[PATCH 4.9 180/206] xfs: new inode extent list lookup helpers

[PATCH 4.9 180/206] xfs: new inode extent list lookup helpers

[Greg Kroah-Hartman]

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------


commit 93533c7855c3c78c8a900cac65c8d669bb14935d upstream.

xfs_iext_lookup_extent looks up a single extent at the passed in offset,
and returns the extent covering the area, or the one behind it in case
of a hole, as well as the index of the returned extent in arguments,
as well as a simple bool as return value that is set to false if no
extent could be found because the offset is behind EOF.  It is a simpler
replacement for xfs_bmap_search_extent that leaves looking up the rarely
needed previous extent to the caller and has a nicer calling convention.

xfs_iext_get_extent is a helper for iterating over the extent list,
it takes an extent index as input, and returns the extent at that index
in it's expanded form in an argument if it exists.  The actual return
value is a bool whether the index is valid or not.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 fs/xfs/libxfs/xfs_inode_fork.c |   46 +++++++++++++++++++++++++++++++++++++++++
 fs/xfs/libxfs/xfs_inode_fork.h |    6 +++++
 2 files changed, 52 insertions(+)

--- a/fs/xfs/libxfs/xfs_inode_fork.c
+++ b/fs/xfs/libxfs/xfs_inode_fork.c
@@ -2003,3 +2003,49 @@ 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 index in *idx.
+ * 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
+ * instead.
+ * If bno is beyond the last extent return false, and return the index after
+ * the last valid index in *idxp.
+ */
+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_bmbt_rec_host *ep;
+
+	XFS_STATS_INC(ip->i_mount, xs_look_exlist);
+
+	ep = xfs_iext_bno_to_ext(ifp, bno, idxp);
+	if (!ep)
+		return false;
+	xfs_bmbt_get_all(ep, gotp);
+	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.
+ */
+bool
+xfs_iext_get_extent(
+	struct xfs_ifork	*ifp,
+	xfs_extnum_t		idx,
+	struct xfs_bmbt_irec	*gotp)
+{
+	if (idx < 0 || idx >= xfs_iext_count(ifp))
+		return false;
+	xfs_bmbt_get_all(xfs_iext_get_ext(ifp, idx), gotp);
+	return true;
+}
--- a/fs/xfs/libxfs/xfs_inode_fork.h
+++ b/fs/xfs/libxfs/xfs_inode_fork.h
@@ -182,6 +182,12 @@ void		xfs_iext_irec_compact_pages(struct
 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,
+			xfs_extnum_t *idxp, struct xfs_bmbt_irec *gotp);
+bool		xfs_iext_get_extent(struct xfs_ifork *ifp, xfs_extnum_t idx,
+			struct xfs_bmbt_irec *gotp);
+
 extern struct kmem_zone	*xfs_ifork_zone;
 
 extern void xfs_ifork_init_cow(struct xfs_inode *ip);

[PATCH 4.9 183/206] xfs: remove prev argument to xfs_bmapi_reserve_delalloc

[Greg Kroah-Hartman]

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------


commit 65c5f419788d623a0410eca1866134f5e4628594 upstream.

We can easily lookup the previous extent for the cases where we need it,
which saves the callers from looking it up for us later in the series.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 fs/xfs/libxfs/xfs_bmap.c |    8 ++++++--
 fs/xfs/libxfs/xfs_bmap.h |    3 +--
 fs/xfs/xfs_iomap.c       |    3 +--
 fs/xfs/xfs_reflink.c     |    2 +-
 4 files changed, 9 insertions(+), 7 deletions(-)

