[PATCH V8 02/19] xfs: Define max extent length based on on-disk format definition

Chandan Babu R
2022-03-21T05:18:32Z

The maximum extent length depends on maximum block count that can be stored in
a BMBT record. Hence this commit defines MAXEXTLEN based on
BMBT_BLOCKCOUNT_BITLEN.

While at it, the commit also renames MAXEXTLEN to XFS_MAX_BMBT_EXTLEN.

Suggested-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Chandan Babu R <chandan.babu@oracle.com>
---
fs/xfs/libxfs/xfs_alloc.c | 2 +-
fs/xfs/libxfs/xfs_bmap.c | 57 +++++++++++++++++-----------------
fs/xfs/libxfs/xfs_format.h | 5 +--
fs/xfs/libxfs/xfs_inode_buf.c | 4 +--
fs/xfs/libxfs/xfs_trans_resv.c | 11 ++++---
fs/xfs/scrub/bmap.c | 2 +-
fs/xfs/xfs_bmap_util.c | 14 +++++----
fs/xfs/xfs_iomap.c | 28 ++++++++---------
8 files changed, 64 insertions(+), 59 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_alloc.c b/fs/xfs/libxfs/xfs_alloc.c
index 353e53b892e6..3f9b9cbfef43 100644
--- a/fs/xfs/libxfs/xfs_alloc.c
+++ b/fs/xfs/libxfs/xfs_alloc.c
@@ -2493,7 +2493,7 @@ __xfs_free_extent_later(

ASSERT(bno != NULLFSBLOCK);
ASSERT(len > 0);
- ASSERT(len <= MAXEXTLEN);
+ ASSERT(len <= XFS_MAX_BMBT_EXTLEN);
ASSERT(!isnullstartblock(bno));
agno = XFS_FSB_TO_AGNO(mp, bno);
agbno = XFS_FSB_TO_AGBNO(mp, bno);
diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
index 74198dd82b03..00b8e6e1c404 100644
--- a/fs/xfs/libxfs/xfs_bmap.c
+++ b/fs/xfs/libxfs/xfs_bmap.c
@@ -1452,7 +1452,7 @@ xfs_bmap_add_extent_delay_real(
LEFT.br_startoff + LEFT.br_blockcount == new->br_startoff &&
LEFT.br_startblock + LEFT.br_blockcount == new->br_startblock &&
LEFT.br_state == new->br_state &&
- LEFT.br_blockcount + new->br_blockcount <= MAXEXTLEN)
+ LEFT.br_blockcount + new->br_blockcount <= XFS_MAX_BMBT_EXTLEN)
state |= BMAP_LEFT_CONTIG;

/*
@@ -1470,13 +1470,13 @@ xfs_bmap_add_extent_delay_real(
new_endoff == RIGHT.br_startoff &&
new->br_startblock + new->br_blockcount == RIGHT.br_startblock &&
new->br_state == RIGHT.br_state &&
- new->br_blockcount + RIGHT.br_blockcount <= MAXEXTLEN &&
+ new->br_blockcount + RIGHT.br_blockcount <= XFS_MAX_BMBT_EXTLEN &&
((state & (BMAP_LEFT_CONTIG | BMAP_LEFT_FILLING |
BMAP_RIGHT_FILLING)) !=
(BMAP_LEFT_CONTIG | BMAP_LEFT_FILLING |
BMAP_RIGHT_FILLING) ||
LEFT.br_blockcount + new->br_blockcount + RIGHT.br_blockcount
- <= MAXEXTLEN))
+ <= XFS_MAX_BMBT_EXTLEN))
state |= BMAP_RIGHT_CONTIG;

error = 0;
@@ -2000,7 +2000,7 @@ xfs_bmap_add_extent_unwritten_real(
LEFT.br_startoff + LEFT.br_blockcount == new->br_startoff &&
LEFT.br_startblock + LEFT.br_blockcount == new->br_startblock &&
LEFT.br_state == new->br_state &&
- LEFT.br_blockcount + new->br_blockcount <= MAXEXTLEN)
+ LEFT.br_blockcount + new->br_blockcount <= XFS_MAX_BMBT_EXTLEN)
state |= BMAP_LEFT_CONTIG;

