1 files changed, 47 insertions, 0 deletions

diff --git a/fs/xfs/xfs_bmap_btree.c b/fs/xfs/xfs_bmap_btree.c
index 862084a47a7e..bddca9b92869 100644
--- a/fs/xfs/xfs_bmap_btree.c
+++ b/fs/xfs/xfs_bmap_btree.c
@@ -36,6 +36,7 @@
 #include "xfs_bmap.h"
 #include "xfs_error.h"
 #include "xfs_quota.h"
+#include "xfs_trace.h"
 
 /*
  * Determine the extent state.
@@ -707,6 +708,51 @@ xfs_bmbt_key_diff(
                                       cur->bc_rec.b.br_startoff;
 }
 
+void
+xfs_bmbt_read_verify(
+        struct xfs_buf          *bp)
+{
+        struct xfs_mount        *mp = bp->b_target->bt_mount;
+        struct xfs_btree_block  *block = XFS_BUF_TO_BLOCK(bp);
+        unsigned int            level;
+        int                     lblock_ok; /* block passes checks */
+
+        /* magic number and level verification.
+         *
+         * We don't know waht fork we belong to, so just verify that the level
+         * is less than the maximum of the two. Later checks will be more
+         * precise.
+         */
+        level = be16_to_cpu(block->bb_level);
+        lblock_ok = block->bb_magic == cpu_to_be32(XFS_BMAP_MAGIC) &&
+                    level < max(mp->m_bm_maxlevels[0], mp->m_bm_maxlevels[1]);
+
+        /* numrecs verification */
+        lblock_ok = lblock_ok &&
+                be16_to_cpu(block->bb_numrecs) <= mp->m_bmap_dmxr[level != 0];
+
+        /* sibling pointer verification */
+        lblock_ok = lblock_ok &&
+                block->bb_u.l.bb_leftsib &&
+                (block->bb_u.l.bb_leftsib == cpu_to_be64(NULLDFSBNO) ||
+                 XFS_FSB_SANITY_CHECK(mp,
+                        be64_to_cpu(block->bb_u.l.bb_leftsib))) &&
+                block->bb_u.l.bb_rightsib &&
+                (block->bb_u.l.bb_rightsib == cpu_to_be64(NULLDFSBNO) ||
+                 XFS_FSB_SANITY_CHECK(mp,
+                        be64_to_cpu(block->bb_u.l.bb_rightsib)));
+
+        if (!lblock_ok) {
+                trace_xfs_btree_corrupt(bp, _RET_IP_);
+                XFS_CORRUPTION_ERROR("xfs_bmbt_read_verify",
+                                        XFS_ERRLEVEL_LOW, mp, block);
+                xfs_buf_ioerror(bp, EFSCORRUPTED);
+        }
+
+        bp->b_iodone = NULL;
+        xfs_buf_ioend(bp, 0);
+}
+
 #ifdef DEBUG
 STATIC int
 xfs_bmbt_keys_inorder(
@@ -746,6 +792,7 @@ static const struct xfs_btree_ops xfs_bmbt_ops = {
         .init_rec_from_cur      = xfs_bmbt_init_rec_from_cur,
         .init_ptr_from_cur      = xfs_bmbt_init_ptr_from_cur,
         .key_diff               = xfs_bmbt_key_diff,
+        .read_verify            = xfs_bmbt_read_verify,
 #ifdef DEBUG
         .keys_inorder           = xfs_bmbt_keys_inorder,
         .recs_inorder           = xfs_bmbt_recs_inorder,