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authorChristoph Hellwig <hch@lst.de>2017-09-17 14:06:40 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-09-20 08:19:59 +0200
commit229980158f95098ba82e7bec91ce8ada18335bdc (patch)
treeb481d6cd30fc85b9eb9c7a9055781fa92b2bacde
parent81e27c94f9ab86c04ba4ca5f1d2bcf9e61f7b5af (diff)
downloadlinux-linaro-stable-229980158f95098ba82e7bec91ce8ada18335bdc.tar.gz
xfs: fix multi-AG deadlock in xfs_bunmapi
commit 5b094d6dac0451ad89b1dc088395c7b399b7e9e8 upstream. Just like in the allocator we must avoid touching multiple AGs out of order when freeing blocks, as freeing still locks the AGF and can cause the same AB-BA deadlocks as in the allocation path. Signed-off-by: Christoph Hellwig <hch@lst.de> Reported-by: Nikolay Borisov <n.borisov.lkml@gmail.com> 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_bmap.c12
1 files changed, 12 insertions, 0 deletions
diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
index 73571fb4dfed..2ab50caca14c 100644
--- a/fs/xfs/libxfs/xfs_bmap.c
+++ b/fs/xfs/libxfs/xfs_bmap.c
@@ -5556,6 +5556,7 @@ __xfs_bunmapi(
xfs_fsblock_t sum;
xfs_filblks_t len = *rlen; /* length to unmap in file */
xfs_fileoff_t max_len;
+ xfs_agnumber_t prev_agno = NULLAGNUMBER, agno;
trace_xfs_bunmap(ip, bno, len, flags, _RET_IP_);
@@ -5658,6 +5659,17 @@ __xfs_bunmapi(
ASSERT(ep != NULL);
del = got;
wasdel = isnullstartblock(del.br_startblock);
+
+ /*
+ * Make sure we don't touch multiple AGF headers out of order
+ * in a single transaction, as that could cause AB-BA deadlocks.
+ */
+ if (!wasdel) {
+ agno = XFS_FSB_TO_AGNO(mp, del.br_startblock);
+ if (prev_agno != NULLAGNUMBER && prev_agno > agno)
+ break;
+ prev_agno = agno;
+ }
if (got.br_startoff < start) {
del.br_startoff = start;
del.br_blockcount -= start - got.br_startoff;