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authorChristoph Hellwig <hch@lst.de>2017-10-03 18:58:33 +0300
committerDarrick J. Wong <darrick.wong@oracle.com>2017-10-04 07:27:55 +0300
commite12199f85d0ad1b04ce6c425ad93cd847fe930bb (patch)
treea4d96867b24d45f6e627b72f9d804ed2cb3e92b1
parent52bfcdd7adbc26639bc7b2356ab9a3f5dad68ad6 (diff)
downloadlinux-e12199f85d0ad1b04ce6c425ad93cd847fe930bb.tar.xz
xfs: handle racy AIO in xfs_reflink_end_cow
If we got two AIO writes into a COW area the second one might not have any COW extents left to convert. Handle that case gracefully instead of triggering an assert or accessing beyond the bounds of the extent list. Signed-off-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>
-rw-r--r--fs/xfs/xfs_reflink.c9
1 files changed, 8 insertions, 1 deletions
diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c
index 3246815c24d6..37e603bf1591 100644
--- a/fs/xfs/xfs_reflink.c
+++ b/fs/xfs/xfs_reflink.c
@@ -736,7 +736,13 @@ xfs_reflink_end_cow(
/* If there is a hole at end_fsb - 1 go to the previous extent */
if (!xfs_iext_lookup_extent(ip, ifp, end_fsb - 1, &idx, &got) ||
got.br_startoff > end_fsb) {
- ASSERT(idx > 0);
+ /*
+ * In case of racing, overlapping AIO writes no COW extents
+ * might be left by the time I/O completes for the loser of
+ * the race. In that case we are done.
+ */
+ if (idx <= 0)
+ goto out_cancel;
xfs_iext_get_extent(ifp, --idx, &got);
}
@@ -809,6 +815,7 @@ next_extent:
out_defer:
xfs_defer_cancel(&dfops);
+out_cancel:
xfs_trans_cancel(tp);
xfs_iunlock(ip, XFS_ILOCK_EXCL);
out: