linux-kernel - Re: [PATCH v1] f2fs: Fix discard bug on zoned block devices with 2MiB zone size

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Message-ID: <ZBzMql6DkrUWiRKP@google.com>
Date:   Thu, 23 Mar 2023 15:03:22 -0700
From:   Jaegeuk Kim <jaegeuk@...nel.org>
To:     Chao Yu <chao@...nel.org>
Cc:     yonggil.song@...sung.com,
        "linux-f2fs-devel@...ts.sourceforge.net" 
        <linux-f2fs-devel@...ts.sourceforge.net>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v1] f2fs: Fix discard bug on zoned block devices with
 2MiB zone size

On 03/23, Chao Yu wrote:
> On 2023/3/13 17:48, Yonggil Song wrote:
> > When using f2fs on a zoned block device with 2MiB zone size, IO errors
> > occurs because f2fs tries to write data to a zone that has not been reset.
> > 
> > The cause is that f2fs tries to discard multiple zones at once. This is
> > caused by a condition in f2fs_clear_prefree_segments that does not check
> > for zoned block devices when setting the discard range. This leads to
> > invalid reset commands and write pointer mismatches.
> > 
> > This patch fixes the zoned block device with 2MiB zone size to reset one
> > zone at a time.
> > 
> > Signed-off-by: Yonggil Song <yonggil.song@...sung.com>
> > ---
> >   fs/f2fs/segment.c | 3 ++-
> >   1 file changed, 2 insertions(+), 1 deletion(-)
> > 
> > diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> > index acf3d3fa4363..2b6cb6df623b 100644
> > --- a/fs/f2fs/segment.c
> > +++ b/fs/f2fs/segment.c
> > @@ -1953,7 +1953,8 @@ void f2fs_clear_prefree_segments(struct f2fs_sb_info *sbi,
> >   					(end - 1) <= cpc->trim_end)
> >   				continue;
> > -		if (!f2fs_lfs_mode(sbi) || !__is_large_section(sbi)) {
> > +		if (!f2fs_sb_has_blkzoned(sbi) &&
> 
> Could you please add one line comment here for this change?

This was merged in -dev a while ago. I don't think this would be critical
to rebase it again.

> 
> Otherwise it looks good to me.
> 
> Thanks,
> 
> > +		    (!f2fs_lfs_mode(sbi) || !__is_large_section(sbi))) {
> >   			f2fs_issue_discard(sbi, START_BLOCK(sbi, start),
> >   				(end - start) << sbi->log_blocks_per_seg);
> >   			continue;