ext4: fix error paths in swap_inode_boot_loader()

In swap_inode_boot_loader() we forgot to release ->i_mutex and resume
unlocked dio for inode and inode_bl if there is an error starting the
journal handle.  This commit fixes this issue.

Reported-by: Ahmed Tamrawi <ahmedtamrawi@gmail.com>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: Dr. Tilmann Bubeck <t.bubeck@reinform.de>
Signed-off-by: Zheng Liu <wenqing.lz@taobao.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: stable@vger.kernel.org  # v3.10+

fs/ext4/ioctl.c

@@ -140,7 +140,7 @@ static long swap_inode_boot_loader(struct super_block *sb,
 	handle = ext4_journal_start(inode_bl, EXT4_HT_MOVE_EXTENTS, 2);
 	if (IS_ERR(handle)) {
 		err = -EINVAL;
-		goto swap_boot_out;
+		goto journal_err_out;
 	}
 
 	/* Protect extent tree against block allocations via delalloc */
@@ -198,6 +198,7 @@ static long swap_inode_boot_loader(struct super_block *sb,
 
 	ext4_double_up_write_data_sem(inode, inode_bl);
 
+journal_err_out:
 	ext4_inode_resume_unlocked_dio(inode);
 	ext4_inode_resume_unlocked_dio(inode_bl);