xfs: remove OWN_AG rmap when allocating a block from the AGFL

When we're really tight on space, xfs_alloc_ag_vextent_small() can
allocate a block from the AGFL and give it to the caller.  Since the
caller is never the AGFL-fixing method, we must remove the OWN_AG
reverse mapping because it will clash with whatever rmap the caller
wants to set up.  This bug was discovered by running generic/299
repeatedly.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

1 files changed, 13 insertions, 0 deletions

diff --git a/fs/xfs/libxfs/xfs_alloc.c b/fs/xfs/libxfs/xfs_alloc.c
index af1a72efa64c..3dd8f1d54498 100644
--- a/fs/xfs/libxfs/xfs_alloc.c
+++ b/fs/xfs/libxfs/xfs_alloc.c
@@ -1582,6 +1582,7 @@ xfs_alloc_ag_vextent_small(
         xfs_extlen_t    *flenp, /* result length */
         int             *stat)  /* status: 0-freelist, 1-normal/none */
 {
+        struct xfs_owner_info   oinfo;
         int             error;
         xfs_agblock_t   fbno;
         xfs_extlen_t    flen;
@@ -1624,6 +1625,18 @@ xfs_alloc_ag_vextent_small(
                                 error0);
                         args->wasfromfl = 1;
                         trace_xfs_alloc_small_freelist(args);
+
+                        /*
+                         * If we're feeding an AGFL block to something that
+                         * doesn't live in the free space, we need to clear
+                         * out the OWN_AG rmap.
+                         */
+                        xfs_rmap_ag_owner(&oinfo, XFS_RMAP_OWN_AG);
+                        error = xfs_rmap_free(args->tp, args->agbp, args->agno,
+                                        fbno, 1, &oinfo);
+                        if (error)
+                                goto error0;
+
                         *stat = 0;
                         return 0;
                 }