jbd2: Unify log messages in jbd2 code

Some jbd2 code prints out kernel messages with "JBD2: " prefix, at the
same time other jbd2 code prints with "JBD: " prefix. Unify the prefix
to "JBD2: ".

Signed-off-by: Eryu Guan <guaneryu@gmail.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

fs/jbd2/transaction.c

@@ -125,7 +125,7 @@ static int start_this_handle(journal_t *journal, handle_t *handle,
 	unsigned long ts = jiffies;
 
 	if (nblocks > journal->j_max_transaction_buffers) {
-		printk(KERN_ERR "JBD: %s wants too many credits (%d > %d)\n",
+		printk(KERN_ERR "JBD2: %s wants too many credits (%d > %d)\n",
 		       current->comm, nblocks,
 		       journal->j_max_transaction_buffers);
 		return -ENOSPC;
@@ -564,7 +564,7 @@ static void warn_dirty_buffer(struct buffer_head *bh)
 	char b[BDEVNAME_SIZE];
 
 	printk(KERN_WARNING
-	       "JBD: Spotted dirty metadata buffer (dev = %s, blocknr = %llu). "
+	       "JBD2: Spotted dirty metadata buffer (dev = %s, blocknr = %llu). "
 	       "There's a risk of filesystem corruption in case of system "
 	       "crash.\n",
 	       bdevname(bh->b_bdev, b), (unsigned long long)bh->b_blocknr);