ocfs2: fix mounting crash if journal is not alloced

Patch series "rewrite error handling during mounting stage".


This patch (of 5):

After commit da5e7c87827e8 ("ocfs2: cleanup journal init and shutdown"),
journal init later than before, it makes NULL pointer access in free
routine.

Crash flow:

ocfs2_fill_super
 + ocfs2_mount_volume
 |  + ocfs2_dlm_init //fail & return, osb->journal is NULL.
 |  + ...
 |  + ocfs2_check_volume //no chance to init osb->journal
 |
 + ...
 + ocfs2_dismount_volume
    ocfs2_release_system_inodes
      ...
       evict
        ...
         ocfs2_clear_inode
          ocfs2_checkpoint_inode
           ocfs2_ci_fully_checkpointed
            time_after(journal->j_trans_id, ci->ci_last_trans)
             + journal is empty, crash!

For fixing, there are three solutions:

1> Partly revert commit da5e7c87827e8

   For avoiding kernel crash, this make sense for us.  We only
   concerned whether there has any non-system inode access before dlm
   init.  The answer is NO.  And all journal replay/recovery handling
   happen after dlm & journal init done.  So this method is not graceful
   but workable.

2> Add osb->journal check in free inode routine (eg ocfs2_clear_inode)

   The fix code is special for mounting phase, but it will continue
   working after mounting stage.  In another word, this method adds
   useless code in normal inode free flow.

3> Do directly free inode in mounting phase

   This method is brutal/complex and may introduce unsafe code,
   currently maintainer didn't like.

At last, we chose method <1> and did partly reverted job.  We reverted
journal init codes, and kept cleanup codes flow.

Link: https://lkml.kernel.org/r/20220424130952.2436-1-heming.zhao@suse.com
Link: https://lkml.kernel.org/r/20220424130952.2436-2-heming.zhao@suse.com
Fixes: da5e7c87827e8 ("ocfs2: cleanup journal init and shutdown")
Signed-off-by: Heming Zhao <heming.zhao@suse.com>
Reviewed-by: Joseph Qi <joseph.qi@linux.alibaba.com>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Changwei Ge <gechangwei@live.cn>
Cc: Gang He <ghe@suse.com>
Cc: Jun Piao <piaojun@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

1 files changed, 2 insertions, 0 deletions

diff --git a/fs/ocfs2/journal.h b/fs/ocfs2/journal.h
index 8dcb2f2cadbc..969d0aa28718 100644
--- a/fs/ocfs2/journal.h
+++ b/fs/ocfs2/journal.h
@@ -154,6 +154,7 @@ int ocfs2_compute_replay_slots(struct ocfs2_super *osb);
  *  Journal Control:
  *  Initialize, Load, Shutdown, Wipe a journal.
  *
+ *  ocfs2_journal_alloc    - Initialize skeleton for journal structure.
  *  ocfs2_journal_init     - Initialize journal structures in the OSB.
  *  ocfs2_journal_load     - Load the given journal off disk. Replay it if
  *                          there's transactions still in there.
@@ -167,6 +168,7 @@ int ocfs2_compute_replay_slots(struct ocfs2_super *osb);
  *  ocfs2_start_checkpoint - Kick the commit thread to do a checkpoint.
  */
 void   ocfs2_set_journal_params(struct ocfs2_super *osb);
+int    ocfs2_journal_alloc(struct ocfs2_super *osb);
 int    ocfs2_journal_init(struct ocfs2_super *osb, int *dirty);
 void   ocfs2_journal_shutdown(struct ocfs2_super *osb);
 int    ocfs2_journal_wipe(struct ocfs2_journal *journal,