ext4: Fix buffer head leaks after calls to ext4_get_inode_loc()

Calls to ext4_get_inode_loc() returns with a reference to a buffer
head in iloc->bh.  The callers of this function in ext4_write_inode()
when in no journal mode and in ext4_xattr_fiemap() don't release the
buffer head after using it.

Addresses-Google-Bug: #2548165
Signed-off-by: NCurt Wohlgemuth <curtw@google.com>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

fs/ext4/extents.c

@@ -3879,6 +3879,7 @@ static int ext4_xattr_fiemap(struct inode *inode,
 		physical += offset;
 		length = EXT4_SB(inode->i_sb)->s_inode_size - offset;
 		flags |= FIEMAP_EXTENT_DATA_INLINE;
+		brelse(iloc.bh);
 	} else { /* external block */
 		physical = EXT4_I(inode)->i_file_acl << blockbits;
 		length = inode->i_sb->s_blocksize;

fs/ext4/inode.c

@@ -5385,6 +5385,7 @@ int ext4_write_inode(struct inode *inode, struct writeback_control *wbc)
 				   (unsigned long long)iloc.bh->b_blocknr);
 			err = -EIO;
 		}
+		brelse(iloc.bh);
 	}
 	return err;
 }