[PATCH 08/23] xfs: verify AGFL blocks as they are read from disk

[Dave Chinner <david@xxxxxxxxxxxxx>]

From: Dave Chinner <dchinner@xxxxxxxxxx>

Add an AGFL block verify callback function and pass it into the
buffer read functions. Add a debug only check for valid block
numbers in the AGFL.

Signed-off-by: Dave Chinner <dchinner@xxxxxxxxxx>
---
 fs/xfs/xfs_alloc.c |   25 ++++++++++++++++++++++++-
 1 file changed, 24 insertions(+), 1 deletion(-)

diff --git a/fs/xfs/xfs_alloc.c b/fs/xfs/xfs_alloc.c
index bd565a2..75c5d82 100644
--- a/fs/xfs/xfs_alloc.c
+++ b/fs/xfs/xfs_alloc.c
@@ -430,6 +430,29 @@ xfs_alloc_fixup_trees(
        return 0;
 }
 
+void
+xfs_agfl_read_verify(
+       struct xfs_buf  *bp)
+{
+       struct xfs_mount *mp = bp->b_target->bt_mount;
+       struct xfs_agfl *agfl = XFS_BUF_TO_AGFL(bp);
+       int             agfl_ok = 1;
+       int             i;
+
+       for (i = 0; i < XFS_AGFL_SIZE(mp); i++) {
+               if (agfl->agfl_bno[i] == 0)
+                       agfl = 0;
+       }
+
+       if (!agfl_ok) {
+               XFS_CORRUPTION_ERROR("xfs_agfl_read_verify",
+                                    XFS_ERRLEVEL_LOW, mp, agfl);
+               xfs_buf_ioerror(bp, EFSCORRUPTED);
+       }
+       bp->b_iodone = NULL;
+       xfs_buf_ioend(bp, 0);
+}
+
 /*
  * Read in the allocation group free block array.
  */
@@ -447,7 +470,7 @@ xfs_alloc_read_agfl(
        error = xfs_trans_read_buf(
                        mp, tp, mp->m_ddev_targp,
                        XFS_AG_DADDR(mp, agno, XFS_AGFL_DADDR(mp)),
-                       XFS_FSS_TO_BB(mp, 1), 0, &bp, NULL);
+                       XFS_FSS_TO_BB(mp, 1), 0, &bp, xfs_agfl_read_verify);
        if (error)
                return error;
        ASSERT(!xfs_buf_geterror(bp));
-- 
1.7.10