mm/shmem.c: fix unused shmem_parse_huge() function warning

When CONFIG_SYSFS is disabled but CONFIG_TMPFS is enabled, we get a
warning about shmem_parse_huge() never being called:

  mm/shmem.c:417:12: error: unused function 'shmem_parse_huge' [-Werror,-Wunused-function]
  static int shmem_parse_huge(const char *str)

Change the #ifdef so we no longer build this function in that configuration.

Link: http://lkml.kernel.org/r/20190712091141.673355-1-arnd@arndb.de
Fixes: 144df3b288c4 ("vfs: Convert ramfs, shmem, tmpfs, devtmpfs, rootfs to use the new mount API")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Hugh Dickins <hughd@google.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: David Howells <dhowells@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Vineeth Remanan Pillai <vpillai@digitalocean.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/shmem.c

@@ -400,7 +400,7 @@ static bool shmem_confirm_swap(struct address_space *mapping,
 
 static int shmem_huge __read_mostly;
 
-#if defined(CONFIG_SYSFS) || defined(CONFIG_TMPFS)
+#if defined(CONFIG_SYSFS)
 static int shmem_parse_huge(const char *str)
 {
 	if (!strcmp(str, "never"))
@@ -417,7 +417,9 @@ static int shmem_parse_huge(const char *str)
 		return SHMEM_HUGE_FORCE;
 	return -EINVAL;
 }
+#endif
 
+#if defined(CONFIG_SYSFS) || defined(CONFIG_TMPFS)
 static const char *shmem_format_huge(int huge)
 {
 	switch (huge) {