linux-kernel - RE:(2) [f2fs-dev] [PATCH] Revert "f2fs: use flush command instead of FUA for zoned device"

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Date: Thu, 20 Jun 2024 14:56:48 +0900
From: Daejun Park <daejun7.park@...sung.com>
To: Chao Yu <chao@...nel.org>, "jaegeuk@...nel.org" <jaegeuk@...nel.org>,
	Wenjie Cheng <cwjhust@...il.com>
CC: "qwjhust@...il.com" <qwjhust@...il.com>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>, "linux-f2fs-devel@...ts.sourceforge.net"
	<linux-f2fs-devel@...ts.sourceforge.net>, Daejun Park
	<daejun7.park@...sung.com>
Subject: RE:(2) [f2fs-dev] [PATCH] Revert
 "f2fs: use flush command instead of FUA for zoned device"

Hi Chao,

> Jaegeuk,
> 
> Quoted commit message from commit c550e25bca66 ("f2fs: use flush command
> instead of FUA for zoned device")
> "
> The block layer for zoned disk can reorder the FUA'ed IOs. Let's use flush
> command to keep the write order.
> "
> 
> It seems mq-deadline use fifo queue and make queue depth of zone device
> as 1 to IO order, so why FUA'ed write node IOs can be reordered by block
> layer?

While other writes are aligned by the mq-deadline, write with FUA is not passed
to the scheduler but handled at the block layer.

Thanks,
Daejun

> 
> Thanks,
> 
> On 2024/6/14 8:48, Wenjie Cheng wrote:
> > This reverts commit c550e25bca660ed2554cbb48d32b82d0bb98e4b1.
> >
> > Commit c550e25bca660ed2554cbb48d32b82d0bb98e4b1 ("f2fs: use flush
> > command instead of FUA for zoned device") used additional flush
> > command to keep write order.
> >
> > Since Commit dd291d77cc90eb6a86e9860ba8e6e38eebd57d12 ("block:
> > Introduce zone write plugging") has enabled the block layer to
> > handle this order issue, there is no need to use flush command.
> >
> > Signed-off-by: Wenjie Cheng <cwjhust@...il.com>
> > ---
> >  fs/f2fs/file.c 3 +--
> >  fs/f2fs/node.c 2 +-
> >  2 files changed, 2 insertions(+), 3 deletions(-)
> >
> > diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> > index eae2e7908072..f08e6208e183 100644
> > --- a/fs/f2fs/file.c
> > +++ b/fs/f2fs/file.c
> > @@ -372,8 +372,7 @@ static int f2fs_do_sync_file(struct file *file, loff_t start, loff_t end,
> >           f2fs_remove_ino_entry(sbi, ino, APPEND_INO);
> >           clear_inode_flag(inode, FI_APPEND_WRITE);
> >  flush_out:
> > -        if ((!atomic && F2FS_OPTION(sbi).fsync_mode != FSYNC_MODE_NOBARRIER)
> > -            (atomic && !test_opt(sbi, NOBARRIER) && f2fs_sb_has_blkzoned(sbi)))
> > +        if (!atomic && F2FS_OPTION(sbi).fsync_mode != FSYNC_MODE_NOBARRIER)
> >                   ret = f2fs_issue_flush(sbi, inode->i_ino);
> >           if (!ret) {
> >                   f2fs_remove_ino_entry(sbi, ino, UPDATE_INO);
> > diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
> > index 144f9f966690..c45d341dcf6e 100644
> > --- a/fs/f2fs/node.c
> > +++ b/fs/f2fs/node.c
> > @@ -1631,7 +1631,7 @@ static int __write_node_page(struct page *page, bool atomic, bool *submitted,
> >                   goto redirty_out;
> >           }
> > 
> > -        if (atomic && !test_opt(sbi, NOBARRIER) && !f2fs_sb_has_blkzoned(sbi))
> > +        if (atomic && !test_opt(sbi, NOBARRIER))
> >                   fio.op_flags = REQ_PREFLUSH REQ_FUA;
> > 
> >           /* should add to global list before clearing PAGECACHE status */