/*
@@ -2018,13 +2018,13 @@ xfs_bmap_add_extent_unwritten_real(
new_endoff == RIGHT.br_startoff &&
new->br_startblock + new->br_blockcount == RIGHT.br_startblock &&
new->br_state == RIGHT.br_state &&
- new->br_blockcount + RIGHT.br_blockcount <= MAXEXTLEN &&
+ new->br_blockcount + RIGHT.br_blockcount <= XFS_MAX_BMBT_EXTLEN &&
((state & (BMAP_LEFT_CONTIG | BMAP_LEFT_FILLING |
BMAP_RIGHT_FILLING)) !=
(BMAP_LEFT_CONTIG | BMAP_LEFT_FILLING |
BMAP_RIGHT_FILLING) ||
LEFT.br_blockcount + new->br_blockcount + RIGHT.br_blockcount
- <= MAXEXTLEN))
+ <= XFS_MAX_BMBT_EXTLEN))
state |= BMAP_RIGHT_CONTIG;

/*
@@ -2510,15 +2510,15 @@ xfs_bmap_add_extent_hole_delay(
*/
if ((state & BMAP_LEFT_VALID) && (state & BMAP_LEFT_DELAY) &&
left.br_startoff + left.br_blockcount == new->br_startoff &&
- left.br_blockcount + new->br_blockcount <= MAXEXTLEN)
+ left.br_blockcount + new->br_blockcount <= XFS_MAX_BMBT_EXTLEN)
state |= BMAP_LEFT_CONTIG;

if ((state & BMAP_RIGHT_VALID) && (state & BMAP_RIGHT_DELAY) &&
new->br_startoff + new->br_blockcount == right.br_startoff &&
- new->br_blockcount + right.br_blockcount <= MAXEXTLEN &&
+ new->br_blockcount + right.br_blockcount <= XFS_MAX_BMBT_EXTLEN &&
(!(state & BMAP_LEFT_CONTIG) ||
(left.br_blockcount + new->br_blockcount +
- right.br_blockcount <= MAXEXTLEN)))
+ right.br_blockcount <= XFS_MAX_BMBT_EXTLEN)))
state |= BMAP_RIGHT_CONTIG;

/*
@@ -2661,17 +2661,17 @@ xfs_bmap_add_extent_hole_real(
left.br_startoff + left.br_blockcount == new->br_startoff &&
left.br_startblock + left.br_blockcount == new->br_startblock &&
left.br_state == new->br_state &&
- left.br_blockcount + new->br_blockcount <= MAXEXTLEN)
+ left.br_blockcount + new->br_blockcount <= XFS_MAX_BMBT_EXTLEN)
state |= BMAP_LEFT_CONTIG;

if ((state & BMAP_RIGHT_VALID) && !(state & BMAP_RIGHT_DELAY) &&
new->br_startoff + new->br_blockcount == right.br_startoff &&
new->br_startblock + new->br_blockcount == right.br_startblock &&
new->br_state == right.br_state &&
- new->br_blockcount + right.br_blockcount <= MAXEXTLEN &&
+ new->br_blockcount + right.br_blockcount <= XFS_MAX_BMBT_EXTLEN &&
(!(state & BMAP_LEFT_CONTIG) ||
left.br_blockcount + new->br_blockcount +
- right.br_blockcount <= MAXEXTLEN))
+ right.br_blockcount <= XFS_MAX_BMBT_EXTLEN))
state |= BMAP_RIGHT_CONTIG;