--- a/fs/xfs/libxfs/xfs_bmap.c
+++ b/fs/xfs/libxfs/xfs_bmap.c
@@ -4250,7 +4250,6 @@ xfs_bmapi_reserve_delalloc(
 	xfs_fileoff_t		aoff,
 	xfs_filblks_t		len,
 	struct xfs_bmbt_irec	*got,
-	struct xfs_bmbt_irec	*prev,
 	xfs_extnum_t		*lastx,
 	int			eof)
 {
@@ -4272,7 +4271,12 @@ xfs_bmapi_reserve_delalloc(
 	else
 		extsz = xfs_get_extsz_hint(ip);
 	if (extsz) {
-		error = xfs_bmap_extsize_align(mp, got, prev, extsz, rt, eof,
+		struct xfs_bmbt_irec	prev;
+
+		if (!xfs_iext_get_extent(ifp, *lastx - 1, &prev))
+			prev.br_startoff = NULLFILEOFF;
+
+		error = xfs_bmap_extsize_align(mp, got, &prev, extsz, rt, eof,
 					       1, 0, &aoff, &alen);
 		ASSERT(!error);
 	}
--- a/fs/xfs/libxfs/xfs_bmap.h
+++ b/fs/xfs/libxfs/xfs_bmap.h
@@ -243,8 +243,7 @@ struct xfs_bmbt_rec_host *
 		struct xfs_bmbt_irec *gotp, struct xfs_bmbt_irec *prevp);
 int	xfs_bmapi_reserve_delalloc(struct xfs_inode *ip, int whichfork,
 		xfs_fileoff_t aoff, xfs_filblks_t len,
-		struct xfs_bmbt_irec *got, struct xfs_bmbt_irec *prev,
-		xfs_extnum_t *lastx, int eof);
+		struct xfs_bmbt_irec *got, xfs_extnum_t *lastx, int eof);
 
 enum xfs_bmap_intent_type {
 	XFS_BMAP_MAP = 1,
--- a/fs/xfs/xfs_iomap.c
+++ b/fs/xfs/xfs_iomap.c
@@ -622,8 +622,7 @@ xfs_file_iomap_begin_delay(
 
 retry:
 	error = xfs_bmapi_reserve_delalloc(ip, XFS_DATA_FORK, offset_fsb,
-			end_fsb - offset_fsb, &got,
-			&prev, &idx, eof);
+			end_fsb - offset_fsb, &got, &idx, eof);
 	switch (error) {
 	case 0:
 		break;
--- a/fs/xfs/xfs_reflink.c
+++ b/fs/xfs/xfs_reflink.c
@@ -293,7 +293,7 @@ xfs_reflink_reserve_cow(
 
 retry:
 	error = xfs_bmapi_reserve_delalloc(ip, XFS_COW_FORK, imap->br_startoff,
-			end_fsb - imap->br_startoff, &got, &prev, &idx, eof);
+			end_fsb - imap->br_startoff, &got, &idx, eof);
 	switch (error) {
 	case 0:
 		break;

[PATCH 4.9 185/206] xfs: use new extent lookup helpers in __xfs_reflink_reserve_cow

[Greg Kroah-Hartman]

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------


commit 2755fc4438501c8c28e7783df890e889f6772bee upstream.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 fs/xfs/xfs_reflink.c |   12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

--- a/fs/xfs/xfs_reflink.c
+++ b/fs/xfs/xfs_reflink.c
@@ -243,10 +243,11 @@ xfs_reflink_reserve_cow(
 	struct xfs_bmbt_irec	*imap,
 	bool			*shared)
 {
-	struct xfs_bmbt_irec	got, prev;
+	struct xfs_ifork	*ifp = XFS_IFORK_PTR(ip, XFS_COW_FORK);
+	struct xfs_bmbt_irec	got;
 	xfs_fileoff_t		end_fsb, orig_end_fsb;
-	int			eof = 0, error = 0;
-	bool			trimmed;
+	int			error = 0;
+	bool			eof = false, trimmed;
 	xfs_extnum_t		idx;
 	xfs_extlen_t		align;
 
