linux-kernel - [PATCH 1/3] ext4: mark all metadata I/O with REQ

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Message-Id: <1366502828-7793-1-git-send-email-tytso@mit.edu>
Date:	Sat, 20 Apr 2013 20:07:06 -0400
From:	Theodore Ts'o <tytso@....edu>
To:	Ext4 Developers List <linux-ext4@...r.kernel.org>
Cc:	linux-mm@...ck.org,
	Linux Kernel Developers List <linux-kernel@...r.kernel.org>,
	mgorman@...e.de, Theodore Ts'o <tytso@....edu>
Subject: [PATCH 1/3] ext4: mark all metadata I/O with REQ_META

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.

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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