diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
index 88d8f22d2cbab02c7a10a21918aee02c990f6f82..67ac91b530508dec9fbb60514fbf218fd53cbb4a 100644
--- a/fs/jbd2/journal.c
+++ b/fs/jbd2/journal.c
@@ -1356,6 +1356,10 @@ static int journal_reset(journal_t *journal)
 	return jbd2_journal_start_thread(journal);
 }
 
+/*
+ * This function expects that the caller will have locked the journal
+ * buffer head, and will return with it unlocked
+ */
 static int jbd2_write_superblock(journal_t *journal, int write_flags)
 {
 	struct buffer_head *bh = journal->j_sb_buffer;
@@ -1365,7 +1369,6 @@ static int jbd2_write_superblock(journal_t *journal, int write_flags)
 	trace_jbd2_write_superblock(journal, write_flags);
 	if (!(journal->j_flags & JBD2_BARRIER))
 		write_flags &= ~(REQ_FUA | REQ_PREFLUSH);
-	lock_buffer(bh);
 	if (buffer_write_io_error(bh)) {
 		/*
 		 * Oh, dear.  A previous attempt to write the journal
@@ -1424,6 +1427,7 @@ int jbd2_journal_update_sb_log_tail(journal_t *journal, tid_t tail_tid,
 	jbd_debug(1, "JBD2: updating superblock (start %lu, seq %u)\n",
 		  tail_block, tail_tid);
 
+	lock_buffer(journal->j_sb_buffer);
 	sb->s_sequence = cpu_to_be32(tail_tid);
 	sb->s_start    = cpu_to_be32(tail_block);
 
@@ -1454,18 +1458,17 @@ static void jbd2_mark_journal_empty(journal_t *journal, int write_op)
 	journal_superblock_t *sb = journal->j_superblock;
 
 	BUG_ON(!mutex_is_locked(&journal->j_checkpoint_mutex));
-	read_lock(&journal->j_state_lock);
-	/* Is it already empty? */
-	if (sb->s_start == 0) {
-		read_unlock(&journal->j_state_lock);
+	lock_buffer(journal->j_sb_buffer);
+	if (sb->s_start == 0) {		/* Is it already empty? */
+		unlock_buffer(journal->j_sb_buffer);
 		return;
 	}
+
 	jbd_debug(1, "JBD2: Marking journal as empty (seq %d)\n",
 		  journal->j_tail_sequence);
 
 	sb->s_sequence = cpu_to_be32(journal->j_tail_sequence);
 	sb->s_start    = cpu_to_be32(0);
-	read_unlock(&journal->j_state_lock);
 
 	jbd2_write_superblock(journal, write_op);
 
@@ -1488,9 +1491,8 @@ void jbd2_journal_update_sb_errno(journal_t *journal)
 	journal_superblock_t *sb = journal->j_superblock;
 	int errcode;
 
-	read_lock(&journal->j_state_lock);
+	lock_buffer(journal->j_sb_buffer);
 	errcode = journal->j_errno;
-	read_unlock(&journal->j_state_lock);
 	if (errcode == -ESHUTDOWN)
 		errcode = 0;
 	jbd_debug(1, "JBD2: updating superblock error (errno %d)\n", errcode);
@@ -1894,28 +1896,27 @@ int jbd2_journal_set_features (journal_t *journal, unsigned long compat,
 
 	sb = journal->j_superblock;
 
+	/* Load the checksum driver if necessary */
+	if ((journal->j_chksum_driver == NULL) &&
+	    INCOMPAT_FEATURE_ON(JBD2_FEATURE_INCOMPAT_CSUM_V3)) {
+		journal->j_chksum_driver = crypto_alloc_shash("crc32c", 0, 0);
+		if (IS_ERR(journal->j_chksum_driver)) {
+			printk(KERN_ERR "JBD2: Cannot load crc32c driver.\n");
+			journal->j_chksum_driver = NULL;
+			return 0;
+		}
+		/* Precompute checksum seed for all metadata */
+		journal->j_csum_seed = jbd2_chksum(journal, ~0, sb->s_uuid,
+						   sizeof(sb->s_uuid));
+	}
+
+	lock_buffer(journal->j_sb_buffer);
+
 	/* If enabling v3 checksums, update superblock */
 	if (INCOMPAT_FEATURE_ON(JBD2_FEATURE_INCOMPAT_CSUM_V3)) {
 		sb->s_checksum_type = JBD2_CRC32C_CHKSUM;
 		sb->s_feature_compat &=
 			~cpu_to_be32(JBD2_FEATURE_COMPAT_CHECKSUM);
-
-		/* Load the checksum driver */
-		if (journal->j_chksum_driver == NULL) {
-			journal->j_chksum_driver = crypto_alloc_shash("crc32c",
-								      0, 0);
-			if (IS_ERR(journal->j_chksum_driver)) {
-				printk(KERN_ERR "JBD2: Cannot load crc32c "
-				       "driver.\n");
-				journal->j_chksum_driver = NULL;
-				return 0;
-			}
-
-			/* Precompute checksum seed for all metadata */
-			journal->j_csum_seed = jbd2_chksum(journal, ~0,
-							   sb->s_uuid,
-							   sizeof(sb->s_uuid));
-		}
 	}
 
 	/* If enabling v1 checksums, downgrade superblock */
@@ -1927,6 +1928,7 @@ int jbd2_journal_set_features (journal_t *journal, unsigned long compat,
 	sb->s_feature_compat    |= cpu_to_be32(compat);
 	sb->s_feature_ro_compat |= cpu_to_be32(ro);
 	sb->s_feature_incompat  |= cpu_to_be32(incompat);
+	unlock_buffer(journal->j_sb_buffer);
 
 	return 1;
 #undef COMPAT_FEATURE_ON