ocfs2: fix mounting crash if journal is not alloced

ocfs2: fix mounting crash if journal is not alloced

Patch series "rewrite error handling during mounting stage".

This patch (of 5):

After commit cdee7671070bd ("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 cdee7671070bd

   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: cdee7671070bd ("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>