linux-kernel - [ 026/167] [PATCH] jbd2: use GFP_NOFS for blkdev_issue

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Message-Id: <20120509055033.164719500@decadent.org.uk>
Date:	Wed, 09 May 2012 06:50:55 +0100
From:	Ben Hutchings <ben@...adent.org.uk>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:	torvalds@...ux-foundation.org, akpm@...ux-foundation.org,
	alan@...rguk.ukuu.org.uk, Shaohua Li <shli@...nel.org>,
	Shaohua Li <shli@...ionio.com>, Theodore Tso <tytso@....edu>,
	Jan Kara <jack@...e.cz>
Subject: [ 026/167] [PATCH] jbd2: use GFP_NOFS for blkdev_issue_flush

3.2-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Shaohua Li <shli@...nel.org>

commit 99aa78466777083255b876293e9e83dec7cd809a upstream.

flush request is issued in transaction commit code path, so looks using
GFP_KERNEL to allocate memory for flush request bio falls into the classic
deadlock issue.  I saw btrfs and dm get it right, but ext4, xfs and md are
using GFP.

Signed-off-by: Shaohua Li <shli@...ionio.com>
Signed-off-by: Theodore Ts'o <tytso@....edu>
Reviewed-by: Jan Kara <jack@...e.cz>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 fs/jbd2/commit.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/jbd2/commit.c b/fs/jbd2/commit.c
index 806525a..840f70f 100644
--- a/fs/jbd2/commit.c
+++ b/fs/jbd2/commit.c
@@ -723,7 +723,7 @@ start_journal_io:
 	if (commit_transaction->t_need_data_flush &&
 	    (journal->j_fs_dev != journal->j_dev) &&
 	    (journal->j_flags & JBD2_BARRIER))
-		blkdev_issue_flush(journal->j_fs_dev, GFP_KERNEL, NULL);
+		blkdev_issue_flush(journal->j_fs_dev, GFP_NOFS, NULL);
 
 	/* Done it all: now write the commit record asynchronously. */
 	if (JBD2_HAS_INCOMPAT_FEATURE(journal,
@@ -859,7 +859,7 @@ wait_for_iobuf:
 	if (JBD2_HAS_INCOMPAT_FEATURE(journal,
 				      JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT) &&
 	    journal->j_flags & JBD2_BARRIER) {
-		blkdev_issue_flush(journal->j_dev, GFP_KERNEL, NULL);
+		blkdev_issue_flush(journal->j_dev, GFP_NOFS, NULL);
 	}
 
 	if (err)
-- 
1.7.10



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