@@ -258,8 +259,9 @@ xfs_reflink_reserve_cow(
 	 * extent list is generally faster than going out to the shared extent
 	 * tree.
 	 */
-	xfs_bmap_search_extents(ip, imap->br_startoff, XFS_COW_FORK, &eof, &idx,
-			&got, &prev);
+
+	if (!xfs_iext_lookup_extent(ip, ifp, imap->br_startoff, &idx, &got))
+		eof = true;
 	if (!eof && got.br_startoff <= imap->br_startoff) {
 		trace_xfs_reflink_cow_found(ip, imap);
 		xfs_trim_extent(imap, got.br_startoff, got.br_blockcount);

[PATCH 4.9 187/206] xfs: use new extent lookup helpers xfs_file_iomap_begin_delay

[Greg Kroah-Hartman]

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------


commit 656152e552e5cbe0c11ad261b524376217c2fb13 upstream.

And only lookup the previous extent inside xfs_iomap_prealloc_size
if we actually need it.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 fs/xfs/xfs_iomap.c |   20 +++++++++-----------
 1 file changed, 9 insertions(+), 11 deletions(-)

--- a/fs/xfs/xfs_iomap.c
+++ b/fs/xfs/xfs_iomap.c
@@ -395,11 +395,12 @@ xfs_iomap_prealloc_size(
 	struct xfs_inode	*ip,
 	loff_t			offset,
 	loff_t			count,
-	xfs_extnum_t		idx,
-	struct xfs_bmbt_irec	*prev)
+	xfs_extnum_t		idx)
 {
 	struct xfs_mount	*mp = ip->i_mount;
+	struct xfs_ifork	*ifp = XFS_IFORK_PTR(ip, XFS_DATA_FORK);
 	xfs_fileoff_t		offset_fsb = XFS_B_TO_FSBT(mp, offset);
+	struct xfs_bmbt_irec	prev;
 	int			shift = 0;
 	int64_t			freesp;
 	xfs_fsblock_t		qblocks;
@@ -419,8 +420,8 @@ xfs_iomap_prealloc_size(
 	 */
 	if ((mp->m_flags & XFS_MOUNT_DFLT_IOSIZE) ||
 	    XFS_ISIZE(ip) < XFS_FSB_TO_B(mp, mp->m_dalign) ||
-	    idx == 0 ||
-	    prev->br_startoff + prev->br_blockcount < offset_fsb)
+	    !xfs_iext_get_extent(ifp, idx - 1, &prev) ||
+	    prev.br_startoff + prev.br_blockcount < offset_fsb)
 		return mp->m_writeio_blocks;
 
 	/*
@@ -439,8 +440,8 @@ xfs_iomap_prealloc_size(
 	 * always extends to MAXEXTLEN rather than falling short due to things
 	 * like stripe unit/width alignment of real extents.
 	 */
-	if (prev->br_blockcount <= (MAXEXTLEN >> 1))
-		alloc_blocks = prev->br_blockcount << 1;
+	if (prev.br_blockcount <= (MAXEXTLEN >> 1))
+		alloc_blocks = prev.br_blockcount << 1;
 	else
 		alloc_blocks = XFS_B_TO_FSB(mp, offset);
 	if (!alloc_blocks)
@@ -538,7 +539,6 @@ xfs_file_iomap_begin_delay(
 	xfs_fileoff_t		end_fsb, orig_end_fsb;
 	int			error = 0, eof = 0;
 	struct xfs_bmbt_irec	got;
-	struct xfs_bmbt_irec	prev;
 	xfs_extnum_t		idx;
 
 	ASSERT(!XFS_IS_REALTIME_INODE(ip));
@@ -563,8 +563,7 @@ xfs_file_iomap_begin_delay(
 			goto out_unlock;
 	}
 
