zpool: clean out dead code

There is a lot of provision for flexibility that isn't actually needed or
used.  Zswap (the only zpool user) always passes zpool_ops with an .evict
method set.  The backends who reclaim only do so for zswap, so they can
also directly call zpool_ops without indirection or checks.

Finally, there is no need to check the retries parameters and bail with
-EINVAL in the reclaim function, when that's called just a few lines below
with a hard-coded 8.  There is no need to duplicate the evictable and
sleep_mapped attrs from the driver in zpool_ops.

Link: https://lkml.kernel.org/r/20221128191616.1261026-3-nphamcs@gmail.com
Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Nhat Pham <nphamcs@gmail.com>
Cc: Dan Streetman <ddstreet@ieee.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Nitin Gupta <ngupta@vflare.org>
Cc: Seth Jennings <sjenning@redhat.com>
Cc: Vitaly Wool <vitaly.wool@konsulko.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

1 files changed, 5 insertions, 31 deletions

diff --git a/mm/z3fold.c b/mm/z3fold.c
index cf71da10d04e..a4de0c317ac7 100644
--- a/mm/z3fold.c
+++ b/mm/z3fold.c
@@ -68,9 +68,6 @@
  * Structures
 *****************/
 struct z3fold_pool;
-struct z3fold_ops {
-	int (*evict)(struct z3fold_pool *pool, unsigned long handle);
-};
 
 enum buddy {
 	HEADLESS = 0,
@@ -138,8 +135,6 @@ struct z3fold_header {
  * @stale:	list of pages marked for freeing
  * @pages_nr:	number of z3fold pages in the pool.
  * @c_handle:	cache for z3fold_buddy_slots allocation
- * @ops:	pointer to a structure of user defined operations specified at
- *		pool creation time.
  * @zpool:	zpool driver
  * @zpool_ops:	zpool operations structure with an evict callback
  * @compact_wq:	workqueue for page layout background optimization
@@ -158,7 +153,6 @@ struct z3fold_pool {
 	struct list_head stale;
 	atomic64_t pages_nr;
 	struct kmem_cache *c_handle;
-	const struct z3fold_ops *ops;
 	struct zpool *zpool;
 	const struct zpool_ops *zpool_ops;
 	struct workqueue_struct *compact_wq;
@@ -907,13 +901,11 @@ out_fail:
  * z3fold_create_pool() - create a new z3fold pool
  * @name:	pool name
  * @gfp:	gfp flags when allocating the z3fold pool structure
- * @ops:	user-defined operations for the z3fold pool
  *
  * Return: pointer to the new z3fold pool or NULL if the metadata allocation
  * failed.
  */
-static struct z3fold_pool *z3fold_create_pool(const char *name, gfp_t gfp,
-		const struct z3fold_ops *ops)
+static struct z3fold_pool *z3fold_create_pool(const char *name, gfp_t gfp)
 {
 	struct z3fold_pool *pool = NULL;
 	int i, cpu;
@@ -949,7 +941,6 @@ static struct z3fold_pool *z3fold_create_pool(const char *name, gfp_t gfp,
 	if (!pool->release_wq)
 		goto out_wq;
 	INIT_WORK(&pool->work, free_pages_work);
-	pool->ops = ops;
 	return pool;
 
 out_wq:
@@ -1230,10 +1221,6 @@ static int z3fold_reclaim_page(struct z3fold_pool *pool, unsigned int retries)
 	slots.pool = (unsigned long)pool | (1 << HANDLES_NOFREE);
 
 	spin_lock(&pool->lock);
-	if (!pool->ops || !pool->ops->evict || retries == 0) {
-		spin_unlock(&pool->lock);
-		return -EINVAL;
-	}
 	for (i = 0; i < retries; i++) {
 		if (list_empty(&pool->lru)) {
 			spin_unlock(&pool->lock);
@@ -1319,17 +1306,17 @@ static int z3fold_reclaim_page(struct z3fold_pool *pool, unsigned int retries)
 		}
 		/* Issue the eviction callback(s) */
 		if (middle_handle) {
-			ret = pool->ops->evict(pool, middle_handle);
+			ret = pool->zpool_ops->evict(pool->zpool, middle_handle);
 			if (ret)
 				goto next;
 		}
 		if (first_handle) {
-			ret = pool->ops->evict(pool, first_handle);
+			ret = pool->zpool_ops->evict(pool->zpool, first_handle);
 			if (ret)
 				goto next;
 		}
 		if (last_handle) {
-			ret = pool->ops->evict(pool, last_handle);
+			ret = pool->zpool_ops->evict(pool->zpool, last_handle);
 			if (ret)
 				goto next;
 		}
@@ -1593,26 +1580,13 @@ static const struct movable_operations z3fold_mops = {
  * zpool
  ****************/
 
-static int z3fold_zpool_evict(struct z3fold_pool *pool, unsigned long handle)
-{
-	if (pool->zpool && pool->zpool_ops && pool->zpool_ops->evict)
-		return pool->zpool_ops->evict(pool->zpool, handle);
-	else
-		return -ENOENT;
-}
-
-static const struct z3fold_ops z3fold_zpool_ops = {
-	.evict =	z3fold_zpool_evict
-};
-
 static void *z3fold_zpool_create(const char *name, gfp_t gfp,
 			       const struct zpool_ops *zpool_ops,
 			       struct zpool *zpool)
 {
 	struct z3fold_pool *pool;
 
-	pool = z3fold_create_pool(name, gfp,
-				zpool_ops ? &z3fold_zpool_ops : NULL);
+	pool = z3fold_create_pool(name, gfp);
 	if (pool) {
 		pool->zpool = zpool;
 		pool->zpool_ops = zpool_ops;