jbd2: clean up how the journal device name is printed

Calculate the journal device name once and stash it away in the
journal_s structure.  This avoids needing to call bdevname()
everywhere and reduces stack usage by not needing to allocate an
on-stack buffer.  In addition, we eliminate the '/' that can appear in
device names (e.g. "cciss/c0d0p9" --- see kernel bugzilla #11321) that
can cause problems when creating proc directory names, and include the
inode number to support ocfs2 which creates multiple journals with
different inode numbers.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index f58cc03..64e1c21 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -1476,15 +1476,9 @@
 			EXT4_INODES_PER_GROUP(sb),
 			sbi->s_mount_opt);
 
-	if (EXT4_SB(sb)->s_journal->j_inode == NULL) {
-		char b[BDEVNAME_SIZE];
-
-		printk(KERN_INFO "EXT4 FS on %s, external journal on %s\n",
-		       sb->s_id, bdevname(EXT4_SB(sb)->s_journal->j_dev, b));
-	} else {
-		printk(KERN_INFO "EXT4 FS on %s, internal journal\n",
-		       sb->s_id);
-	}
+	printk(KERN_INFO "EXT4 FS on %s, %s journal on %s\n",
+	       sb->s_id, EXT4_SB(sb)->s_journal->j_inode ? "internal" :
+	       "external", EXT4_SB(sb)->s_journal->j_devname);
 	return res;
 }