[PATCH 4/5] zsmalloc: Add ops fields to zs_pool to store evict handlers

[Nhat Pham <nphamcs@gmail.com>]

This adds fields to zs_pool to store evict handlers for writeback,
analogous to the zbud allocator.

Signed-off-by: Nhat Pham <nphamcs@gmail.com>
---
 mm/zsmalloc.c | 36 +++++++++++++++++++++++++++++++++++-
 1 file changed, 35 insertions(+), 1 deletion(-)

diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index 600c40121544..76ff2ed839d0 100644
--- a/mm/zsmalloc.c
+++ b/mm/zsmalloc.c
@@ -225,6 +225,12 @@ struct link_free {
 	};
 };
 
+struct zs_pool;
+
+struct zs_ops {
+	int (*evict)(struct zs_pool *pool, unsigned long handle);
+};
+
 struct zs_pool {
 	const char *name;
 
@@ -242,6 +248,12 @@ struct zs_pool {
 	/* List tracking the zspages in LRU order by most recently added object */
 	struct list_head lru;
 
+#ifdef CONFIG_ZPOOL
+	const struct zs_ops *ops;
+	struct zpool *zpool;
+	const struct zpool_ops *zpool_ops;
+#endif
+
 #ifdef CONFIG_ZSMALLOC_STAT
 	struct dentry *stat_dentry;
 #endif
@@ -379,6 +391,18 @@ static void record_obj(unsigned long handle, unsigned long obj)
 
 #ifdef CONFIG_ZPOOL
 
+static int zs_zpool_evict(struct zs_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 zs_ops zs_zpool_ops = {
+	.evict =	zs_zpool_evict
+};
+
 static void *zs_zpool_create(const char *name, gfp_t gfp,
 			     const struct zpool_ops *zpool_ops,
 			     struct zpool *zpool)
@@ -388,7 +412,17 @@ static void *zs_zpool_create(const char *name, gfp_t gfp,
 	 * different contexts and its caller must provide a valid
 	 * gfp mask.
 	 */
-	return zs_create_pool(name);
+	struct zs_pool *pool = zs_create_pool(name);
+
+	if (pool) {
+		pool->zpool = zpool;
+		pool->zpool_ops = zpool_ops;
+
+		if (zpool_ops)
+			pool->ops = &zs_zpool_ops;
+	}
+
+	return pool;
 }
 
 static void zs_zpool_destroy(void *pool)
-- 
2.30.2