[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, 26 insertions, 46 deletions

diff --git a/fs/xfs/xfs_log_recover.c b/fs/xfs/xfs_log_recover.c
index b411d4947318..b552676ca5c4 100644
--- a/fs/xfs/xfs_log_recover.c
+++ b/fs/xfs/xfs_log_recover.c
@@ -3117,19 +3117,16 @@ xlog_recover_clear_agi_bucket(
         int             error;
 
         tp = xfs_trans_alloc(mp, XFS_TRANS_CLEAR_AGI_BUCKET);
-        error = xfs_trans_reserve(tp, 0, XFS_CLEAR_AGI_BUCKET_LOG_RES(mp), 0, 0, 0);
-        if (!error)
-                error = xfs_trans_read_buf(mp, tp, mp->m_ddev_targp,
-                                   XFS_AG_DADDR(mp, agno, XFS_AGI_DADDR(mp)),
-                                   XFS_FSS_TO_BB(mp, 1), 0, &agibp);
+        error = xfs_trans_reserve(tp, 0, XFS_CLEAR_AGI_BUCKET_LOG_RES(mp),
+                                  0, 0, 0);
         if (error)
                 goto out_abort;
 
-        error = EINVAL;
-        agi = XFS_BUF_TO_AGI(agibp);
-        if (be32_to_cpu(agi->agi_magicnum) != XFS_AGI_MAGIC)
+        error = xfs_read_agi(mp, tp, agno, &agibp);
+        if (error)
                 goto out_abort;
 
+        agi = XFS_BUF_TO_AGI(agibp);
         agi->agi_unlinked[bucket] = cpu_to_be32(NULLAGINO);
         offset = offsetof(xfs_agi_t, agi_unlinked) +
                  (sizeof(xfs_agino_t) * bucket);
@@ -3190,16 +3187,17 @@ xlog_recover_process_iunlinks(
                 /*
                  * Find the agi for this ag.
                  */
-                agibp = xfs_buf_read(mp->m_ddev_targp,
-                                XFS_AG_DADDR(mp, agno, XFS_AGI_DADDR(mp)),
-                                XFS_FSS_TO_BB(mp, 1), 0);
-                if (XFS_BUF_ISERROR(agibp)) {
-                        xfs_ioerror_alert("xlog_recover_process_iunlinks(#1)",
-                                log->l_mp, agibp,
-                                XFS_AG_DADDR(mp, agno, XFS_AGI_DADDR(mp)));
+                error = xfs_read_agi(mp, NULL, agno, &agibp);
+                if (error) {
+                        /*
+                         * AGI is b0rked. Don't process it.
+                         *
+                         * We should probably mark the filesystem as corrupt
+                         * after we've recovered all the ag's we can....
+                         */
+                        continue;
                 }
                 agi = XFS_BUF_TO_AGI(agibp);
-                ASSERT(XFS_AGI_MAGIC == be32_to_cpu(agi->agi_magicnum));
 
                 for (bucket = 0; bucket < XFS_AGI_UNLINKED_BUCKETS; bucket++) {
 
@@ -3278,22 +3276,12 @@ xlog_recover_process_iunlinks(
 
                                 /*
                                  * Reacquire the agibuffer and continue around
-                                 * the loop.
+                                 * the loop. This should never fail as we know
+                                 * the buffer was good earlier on.
                                  */
-                                agibp = xfs_buf_read(mp->m_ddev_targp,
-                                                XFS_AG_DADDR(mp, agno,
-                                                        XFS_AGI_DADDR(mp)),
-                                                XFS_FSS_TO_BB(mp, 1), 0);
-                                if (XFS_BUF_ISERROR(agibp)) {
-                                        xfs_ioerror_alert(
-                                "xlog_recover_process_iunlinks(#2)",
-                                                log->l_mp, agibp,
-                                                XFS_AG_DADDR(mp, agno,
-                                                        XFS_AGI_DADDR(mp)));
-                                }
+                                error = xfs_read_agi(mp, NULL, agno, &agibp);
+                                ASSERT(error == 0);
                                 agi = XFS_BUF_TO_AGI(agibp);
-                                ASSERT(XFS_AGI_MAGIC == be32_to_cpu(
-                                        agi->agi_magicnum));
                         }
                 }
 
@@ -3980,11 +3968,9 @@ xlog_recover_check_summary(
 {
         xfs_mount_t     *mp;
         xfs_agf_t       *agfp;
-        xfs_agi_t       *agip;
         xfs_buf_t       *agfbp;
         xfs_buf_t       *agibp;
         xfs_daddr_t     agfdaddr;
-        xfs_daddr_t     agidaddr;
         xfs_buf_t       *sbbp;
 #ifdef XFS_LOUD_RECOVERY
         xfs_sb_t        *sbp;
@@ -3993,6 +3979,7 @@ xlog_recover_check_summary(
         __uint64_t      freeblks;
         __uint64_t      itotal;
         __uint64_t      ifree;
+        int             error;
 
         mp = log->l_mp;
 
@@ -4016,21 +4003,14 @@ xlog_recover_check_summary(
                             be32_to_cpu(agfp->agf_flcount);
                 xfs_buf_relse(agfbp);
 
-                agidaddr = XFS_AG_DADDR(mp, agno, XFS_AGI_DADDR(mp));
-                agibp = xfs_buf_read(mp->m_ddev_targp, agidaddr,
-                                XFS_FSS_TO_BB(mp, 1), 0);
-                if (XFS_BUF_ISERROR(agibp)) {
-                        xfs_ioerror_alert("xlog_recover_check_summary(agi)",
-                                          mp, agibp, agidaddr);
-                }
-                agip = XFS_BUF_TO_AGI(agibp);
-                ASSERT(XFS_AGI_MAGIC == be32_to_cpu(agip->agi_magicnum));
-                ASSERT(XFS_AGI_GOOD_VERSION(be32_to_cpu(agip->agi_versionnum)));
-                ASSERT(be32_to_cpu(agip->agi_seqno) == agno);
+                error = xfs_read_agi(mp, NULL, agno, &agibp);
+                if (!error) {
+                        struct xfs_agi  *agi = XFS_BUF_TO_AGI(agibp);
 
-                itotal += be32_to_cpu(agip->agi_count);
-                ifree += be32_to_cpu(agip->agi_freecount);
-                xfs_buf_relse(agibp);
+                        itotal += be32_to_cpu(agi->agi_count);
+                        ifree += be32_to_cpu(agi->agi_freecount);
+                        xfs_buf_relse(agibp);
+                }
         }
 
         sbbp = xfs_getsb(mp, 0);