Re: [PATCH ] Fix some problems with truncate and mtime semantics.

From: Neil Brown
Date: Mon Nov 14 2005 - 21:09:30 EST


On Monday November 14, trond.myklebust@xxxxxxxxxx wrote:
> On Tue, 2005-11-15 at 13:00 +1100, NeilBrown wrote:
> > Resubmitting this patch to fix truncate/mtime semantics.
> >
> > It is against 2.6.14-mm2 and is probably suitable for 2.6.15, but can
> > be held over to 2.6.16 if you are feeling cautious.
> >
> > NeilBrown
> >
> > ### Comments for Changeset
> >
> > SUS requires that when truncating a file to the size that it currently
> > is:
> > truncate and ftruncate should NOT modify ctime or mtime
> > O_EXCL SHOULD modify ctime and mtime.
> ^^^^^ O_CREAT ;-)

Groan... thanks Trond.
Andrew .. if you could just do a little edit there for me, I'd really
appreciate it :-(

NeilBrown

>
> > Currently mtime and ctime are always modified on most local
> > filesystems (side effect of ->truncate) or never modified (on NFS).
> >
> > With this patch:
> > ATTR_CTIME|ATTR_MTIME are sent with ATTR_SIZE precisely when
> > an update of these times is required whether size changes or not
> > (via a new argument to do_truncate). This allows NFS to do
> > the right thing for O_EXCL.
> ^^^^^
>
> Cheers,
> Trond
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