-	xfs_bmap_search_extents(ip, offset_fsb, XFS_DATA_FORK, &eof, &idx,
-			&got, &prev);
+	eof = !xfs_iext_lookup_extent(ip, ifp, offset_fsb, &idx, &got);
 	if (!eof && got.br_startoff <= offset_fsb) {
 		if (xfs_is_reflink_inode(ip)) {
 			bool		shared;
@@ -601,8 +600,7 @@ xfs_file_iomap_begin_delay(
 	if (eof) {
 		xfs_fsblock_t	prealloc_blocks;
 
-		prealloc_blocks =
-			xfs_iomap_prealloc_size(ip, offset, count, idx, &prev);
+		prealloc_blocks = xfs_iomap_prealloc_size(ip, offset, count, idx);
 		if (prealloc_blocks) {
 			xfs_extlen_t	align;
 			xfs_off_t	end_offset;

[PATCH 4.9 201/206] xfs: fix double-cleanup when CUI recovery fails

[Greg Kroah-Hartman]

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------


From: "Darrick J. Wong" <darrick.wong@oracle.com>

commit 7a21272b088894070391a94fdd1c67014020fa1d upstream.

Dan Carpenter reported a double-free of rcur if _defer_finish fails
while we're recovering CUI items.  Fix the error recovery to prevent
this.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 fs/xfs/xfs_refcount_item.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/fs/xfs/xfs_refcount_item.c
+++ b/fs/xfs/xfs_refcount_item.c
@@ -526,13 +526,14 @@ xfs_cui_recover(
 	xfs_refcount_finish_one_cleanup(tp, rcur, error);
 	error = xfs_defer_finish(&tp, &dfops, NULL);
 	if (error)
-		goto abort_error;
+		goto abort_defer;
 	set_bit(XFS_CUI_RECOVERED, &cuip->cui_flags);
 	error = xfs_trans_commit(tp);
 	return error;
 
 abort_error:
 	xfs_refcount_finish_one_cleanup(tp, rcur, error);
+abort_defer:
 	xfs_defer_cancel(&dfops);
 	xfs_trans_cancel(tp);
 	return error;

[PATCH 4.9 202/206] xfs: use the actual AG length when reserving blocks

[Greg Kroah-Hartman]

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------


From: "Darrick J. Wong" <darrick.wong@oracle.com>

commit 20e73b000bcded44a91b79429d8fa743247602ad upstream.

We need to use the actual AG length when making per-AG reservations,
since we could otherwise end up reserving more blocks out of the last
AG than there are actual blocks.

Complained-about-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 fs/xfs/libxfs/xfs_ag_resv.c        |    3 +++
 fs/xfs/libxfs/xfs_refcount_btree.c |    9 ++++++---
 fs/xfs/libxfs/xfs_refcount_btree.h |    3 ++-
 fs/xfs/libxfs/xfs_rmap_btree.c     |   14 +++++++-------
 fs/xfs/libxfs/xfs_rmap_btree.h     |    3 ++-
 fs/xfs/xfs_fsops.c                 |   14 ++++++++++++++
 6 files changed, 34 insertions(+), 12 deletions(-)

--- a/fs/xfs/libxfs/xfs_ag_resv.c
+++ b/fs/xfs/libxfs/xfs_ag_resv.c
@@ -256,6 +256,9 @@ xfs_ag_resv_init(
 			goto out;
 	}
 
+	ASSERT(xfs_perag_resv(pag, XFS_AG_RESV_METADATA)->ar_reserved +
+	       xfs_perag_resv(pag, XFS_AG_RESV_AGFL)->ar_reserved <=
+	       pag->pagf_freeblks + pag->pagf_flcount);
 out:
 	return error;
 }
--- a/fs/xfs/libxfs/xfs_refcount_btree.c
+++ b/fs/xfs/libxfs/xfs_refcount_btree.c
@@ -408,13 +408,14 @@ xfs_refcountbt_calc_size(
  */
 xfs_extlen_t
 xfs_refcountbt_max_size(
-	struct xfs_mount	*mp)
+	struct xfs_mount	*mp,
+	xfs_agblock_t		agblocks)
 {
 	/* Bail out if we're uninitialized, which can happen in mkfs. */
 	if (mp->m_refc_mxr[0] == 0)
 		return 0;
 
