Re: [PATCH v2] Introduce the end_syncfs option

Jens Axboe
2026-01-27T03:59:38Z

On 1/26/26 7:18 PM, Damien Le Moal wrote:
> On 1/27/26 11:15, Vincent Fu wrote:
>> On Mon, Jan 26, 2026 at 9:05?PM Damien Le Moal <dlemoal@kernel.org> wrote:
>>>
>>> On 1/27/26 10:01, Vincent Fu wrote:
>>>> On Mon, Jan 26, 2026 at 1:22?AM Damien Le Moal <dlemoal@kernel.org> wrote:
>>>>>
>>>> <snip>
>>>>> }
>>>>> +
>>>>> + if (td->o.end_syncfs) {
>>>>> + td_set_runstate(td, TD_FSYNCING);
>>>>> +
>>>>> + for_each_file(td, f, i) {
>>>>> + if (fio_file_syncfs(td, f))
>>>>> + log_err("fio: end_syncfs failed\n");
>>>>> + break;
>>>>
>>>> This seems like it will break out of the loop after syncfs-ing the first file.
>>>> Is this intentional or should fio break only if there is an error?
>>>
>>> It is intentional and it is the entire point of this patch: doing syncfs for the
>>> first file will sync the entire FS, so all the other files will be sync-ed as
>>> well. We thus avoid the entire loop on all files which is extremely slow when
>>> running with a large number of files. We only need to do syncfs() once for the
>>> first file. Ideally, we should do it for the directory specified for the files,
>>> but that is a little more involved as a change.
>>
>> Ok thank you for clarifying.
>> Please emphasize in the documentation that this feature assumes that
>> all files will reside on the same file system.
>
> OK. Will do in v3.

That seems like a very odd limitation that people will never know about,
and hence it won't do what they think it does. We stat these files for
getting the size, right? Then do a sync for each fs. Only doing the
first is a cop-out imho, and somewhat of a lazy way of doing it.

We either sync any fs that has a file that was written, or let's not add
this feature. That can be done in any number of ways. It's a terrible
option otherwise.

--
Jens Axbo