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[PATCH 06/23] xfs: verify AGF blocks as they are read from disk

To: xfs@xxxxxxxxxxx
Subject: [PATCH 06/23] xfs: verify AGF blocks as they are read from disk
From: Dave Chinner <david@xxxxxxxxxxxxx>
Date: Fri, 12 Oct 2012 16:44:12 +1100
In-reply-to: <1350020669-19504-1-git-send-email-david@xxxxxxxxxxxxx>
References: <1350020669-19504-1-git-send-email-david@xxxxxxxxxxxxx>
From: Dave Chinner <dchinner@xxxxxxxxxx>

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@xxxxxxxxxx>
---
 fs/xfs/xfs_alloc.c |   60 +++++++++++++++++++++++++++++-----------------------
 1 file changed, 34 insertions(+), 26 deletions(-)

diff --git a/fs/xfs/xfs_alloc.c b/fs/xfs/xfs_alloc.c
index 21c3db0..bd565a2 100644
--- a/fs/xfs/xfs_alloc.c
+++ b/fs/xfs/xfs_alloc.c
@@ -2091,6 +2091,39 @@ 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) &&
+               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("xfs_alloc_read_agf",
+                                    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 +2135,19 @@ 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;
 }
-- 
1.7.10

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