mm/z3fold.c: use gfpflags_allow_blocking

We have a perfectly good macro to determine whether the gfp flags allow
you to sleep or not; use it instead of trying to infer it.

Link: http://lkml.kernel.org/r/20180408062206.GC16007@bombadil.infradead.org
Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Vitaly Wool <vitalywool@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/z3fold.c

@@ -538,7 +538,7 @@ static int z3fold_alloc(struct z3fold_pool *pool, size_t size, gfp_t gfp,
 	struct z3fold_header *zhdr = NULL;
 	struct page *page = NULL;
 	enum buddy bud;
-	bool can_sleep = (gfp & __GFP_RECLAIM) == __GFP_RECLAIM;
+	bool can_sleep = gfpflags_allow_blocking(gfp);
 
 	if (!size || (gfp & __GFP_HIGHMEM))
 		return -EINVAL;