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/jbd2/commit.c b/fs/jbd2/commit.c
index f2ad061..b091e53 100644
--- a/fs/jbd2/commit.c
+++ b/fs/jbd2/commit.c
@@ -147,12 +147,9 @@
 	 * to remember if we sent a barrier request
 	 */
 	if (ret == -EOPNOTSUPP && barrier_done) {
-		char b[BDEVNAME_SIZE];
-
 		printk(KERN_WARNING
-			"JBD: barrier-based sync failed on %s - "
-			"disabling barriers\n",
-			bdevname(journal->j_dev, b));
+		       "JBD: barrier-based sync failed on %s - "
+		       "disabling barriers\n", journal->j_devname);
 		spin_lock(&journal->j_state_lock);
 		journal->j_flags &= ~JBD2_BARRIER;
 		spin_unlock(&journal->j_state_lock);
@@ -681,11 +678,9 @@
 	 */
 	err = journal_finish_inode_data_buffers(journal, commit_transaction);
 	if (err) {
-		char b[BDEVNAME_SIZE];
-
 		printk(KERN_WARNING
 			"JBD2: Detected IO errors while flushing file data "
-			"on %s\n", bdevname(journal->j_fs_dev, b));
+		       "on %s\n", journal->j_devname);
 		err = 0;
 	}