[PATCH] xfs: Fix oops on IO error during xlog_recover_process_iunlinks()

[Jan Kara <jack@xxxxxxx>]

When an IO error happens during inode deletion run from
xlog_recover_process_iunlinks() filesystem gets shutdown. Thus any subsequent
attempt to read buffers fails. Code in xlog_recover_process_iunlinks() does not
count with the fact that read of a buffer which was read a while ago can
really fail which results in the oops on
  agi = XFS_BUF_TO_AGI(agibp);

Fix the problem by handling error from xfs_read_agi() in all cases.

Signed-off-by: Jan Kara <jack@xxxxxxx>
---
 fs/xfs/xfs_log_recover.c |   15 ++++++++++++---
 1 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/fs/xfs/xfs_log_recover.c b/fs/xfs/xfs_log_recover.c
index 0ed9ee7..3899264 100644
--- a/fs/xfs/xfs_log_recover.c
+++ b/fs/xfs/xfs_log_recover.c
@@ -3178,11 +3178,17 @@ xlog_recover_process_iunlinks(
 
                                /*
                                 * Reacquire the agibuffer and continue around
-                                * the loop. This should never fail as we know
-                                * the buffer was good earlier on.
+                                * the loop.
                                 */
                                error = xfs_read_agi(mp, NULL, agno, &agibp);
-                               ASSERT(error == 0);
+                               /*
+                                * We failed to read a buffer we succeeded
+                                * reading just a while ago. Likely because the
+                                * filesystem is shutdown now. Just try the
+                                * next AG.
+                                */
+                               if (error)
+                                       goto next_ag;
                                agi = XFS_BUF_TO_AGI(agibp);
                        }
                }
@@ -3192,6 +3198,9 @@ xlog_recover_process_iunlinks(
                 * go on to the next one.
                 */
                xfs_buf_relse(agibp);
+next_ag:
+               /* Hrm... C9x seems to require this */
+               ;
        }
 
        mp->m_dmevmask = mp_dmevmask;
-- 
1.7.1