[PATCH 1/2] zpool: define and use max type length

[Dan Streetman]

Add ZPOOL_MAX_TYPE_NAME define, and change zpool_driver *type field to
type[ZPOOL_MAX_TYPE_NAME].  Remove redundant type field from struct zpool
and use zpool->driver->type instead.

The define will be used by zswap for its zpool param type name length.

Signed-off-by: Dan Streetman <ddstreet@xxxxxxxx>
---
 include/linux/zpool.h |  5 +++--
 mm/zpool.c            | 11 ++++-------
 2 files changed, 7 insertions(+), 9 deletions(-)

diff --git a/include/linux/zpool.h b/include/linux/zpool.h
index 42f8ec9..cf70312 100644
--- a/include/linux/zpool.h
+++ b/include/linux/zpool.h
@@ -41,7 +41,7 @@ bool zpool_has_pool(char *type);
 struct zpool *zpool_create_pool(char *type, char *name,
 			gfp_t gfp, const struct zpool_ops *ops);
 
-char *zpool_get_type(struct zpool *pool);
+const char *zpool_get_type(struct zpool *pool);
 
 void zpool_destroy_pool(struct zpool *pool);
 
@@ -60,6 +60,7 @@ void zpool_unmap_handle(struct zpool *pool, unsigned long handle);
 
 u64 zpool_get_total_size(struct zpool *pool);
 
+#define ZPOOL_MAX_TYPE_NAME 64
 
 /**
  * struct zpool_driver - driver implementation for zpool
@@ -78,7 +79,7 @@ u64 zpool_get_total_size(struct zpool *pool);
  * with zpool.
  */
 struct zpool_driver {
-	char *type;
+	char type[ZPOOL_MAX_TYPE_NAME];
 	struct module *owner;
 	atomic_t refcount;
 	struct list_head list;
diff --git a/mm/zpool.c b/mm/zpool.c
index 8f670d3..8a0ef86 100644
--- a/mm/zpool.c
+++ b/mm/zpool.c
@@ -18,8 +18,6 @@
 #include <linux/zpool.h>
 
 struct zpool {
-	char *type;
-
 	struct zpool_driver *driver;
 	void *pool;
 	const struct zpool_ops *ops;
@@ -79,7 +77,7 @@ static struct zpool_driver *zpool_get_driver(char *type)
 
 	spin_lock(&drivers_lock);
 	list_for_each_entry(driver, &drivers_head, list) {
-		if (!strcmp(driver->type, type)) {
+		if (!strncmp(driver->type, type, ZPOOL_MAX_TYPE_NAME)) {
 			bool got = try_module_get(driver->owner);
 
 			if (got)
@@ -174,7 +172,6 @@ struct zpool *zpool_create_pool(char *type, char *name, gfp_t gfp,
 		return NULL;
 	}
 
-	zpool->type = driver->type;
 	zpool->driver = driver;
 	zpool->pool = driver->create(name, gfp, ops, zpool);
 	zpool->ops = ops;
@@ -208,7 +205,7 @@ struct zpool *zpool_create_pool(char *type, char *name, gfp_t gfp,
  */
 void zpool_destroy_pool(struct zpool *zpool)
 {
-	pr_debug("destroying pool type %s\n", zpool->type);
+	pr_debug("destroying pool type %s\n", zpool->driver->type);
 
 	spin_lock(&pools_lock);
 	list_del(&zpool->list);
@@ -228,9 +225,9 @@ void zpool_destroy_pool(struct zpool *zpool)
  *
  * Returns: The type of zpool.
  */
-char *zpool_get_type(struct zpool *zpool)
+const char *zpool_get_type(struct zpool *zpool)
 {
-	return zpool->type;
+	return zpool->driver->type;
 }
 
 /**
-- 
2.1.0

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