Hi Alex,
On 2017/10/28 10:35, alex chen wrote:
> Hi Changwei,
>
> Thanks for you reply.
>
> On 2017/10/27 18:21, Changwei Ge wrote:
>> Hi Alex,
>>
>> Thanks for reporting.
>> I probably get your point. You mean that for a lock resource(say A), it
>> is used to protect metadata changing among nodes in cluster.
>>
>> Unfortunately, it was marks as BLOCKED since it was granted with a EX
>> lock, and the lock can't be unblocked since it has more or equal to one
>> ::ex_holder(s), furthermore, since process 1 is waiting for all inflight
>> dio accomplishment, it won't give up its ownership of lock source A.
>>
>> Thus, hang, right?
>
> Yes, I'm glad you can understand this.
>
>>
>> From code reviewing, I admit that the hang situation does exit.
>>
>> But as for your patch, how can you guarantee no more bio will be issued
>> from other nodes in cluster?
>>
>
> First of all, we use the inode_lock() in do_truncate() to prevent another bio
> to
> be issued from this node.
> Furthermore, we use the ocfs2_rw_lock() and ocfs2_inode_lock() in
> ocfs2_setattr()
> to guarantee no more bio will be issued from the other nodes in this cluster.
Thanks for your particular elaboration.
I think this patch makes sense.
Acked.
Thanks,
Changwei
>
> Thanks,
> Alex
>
>> Also, I cc this patch to ocfs2 maintainers.
>>
>> Thanks,
>> Changwei
>>
>> On 2017/10/27 16:01, alex chen wrote:
>>> we should wait dio requests to finish before inode lock in
>>> ocfs2_setattr(), otherwise the following deadlock will be happened:
>>> process 1 process 2 process 3
>>> truncate file 'A' end_io of writing file 'A' receiving the bast
>>> messages
>>> ocfs2_setattr
>>> ocfs2_inode_lock_tracker
>>> ocfs2_inode_lock_full
>>> inode_dio_wait
>>> __inode_dio_wait
>>> -->waiting for all dio
>>> requests finish
>>>
>>> dlm_proxy_ast_handler
>>> dlm_do_local_bast
>>>
>>> ocfs2_blocking_ast
>>>
>>> ocfs2_generic_handle_bast
>>> set
>>> OCFS2_LOCK_BLOCKED flag
>>> dio_end_io
>>> dio_bio_end_aio
>>> dio_complete
>>> ocfs2_dio_end_io
>>> ocfs2_dio_end_io_write
>>> ocfs2_inode_lock
>>> __ocfs2_cluster_lock
>>> ocfs2_wait_for_mask
>>> -->waiting for OCFS2_LOCK_BLOCKED
>>> flag to be cleared, that is waiting
>>> for 'process 1' unlocking the inode lock
>>> inode_dio_end
>>> -->here dec the i_dio_count, but will never
>>> be called, so a deadlock happened.
>>>
>>> Signed-off-by: Alex Chen <alex.c...@huawei.com>
>>> Reviewed-by: Jun Piao <piao...@huawei.com>
Acked-by: Changwei Ge <ge.chang...@h3c.com>
>>>
>>> ---
>>> fs/ocfs2/file.c | 9 +++++++--
>>> 1 file changed, 7 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c
>>> index 6e41fc8..50e09a6 100644
>>> --- a/fs/ocfs2/file.c
>>> +++ b/fs/ocfs2/file.c
>>> @@ -1161,6 +1161,13 @@ int ocfs2_setattr(struct dentry *dentry, struct
>>> iattr *attr)
>>> }
>>> size_change = S_ISREG(inode->i_mode) && attr->ia_valid & ATTR_SIZE;
>>> if (size_change) {
>>> +
>>> + /* here we should wait dio to finish before inode lock
>>> + * to avoid a deadlock between ocfs2_setattr() and
>>> + * ocfs2_dio_end_io_write()
>>> + */
>>> + inode_dio_wait(inode);
>>> +
>>> status = ocfs2_rw_lock(inode, 1);
>>> if (status < 0) {
>>> mlog_errno(status);
>>> @@ -1200,8 +1207,6 @@ int ocfs2_setattr(struct dentry *dentry, struct iattr
>>> *attr)
>>> if (status)
>>> goto bail_unlock;
>>>
>>> - inode_dio_wait(inode);
>>> -
>>> if (i_size_read(inode) >= attr->ia_size) {
>>> if (ocfs2_should_order_data(inode)) {
>>> status = ocfs2_begin_ordered_truncate(inode,
>>>
>>
>>
>> .
>>
>
>
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