From: Christoph Hellwig Date: Tue, 3 Oct 2017 15:58:33 +0000 (-0700) Subject: xfs: handle racy AIO in xfs_reflink_end_cow X-Git-Tag: v4.13.10~9 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=199a7448c097514a029d29e666e3dbb3bdd01f92;p=thirdparty%2Fkernel%2Fstable.git xfs: handle racy AIO in xfs_reflink_end_cow commit e12199f85d0ad1b04ce6c425ad93cd847fe930bb upstream. 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 Reviewed-by: Darrick J. Wong Signed-off-by: Darrick J. Wong Signed-off-by: Greg Kroah-Hartman --- diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c index f45fbf0db9bbe..8c8390a7f121e 100644 --- a/fs/xfs/xfs_reflink.c +++ b/fs/xfs/xfs_reflink.c @@ -735,7 +735,13 @@ 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); } @@ -807,6 +813,7 @@ next_extent: out_defer: xfs_defer_cancel(&dfops); +out_cancel: xfs_trans_cancel(tp); xfs_iunlock(ip, XFS_ILOCK_EXCL); out: