swapfile: fix name leak in swapoff

There's a name leak introduced by commit 91a27b2a7567 ("vfs: define
struct filename and have getname() return it").  Add the missing
putname.

[akpm@linux-foundation.org: cleanup]
Signed-off-by: Xiaotian Feng <dannyfeng@tencent.com>
Reviewed-by: Jeff Layton <jlayton@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/swapfile.c

@@ -1494,9 +1494,8 @@ SYSCALL_DEFINE1(swapoff, const char __user *, specialfile)
 	BUG_ON(!current->mm);
 
 	pathname = getname(specialfile);
-	err = PTR_ERR(pathname);
 	if (IS_ERR(pathname))
-		goto out;
+		return PTR_ERR(pathname);
 
 	victim = file_open_name(pathname, O_RDWR|O_LARGEFILE, 0);
 	err = PTR_ERR(victim);
@@ -1608,6 +1607,7 @@ SYSCALL_DEFINE1(swapoff, const char __user *, specialfile)
 out_dput:
 	filp_close(victim, NULL);
 out:
+	putname(pathname);
 	return err;
 }