[PATCH] ext3: bd_claim for journal device

From: Neil Brown <neilb@cse.unsw.edu.au>

Change ext3 to run bd_claim() against external journal devices. It is
significant only for those who have ext3 journals on a separate device, and
gets exclusive access to that device.

fs/ext3/super.c

@@ -340,6 +340,7 @@ static struct block_device *ext3_blkdev_get(dev_t dev)
  */
 static int ext3_blkdev_put(struct block_device *bdev)
 {
+	bd_release(bdev);
 	return blkdev_put(bdev, BDEV_FS);
 }
 
@@ -1480,6 +1481,13 @@ static journal_t *ext3_get_dev_journal(struct super_block *sb,
 	if (bdev == NULL)
 		return NULL;
 
+	if (bd_claim(bdev, sb)) {
+		printk(KERN_ERR
+		        "EXT3: failed to claim external journal device.\n");
+		blkdev_put(bdev, BDEV_FS);
+		return NULL;
+	}
+
 	blocksize = sb->s_blocksize;
 	hblock = bdev_hardsect_size(bdev);
 	if (blocksize < hblock) {