Re: [PATCH 1/5][TAKE3] fallocate() implementation on i86, x86_64 and powerpc

Amit K. Arora
2007-05-16T12:37:04Z

On Wed, May 16, 2007 at 07:21:16AM -0500, Dave Kleikamp wrote:
> On Wed, 2007-05-16 at 13:16 +1000, David Chinner wrote:
> > On Wed, May 16, 2007 at 01:33:59AM +0530, Amit K. Arora wrote:
>
> > > Following changes were made to the previous version:
> > > 1) Added description before sys_fallocate() definition.
> > > 2) Return EINVAL for len<=0 (With new draft that Ulrich pointed to,
> > > posix_fallocate should return EINVAL for len <= 0.
> > > 3) Return EOPNOTSUPP if mode is not one of FA_ALLOCATE or FA_DEALLOCATE
> > > 4) Do not return ENODEV for dirs (let individual file systems decide if
> > > they want to support preallocation to directories or not.
> > > 5) Check for wrap through zero.
> > > 6) Update c/mtime if fallocate() succeeds.
> >
> > Please don't make this always happen. c/mtime updates should be dependent
> > on the mode being used and whether there is visible change to the file. If no
> > userspace visible changes to the file occurred, then timestamps should not
> > be changed.
>
> i_blocks will be updated, so it seems reasonable to update ctime. mtime
> shouldn't be changed, though, since the contents of the file will be
> unchanged.

I agree. Thus the ctime should change for FA_PREALLOCATE mode also
(which does not change the file size) - if we end up having this
additional mode in near future.

--
Regards,
Amit Arora

> > e.g. FA_ALLOCATE that changes file size requires same semantics of ftruncate()
> > extending the file, otherwise no change in timestamps should occur.
> >
> > Cheers,
> >
> > Dave.
> --
> David Kleikamp
> IBM Linux Technology Center