error = 0;
@@ -2906,15 +2906,15 @@ xfs_bmap_extsize_align(

/*
* For large extent hint sizes, the aligned extent might be larger than
- * MAXEXTLEN. In that case, reduce the size by an extsz so that it pulls
- * the length back under MAXEXTLEN. The outer allocation loops handle
- * short allocation just fine, so it is safe to do this. We only want to
- * do it when we are forced to, though, because it means more allocation
- * operations are required.
+ * XFS_BMBT_MAX_EXTLEN. In that case, reduce the size by an extsz so
+ * that it pulls the length back under XFS_BMBT_MAX_EXTLEN. The outer
+ * allocation loops handle short allocation just fine, so it is safe to
+ * do this. We only want to do it when we are forced to, though, because
+ * it means more allocation operations are required.
*/
- while (align_alen > MAXEXTLEN)
+ while (align_alen > XFS_MAX_BMBT_EXTLEN)
align_alen -= extsz;
- ASSERT(align_alen <= MAXEXTLEN);
+ ASSERT(align_alen <= XFS_MAX_BMBT_EXTLEN);

/*
* If the previous block overlaps with this proposed allocation
@@ -3004,9 +3004,9 @@ xfs_bmap_extsize_align(
return -EINVAL;
} else {
ASSERT(orig_off >= align_off);
- /* see MAXEXTLEN handling above */
+ /* see XFS_BMBT_MAX_EXTLEN handling above */
ASSERT(orig_end <= align_off + align_alen ||
- align_alen + extsz > MAXEXTLEN);
+ align_alen + extsz > XFS_MAX_BMBT_EXTLEN);
}

#ifdef DEBUG
@@ -3971,7 +3971,7 @@ xfs_bmapi_reserve_delalloc(
* Cap the alloc length. Keep track of prealloc so we know whether to
* tag the inode before we return.
*/
- alen = XFS_FILBLKS_MIN(len + prealloc, MAXEXTLEN);
+ alen = XFS_FILBLKS_MIN(len + prealloc, XFS_MAX_BMBT_EXTLEN);
if (!eof)
alen = XFS_FILBLKS_MIN(alen, got->br_startoff - aoff);
if (prealloc && alen >= len)
@@ -4104,7 +4104,7 @@ xfs_bmapi_allocate(
if (!xfs_iext_peek_prev_extent(ifp, &bma->icur, &bma->prev))
bma->prev.br_startoff = NULLFILEOFF;
} else {
- bma->length = XFS_FILBLKS_MIN(bma->length, MAXEXTLEN);
+ bma->length = XFS_FILBLKS_MIN(bma->length, XFS_MAX_BMBT_EXTLEN);
if (!bma->eof)
bma->length = XFS_FILBLKS_MIN(bma->length,
bma->got.br_startoff - bma->offset);
@@ -4424,8 +4424,8 @@ xfs_bmapi_write(
* xfs_extlen_t and therefore 32 bits. Hence we have to
* check for 32-bit overflows and handle them here.
*/
- if (len > (xfs_filblks_t)MAXEXTLEN)
- bma.length = MAXEXTLEN;
+ if (len > (xfs_filblks_t)XFS_MAX_BMBT_EXTLEN)
+ bma.length = XFS_MAX_BMBT_EXTLEN;
else
bma.length = len;

@@ -4560,7 +4560,8 @@ xfs_bmapi_convert_delalloc(
bma.ip = ip;
bma.wasdel = true;
bma.offset = bma.got.br_startoff;
- bma.length = max_t(xfs_filblks_t, bma.got.br_blockcount, MAXEXTLEN);
+ bma.length = max_t(xfs_filblks_t, bma.got.br_blockcount,
+ XFS_MAX_BMBT_EXTLEN);
bma.minleft = xfs_bmapi_minleft(tp, ip, whichfork);

