[XFS] factor out xfs_read_agi helper

Add a helper to read the AGI header and perform basic verification.
Based on hunks from a larger patch from Dave Chinner.

(First sent on Juli 23rd)

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <david@fromorbit.com>
Signed-off-by: Niv Sardi <xaiki@sgi.com>

1 files changed, 6 insertions, 51 deletions

diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
index b97710047062..46b0526acd4e 100644
--- a/fs/xfs/xfs_inode.c
+++ b/fs/xfs/xfs_inode.c
@@ -1843,13 +1843,10 @@ xfs_iunlink(
         xfs_dinode_t    *dip;
         xfs_buf_t       *agibp;
         xfs_buf_t       *ibp;
-        xfs_agnumber_t  agno;
-        xfs_daddr_t     agdaddr;
         xfs_agino_t     agino;
         short           bucket_index;
         int             offset;
         int             error;
-        int             agi_ok;
 
         ASSERT(ip->i_d.di_nlink == 0);
         ASSERT(ip->i_d.di_mode != 0);
@@ -1857,31 +1854,15 @@ xfs_iunlink(
 
         mp = tp->t_mountp;
 
-        agno = XFS_INO_TO_AGNO(mp, ip->i_ino);
-        agdaddr = XFS_AG_DADDR(mp, agno, XFS_AGI_DADDR(mp));
-
         /*
          * Get the agi buffer first.  It ensures lock ordering
          * on the list.
          */
-        error = xfs_trans_read_buf(mp, tp, mp->m_ddev_targp, agdaddr,
-                                   XFS_FSS_TO_BB(mp, 1), 0, &agibp);
+        error = xfs_read_agi(mp, tp, XFS_INO_TO_AGNO(mp, ip->i_ino), &agibp);
         if (error)
                 return error;
-
-        /*
-         * Validate the magic number of the agi block.
-         */
         agi = XFS_BUF_TO_AGI(agibp);
-        agi_ok =
-                be32_to_cpu(agi->agi_magicnum) == XFS_AGI_MAGIC &&
-                XFS_AGI_GOOD_VERSION(be32_to_cpu(agi->agi_versionnum));
-        if (unlikely(XFS_TEST_ERROR(!agi_ok, mp, XFS_ERRTAG_IUNLINK,
-                        XFS_RANDOM_IUNLINK))) {
-                XFS_CORRUPTION_ERROR("xfs_iunlink", XFS_ERRLEVEL_LOW, mp, agi);
-                xfs_trans_brelse(tp, agibp);
-                return XFS_ERROR(EFSCORRUPTED);
-        }
+
         /*
          * Get the index into the agi hash table for the
          * list this inode will go on.
@@ -1941,7 +1922,6 @@ xfs_iunlink_remove(
         xfs_buf_t       *agibp;
         xfs_buf_t       *ibp;
         xfs_agnumber_t  agno;
-        xfs_daddr_t     agdaddr;
         xfs_agino_t     agino;
         xfs_agino_t     next_agino;
         xfs_buf_t       *last_ibp;
@@ -1949,45 +1929,20 @@ xfs_iunlink_remove(
         short           bucket_index;
         int             offset, last_offset = 0;
         int             error;
-        int             agi_ok;
 
-        /*
-         * First pull the on-disk inode from the AGI unlinked list.
-         */
         mp = tp->t_mountp;
-
         agno = XFS_INO_TO_AGNO(mp, ip->i_ino);
-        agdaddr = XFS_AG_DADDR(mp, agno, XFS_AGI_DADDR(mp));
 
         /*
          * Get the agi buffer first.  It ensures lock ordering
          * on the list.
          */
-        error = xfs_trans_read_buf(mp, tp, mp->m_ddev_targp, agdaddr,
-                                   XFS_FSS_TO_BB(mp, 1), 0, &agibp);
-        if (error) {
-                cmn_err(CE_WARN,
-                        "xfs_iunlink_remove: xfs_trans_read_buf()  returned an error %d on %s.  Returning error.",
-                        error, mp->m_fsname);
+        error = xfs_read_agi(mp, tp, agno, &agibp);
+        if (error)
                 return error;
-        }
-        /*
-         * Validate the magic number of the agi block.
-         */
+
         agi = XFS_BUF_TO_AGI(agibp);
-        agi_ok =
-                be32_to_cpu(agi->agi_magicnum) == XFS_AGI_MAGIC &&
-                XFS_AGI_GOOD_VERSION(be32_to_cpu(agi->agi_versionnum));
-        if (unlikely(XFS_TEST_ERROR(!agi_ok, mp, XFS_ERRTAG_IUNLINK_REMOVE,
-                        XFS_RANDOM_IUNLINK_REMOVE))) {
-                XFS_CORRUPTION_ERROR("xfs_iunlink_remove", XFS_ERRLEVEL_LOW,
-                                     mp, agi);
-                xfs_trans_brelse(tp, agibp);
-                cmn_err(CE_WARN,
-                        "xfs_iunlink_remove: XFS_TEST_ERROR()  returned an error on %s.  Returning EFSCORRUPTED.",
-                         mp->m_fsname);
-                return XFS_ERROR(EFSCORRUPTED);
-        }
+
         /*
          * Get the index into the agi hash table for the
          * list this inode will go on.