xfs: verify AGF blocks as they are read from disk

Add an AGF block verify callback function and pass it into the
buffer read functions. This replaces the existing verification that
is done after the read completes.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>

diff --git a/fs/xfs/xfs_alloc.c b/fs/xfs/xfs_alloc.c
index 21c3db08fd014277f90fb1ad3f97cef4df80998f..c9eb955a49c71fe4e6f3d845c19454d3df00495e 100644 (file)
--- a/fs/xfs/xfs_alloc.c
+++ b/fs/xfs/xfs_alloc.c
@@ -2091,6 +2091,47 @@ xfs_alloc_put_freelist(
        return 0;
 }
 
+static void
+xfs_agf_read_verify(
+       struct xfs_buf  *bp)
+ {
+       struct xfs_mount *mp = bp->b_target->bt_mount;
+       struct xfs_agf  *agf;
+       int             agf_ok;
+
+       agf = XFS_BUF_TO_AGF(bp);
+
+       agf_ok = agf->agf_magicnum == cpu_to_be32(XFS_AGF_MAGIC) &&
+               XFS_AGF_GOOD_VERSION(be32_to_cpu(agf->agf_versionnum)) &&
+               be32_to_cpu(agf->agf_freeblks) <= be32_to_cpu(agf->agf_length) &&
+               be32_to_cpu(agf->agf_flfirst) < XFS_AGFL_SIZE(mp) &&
+               be32_to_cpu(agf->agf_fllast) < XFS_AGFL_SIZE(mp) &&
+               be32_to_cpu(agf->agf_flcount) <= XFS_AGFL_SIZE(mp);
+
+       /*
+        * during growfs operations, the perag is not fully initialised,
+        * so we can't use it for any useful checking. growfs ensures we can't
+        * use it by using uncached buffers that don't have the perag attached
+        * so we can detect and avoid this problem.
+        */
+       if (bp->b_pag)
+               agf_ok = agf_ok && be32_to_cpu(agf->agf_seqno) ==
+                                               bp->b_pag->pag_agno;
+
+       if (xfs_sb_version_haslazysbcount(&mp->m_sb))
+               agf_ok = agf_ok && be32_to_cpu(agf->agf_btreeblks) <=
+                                               be32_to_cpu(agf->agf_length);
+
+       if (unlikely(XFS_TEST_ERROR(!agf_ok, mp, XFS_ERRTAG_ALLOC_READ_AGF,
+                       XFS_RANDOM_ALLOC_READ_AGF))) {
+               XFS_CORRUPTION_ERROR(__func__, XFS_ERRLEVEL_LOW, mp, agf);
+               xfs_buf_ioerror(bp, EFSCORRUPTED);
+       }
+
+       bp->b_iodone = NULL;
+       xfs_buf_ioend(bp, 0);
+}
+
 /*
  * Read in the allocation group header (free/alloc section).
  */
@@ -2102,44 +2143,19 @@ xfs_read_agf(
        int                     flags,  /* XFS_BUF_ */
        struct xfs_buf          **bpp)  /* buffer for the ag freelist header */
 {
-       struct xfs_agf  *agf;           /* ag freelist header */
-       int             agf_ok;         /* set if agf is consistent */
        int             error;
 
        ASSERT(agno != NULLAGNUMBER);
        error = xfs_trans_read_buf(
                        mp, tp, mp->m_ddev_targp,
                        XFS_AG_DADDR(mp, agno, XFS_AGF_DADDR(mp)),
-                       XFS_FSS_TO_BB(mp, 1), flags, bpp, NULL);
+                       XFS_FSS_TO_BB(mp, 1), flags, bpp, xfs_agf_read_verify);
        if (error)
                return error;
        if (!*bpp)
                return 0;
 
        ASSERT(!(*bpp)->b_error);
-       agf = XFS_BUF_TO_AGF(*bpp);
-
-       /*
-        * Validate the magic number of the agf block.
-        */
-       agf_ok =
-               agf->agf_magicnum == cpu_to_be32(XFS_AGF_MAGIC) &&
-               XFS_AGF_GOOD_VERSION(be32_to_cpu(agf->agf_versionnum)) &&
-               be32_to_cpu(agf->agf_freeblks) <= be32_to_cpu(agf->agf_length) &&
-               be32_to_cpu(agf->agf_flfirst) < XFS_AGFL_SIZE(mp) &&
-               be32_to_cpu(agf->agf_fllast) < XFS_AGFL_SIZE(mp) &&
-               be32_to_cpu(agf->agf_flcount) <= XFS_AGFL_SIZE(mp) &&
-               be32_to_cpu(agf->agf_seqno) == agno;
-       if (xfs_sb_version_haslazysbcount(&mp->m_sb))
-               agf_ok = agf_ok && be32_to_cpu(agf->agf_btreeblks) <=
-                                               be32_to_cpu(agf->agf_length);
-       if (unlikely(XFS_TEST_ERROR(!agf_ok, mp, XFS_ERRTAG_ALLOC_READ_AGF,
-                       XFS_RANDOM_ALLOC_READ_AGF))) {
-               XFS_CORRUPTION_ERROR("xfs_alloc_read_agf",
-                                    XFS_ERRLEVEL_LOW, mp, agf);
-               xfs_trans_brelse(tp, *bpp);
-               return XFS_ERROR(EFSCORRUPTED);
-       }
        xfs_buf_set_ref(*bpp, XFS_AGF_REF);
        return 0;
 }