linux-kernel - Re: [PATCH V2] f2fs: fix to adjust appropirate defragment pg

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Message-ID: <CAHJ8P3J3xK2uz7egvShyCeAjGFJ87AvqKxVN=NFiKDgMLMJDPg@mail.gmail.com>
Date: Wed, 27 Mar 2024 09:26:58 +0800
From: Zhiguo Niu <niuzhiguo84@...il.com>
To: Chao Yu <chao@...nel.org>
Cc: Zhiguo Niu <zhiguo.niu@...soc.com>, jaegeuk@...nel.org, 
	linux-f2fs-devel@...ts.sourceforge.net, linux-kernel@...r.kernel.org, 
	ke.wang@...soc.com, hongyu.jin@...soc.com
Subject: Re: [PATCH V2] f2fs: fix to adjust appropirate defragment pg_end

On Tue, Mar 26, 2024 at 7:11 PM Chao Yu <chao@...nel.org> wrote:
>
> On 2024/3/25 13:56, Zhiguo Niu wrote:
> > A length that exceeds the real size of the inode may be
> > specified from user, although these out-of-range areas
> > are not mapped, but they still need to be check in
> > while loop, which is unnecessary.
> >
> > Signed-off-by: Zhiguo Niu <zhiguo.niu@...soc.com>
> > ---
> > v2: check i_size within inode lock according to Chao's suggestions
> > ---
> > ---
> >   fs/f2fs/file.c | 11 +++++++----
> >   1 file changed, 7 insertions(+), 4 deletions(-)
> >
> > diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> > index 128e53d..cf63db7 100644
> > --- a/fs/f2fs/file.c
> > +++ b/fs/f2fs/file.c
> > @@ -2608,9 +2608,6 @@ static int f2fs_defragment_range(struct f2fs_sb_info *sbi,
> >       bool fragmented = false;
> >       int err;
> >
> > -     pg_start = range->start >> PAGE_SHIFT;
> > -     pg_end = (range->start + range->len) >> PAGE_SHIFT;
> > -
> >       f2fs_balance_fs(sbi, true);
> >
> >       inode_lock(inode);
> > @@ -2629,10 +2626,16 @@ static int f2fs_defragment_range(struct f2fs_sb_info *sbi,
>
> pg_start = range->start >> PAGE_SHIFT;
> pg_end = min_t(pgoff_t, (range->start + range->len) >> PAGE_SHIFT,
>                         DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE));
>
> >
> >       /* writeback all dirty pages in the range */
> >       err = filemap_write_and_wait_range(inode->i_mapping, range->start,
> > -                                             range->start + range->len - 1);
> > +                                             min_t(loff_t, range->start + range->len - 1,
> > +                                             i_size_read(inode) - 1));
>
> , pg_start << PAGE_SHIFT - 1, pg_end << PAGE_SHIFT - 1); ?
should be  pg_start << PAGE_SHIFT , pg_end << PAGE_SHIFT - 1)??
if range.start=0, pg_start is also 0, lstart in
filemap_write_and_wait_range is 0,
but pg_start << PAGE_SHIFT - 1 will get lstart=-1?
thanks！
>
> Thanks,
>
> >       if (err)
> >               goto out;
> >
> > +     pg_start = range->start >> PAGE_SHIFT;
> > +     pg_end = min_t(pgoff_t,
> > +                             (range->start + range->len) >> PAGE_SHIFT,
> > +                             DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE));
> > +
> >       /*
> >        * lookup mapping info in extent cache, skip defragmenting if physical
> >        * block addresses are continuous.