diff mbox series

[v2,1/5] ocfs2: fix mounting crash if journal is not alloced

Message ID 20220413082957.28774-2-heming.zhao@suse.com (mailing list archive)
State New
Headers show
Series rewrite error handling during mounting stage | expand

Commit Message

Heming Zhao April 13, 2022, 8:29 a.m. UTC
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.

Fixes: da5e7c87827e8 ("ocfs2: cleanup journal init and shutdown")
Signed-off-by: Heming Zhao <heming.zhao@suse.com>
---
 fs/ocfs2/inode.c   |  4 ++--
 fs/ocfs2/journal.c | 32 ++++++++++++++++++++++----------
 fs/ocfs2/super.c   | 16 ++++++++++++++++
 3 files changed, 40 insertions(+), 12 deletions(-)
diff mbox series

Patch

diff --git a/fs/ocfs2/inode.c b/fs/ocfs2/inode.c
index 5739dc301569..bb116c39b581 100644
--- a/fs/ocfs2/inode.c
+++ b/fs/ocfs2/inode.c
@@ -125,6 +125,7 @@  struct inode *ocfs2_iget(struct ocfs2_super *osb, u64 blkno, unsigned flags,
 	struct inode *inode = NULL;
 	struct super_block *sb = osb->sb;
 	struct ocfs2_find_inode_args args;
+	journal_t *journal = osb->journal->j_journal;
 
 	trace_ocfs2_iget_begin((unsigned long long)blkno, flags,
 			       sysfile_type);
@@ -171,11 +172,10 @@  struct inode *ocfs2_iget(struct ocfs2_super *osb, u64 blkno, unsigned flags,
 	 * part of the transaction - the inode could have been reclaimed and
 	 * now it is reread from disk.
 	 */
-	if (osb->journal) {
+	if (journal) {
 		transaction_t *transaction;
 		tid_t tid;
 		struct ocfs2_inode_info *oi = OCFS2_I(inode);
-		journal_t *journal = osb->journal->j_journal;
 
 		read_lock(&journal->j_state_lock);
 		if (journal->j_running_transaction)
diff --git a/fs/ocfs2/journal.c b/fs/ocfs2/journal.c
index 1887a2708709..49255fddce45 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 +837,20 @@  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;
+
 	/* already have the inode for our journal */
 	inode = ocfs2_get_system_file_inode(osb, JOURNAL_SYSTEM_INODE,
 					    osb->slot_num);
diff --git a/fs/ocfs2/super.c b/fs/ocfs2/super.c
index 477cdf94122e..babec2c9d638 100644
--- a/fs/ocfs2/super.c
+++ b/fs/ocfs2/super.c
@@ -2015,6 +2015,7 @@  static int ocfs2_initialize_super(struct super_block *sb,
 	int i, cbits, bbits;
 	struct ocfs2_dinode *di = (struct ocfs2_dinode *)bh->b_data;
 	struct inode *inode = NULL;
+	struct ocfs2_journal *journal;
 	struct ocfs2_super *osb;
 	u64 total_blocks;
 
@@ -2195,6 +2196,15 @@  static int ocfs2_initialize_super(struct super_block *sb,
 
 	get_random_bytes(&osb->s_next_generation, sizeof(u32));
 
+	/*
+	 * FIXME
+	 * This should be done in ocfs2_journal_init(), but any inode
+	 * writes back operation will cause the filesystem to crash.
+	 */
+	status = ocfs2_journal_alloc(osb);
+	if (status)
+		goto bail;
+
 	INIT_WORK(&osb->dquot_drop_work, ocfs2_drop_dquot_refs);
 	init_llist_head(&osb->dquot_drop_list);
 
@@ -2483,6 +2493,12 @@  static void ocfs2_delete_osb(struct ocfs2_super *osb)
 
 	kfree(osb->osb_orphan_wipes);
 	kfree(osb->slot_recovery_generations);
+	/* FIXME
+	 * This belongs in journal shutdown, but because we have to
+	 * allocate osb->journal at the middle of ocfs2_initialize_super(),
+	 * we free it here.
+	 */
+	kfree(osb->journal);
 	kfree(osb->local_alloc_copy);
 	kfree(osb->uuid_str);
 	kfree(osb->vol_label);