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authorOmar Sandoval <osandov@fb.com>2017-09-17 14:06:42 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-09-20 08:19:59 +0200
commit8edd73a13dc03d4bdcb25d9273908a901f880d09 (patch)
tree76dbd59d6d18d37f654c57ae26db3c4296222658
parentf90756d75d69cb05d82a061c799c54dc46e1db1b (diff)
downloadlinux-linaro-stable-8edd73a13dc03d4bdcb25d9273908a901f880d09.tar.gz
xfs: fix inobt inode allocation search optimization
commit c44245b3d5435f533ca8346ece65918f84c057f9 upstream. When we try to allocate a free inode by searching the inobt, we try to find the inode nearest the parent inode by searching chunks both left and right of the chunk containing the parent. As an optimization, we cache the leftmost and rightmost records that we previously searched; if we do another allocation with the same parent inode, we'll pick up the search where it last left off. There's a bug in the case where we found a free inode to the left of the parent's chunk: we need to update the cached left and right records, but because we already reassigned the right record to point to the left, we end up assigning the left record to both the cached left and right records. This isn't a correctness problem strictly, but it can result in the next allocation rechecking chunks unnecessarily or allocating inodes further away from the parent than it needs to. Fix it by swapping the record pointer after we update the cached left and right records. Fixes: bd169565993b ("xfs: speed up free inode search") Signed-off-by: Omar Sandoval <osandov@fb.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--fs/xfs/libxfs/xfs_ialloc.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/fs/xfs/libxfs/xfs_ialloc.c b/fs/xfs/libxfs/xfs_ialloc.c
index a2818f6e8598..af6acd5f276c 100644
--- a/fs/xfs/libxfs/xfs_ialloc.c
+++ b/fs/xfs/libxfs/xfs_ialloc.c
@@ -1236,13 +1236,13 @@ xfs_dialloc_ag_inobt(
/* free inodes to the left? */
if (useleft && trec.ir_freecount) {
- rec = trec;
xfs_btree_del_cursor(cur, XFS_BTREE_NOERROR);
cur = tcur;
pag->pagl_leftrec = trec.ir_startino;
pag->pagl_rightrec = rec.ir_startino;
pag->pagl_pagino = pagino;
+ rec = trec;
goto alloc_inode;
}