From 7604ff9ce747b74ddff6ac5d118a442122fdcbd7 Mon Sep 17 00:00:00 2001
From: Shaohua Li <shli@kernel.org>
Date: Fri, 13 Apr 2012 10:27:35 +0800
Subject: [PATCH] jbd2: use GFP_NOFS for blkdev_issue_flush

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@fusionio.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 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 eef6979821a4..36c2e800e734 100644
--- a/fs/jbd2/commit.c
+++ b/fs/jbd2/commit.c
@@ -683,7 +683,7 @@ 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,
@@ -819,7 +819,7 @@ 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)
-- 
2.34.1