Re: [fuse-devel] [fuse] How to trigger writeback?

[Nikolaus Rath <Nikolaus@rath.org>]

On Sep 25 2018, Miklos Szeredi <miklos@szeredi.hu> wrote:
> On Tue, Sep 25, 2018 at 10:30 AM, Nikolaus Rath <Nikolaus@rath.org> wrote:
>> On Sep 24 2018, Miklos Szeredi <miklos@szeredi.hu> wrote:
>>> On Mon, Sep 24, 2018 at 10:02 AM, Nikolaus Rath <Nikolaus@rath.org> wrote:
>>>> Hi,
>>>>
>>>> How do I trigger writeback from a (writeback-cache enabled) FUSE
>>>> filesystem?
>>>
>>> No way, currently (well, triggering fsync(2)/fdatasync(2) on the
>>> filesystem would work, but such recursion is considered highly
>>> hackish).
>>
>>
>> You mean sync(2)/syncfs(2), not fsync(), right? Unless my manpages are
>> out of date, fsync() only works on a specific inode.
>
> I would've thought you only need writeback of a specific inode for reflink, no?

Aeh, yeah, I did not mention that. Since I couldn't implement real
reflink support but have to go through xattrs, my "reflink" also
supports reflinking entire directory trees. I guess I could still issue
a bunch of fsyncs(), but I think syncfs() is nicer (I can even move it
into the client program that sets the magic xattr so that the filesystem
does not call into itself).


Best,
-Nikolaus

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