linux fsync behaviour

[yuanh]

Hi all,

Two file descriptors are pointing the same file. When fsync is called on
one fd, the data written by the other fd will also be flushed? We are using
linux XFS.

Thanks,

-Yuan



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[Dave Chinner]

On Thu, Jul 24, 2014 at 03:41:31PM -0700, yuanh wrote:
> Hi all,
>
> Two file descriptors are pointing the same file. When fsync is called on
> one fd, the data written by the other fd will also be flushed? We are using
> linux XFS.

Yes.

-Dave.
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Dave Chinner
da...@fromorbit.com

[Anton Altaparmakov]

Hi,

On 25 Jul 2014, at 02:17, Dave Chinner <da...@fromorbit.com> wrote:
> On Thu, Jul 24, 2014 at 03:41:31PM -0700, yuanh wrote:
>> Hi all,
>>
>> Two file descriptors are pointing the same file. When fsync is called on
>> one fd, the data written by the other fd will also be flushed? We are using
>> linux XFS.
>
> Yes.

But beware of the common mistake of using fwrite + fsync which does not actually do what you intend at all and you must instead use fwrite + fflush + fsync... If you are using write(2) then just fsync is obviously fine.

Best regards,

Anton
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Anton Altaparmakov <aia21 at cam.ac.uk> (replace at with @)
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