diff options
| author | Darrick J. Wong <djwong@kernel.org> | 2024-08-30 15:37:06 -0700 |
|---|---|---|
| committer | Darrick J. Wong <djwong@kernel.org> | 2024-09-01 08:58:19 -0700 |
| commit | 9e9be9840fad01dec3ee958fc401c4863c360202 (patch) | |
| tree | 5e794f5c40ba329131d449fa22adb1972fe6d71c /fs/xfs | |
| parent | 74c234bbe51a1b142400ab018b605e2f16274e10 (diff) | |
xfs: fix broken variable-sized allocation detection in xfs_rtallocate_extent_block
This function tries to find a suitable free space extent starting from
a particular rtbitmap block. Some time ago, I added a clamping function
to prevent the free space scans from running off the end of the bitmap,
but I didn't quite get the logic right.
Let's say there's an allocation request with a minlen of 5 and a maxlen
of 32 and we're scanning the last rtbitmap block. If we come within 4
rtx of the end of the rt volume, maxlen will get clamped to 4. If the
next 3 rtx are free, we could have satisfied the allocation, but the
code setting partial besti/bestlen for "minlen < maxlen" will think that
we're doing a non-variable allocation and ignore it.
The root of this problem is overwriting maxlen; I should have stuffed
the results in a different variable, which would not have introduced
this bug.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Diffstat (limited to 'fs/xfs')
| -rw-r--r-- | fs/xfs/xfs_rtalloc.c | 15 |
1 files changed, 9 insertions, 6 deletions
diff --git a/fs/xfs/xfs_rtalloc.c b/fs/xfs/xfs_rtalloc.c index d27bfec08ef8..72123e2337d8 100644 --- a/fs/xfs/xfs_rtalloc.c +++ b/fs/xfs/xfs_rtalloc.c @@ -244,6 +244,7 @@ xfs_rtallocate_extent_block( xfs_rtxnum_t end; /* last rtext in chunk */ xfs_rtxnum_t i; /* current rtext trying */ xfs_rtxnum_t next; /* next rtext to try */ + xfs_rtxlen_t scanlen; /* number of free rtx to look for */ xfs_rtxlen_t bestlen = 0; /* best length found so far */ int stat; /* status from internal calls */ int error; @@ -255,20 +256,22 @@ xfs_rtallocate_extent_block( end = min(mp->m_sb.sb_rextents, xfs_rbmblock_to_rtx(mp, bbno + 1)) - 1; for (i = xfs_rbmblock_to_rtx(mp, bbno); i <= end; i++) { /* Make sure we don't scan off the end of the rt volume. */ - maxlen = xfs_rtallocate_clamp_len(mp, i, maxlen, prod); + scanlen = xfs_rtallocate_clamp_len(mp, i, maxlen, prod); + if (scanlen < minlen) + break; /* - * See if there's a free extent of maxlen starting at i. + * See if there's a free extent of scanlen starting at i. * If it's not so then next will contain the first non-free. */ - error = xfs_rtcheck_range(args, i, maxlen, 1, &next, &stat); + error = xfs_rtcheck_range(args, i, scanlen, 1, &next, &stat); if (error) return error; if (stat) { /* - * i for maxlen is all free, allocate and return that. + * i to scanlen is all free, allocate and return that. */ - *len = maxlen; + *len = scanlen; *rtx = i; return 0; } @@ -299,7 +302,7 @@ xfs_rtallocate_extent_block( } /* Searched the whole thing & didn't find a maxlen free extent. */ - if (minlen > maxlen || besti == -1) + if (besti == -1) goto nospace; /* |