[Ocfs2-devel] [PATCH v1 1/5] ocfs2: partly revert da5e7c87827e8 for mounting crash issue
heming.zhao at suse.com
heming.zhao at suse.com
Sat Apr 9 16:28:09 UTC 2022
On 4/9/22 21:11, Joseph Qi wrote:
> Suggest rename the subject, something like
> ocfs2: fix mount crash if journal is not alloced
OK.
>
> On 4/8/22 6:30 PM, Heming Zhao wrote:
>> 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> 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 partly reverted commit da5e7c87827e8.
>> We reverted journal init code, and kept cleanup code flow.
>>
>> Fixes: da5e7c87827e8 ("ocfs2: cleanup journal init and shutdown")
>> Signed-off-by: Heming Zhao <heming.zhao at suse.com>
>> ---
>> fs/ocfs2/inode.c | 4 ++--
>> fs/ocfs2/journal.c | 21 +--------------------
>> fs/ocfs2/super.c | 33 +++++++++++++++++++++++++++++++++
>> 3 files changed, 36 insertions(+), 22 deletions(-)
>>
>> 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..afb85de3bb60 100644
>> --- a/fs/ocfs2/journal.c
>> +++ b/fs/ocfs2/journal.c
>> @@ -815,30 +815,11 @@ 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 = NULL;
>> + struct ocfs2_journal *journal = osb->journal;
>> struct ocfs2_dinode *di = NULL;
>> struct buffer_head *bh = NULL;
>> int inode_lock = 0;
>>
>> - /* 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;
>> - }
>> - osb->journal = journal;
>> - journal->j_osb = osb;
>> -
>> - atomic_set(&journal->j_num_trans, 0);
>> - init_rwsem(&journal->j_trans_barrier);
>> - init_waitqueue_head(&journal->j_checkpointed);
>> - spin_lock_init(&journal->j_lock);
>> - journal->j_trans_id = 1UL;
>> - INIT_LIST_HEAD(&journal->j_la_cleanups);
>> - INIT_WORK(&journal->j_recovery_work, ocfs2_complete_recovery);
>> - journal->j_state = OCFS2_JOURNAL_FREE;
>> -
>> /* 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..5f63a2333e52 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 +2196,32 @@ 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 unknown
>> + * ordering issues will cause the filesystem to crash.
>> + * If anyone wants to figure out what part of the code
>> + * refers to osb->journal before ocfs2_journal_init() is run,
>> + * be my guest.
>> + */
>> + /* 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 bail;
>> + }
>> + osb->journal = journal;
>> + journal->j_osb = osb;
>> +
>> + atomic_set(&journal->j_num_trans, 0);
>> + init_rwsem(&journal->j_trans_barrier);
>> + init_waitqueue_head(&journal->j_checkpointed);
>> + spin_lock_init(&journal->j_lock);
>> + journal->j_trans_id = 1UL;
>> + INIT_LIST_HEAD(&journal->j_la_cleanups);
>> + INIT_WORK(&journal->j_recovery_work, ocfs2_complete_recovery);
>> + journal->j_state = OCFS2_JOURNAL_FREE;
>> +
> We may fold these into a new function, such as ocfs2_journal_alloc().
>
OK, will create a new function in journal.c
For this area FIXME comment, the legacy comment humor & vague. In my view, we
already got the order issue clearly, why not we change it as below?
/*
* FIXME
* This should be done in ocfs2_journal_init(), but any inode
* writes back operation will cause the filesystem to crash.
*/
Thanks,
Heming
>
>> INIT_WORK(&osb->dquot_drop_work, ocfs2_drop_dquot_refs);
>> init_llist_head(&osb->dquot_drop_list);
>>
>> @@ -2483,6 +2510,12 @@ 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);
>
More information about the Ocfs2-devel
mailing list