Re: [PATCH] vfs: does call expand_files when needed

[Liu Aleaxander]

On Wed, Nov 18, 2009 at 3:17 PM, Américo Wang <xiyou.wangcong@xxxxxxxxx> wrote:
>
> On Wed, Nov 18, 2009 at 1:54 PM, Liu Aleaxander <aleaxander@xxxxxxxxx> wrote:
> > From: Liu Aleaxander <Aleaxander@xxxxxxxxx>
> > Date: Wed, 18 Nov 2009 10:59:09 +0800
> > Subject: [PATCH] vfs: does call expand_files when needed
> >
> > I don't think we should call expand_files every time we open a
> > file for a new unused fd, so does the expand when necessary.
> >
> > Signed-off-by: Liu Aleaxander <Aleaxander@xxxxxxxxx>
> > ---
> >  fs/file.c |   27 ++++++++++++++-------------
> >  1 files changed, 14 insertions(+), 13 deletions(-)
> >
> > diff --git a/fs/file.c b/fs/file.c
> > index 87e1290..3f3d0fc 100644
> > --- a/fs/file.c
> > +++ b/fs/file.c
> > @@ -452,22 +452,22 @@ repeat:
> >        if (fd < files->next_fd)
> >                fd = files->next_fd;
> >
> > -       if (fd < fdt->max_fds)
> > +       if (likely(fd < fdt->max_fds)) {
> >                fd = find_next_zero_bit(fdt->open_fds->fds_bits,
> >                                           fdt->max_fds, fd);
> > -
> > -       error = expand_files(files, fd);
> > -       if (error < 0)
> > -               goto out;
> > -
> > -       /*
> > -        * If we needed to expand the fs array we
> > -        * might have blocked - try again.
> > -        */
> > -       if (error)
> > -               goto repeat;
> > -
> > +       } else {
> > +               error = expand_files(files, fd);
>
>
> In expand_files(), it has the check for
> ' < fdt->max_fds', so this change is not necessary.

Yeah, indeed. But why we should go into an another function to do a
_double_ check especially we mostly don't need to do that?

>
> > +               if (error < 0)
> > +                       goto out;
> > +
> > +               /*
> > +                * If we needed to expand the fs array we
> > +                * might have blocked - try again.
> > +                */
> > +               if (error)
> > +                       goto repeat;
> > +       }
> > +
> >        if (start <= files->next_fd)
> >                files->next_fd = fd + 1;
> >
> > --
> > 1.6.2.5
> >
> > --
> > regards
> > Liu Aleaxander
> > --
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> >



--
regards
Liu Aleaxander
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