linux-ext4 - Re: [PATCH 1/5][TAKE3] fallocate() implementation on i86, x86

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Message-ID: <20070517122840.GA12381@amitarora.in.ibm.com>
Date:	Thu, 17 May 2007 17:58:40 +0530
From:	"Amit K. Arora" <aarora@...ux.vnet.ibm.com>
To:	David Chinner <dgc@....com>
Cc:	Dave Kleikamp <shaggy@...ux.vnet.ibm.com>, torvalds@...l.org,
	akpm@...ux-foundation.org, linux-fsdevel@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-ext4@...r.kernel.org,
	xfs@....sgi.com, suparna@...ibm.com, cmm@...ibm.com
Subject: Re: [PATCH 1/5][TAKE3] fallocate() implementation on i86, x86_64 and powerpc

On Thu, May 17, 2007 at 09:40:36AM +1000, David Chinner wrote:
> 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.
> 
> That's assuming blocks were actually allocated - if the prealloc range already
> has underlying blocks there is no change and so we should not be changing
> mtime either. Only the filesystem will know if it has changed the file, so I
> think that timestamp updates need to be driven down to that level, not done
> blindy at the highest layer....

Ok. Will make this change in the next post.

--
Regards,
Amit Arora
> 
> Cheers,
> 
> Dave.
> -- 
> Dave Chinner
> Principal Engineer
> SGI Australian Software Group
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