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Date:   Fri, 24 Mar 2023 09:54:39 -0700
From:   Jaegeuk Kim <jaegeuk@kernel.org>
To:     Chao Yu <chao@kernel.org>
Cc:     yonggil.song@samsung.com,
        "linux-f2fs-devel@lists.sourceforge.net" 
        <linux-f2fs-devel@lists.sourceforge.net>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v1] f2fs: Fix discard bug on zoned block devices with
 2MiB zone size
Message-ID: <ZB3Vz9w2ybNVSY8C@google.com>
References: <CGME20230313094825epcms2p71e6cb549251dc55e8d202dd64b9913a6@epcms2p7>
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 <a24d66ad-4048-fd5c-ae47-2dd17c87bcbe@kernel.org>
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 <35dd1eea-f1b9-418e-5f97-cfd10b7ff803@kernel.org>
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On 03/24, Chao Yu wrote:
> On 2023/3/24 6:03, Jaegeuk Kim wrote:
> > 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@samsung.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.
> 
> Yes, it's not critical, fine to me.

Added:

/* Should cover 2MB zoned device for zone-based reset */

So lucky since I had to rebase to fix other patch. :(

"f2fs: factor out discard_cmd usage from general rb_tree use"


> 
> Thanks,
> 
> > 
> > > 
> > > 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;