1 files changed, 35 insertions, 16 deletions

diff --git a/mm/zpool.c b/mm/zpool.c
index 722a4f60e..8f670d3e8 100644
--- a/mm/zpool.c
+++ b/mm/zpool.c
@@ -22,7 +22,7 @@ struct zpool {
 
 	struct zpool_driver *driver;
 	void *pool;
-	struct zpool_ops *ops;
+	const struct zpool_ops *ops;
 
 	struct list_head list;
 };
@@ -100,6 +100,39 @@ static void zpool_put_driver(struct zpool_driver *driver)
 }
 
 /**
+ * zpool_has_pool() - Check if the pool driver is available
+ * @type	The type of the zpool to check (e.g. zbud, zsmalloc)
+ *
+ * This checks if the @type pool driver is available.  This will try to load
+ * the requested module, if needed, but there is no guarantee the module will
+ * still be loaded and available immediately after calling.  If this returns
+ * true, the caller should assume the pool is available, but must be prepared
+ * to handle the @zpool_create_pool() returning failure.  However if this
+ * returns false, the caller should assume the requested pool type is not
+ * available; either the requested pool type module does not exist, or could
+ * not be loaded, and calling @zpool_create_pool() with the pool type will
+ * fail.
+ *
+ * Returns: true if @type pool is available, false if not
+ */
+bool zpool_has_pool(char *type)
+{
+	struct zpool_driver *driver = zpool_get_driver(type);
+
+	if (!driver) {
+		request_module("zpool-%s", type);
+		driver = zpool_get_driver(type);
+	}
+
+	if (!driver)
+		return false;
+
+	zpool_put_driver(driver);
+	return true;
+}
+EXPORT_SYMBOL(zpool_has_pool);
+
+/**
  * zpool_create_pool() - Create a new zpool
  * @type	The type of the zpool to create (e.g. zbud, zsmalloc)
  * @name	The name of the zpool (e.g. zram0, zswap)
@@ -115,7 +148,7 @@ static void zpool_put_driver(struct zpool_driver *driver)
  * Returns: New zpool on success, NULL on failure.
  */
 struct zpool *zpool_create_pool(char *type, char *name, gfp_t gfp,
-		struct zpool_ops *ops)
+		const struct zpool_ops *ops)
 {
 	struct zpool_driver *driver;
 	struct zpool *zpool;
@@ -320,20 +353,6 @@ u64 zpool_get_total_size(struct zpool *zpool)
 	return zpool->driver->total_size(zpool->pool);
 }
 
-static int __init init_zpool(void)
-{
-	pr_info("loaded\n");
-	return 0;
-}
-
-static void __exit exit_zpool(void)
-{
-	pr_info("unloaded\n");
-}
-
-module_init(init_zpool);
-module_exit(exit_zpool);
-
 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("Dan Streetman <ddstreet@ieee.org>");
 MODULE_DESCRIPTION("Common API for compressed memory storage");