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: Ben Hutchings <ben@decadent.org.uk>

diff --git a/fs/jbd2/commit.c b/fs/jbd2/commit.c
index 68d704db787f108350f9cc47fd506628685399c7..d751f04763c1b740d7aa6b53f9a725027b01a1d9 100644 (file)
--- 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)