xfs: detect empty attr leaf blocks in xfs_attr3_leaf_verify

xfs_repair flags these as a corruption error, so the verifier should
catch software bugs that result in empty leaf blocks being written
to disk, too.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Allison Henderson <allison.henderson@oracle.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Dave Chinner <david@fromorbit.com>

diff --git a/fs/xfs/libxfs/xfs_attr_leaf.c b/fs/xfs/libxfs/xfs_attr_leaf.c
index d15e92858bf0c3f003c19746a5f66f0873f4c666..15a99040946345ace573fb3eeaa706220f1fb626 100644 (file)
--- a/fs/xfs/libxfs/xfs_attr_leaf.c
+++ b/fs/xfs/libxfs/xfs_attr_leaf.c
@@ -310,6 +310,15 @@ xfs_attr3_leaf_verify(
        if (fa)
                return fa;
 
+       /*
+        * Empty leaf blocks should never occur;  they imply the existence of a
+        * software bug that needs fixing. xfs_repair also flags them as a
+        * corruption that needs fixing, so we should never let these go to
+        * disk.
+        */
+       if (ichdr.count == 0)
+               return __this_address;
+
        /*
         * firstused is the block offset of the first name info structure.
         * Make sure it doesn't go off the block or crash into the header.