-	return xfs_refcountbt_calc_size(mp, mp->m_sb.sb_agblocks);
+	return xfs_refcountbt_calc_size(mp, agblocks);
 }
 
 /*
@@ -429,22 +430,24 @@ xfs_refcountbt_calc_reserves(
 {
 	struct xfs_buf		*agbp;
 	struct xfs_agf		*agf;
+	xfs_agblock_t		agblocks;
 	xfs_extlen_t		tree_len;
 	int			error;
 
 	if (!xfs_sb_version_hasreflink(&mp->m_sb))
 		return 0;
 
-	*ask += xfs_refcountbt_max_size(mp);
 
 	error = xfs_alloc_read_agf(mp, NULL, agno, 0, &agbp);
 	if (error)
 		return error;
 
 	agf = XFS_BUF_TO_AGF(agbp);
+	agblocks = be32_to_cpu(agf->agf_length);
 	tree_len = be32_to_cpu(agf->agf_refcount_blocks);
 	xfs_buf_relse(agbp);
 
+	*ask += xfs_refcountbt_max_size(mp, agblocks);
 	*used += tree_len;
 
 	return error;
--- a/fs/xfs/libxfs/xfs_refcount_btree.h
+++ b/fs/xfs/libxfs/xfs_refcount_btree.h
@@ -66,7 +66,8 @@ extern void xfs_refcountbt_compute_maxle
 
 extern xfs_extlen_t xfs_refcountbt_calc_size(struct xfs_mount *mp,
 		unsigned long long len);
-extern xfs_extlen_t xfs_refcountbt_max_size(struct xfs_mount *mp);
+extern xfs_extlen_t xfs_refcountbt_max_size(struct xfs_mount *mp,
+		xfs_agblock_t agblocks);
 
 extern int xfs_refcountbt_calc_reserves(struct xfs_mount *mp,
 		xfs_agnumber_t agno, xfs_extlen_t *ask, xfs_extlen_t *used);
--- a/fs/xfs/libxfs/xfs_rmap_btree.c
+++ b/fs/xfs/libxfs/xfs_rmap_btree.c
@@ -549,13 +549,14 @@ xfs_rmapbt_calc_size(
  */
 xfs_extlen_t
 xfs_rmapbt_max_size(
-	struct xfs_mount	*mp)
+	struct xfs_mount	*mp,
+	xfs_agblock_t		agblocks)
 {
 	/* Bail out if we're uninitialized, which can happen in mkfs. */
 	if (mp->m_rmap_mxr[0] == 0)
 		return 0;
 
-	return xfs_rmapbt_calc_size(mp, mp->m_sb.sb_agblocks);
+	return xfs_rmapbt_calc_size(mp, agblocks);
 }
 
 /*
@@ -570,25 +571,24 @@ xfs_rmapbt_calc_reserves(
 {
 	struct xfs_buf		*agbp;
 	struct xfs_agf		*agf;
-	xfs_extlen_t		pool_len;
+	xfs_agblock_t		agblocks;
 	xfs_extlen_t		tree_len;
 	int			error;
 
 	if (!xfs_sb_version_hasrmapbt(&mp->m_sb))
 		return 0;
 
-	/* Reserve 1% of the AG or enough for 1 block per record. */
-	pool_len = max(mp->m_sb.sb_agblocks / 100, xfs_rmapbt_max_size(mp));
-	*ask += pool_len;
-
 	error = xfs_alloc_read_agf(mp, NULL, agno, 0, &agbp);
 	if (error)
 		return error;
 
 	agf = XFS_BUF_TO_AGF(agbp);
+	agblocks = be32_to_cpu(agf->agf_length);
 	tree_len = be32_to_cpu(agf->agf_rmap_blocks);
 	xfs_buf_relse(agbp);
 
