linux-kernel - Re: [PATCH v2] FAT: use schedule_timeout_uninterruptible() instead of congestion

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Date:   Sat, 11 Dec 2021 17:27:39 +0900
From:   OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>
To:     "NeilBrown" <neilb@...e.de>
Cc:     linux-kernel@...r.kernel.org, linux-block@...r.kernel.org,
        "Christoph Hellwig" <hch@...radead.org>
Subject: Re: [PATCH v2] FAT: use schedule_timeout_uninterruptible() instead
 of congestion_wait()

"NeilBrown" <neilb@...e.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@...l.parknet.co.jp>

> Signed-off-by: NeilBrown <neilb@...e.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@...l.parknet.co.jp>