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authorDavid Chinner <dgc@sgi.com>2006-09-07 08:26:50 +0400
committerDavid Chatterton <chatz@sgi.com>2006-09-07 08:26:50 +0400
commit4be536debe3f7b0c62283e77fd6bd8bdb9f83c6f (patch)
tree0b1ce616c52cb659fc4341afb13bcccaa2499b6c /fs/xfs/xfs_fsops.c
parent10387e5eb45c6e48d67102b88229f5bc6037461c (diff)
downloadlinux-4be536debe3f7b0c62283e77fd6bd8bdb9f83c6f.tar.xz
[XFS] Prevent free space oversubscription and xfssyncd looping.
The fix for recent ENOSPC deadlocks introduced certain limitations on allocations. The fix could cause xfssyncd to loop endlessly if we did not leave some space free for the allocator to work correctly. Basically, we needed to ensure that we had at least 4 blocks free for an AG free list and a block for the inode bmap btree at all times. However, this did not take into account the fact that each AG has a free list that needs 4 blocks. Hence any filesystem with more than one AG could cause oversubscription of free space and make xfssyncd spin forever trying to allocate space needed for AG freelists that was not available in the AG. The following patch reserves space for the free lists in all AGs plus the inode bmap btree which prevents oversubscription. It also prevents those blocks from being reported as free space (as they can never be used) and makes the SMP in-core superblock accounting code and the reserved block ioctl respect this requirement. SGI-PV: 955674 SGI-Modid: xfs-linux-melb:xfs-kern:26894a Signed-off-by: David Chinner <dgc@sgi.com> Signed-off-by: David Chatterton <chatz@sgi.com>
Diffstat (limited to 'fs/xfs/xfs_fsops.c')
-rw-r--r--fs/xfs/xfs_fsops.c16
1 files changed, 10 insertions, 6 deletions
diff --git a/fs/xfs/xfs_fsops.c b/fs/xfs/xfs_fsops.c
index 077629bab532..c064e72ada9e 100644
--- a/fs/xfs/xfs_fsops.c
+++ b/fs/xfs/xfs_fsops.c
@@ -462,7 +462,7 @@ xfs_fs_counts(
xfs_icsb_sync_counters_lazy(mp);
s = XFS_SB_LOCK(mp);
- cnt->freedata = mp->m_sb.sb_fdblocks;
+ cnt->freedata = mp->m_sb.sb_fdblocks - XFS_ALLOC_SET_ASIDE(mp);
cnt->freertx = mp->m_sb.sb_frextents;
cnt->freeino = mp->m_sb.sb_ifree;
cnt->allocino = mp->m_sb.sb_icount;
@@ -519,15 +519,19 @@ xfs_reserve_blocks(
}
mp->m_resblks = request;
} else {
+ __int64_t free;
+
+ free = mp->m_sb.sb_fdblocks - XFS_ALLOC_SET_ASIDE(mp);
delta = request - mp->m_resblks;
- lcounter = mp->m_sb.sb_fdblocks - delta;
+ lcounter = free - delta;
if (lcounter < 0) {
/* We can't satisfy the request, just get what we can */
- mp->m_resblks += mp->m_sb.sb_fdblocks;
- mp->m_resblks_avail += mp->m_sb.sb_fdblocks;
- mp->m_sb.sb_fdblocks = 0;
+ mp->m_resblks += free;
+ mp->m_resblks_avail += free;
+ mp->m_sb.sb_fdblocks = XFS_ALLOC_SET_ASIDE(mp);
} else {
- mp->m_sb.sb_fdblocks = lcounter;
+ mp->m_sb.sb_fdblocks =
+ lcounter + XFS_ALLOC_SET_ASIDE(mp);
mp->m_resblks = request;
mp->m_resblks_avail += delta;
}