[LTP] [PATCH 1/2] scsi_debug/tlibio/lio_write_buffer: Always return total amount of written bytes

[Konstantin Khorenko]

On 17.05.2023 02:23, Petr Vorel wrote:
> Hi Konstantin,
> 
>> Sometimes we got failures like:
>>   growfiles(gf217): 65884 growfiles.c/2262: 104203 tlibio.c/744 write(3, buf, 5000) returned=2288
>>   growfiles(gf217): 65884 growfiles.c/1765: 104203 Hit max errors value of 1
>>   gf217       1  TFAIL  :  growfiles.c:134: Test failed
> 
> I wonder on which circumstances do you get this error. Running on container?

Yes, your guess is correct. :) Our QA runs ltp in Containers and VMs under high load,
i mean when many Containers/VMs host on a physical Node and run in parallel different tests.

>> Which looked strange as partial write is something usual and valid.
>> It turned out that lio_write_buffer() has the code cycle writes in case
>> of a partial write happens, but it anyway returns the amount of bytes
>> written by the LAST write.
> 
>> And upper growfile() consider the returned amount from
>> lio_write_buffer() to be less than it tried to write and fails the
>> testcase.
> 
>> Fix lio_write_buffer() to always return total bytes written, even in
>> case partial writes.
> 
>> Signed-off-by: Konstantin Khorenko <khorenko@virtuozzo.com>
>> ---
>>   lib/tlibio.c | 5 ++++-
>>   1 file changed, 4 insertions(+), 1 deletion(-)
> 
>> diff --git a/lib/tlibio.c b/lib/tlibio.c
>> index cc110d1c9..8298e2de9 100644
>> --- a/lib/tlibio.c
>> +++ b/lib/tlibio.c
>> @@ -539,6 +539,8 @@ int lio_write_buffer(int fd,		/* open file descriptor */
>>   		long wrd)	/* to allow future features, use zero for now */
>>   {
>>   	int ret = 0;		/* syscall return or used to get random method */
>> +	int totally_written = 0;/* as we cycle writes in case of partial writes, */
>> +				/* we have to report up total bytes written */
> 
> Nit: I'd do multiline comment (much more readable):

No problem, will redo and resend.

Thank you for the review!


Best regards,
Konstantin Khorenko

> 
> 	/* as we cycle writes in case of partial writes,
> 	 * we have to report up total bytes written */
> 	int totally_written = 0;
> 
> Otherwise LGTM.
> 
> Reviewed-by: Petr Vorel <pvorel@suse.cz>
> 
>>   	char *io_type;		/* Holds string of type of io */
>>   	int omethod = method;
>>   	int listio_cmd;		/* Holds the listio/lio_listio cmd */
>> @@ -745,13 +747,14 @@ int lio_write_buffer(int fd,		/* open file descriptor */
>>   						fd, size, ret);
>>   					size -= ret;
>>   					buffer += ret;
>> +					totally_written += ret;
>>   				} else {
>>   					if (Debug_level > 1)
>>   						printf
>>   						    ("DEBUG %s/%d: write completed without error (ret %d)\n",
>>   						     __FILE__, __LINE__, ret);
> 
> BTW growfiles.c and other files based on tlibio.c would deserve big cleanup and
> rewrite into new API.
> 
> Kind regards,
> Petr
> 
>> -					return ret;
>> +					return totally_written + ret;
>>   				}
>>   			}
>>   			wait4sync_io(fd, 0);