smaps: fix defined but not used smaps_shmem_walk_ops

When !CONFIG_SHMEM smaps_shmem_walk_ops is defined but not used,
triggering a compiler warning.  To avoid the warning remove the #ifdef
around the usage.  This has no effect because shmem_mapping() is a stub
returning false when !CONFIG_SHMEM so the code will be compiled out,
however we now need to also provide a stub for shmem_swap_usage().

Link: https://lkml.kernel.org/r/20230405103819.151246-1-steven.price@arm.com
Fixes: 7b86ac3371b7 ("pagewalk: separate function pointers from iterator data")
Signed-off-by: Steven Price <steven.price@arm.com>
Reported-by: kernel test robot <lkp@intel.com>
  Link: https://lore.kernel.org/oe-kbuild-all/202304031749.UiyJpxzF-lkp@intel.com/
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

1 files changed, 7 insertions, 0 deletions

diff --git a/include/linux/shmem_fs.h b/include/linux/shmem_fs.h
index 3bb8d21edbb3..b9516a9802bf 100644
--- a/include/linux/shmem_fs.h
+++ b/include/linux/shmem_fs.h
@@ -96,7 +96,14 @@ int shmem_unuse(unsigned int type);
 
 extern bool shmem_is_huge(struct inode *inode, pgoff_t index, bool shmem_huge_force,
 			  struct mm_struct *mm, unsigned long vm_flags);
+#ifdef CONFIG_SHMEM
 extern unsigned long shmem_swap_usage(struct vm_area_struct *vma);
+#else
+static inline unsigned long shmem_swap_usage(struct vm_area_struct *vma)
+{
+	return 0;
+}
+#endif
 extern unsigned long shmem_partial_swap_usage(struct address_space *mapping,
 						pgoff_t start, pgoff_t end);