+	/* Reserve 1% of the AG or enough for 1 block per record. */
+	*ask += max(agblocks / 100, xfs_rmapbt_max_size(mp, agblocks));
 	*used += tree_len;
 
 	return error;
--- a/fs/xfs/libxfs/xfs_rmap_btree.h
+++ b/fs/xfs/libxfs/xfs_rmap_btree.h
@@ -60,7 +60,8 @@ extern void xfs_rmapbt_compute_maxlevels
 
 extern xfs_extlen_t xfs_rmapbt_calc_size(struct xfs_mount *mp,
 		unsigned long long len);
-extern xfs_extlen_t xfs_rmapbt_max_size(struct xfs_mount *mp);
+extern xfs_extlen_t xfs_rmapbt_max_size(struct xfs_mount *mp,
+		xfs_agblock_t agblocks);
 
 extern int xfs_rmapbt_calc_reserves(struct xfs_mount *mp,
 		xfs_agnumber_t agno, xfs_extlen_t *ask, xfs_extlen_t *used);
--- a/fs/xfs/xfs_fsops.c
+++ b/fs/xfs/xfs_fsops.c
@@ -631,6 +631,20 @@ xfs_growfs_data_private(
 	xfs_set_low_space_thresholds(mp);
 	mp->m_alloc_set_aside = xfs_alloc_set_aside(mp);
 
+	/*
+	 * If we expanded the last AG, free the per-AG reservation
+	 * so we can reinitialize it with the new size.
+	 */
+	if (new) {
+		struct xfs_perag	*pag;
+
+		pag = xfs_perag_get(mp, agno);
+		error = xfs_ag_resv_free(pag);
+		xfs_perag_put(pag);
+		if (error)
+			goto out;
+	}
+
 	/* Reserve AG metadata blocks. */
 	error = xfs_fs_reserve_ag_blocks(mp);
 	if (error && error != -ENOSPC)

[PATCH 4.9 203/206] xfs: fix crash and data corruption due to removal of busy COW extents

[Greg Kroah-Hartman]

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------


commit a1b7a4dea6166cf46be895bce4aac67ea5160fe8 upstream.

There is a race window between write_cache_pages calling
clear_page_dirty_for_io and XFS calling set_page_writeback, in which
the mapping for an inode is tagged neither as dirty, nor as writeback.

If the COW shrinker hits in exactly that window we'll remove the delayed
COW extents and writepages trying to write it back, which in release
kernels will manifest as corruption of the bmap btree, and in debug
kernels will trip the ASSERT about now calling xfs_bmapi_write with the
COWFORK flag for holes.  A complex customer load manages to hit this
window fairly reliably, probably by always having COW writeback in flight
while the cow shrinker runs.

This patch adds another check for having the I_DIRTY_PAGES flag set,
which is still set during this race window.  While this fixes the problem
I'm still not overly happy about the way the COW shrinker works as it
still seems a bit fragile.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 fs/xfs/xfs_icache.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/fs/xfs/xfs_icache.c
+++ b/fs/xfs/xfs_icache.c
@@ -1599,7 +1599,8 @@ xfs_inode_free_cowblocks(
 	 * If the mapping is dirty or under writeback we cannot touch the
 	 * CoW fork.  Leave it alone if we're in the midst of a directio.
 	 */
-	if (mapping_tagged(VFS_I(ip)->i_mapping, PAGECACHE_TAG_DIRTY) ||
+	if ((VFS_I(ip)->i_state & I_DIRTY_PAGES) ||
+	    mapping_tagged(VFS_I(ip)->i_mapping, PAGECACHE_TAG_DIRTY) ||
 	    mapping_tagged(VFS_I(ip)->i_mapping, PAGECACHE_TAG_WRITEBACK) ||
 	    atomic_read(&VFS_I(ip)->i_dio_count))
 		return 0;