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, 23 insertions, 10 deletions

diff --git a/fs/ocfs2/journal.c b/fs/ocfs2/journal.c
index 1887a2708709..fa87d89cf754 100644
--- a/fs/ocfs2/journal.c
+++ b/fs/ocfs2/journal.c
@@ -810,22 +810,20 @@ void ocfs2_set_journal_params(struct ocfs2_super *osb)
 	write_unlock(&journal->j_state_lock);
 }
 
-int ocfs2_journal_init(struct ocfs2_super *osb, int *dirty)
+/*
+ * alloc & initialize skeleton for journal structure.
+ * ocfs2_journal_init() will make fs have journal ability.
+ */
+int ocfs2_journal_alloc(struct ocfs2_super *osb)
 {
-	int status = -1;
-	struct inode *inode = NULL; /* the journal inode */
-	journal_t *j_journal = NULL;
-	struct ocfs2_journal *journal = NULL;
-	struct ocfs2_dinode *di = NULL;
-	struct buffer_head *bh = NULL;
-	int inode_lock = 0;
+	int status = 0;
+	struct ocfs2_journal *journal;
 
-	/* initialize our journal structure */
 	journal = kzalloc(sizeof(struct ocfs2_journal), GFP_KERNEL);
 	if (!journal) {
 		mlog(ML_ERROR, "unable to alloc journal\n");
 		status = -ENOMEM;
-		goto done;
+		goto bail;
 	}
 	osb->journal = journal;
 	journal->j_osb = osb;
@@ -839,6 +837,21 @@ int ocfs2_journal_init(struct ocfs2_super *osb, int *dirty)
 	INIT_WORK(&journal->j_recovery_work, ocfs2_complete_recovery);
 	journal->j_state = OCFS2_JOURNAL_FREE;
 
+bail:
+	return status;
+}
+
+int ocfs2_journal_init(struct ocfs2_super *osb, int *dirty)
+{
+	int status = -1;
+	struct inode *inode = NULL; /* the journal inode */
+	journal_t *j_journal = NULL;
+	struct ocfs2_journal *journal = osb->journal;
+	struct ocfs2_dinode *di = NULL;
+	struct buffer_head *bh = NULL;
+	int inode_lock = 0;
+
+	BUG_ON(!journal);
 	/* already have the inode for our journal */
 	inode = ocfs2_get_system_file_inode(osb, JOURNAL_SYSTEM_INODE,
 					    osb->slot_num);