/*
@@ -4641,7 +4642,7 @@ xfs_bmapi_remap(

ifp = XFS_IFORK_PTR(ip, whichfork);
ASSERT(len > 0);
- ASSERT(len <= (xfs_filblks_t)MAXEXTLEN);
+ ASSERT(len <= (xfs_filblks_t)XFS_MAX_BMBT_EXTLEN);
ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
ASSERT(!(flags & ~(XFS_BMAPI_ATTRFORK | XFS_BMAPI_PREALLOC |
XFS_BMAPI_NORMAP)));
@@ -5641,7 +5642,7 @@ xfs_bmse_can_merge(
if ((left->br_startoff + left->br_blockcount != startoff) ||
(left->br_startblock + left->br_blockcount != got->br_startblock) ||
(left->br_state != got->br_state) ||
- (left->br_blockcount + got->br_blockcount > MAXEXTLEN))
+ (left->br_blockcount + got->br_blockcount > XFS_MAX_BMBT_EXTLEN))
return false;

return true;
diff --git a/fs/xfs/libxfs/xfs_format.h b/fs/xfs/libxfs/xfs_format.h
index d75e5b16da7e..66594853a88b 100644
--- a/fs/xfs/libxfs/xfs_format.h
+++ b/fs/xfs/libxfs/xfs_format.h
@@ -870,9 +870,8 @@ enum xfs_dinode_fmt {
{ XFS_DINODE_FMT_UUID, "uuid" }

/*
- * Max values for extlen, extnum, aextnum.
+ * Max values for extnum and aextnum.
*/
-#define MAXEXTLEN ((xfs_extlen_t)0x001fffff) /* 21 bits */
#define MAXEXTNUM ((xfs_extnum_t)0x7fffffff) /* signed int */
#define MAXAEXTNUM ((xfs_aextnum_t)0x7fff) /* signed short */

@@ -1603,6 +1602,8 @@ typedef struct xfs_bmdr_block {
#define BMBT_STARTOFF_MASK ((1ULL << BMBT_STARTOFF_BITLEN) - 1)
#define BMBT_BLOCKCOUNT_MASK ((1ULL << BMBT_BLOCKCOUNT_BITLEN) - 1)

+#define XFS_MAX_BMBT_EXTLEN ((xfs_extlen_t)(BMBT_BLOCKCOUNT_MASK))
+
/*
* bmbt records have a file offset (block) field that is 54 bits wide, so this
* is the largest xfs_fileoff_t that we ever expect to see.
diff --git a/fs/xfs/libxfs/xfs_inode_buf.c b/fs/xfs/libxfs/xfs_inode_buf.c
index cae9708c8587..87781a5d5a45 100644
--- a/fs/xfs/libxfs/xfs_inode_buf.c
+++ b/fs/xfs/libxfs/xfs_inode_buf.c
@@ -639,7 +639,7 @@ xfs_inode_validate_extsize(
if (extsize_bytes % blocksize_bytes)
return __this_address;

- if (extsize > MAXEXTLEN)
+ if (extsize > XFS_MAX_BMBT_EXTLEN)
return __this_address;

if (!rt_flag && extsize > mp->m_sb.sb_agblocks / 2)
@@ -696,7 +696,7 @@ xfs_inode_validate_cowextsize(
if (cowextsize_bytes % mp->m_sb.sb_blocksize)
return __this_address;

- if (cowextsize > MAXEXTLEN)
+ if (cowextsize > XFS_MAX_BMBT_EXTLEN)
return __this_address;

if (cowextsize > mp->m_sb.sb_agblocks / 2)
diff --git a/fs/xfs/libxfs/xfs_trans_resv.c b/fs/xfs/libxfs/xfs_trans_resv.c
index 6f83d9b306ee..8e1d09e8cc9a 100644
--- a/fs/xfs/libxfs/xfs_trans_resv.c
+++ b/fs/xfs/libxfs/xfs_trans_resv.c
@@ -199,8 +199,8 @@ xfs_calc_inode_chunk_res(
/*
* Per-extent log reservation for the btree changes involved in freeing or
* allocating a realtime extent. We have to be able to log as many rtbitmap
- * blocks as needed to mark inuse MAXEXTLEN blocks' worth of realtime extents,
- * as well as the realtime summary block.
+ * blocks as needed to mark inuse XFS_BMBT_MAX_EXTLEN blocks' worth of realtime
+ * extents, as well as the realtime summary block.
*/
static unsigned int
xfs_rtalloc_log_count(
@@ -210,7 +210,7 @@ xfs_rtalloc_log_count(
unsigned int blksz = XFS_FSB_TO_B(mp, 1);
unsigned int rtbmp_bytes;

