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>

1 files changed, 2 insertions, 2 deletions

diff --git a/fs/jbd2/commit.c b/fs/jbd2/commit.c
index eef6979821a..36c2e800e73 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)