Re: New copyfile system call - discuss before LSF?

[Ric Wheeler]

On 03/30/2013 05:57 PM, Myklebust, Trond wrote:
> On Mar 30, 2013, at 5:45 PM, Pavel Machek <pavel@xxxxxx>
>   wrote:
>
> > On Sat 2013-03-30 13:08:39, Andreas Dilger wrote:
> > > On 2013-03-30, at 12:49 PM, Pavel Machek wrote:
> > > > Hmm, really? AFAICT it would be simple to provide an
> > > > open_deleted_file("directory") syscall. You'd open_deleted_file(),
> > > > copy source file into it, then fsync(), then link it into filesystem.
> > > >
> > > > That should have atomicity properties reflected.
> > > Actually, the open_deleted_file() syscall is quite useful for many
> > > different things all by itself.  Lots of applications need to create
> > > temporary files that are unlinked at application failure (without a
> > > race if app crashes after creating the file, but before unlinking).
> > > It also avoids exposing temporary files into the namespace if other
> > > applications are accessing the directory.
> > Hmm. open_deleted_file() will still need to get a directory... so it
> > will still need a path. Perhaps open("/foo/bar/mnt", O_DELETED) would
> > be acceptable interface?
> > 									Pavel
> ...and what's the big plan to make this work on anything other than ext4 and btrfs?
>
> Cheers,
>    Trond

I know that change can be a good thing, but are we really solving a pressing 
problem given that application developers have dealt with open/rename as the way 
to get "atomic" file creation for several decades now ?

Regards,

Ric

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