ext4: mark metadata blocks using bh flags

This allows metadata writebacks which are issued via block device
writeback to be sent with the current write request flags.
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

fs/ext4/ext4_jbd2.c

@@ -215,6 +215,8 @@ int __ext4_handle_dirty_metadata(const char *where, unsigned int line,
 
 	might_sleep();
 
+	set_buffer_meta(bh);
+	set_buffer_prio(bh);
 	if (ext4_handle_valid(handle)) {
 		err = jbd2_journal_dirty_metadata(handle, bh);
 		if (err) {

fs/ext4/inode.c

@@ -1080,10 +1080,14 @@ static int ext4_write_begin(struct file *file, struct address_space *mapping,
 /* For write_end() in data=journal mode */
 static int write_end_fn(handle_t *handle, struct buffer_head *bh)
 {
+	int ret;
 	if (!buffer_mapped(bh) || buffer_freed(bh))
 		return 0;
 	set_buffer_uptodate(bh);
-	return ext4_handle_dirty_metadata(handle, NULL, bh);
+	ret = ext4_handle_dirty_metadata(handle, NULL, bh);
+	clear_buffer_meta(bh);
+	clear_buffer_prio(bh);
+	return ret;
 }
 
 /*