linux-kernel - Re: [f2fs-dev][PATCH] f2fs: not allowed to set file both cold and hot

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Date:   Mon, 26 Jun 2023 06:16:59 -0700
From:   Jaegeuk Kim <jaegeuk@...nel.org>
To:     何云蕾(Yunlei he) <heyunlei@...o.com>
Cc:     Chao Yu <chao@...nel.org>, linux-f2fs-devel@...ts.sourceforge.net,
        linux-kernel@...r.kernel.org
Subject: Re: [f2fs-dev][PATCH] f2fs: not allowed to set file both cold and hot

On 06/25, 何云蕾(Yunlei he) wrote:
> 
> On 2023/6/24 3:07, Jaegeuk Kim wrote:
> > On 06/20, Chao Yu wrote:
> > > On 2023/6/20 10:42, 何云蕾(Yunlei he) wrote:
> > > > On 2023/6/20 8:33, Chao Yu wrote:
> > > > > On 2023/6/13 16:52, Yunlei He wrote:
> > > > > > File set both cold and hot advise bit is confusion, so
> > > > > > return EINVAL to avoid this case.
> > > > > > 
> > > > > > Signed-off-by: Yunlei He<heyunlei@...o.com>
> > > > > > ---
> > > > > >    fs/f2fs/xattr.c | 3 +++
> > > > > >    1 file changed, 3 insertions(+)
> > > > > > 
> > > > > > diff --git a/fs/f2fs/xattr.c b/fs/f2fs/xattr.c
> > > > > > index 213805d3592c..917f3ac9f1a1 100644
> > > > > > --- a/fs/f2fs/xattr.c
> > > > > > +++ b/fs/f2fs/xattr.c
> > > > > > @@ -127,6 +127,9 @@ static int f2fs_xattr_advise_set(const struct xattr_handler *handler,
> > > > > >                   return -EINVAL;
> > > > > > 
> > > > > >           new_advise = new_advise & FADVISE_MODIFIABLE_BITS;
> > > > > > +       if ((new_advise & FADVISE_COLD_BIT) && (new_advise & FADVISE_HOT_BIT))
> > > > > > +               return -EINVAL;
> > Why not this to allow setting one bit only?
> > 
> > @@ -123,7 +123,8 @@ static int f2fs_xattr_advise_set(const struct xattr_handler *handler,
> >                  return -EINVAL;
> > 
> >          new_advise = *(char *)value;
> > -       if (new_advise & ~FADVISE_MODIFIABLE_BITS)
> > +       if (new_advise & ~FADVISE_MODIFIABLE_BITS ||
> > +           new_advise == FADVISE_MODIFIABLE_BITS)
> >                  return -EINVAL;
> 
> Hi,Jaegeuk,
> 
>     If new modifiable advise bit is added in the future, maybe multi-bits
> is allowed?
> 

Looks like making a single bit assumption would be better in general at this
moment.

> Thanks
> 
> > 
> > > > > Yunlei,
> > > > > 
> > > > > What about the below case:
> > > > > 
> > > > > 1. f2fs_xattr_advise_set(FADVISE_COLD_BIT)
> > > > > 2. f2fs_xattr_advise_set(FADVISE_HOT_BIT)
> > > > Hi,  Chao,
> > > > 
> > > >       I test this case work well with this patch,  case below will return -EINVAL:
> > > > 
> > > >       f2fs_xattr_advise_set(FADVISE_COLD_BIT | FADVISE_HOT_BIT)
> > > Correct, I missed to check below statement.
> > > 
> > > new_advise |= old_advise & ~FADVISE_MODIFIABLE_BITS;
> > > 
> > > Anyway, the patch looks good to me.
> > > 
> > > Reviewed-by: Chao Yu<chao@...nel.org>
> > > 
> > > Thanks,