mm/zbud.c: make size unsigned like unique callsite

zbud_alloc is only called by zswap_frontswap_store with unsigned int len.
Change function parameter + update >= 0 check.

Signed-off-by: Fabian Frederick <fabf@skynet.be>
Acked-by: Seth Jennings <sjennings@variantweb.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/zbud.h

@@ -11,7 +11,7 @@ struct zbud_ops {
 
 struct zbud_pool *zbud_create_pool(gfp_t gfp, struct zbud_ops *ops);
 void zbud_destroy_pool(struct zbud_pool *pool);
-int zbud_alloc(struct zbud_pool *pool, int size, gfp_t gfp,
+int zbud_alloc(struct zbud_pool *pool, unsigned int size, gfp_t gfp,
 	unsigned long *handle);
 void zbud_free(struct zbud_pool *pool, unsigned long handle);
 int zbud_reclaim_page(struct zbud_pool *pool, unsigned int retries);

mm/zbud.c

@@ -247,7 +247,7 @@ void zbud_destroy_pool(struct zbud_pool *pool)
  * gfp arguments are invalid or -ENOMEM if the pool was unable to allocate
  * a new page.
  */
-int zbud_alloc(struct zbud_pool *pool, int size, gfp_t gfp,
+int zbud_alloc(struct zbud_pool *pool, unsigned int size, gfp_t gfp,
 			unsigned long *handle)
 {
 	int chunks, i, freechunks;
@@ -255,7 +255,7 @@ int zbud_alloc(struct zbud_pool *pool, int size, gfp_t gfp,
 	enum buddy bud;
 	struct page *page;
 
-	if (size <= 0 || gfp & __GFP_HIGHMEM)
+	if (!size || (gfp & __GFP_HIGHMEM))
 		return -EINVAL;
 	if (size > PAGE_SIZE - ZHDR_SIZE_ALIGNED - CHUNK_SIZE)
 		return -ENOSPC;