[Ocfs2-devel] [PATCH V2] ocfs2: free up write context when direct IO failed

[Wengang Wang]

Hi AKPM,

Now we have three reviewed-bys for this patch:

Reviewed-by: Junxiao Bi <junxiao.bi at oracle.com>
Reviewed-by: Changwei Ge <ge.changwei at h3c.com>
Reviewed-by: Joseph Qi <jiangqi903 at gmail.com>

Could you please merge it to mainline code?

Also thanks Junxiao, Changwei and Joseph for the reviews!

Thanks,
Wengang

On 2018/11/4 18:05, Joseph Qi wrote:
>
> On 18/11/3 01:06, Wengang Wang wrote:
>> The write context should also be freed even when direct IO failed.
>> Otherwise a memory leak is introduced and entries remain in
>> oi->ip_unwritten_list causing the following BUG later in unlink path:
>>
>> ERROR: bug expression: !list_empty(&oi->ip_unwritten_list)
>> ERROR: Clear inode of 215043, inode has unwritten extents
>> ...
>> Call Trace:
>> ? __set_current_blocked+0x42/0x68
>> ocfs2_evict_inode+0x91/0x6a0 [ocfs2]
>> ? bit_waitqueue+0x40/0x33
>> evict+0xdb/0x1af
>> iput+0x1a2/0x1f7
>> do_unlinkat+0x194/0x28f
>> SyS_unlinkat+0x1b/0x2f
>> do_syscall_64+0x79/0x1ae
>> entry_SYSCALL_64_after_hwframe+0x151/0x0
>>
>> This patch also logs, with frequency limit, direct IO failures.
>>
>> Signed-off-by: Wengang Wang <wen.gang.wang at oracle.com>
> Reviewed-by: Joseph Qi <jiangqi903 at gmail.com>
>
>> ---
>> v1 -> v2: log direct IO failures
>> ---
>>   fs/ocfs2/aops.c            | 12 ++++++++++--
>>   fs/ocfs2/cluster/masklog.h |  9 +++++++++
>>   2 files changed, 19 insertions(+), 2 deletions(-)
>>
>> diff --git a/fs/ocfs2/aops.c b/fs/ocfs2/aops.c
>> index 302cd7c..7578bd5 100644
>> --- a/fs/ocfs2/aops.c
>> +++ b/fs/ocfs2/aops.c
>> @@ -2412,8 +2412,16 @@ static int ocfs2_dio_end_io(struct kiocb *iocb,
>>   	/* this io's submitter should not have unlocked this before we could */
>>   	BUG_ON(!ocfs2_iocb_is_rw_locked(iocb));
>>   
>> -	if (bytes > 0 && private)
>> -		ret = ocfs2_dio_end_io_write(inode, private, offset, bytes);
>> +	if (bytes <= 0)
>> +		mlog_ratelimited(ML_ERROR, "Direct IO failed, bytes = %lld",
>> +				 (long long)bytes);
>> +	if (private) {
>> +		if (bytes > 0)
>> +			ret = ocfs2_dio_end_io_write(inode, private, offset,
>> +						     bytes);
>> +		else
>> +			ocfs2_dio_free_write_ctx(inode, private);
>> +	}
>>   
>>   	ocfs2_iocb_clear_rw_locked(iocb);
>>   
>> diff --git a/fs/ocfs2/cluster/masklog.h b/fs/ocfs2/cluster/masklog.h
>> index 308ea0e..a396096 100644
>> --- a/fs/ocfs2/cluster/masklog.h
>> +++ b/fs/ocfs2/cluster/masklog.h
>> @@ -178,6 +178,15 @@ do {									\
>>   			      ##__VA_ARGS__);				\
>>   } while (0)
>>   
>> +#define mlog_ratelimited(mask, fmt, ...)				\
>> +do {									\
>> +	static DEFINE_RATELIMIT_STATE(_rs,				\
>> +				      DEFAULT_RATELIMIT_INTERVAL,	\
>> +				      DEFAULT_RATELIMIT_BURST);		\
>> +	if (__ratelimit(&_rs))						\
>> +		mlog(mask, fmt, ##__VA_ARGS__);				\
>> +} while (0)
>> +
>>   #define mlog_errno(st) ({						\
>>   	int _st = (st);							\
>>   	if (_st != -ERESTARTSYS && _st != -EINTR &&			\
>>