When write in ext4_quota_write() fails, we have to properly release
i_mutex.  One error path has been missing the unlock...
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
                blk++;
        }
 out:
-       if (len == towrite)
+       if (len == towrite) {
+               mutex_unlock(&inode->i_mutex);
                return err;
+       }
        if (inode->i_size < off+len-towrite) {
                i_size_write(inode, off+len-towrite);
                EXT4_I(inode)->i_disksize = inode->i_size;