From:   OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
To:     "NeilBrown" <neilb@suse.de>
Cc:     linux-kernel@vger.kernel.org, linux-block@vger.kernel.org,
        "Christoph Hellwig" <hch@infradead.org>
Subject: Re: [PATCH v2] FAT: use schedule_timeout_uninterruptible() instead
 of congestion_wait()
References: <163712349419.13692.2859038330142282757@noble.neil.brown.name>
        <87ee79yiik.fsf@mail.parknet.co.jp>
        <163754226639.13692.10449616189734943162@noble.neil.brown.name>
        <874k84hi5q.fsf@mail.parknet.co.jp>
        <163911011670.9928.6438117555175130033@noble.neil.brown.name>
        <163911016975.9928.6568675782275129@noble.neil.brown.name>
Date:   Sat, 11 Dec 2021 17:27:39 +0900
In-Reply-To: <163911016975.9928.6568675782275129@noble.neil.brown.name>
        (NeilBrown's message of "Fri, 10 Dec 2021 15:22:49 +1100")
Message-ID: <87h7bfmtqc.fsf@mail.parknet.co.jp>
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"NeilBrown" <neilb@suse.de> writes:

> congestion_wait() in this context is just a sleep - block devices do not
> in general support congestion signalling any more.
>
> The goal here is to wait for any recently written data to get to
> storage.  blkdev_issue_flush() is thought to be too expensive, so
> replace congestion_wait() with an explicit timeout.

If just replace, the following looks better

	set_current_state(TASK_UNINTERRUPTIBLE);
	io_schedule_timeout(HZ/10);

Otherwise,

Acked-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>

> Signed-off-by: NeilBrown <neilb@suse.de>
> ---
>  fs/fat/file.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/fs/fat/file.c b/fs/fat/file.c
> index 13855ba49cd9..2321fb3eded5 100644
> --- a/fs/fat/file.c
> +++ b/fs/fat/file.c
> @@ -175,9 +175,9 @@ long fat_generic_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
>  static int fat_file_release(struct inode *inode, struct file *filp)
>  {
>  	if ((filp->f_mode & FMODE_WRITE) &&
> -	     MSDOS_SB(inode->i_sb)->options.flush) {
> +	    MSDOS_SB(inode->i_sb)->options.flush) {
>  		fat_flush_inodes(inode->i_sb, inode, NULL);
> -		congestion_wait(BLK_RW_ASYNC, HZ/10);
> +		schedule_timeout_uninterruptible(HZ/10);
>  	}
>  	return 0;
>  }

-- 
OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>