- rtbmp_bytes = (MAXEXTLEN / mp->m_sb.sb_rextsize) / NBBY;
+ rtbmp_bytes = (XFS_MAX_BMBT_EXTLEN / mp->m_sb.sb_rextsize) / NBBY;
return (howmany(rtbmp_bytes, blksz) + 1) * num_ops;
}

@@ -247,7 +247,7 @@ xfs_rtalloc_log_count(
* the inode's bmap btree: max depth * block size
* the agfs of the ags from which the extents are allocated: 2 * sector
* the superblock free block counter: sector size
- * the realtime bitmap: ((MAXEXTLEN / rtextsize) / NBBY) bytes
+ * the realtime bitmap: ((XFS_BMBT_MAX_EXTLEN / rtextsize) / NBBY) bytes
* the realtime summary: 1 block
* the allocation btrees: 2 trees * (2 * max depth - 1) * block size
* And the bmap_finish transaction can free bmap blocks in a join (t3):
@@ -299,7 +299,8 @@ xfs_calc_write_reservation(
* the agf for each of the ags: 2 * sector size
* the agfl for each of the ags: 2 * sector size
* the super block to reflect the freed blocks: sector size
- * the realtime bitmap: 2 exts * ((MAXEXTLEN / rtextsize) / NBBY) bytes
+ * the realtime bitmap:
+ * 2 exts * ((XFS_BMBT_MAX_EXTLEN / rtextsize) / NBBY) bytes
* the realtime summary: 2 exts * 1 block
* worst case split in allocation btrees per extent assuming 2 extents:
* 2 exts * 2 trees * (2 * max depth - 1) * block size
diff --git a/fs/xfs/scrub/bmap.c b/fs/xfs/scrub/bmap.c
index a4cbbc346f60..c357593e0a02 100644
--- a/fs/xfs/scrub/bmap.c
+++ b/fs/xfs/scrub/bmap.c
@@ -350,7 +350,7 @@ xchk_bmap_iextent(
irec->br_startoff);

/* Make sure the extent points to a valid place. */
- if (irec->br_blockcount > MAXEXTLEN)
+ if (irec->br_blockcount > XFS_MAX_BMBT_EXTLEN)
xchk_fblock_set_corrupt(info->sc, info->whichfork,
irec->br_startoff);
if (info->is_rt &&
diff --git a/fs/xfs/xfs_bmap_util.c b/fs/xfs/xfs_bmap_util.c
index eb2e387ba528..18c1b99311a8 100644
--- a/fs/xfs/xfs_bmap_util.c
+++ b/fs/xfs/xfs_bmap_util.c
@@ -119,14 +119,14 @@ xfs_bmap_rtalloc(
*/
ralen = ap->length / mp->m_sb.sb_rextsize;
/*
- * If the old value was close enough to MAXEXTLEN that
+ * If the old value was close enough to XFS_BMBT_MAX_EXTLEN that
* we rounded up to it, cut it back so it's valid again.
* Note that if it's a really large request (bigger than
- * MAXEXTLEN), we don't hear about that number, and can't
+ * XFS_BMBT_MAX_EXTLEN), we don't hear about that number, and can't
* adjust the starting point to match it.
*/
- if (ralen * mp->m_sb.sb_rextsize >= MAXEXTLEN)
- ralen = MAXEXTLEN / mp->m_sb.sb_rextsize;
+ if (ralen * mp->m_sb.sb_rextsize >= XFS_MAX_BMBT_EXTLEN)
+ ralen = XFS_MAX_BMBT_EXTLEN / mp->m_sb.sb_rextsize;

