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authorBrian Foster <bfoster@redhat.com>2016-11-10 00:23:22 +0300
committerDave Chinner <david@fromorbit.com>2016-11-10 00:23:22 +0300
commit98efe8af1c9ffac47e842b7a75ded903e2f028da (patch)
tree9305e6e6013f166bb305a612b24121efd5769617 /fs/xfs/xfs_inode.h
parent5d829300bee000980a09ac2ccb761cb25867b67c (diff)
downloadlinux-98efe8af1c9ffac47e842b7a75ded903e2f028da.tar.xz
xfs: fix unbalanced inode reclaim flush locking
Filesystem shutdown testing on an older distro kernel has uncovered an imbalanced locking pattern for the inode flush lock in xfs_reclaim_inode(). Specifically, there is a double unlock sequence between the call to xfs_iflush_abort() and xfs_reclaim_inode() at the "reclaim:" label. This actually does not cause obvious problems on current kernels due to the current flush lock implementation. Older kernels use a counting based flush lock mechanism, however, which effectively breaks the lock indefinitely when an already unlocked flush lock is repeatedly unlocked. Though this only currently occurs on filesystem shutdown, it has reproduced the effect of elevating an fs shutdown to a system-wide crash or hang. As it turns out, the flush lock is not actually required for the reclaim logic in xfs_reclaim_inode() because by that time we have already cycled the flush lock once while holding ILOCK_EXCL. Therefore, remove the additional flush lock/unlock cycle around the 'reclaim:' label and update branches into this label to release the flush lock where appropriate. Add an assert to xfs_ifunlock() to help prevent future occurences of the same problem. Reported-by: Zorro Lang <zlang@redhat.com> Signed-off-by: Brian Foster <bfoster@redhat.com> Reviewed-by: Dave Chinner <dchinner@redhat.com> Signed-off-by: Dave Chinner <david@fromorbit.com>
Diffstat (limited to 'fs/xfs/xfs_inode.h')
-rw-r--r--fs/xfs/xfs_inode.h11
1 files changed, 6 insertions, 5 deletions
diff --git a/fs/xfs/xfs_inode.h b/fs/xfs/xfs_inode.h
index f14c1de2549d..71e8a81c91a3 100644
--- a/fs/xfs/xfs_inode.h
+++ b/fs/xfs/xfs_inode.h
@@ -246,6 +246,11 @@ static inline bool xfs_is_reflink_inode(struct xfs_inode *ip)
* Synchronize processes attempting to flush the in-core inode back to disk.
*/
+static inline int xfs_isiflocked(struct xfs_inode *ip)
+{
+ return xfs_iflags_test(ip, XFS_IFLOCK);
+}
+
extern void __xfs_iflock(struct xfs_inode *ip);
static inline int xfs_iflock_nowait(struct xfs_inode *ip)
@@ -261,16 +266,12 @@ static inline void xfs_iflock(struct xfs_inode *ip)
static inline void xfs_ifunlock(struct xfs_inode *ip)
{
+ ASSERT(xfs_isiflocked(ip));
xfs_iflags_clear(ip, XFS_IFLOCK);
smp_mb();
wake_up_bit(&ip->i_flags, __XFS_IFLOCK_BIT);
}
-static inline int xfs_isiflocked(struct xfs_inode *ip)
-{
- return xfs_iflags_test(ip, XFS_IFLOCK);
-}
-
/*
* Flags for inode locking.
* Bit ranges: 1<<1 - 1<<16-1 -- iolock/ilock modes (bitfield)