfs/libxfs/xfs_format.h
+++ b/fs/xfs/libxfs/xfs_format.h
@@ -1577,24 +1577,6 @@ static inline xfs_filblks_t startblockval(xfs_fsblock_t x)
 	return (xfs_filblks_t)((x) & ~STARTBLOCKMASK);
 }
 
-/*
- * Possible extent states.
- */
-typedef enum {
-	XFS_EXT_NORM, XFS_EXT_UNWRITTEN,
-} xfs_exntst_t;
-
-/*
- * Incore version of above.
- */
-typedef struct xfs_bmbt_irec
-{
-	xfs_fileoff_t	br_startoff;	/* starting file offset */
-	xfs_fsblock_t	br_startblock;	/* starting block number */
-	xfs_filblks_t	br_blockcount;	/* number of blocks */
-	xfs_exntst_t	br_state;	/* extent state */
-} xfs_bmbt_irec_t;
-
 /*
  * Key structure for non-leaf levels of the tree.
  */
diff --git a/fs/xfs/libxfs/xfs_types.h b/fs/xfs/libxfs/xfs_types.h
index 983878019097..3c560695c546 100644
--- a/fs/xfs/libxfs/xfs_types.h
+++ b/fs/xfs/libxfs/xfs_types.h
@@ -147,4 +147,16 @@ struct xfs_iext_cursor {
 	int			pos;
 };
 
+typedef enum {
+	XFS_EXT_NORM, XFS_EXT_UNWRITTEN,
+} xfs_exntst_t;
+
+typedef struct xfs_bmbt_irec
+{
+	xfs_fileoff_t	br_startoff;	/* starting file offset */
+	xfs_fsblock_t	br_startblock;	/* starting block number */
+	xfs_filblks_t	br_blockcount;	/* number of blocks */
+	xfs_exntst_t	br_state;	/* extent state */
+} xfs_bmbt_irec_t;
+
 #endif	/* __XFS_TYPES_H__ */
-- 
2.14.2

Re: [PATCH 21/21] xfs: move xfs_bmbt_irec and xfs_exntst_t to xfs_types.h

[Darrick J. Wong]

On Fri, Nov 03, 2017 at 05:45:39PM +0300, Christoph Hellwig wrote:
> Neither defines an on-disk format, so move them out of xfs_format.h.

/me wonders if the other irec structures ought to move too, but that's
no reason not to:

Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>

--D

> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>  fs/xfs/libxfs/xfs_format.h | 18 ------------------
>  fs/xfs/libxfs/xfs_types.h  | 12 ++++++++++++
>  2 files changed, 12 insertions(+), 18 deletions(-)
> 
> diff --git a/fs/xfs/libxfs/xfs_format.h b/fs/xfs/libxfs/xfs_format.h
> index fbe7d3c31345..2e047e76db2f 100644
> --- a/fs/xfs/libxfs/xfs_format.h
> +++ b/fs/xfs/libxfs/xfs_format.h
> @@ -1577,24 +1577,6 @@ static inline xfs_filblks_t startblockval(xfs_fsblock_t x)
>  	return (xfs_filblks_t)((x) & ~STARTBLOCKMASK);
>  }
>  
> -/*
> - * Possible extent states.
> - */
> -typedef enum {
> -	XFS_EXT_NORM, XFS_EXT_UNWRITTEN,
> -} xfs_exntst_t;
> -
> -/*
> - * Incore version of above.
> - */
> -typedef struct xfs_bmbt_irec
> -{
> -	xfs_fileoff_t	br_startoff;	/* starting file offset */
> -	xfs_fsblock_t	br_startblock;	/* starting block number */
> -	xfs_filblks_t	br_blockcount;	/* number of blocks */
> -	xfs_exntst_t	br_state;	/* extent state */
> -} xfs_bmbt_irec_t;
> -
>  /*
>   * Key structure for non-leaf levels of the tree.
>   */
> diff --git a/fs/xfs/libxfs/xfs_types.h b/fs/xfs/libxfs/xfs_types.h
> index 983878019097..3c560695c546 100644
> --- a/fs/xfs/libxfs/xfs_types.h
> +++ b/fs/xfs/libxfs/xfs_types.h
> @@ -147,4 +147,16 @@ struct xfs_iext_cursor {
>  	int			pos;
>  };
>  
> +typedef enum {
> +	XFS_EXT_NORM, XFS_EXT_UNWRITTEN,
> +} xfs_exntst_t;
> +
> +typedef struct xfs_bmbt_irec
> +{
> +	xfs_fileoff_t	br_startoff;	/* starting file offset */
> +	xfs_fsblock_t	br_startblock;	/* starting block number */
> +	xfs_filblks_t	br_blockcount;	/* number of blocks */
> +	xfs_exntst_t	br_state;	/* extent state */
> +} xfs_bmbt_irec_t;
> +
>  #endif	/* __XFS_TYPES_H__ */
> -- 
> 2.14.2
> 
> --
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> the body of a message to majordomo@vger.kernel.org
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