xfs: correctly decrement the extent buffer index in xfs_bmap_del_extent

The code in xfs_bmap_del_extent does not correctly decrement the
extent buffer index when deleting a whole extent.  Most of the time
this gets caught by checks in xfs_bmapi that work around it and
decrement it manually and thus wasn't noticed so far.

Based on an earlier patch from Lachlan McIlroy.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Lachlan McIlroy <lmcilroy@redhat.com>
Signed-off-by: Alex Elder <aelder@sgi.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/fs/xfs/xfs_bmap.c b/fs/xfs/xfs_bmap.c
index 896e16f08ed9..e546a33214c9 100644
--- a/fs/xfs/xfs_bmap.c
+++ b/fs/xfs/xfs_bmap.c
@@ -2916,8 +2916,10 @@ xfs_bmap_del_extent(
                  */
                 xfs_iext_remove(ip, *idx, 1,
                                 whichfork == XFS_ATTR_FORK ? BMAP_ATTRFORK : 0);
+                --*idx;
                 if (delay)
                         break;
+
                 XFS_IFORK_NEXT_SET(ip, whichfork,
                         XFS_IFORK_NEXTENTS(ip, whichfork) - 1);
                 flags |= XFS_ILOG_CORE;