mm/zsmalloc.c: make several functions and a struct static

The functions zs_page_isolate, zs_page_migrate, zs_page_putback,
lock_zspage, trylock_zspage and structure zsmalloc_aops are local to
source and do not need to be in global scope, so make them static.

Cleans up sparse warnings:
  symbol 'zs_page_isolate' was not declared. Should it be static?
  symbol 'zs_page_migrate' was not declared. Should it be static?
  symbol 'zs_page_putback' was not declared. Should it be static?
  symbol 'zsmalloc_aops' was not declared. Should it be static?
  symbol 'lock_zspage' was not declared. Should it be static?
  symbol 'trylock_zspage' was not declared. Should it be static?

[arnd@arndb.de: hide unused lock_zspage]
  Link: http://lkml.kernel.org/r/20180706130924.3891230-1-arnd@arndb.de
Link: http://lkml.kernel.org/r/20180624213322.13776-1-colin.king@canonical.com
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/zsmalloc.c

@@ -924,20 +924,7 @@ static void reset_page(struct page *page)
 	page->freelist = NULL;
 }
 
-/*
- * To prevent zspage destroy during migration, zspage freeing should
- * hold locks of all pages in the zspage.
- */
-void lock_zspage(struct zspage *zspage)
-{
-	struct page *page = get_first_page(zspage);
-
-	do {
-		lock_page(page);
-	} while ((page = get_next_page(page)) != NULL);
-}
-
-int trylock_zspage(struct zspage *zspage)
+static int trylock_zspage(struct zspage *zspage)
 {
 	struct page *cursor, *fail;
 
@@ -1814,6 +1801,19 @@ static enum fullness_group putback_zspage(struct size_class *class,
 }
 
 #ifdef CONFIG_COMPACTION
+/*
+ * To prevent zspage destroy during migration, zspage freeing should
+ * hold locks of all pages in the zspage.
+ */
+static void lock_zspage(struct zspage *zspage)
+{
+	struct page *page = get_first_page(zspage);
+
+	do {
+		lock_page(page);
+	} while ((page = get_next_page(page)) != NULL);
+}
+
 static struct dentry *zs_mount(struct file_system_type *fs_type,
 				int flags, const char *dev_name, void *data)
 {
@@ -1905,7 +1905,7 @@ static void replace_sub_page(struct size_class *class, struct zspage *zspage,
 	__SetPageMovable(newpage, page_mapping(oldpage));
 }
 
-bool zs_page_isolate(struct page *page, isolate_mode_t mode)
+static bool zs_page_isolate(struct page *page, isolate_mode_t mode)
 {
 	struct zs_pool *pool;
 	struct size_class *class;
@@ -1960,7 +1960,7 @@ bool zs_page_isolate(struct page *page, isolate_mode_t mode)
 	return true;
 }
 
-int zs_page_migrate(struct address_space *mapping, struct page *newpage,
+static int zs_page_migrate(struct address_space *mapping, struct page *newpage,
 		struct page *page, enum migrate_mode mode)
 {
 	struct zs_pool *pool;
@@ -2076,7 +2076,7 @@ unpin_objects:
 	return ret;
 }
 
-void zs_page_putback(struct page *page)
+static void zs_page_putback(struct page *page)
 {
 	struct zs_pool *pool;
 	struct size_class *class;
@@ -2108,7 +2108,7 @@ void zs_page_putback(struct page *page)
 	spin_unlock(&class->lock);
 }
 
-const struct address_space_operations zsmalloc_aops = {
+static const struct address_space_operations zsmalloc_aops = {
 	.isolate_page = zs_page_isolate,
 	.migratepage = zs_page_migrate,
 	.putback_page = zs_page_putback,