zpool: add malloc_support_movable to zpool_driver

As a zpool_driver, zsmalloc can allocate movable memory because it support
migate pages.  But zbud and z3fold cannot allocate movable memory.

Add malloc_support_movable to zpool_driver.  If a zpool_driver support
allocate movable memory, set it to true.  And add
zpool_malloc_support_movable check malloc_support_movable to make sure if
a zpool support allocate movable memory.

Link: http://lkml.kernel.org/r/20190605100630.13293-1-teawaterz@linux.alibaba.com
Signed-off-by: Hui Zhu <teawaterz@linux.alibaba.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Cc: Dan Streetman <ddstreet@ieee.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Nitin Gupta <ngupta@vflare.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Cc: Seth Jennings <sjenning@redhat.com>
Cc: Vitaly Wool <vitalywool@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/zpool.h

@@ -46,6 +46,8 @@ const char *zpool_get_type(struct zpool *pool);
 
 void zpool_destroy_pool(struct zpool *pool);
 
+bool zpool_malloc_support_movable(struct zpool *pool);
+
 int zpool_malloc(struct zpool *pool, size_t size, gfp_t gfp,
 			unsigned long *handle);
 
@@ -90,6 +92,7 @@ struct zpool_driver {
 			struct zpool *zpool);
 	void (*destroy)(void *pool);
 
+	bool malloc_support_movable;
 	int (*malloc)(void *pool, size_t size, gfp_t gfp,
 				unsigned long *handle);
 	void (*free)(void *pool, unsigned long handle);

mm/zpool.c

@@ -238,6 +238,22 @@ const char *zpool_get_type(struct zpool *zpool)
 	return zpool->driver->type;
 }
 
+/**
+ * zpool_malloc_support_movable() - Check if the zpool support
+ * allocate movable memory
+ * @zpool:	The zpool to check
+ *
+ * This returns if the zpool support allocate movable memory.
+ *
+ * Implementations must guarantee this to be thread-safe.
+ *
+ * Returns: true if if the zpool support allocate movable memory, false if not
+ */
+bool zpool_malloc_support_movable(struct zpool *zpool)
+{
+	return zpool->driver->malloc_support_movable;
+}
+
 /**
  * zpool_malloc() - Allocate memory
  * @zpool:	The zpool to allocate from.

mm/zsmalloc.c

@@ -447,6 +447,7 @@ static struct zpool_driver zs_zpool_driver = {
 	.owner =		  THIS_MODULE,
 	.create =		  zs_zpool_create,
 	.destroy =		  zs_zpool_destroy,
+	.malloc_support_movable = true,
 	.malloc =		  zs_zpool_malloc,
 	.free =			  zs_zpool_free,
 	.map =			  zs_zpool_map,