mutex_unlock() later in seq_lseek()

All manipulations with struct seq_file::version are done under
struct seq_file::lock except one introduced in commit
d6b7a781c51c91dd054e5c437885205592faac21
aka "[PATCH] Speed up /proc/pid/maps"

Signed-off-by: Alexey Dobriyan <adobriyan@sw.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/seq_file.c

@@ -260,8 +260,8 @@ loff_t seq_lseek(struct file *file, loff_t offset, int origin)
 				}
 			}
 	}
-	mutex_unlock(&m->lock);
 	file->f_version = m->version;
+	mutex_unlock(&m->lock);
 	return retval;
 }
 EXPORT_SYMBOL(seq_lseek);