Re: replace() system call needed (was Re: EXT4-ish "fixes" in UBIFS)

[Artem Bityutskiy]

ext Pavel Machek wrote:
> On Sun 2009-03-29 16:07:35, Artem Bityutskiy wrote:
> > Pavel Machek wrote:
> > > On Sun 2009-03-29 16:00:45, Artem Bityutskiy wrote:
> > > > Pavel Machek wrote:
> > > > > > > > 2. create/write/rename leads to empty files
> > > > > > > ..but this should not be. If we want to make that explicit, we should
> > > > > > > provide "replace()" operation; where replace is rename that makes sure
> > > > > > > that source file is completely on media before commiting the rename.
> > > > > > Well, OK, we can fsync() before rename, we just need clean rules
> > > > > > for this, so that all Linux FSes would follow them. Would be nice
> > > > > > to have final agreement on all this stuff.
> > > > > My proposal is 
> > > > >
> > > > > rename() stays.
> > > > It stays and:
> > > >
> > > > 1. does _not_ fsync
> > > Does not fsync. If someone wants to make sure one of the files is on
> > > the disk, he should use replace(). [On non-linux systems, replace()
> > > should be implemented as fsync/rename in libc or something.]
> > I would be happy with these rules. But the fact is, application
> > people just refuse to add fsync before rename. They say that the
> > FS has to do this. And they say that even Linus supports them,
>
> That's good. fsync before rename would be ugly regression (on ext3 at
> least). We should get them to use replace() syscall, not get them to
> add fsyncs. [Of course, that means we need replace syscall first. :-)]

I'd say it is better to fix ext3 then.

--
Best Regards,
Artem Bityutskiy (ÐÑÑÑÐ ÐÐÑÑÑÐÐÐ)
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