/*
* Lock out modifications to both the RT bitmap and summary inodes
@@ -839,9 +839,11 @@ xfs_alloc_file_space(
* count, hence we need to limit the number of blocks we are
* trying to reserve to avoid an overflow. We can't allocate
* more than @nimaps extents, and an extent is limited on disk
- * to MAXEXTLEN (21 bits), so use that to enforce the limit.
+ * to XFS_BMBT_MAX_EXTLEN (21 bits), so use that to enforce the
+ * limit.
*/
- resblks = min_t(xfs_fileoff_t, (e - s), (MAXEXTLEN * nimaps));
+ resblks = min_t(xfs_fileoff_t, (e - s),
+ (XFS_MAX_BMBT_EXTLEN * nimaps));
if (unlikely(rt)) {
dblocks = XFS_DIOSTRAT_SPACE_RES(mp, 0);
rblocks = resblks;
diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c
index e552ce541ec2..87e1cf5060bd 100644
--- a/fs/xfs/xfs_iomap.c
+++ b/fs/xfs/xfs_iomap.c
@@ -402,7 +402,7 @@ xfs_iomap_prealloc_size(
*/
plen = prev.br_blockcount;
while (xfs_iext_prev_extent(ifp, &ncur, &got)) {
- if (plen > MAXEXTLEN / 2 ||
+ if (plen > XFS_MAX_BMBT_EXTLEN / 2 ||
isnullstartblock(got.br_startblock) ||
got.br_startoff + got.br_blockcount != prev.br_startoff ||
got.br_startblock + got.br_blockcount != prev.br_startblock)
@@ -414,23 +414,23 @@ xfs_iomap_prealloc_size(
/*
* If the size of the extents is greater than half the maximum extent
* length, then use the current offset as the basis. This ensures that
- * for large files the preallocation size always extends to MAXEXTLEN
- * rather than falling short due to things like stripe unit/width
- * alignment of real extents.
+ * for large files the preallocation size always extends to
+ * XFS_BMBT_MAX_EXTLEN rather than falling short due to things like stripe
+ * unit/width alignment of real extents.
*/
alloc_blocks = plen * 2;
- if (alloc_blocks > MAXEXTLEN)
+ if (alloc_blocks > XFS_MAX_BMBT_EXTLEN)
alloc_blocks = XFS_B_TO_FSB(mp, offset);
qblocks = alloc_blocks;

/*
- * MAXEXTLEN is not a power of two value but we round the prealloc down
- * to the nearest power of two value after throttling. To prevent the
- * round down from unconditionally reducing the maximum supported
- * prealloc size, we round up first, apply appropriate throttling,
- * round down and cap the value to MAXEXTLEN.
+ * XFS_BMBT_MAX_EXTLEN is not a power of two value but we round the prealloc
+ * down to the nearest power of two value after throttling. To prevent
+ * the round down from unconditionally reducing the maximum supported
+ * prealloc size, we round up first, apply appropriate throttling, round
+ * down and cap the value to XFS_BMBT_MAX_EXTLEN.
*/
- alloc_blocks = XFS_FILEOFF_MIN(roundup_pow_of_two(MAXEXTLEN),
+ alloc_blocks = XFS_FILEOFF_MIN(roundup_pow_of_two(XFS_MAX_BMBT_EXTLEN),
alloc_blocks);

freesp = percpu_counter_read_positive(&mp->m_fdblocks);
@@ -478,14 +478,14 @@ xfs_iomap_prealloc_size(
*/
if (alloc_blocks)
alloc_blocks = rounddown_pow_of_two(alloc_blocks);
- if (alloc_blocks > MAXEXTLEN)
- alloc_blocks = MAXEXTLEN;
+ if (alloc_blocks > XFS_MAX_BMBT_EXTLEN)
+ alloc_blocks = XFS_MAX_BMBT_EXTLEN;

/*
* If we are still trying to allocate more space than is
* available, squash the prealloc hard. This can happen if we
* have a large file on a small filesystem and the above
- * lowspace thresholds are smaller than MAXEXTLEN.
+ * lowspace thresholds are smaller than XFS_BMBT_MAX_EXTLEN.
*/
while (alloc_blocks && alloc_blocks >= freesp)
alloc_blocks >>= 4;
--
2.30.2