linux-ext4 - Re: [PATCH] ext4: mark all metadata I/O with REQ

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Date:	Wed, 24 Apr 2013 12:15:18 +0200
From:	Jan Kara <jack@...e.cz>
To:	Theodore Ts'o <tytso@....edu>
Cc:	Ext4 Developers List <linux-ext4@...r.kernel.org>
Subject: Re: [PATCH] ext4: mark all metadata I/O with REQ_META

On Sat 20-04-13 15:46:58, Ted Tso wrote:
> As Dave Chinner pointed out at the 2013 LSF/MM workshop, it's
> important that metadata I/O requests are marked as such to avoid
> priority inversions caused by I/O bandwidth throttling.
  OK, but then you also need this for all the journal & checkpoint IO from
JBD2 don't you?

								Honza

> 
> Signed-off-by: "Theodore Ts'o" <tytso@....edu>
> ---
>  fs/ext4/balloc.c | 2 +-
>  fs/ext4/ialloc.c | 2 +-
>  fs/ext4/mmp.c    | 4 ++--
>  fs/ext4/super.c  | 2 +-
>  4 files changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/fs/ext4/balloc.c b/fs/ext4/balloc.c
> index 8dcaea6..d0f13ea 100644
> --- a/fs/ext4/balloc.c
> +++ b/fs/ext4/balloc.c
> @@ -441,7 +441,7 @@ ext4_read_block_bitmap_nowait(struct super_block *sb, ext4_group_t block_group)
>  	trace_ext4_read_block_bitmap_load(sb, block_group);
>  	bh->b_end_io = ext4_end_bitmap_read;
>  	get_bh(bh);
> -	submit_bh(READ, bh);
> +	submit_bh(READ | REQ_META | REQ_PRIO, bh);
>  	return bh;
>  verify:
>  	ext4_validate_block_bitmap(sb, desc, block_group, bh);
> diff --git a/fs/ext4/ialloc.c b/fs/ext4/ialloc.c
> index 18d36d8..00a818d 100644
> --- a/fs/ext4/ialloc.c
> +++ b/fs/ext4/ialloc.c
> @@ -166,7 +166,7 @@ ext4_read_inode_bitmap(struct super_block *sb, ext4_group_t block_group)
>  	trace_ext4_load_inode_bitmap(sb, block_group);
>  	bh->b_end_io = ext4_end_bitmap_read;
>  	get_bh(bh);
> -	submit_bh(READ, bh);
> +	submit_bh(READ | REQ_META | REQ_PRIO, bh);
>  	wait_on_buffer(bh);
>  	if (!buffer_uptodate(bh)) {
>  		put_bh(bh);
> diff --git a/fs/ext4/mmp.c b/fs/ext4/mmp.c
> index b3b1f7d..214461e 100644
> --- a/fs/ext4/mmp.c
> +++ b/fs/ext4/mmp.c
> @@ -54,7 +54,7 @@ static int write_mmp_block(struct super_block *sb, struct buffer_head *bh)
>  	lock_buffer(bh);
>  	bh->b_end_io = end_buffer_write_sync;
>  	get_bh(bh);
> -	submit_bh(WRITE_SYNC, bh);
> +	submit_bh(WRITE_SYNC | REQ_META | REQ_PRIO, bh);
>  	wait_on_buffer(bh);
>  	sb_end_write(sb);
>  	if (unlikely(!buffer_uptodate(bh)))
> @@ -86,7 +86,7 @@ static int read_mmp_block(struct super_block *sb, struct buffer_head **bh,
>  		get_bh(*bh);
>  		lock_buffer(*bh);
>  		(*bh)->b_end_io = end_buffer_read_sync;
> -		submit_bh(READ_SYNC, *bh);
> +		submit_bh(READ_SYNC | REQ_META | REQ_PRIO, *bh);
>  		wait_on_buffer(*bh);
>  		if (!buffer_uptodate(*bh)) {
>  			brelse(*bh);
> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> index bfa29ec..dbc7c09 100644
> --- a/fs/ext4/super.c
> +++ b/fs/ext4/super.c
> @@ -4252,7 +4252,7 @@ static journal_t *ext4_get_dev_journal(struct super_block *sb,
>  		goto out_bdev;
>  	}
>  	journal->j_private = sb;
> -	ll_rw_block(READ, 1, &journal->j_sb_buffer);
> +	ll_rw_block(READ | REQ_META | REQ_PRIO, 1, &journal->j_sb_buffer);
>  	wait_on_buffer(journal->j_sb_buffer);
>  	if (!buffer_uptodate(journal->j_sb_buffer)) {
>  		ext4_msg(sb, KERN_ERR, "I/O error on journal device");
> -- 
> 1.7.12.rc0.22.gcdd159b
> 
> --
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-- 
Jan Kara <jack@...e.cz>
SUSE Labs, CR
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