[PATCH 3/5] mm/zswap: refactor out __zswap_load()

[Chengming Zhou]

The zswap_load() and zswap_writeback_entry() have the same part that
decompress the data from zswap_entry to page, so refactor out the
common part as __zswap_load(entry, page).

Signed-off-by: Chengming Zhou <zhouchengming@xxxxxxxxxxxxx>
Reviewed-by: Nhat Pham <nphamcs@xxxxxxxxx>
---
 mm/zswap.c | 107 ++++++++++++++++++++++---------------------------------------
 1 file changed, 38 insertions(+), 69 deletions(-)

diff --git a/mm/zswap.c b/mm/zswap.c
index fa186945010d..2f095c919a5c 100644
--- a/mm/zswap.c
+++ b/mm/zswap.c
@@ -1392,6 +1392,41 @@ static int zswap_enabled_param_set(const char *val,
 	return ret;
 }
 
+static void __zswap_load(struct zswap_entry *entry, struct page *page)
+{
+	struct scatterlist input, output;
+	unsigned int dlen = PAGE_SIZE;
+	struct crypto_acomp_ctx *acomp_ctx;
+	struct zpool *zpool;
+	u8 *src;
+	int ret;
+
+	acomp_ctx = raw_cpu_ptr(entry->pool->acomp_ctx);
+	mutex_lock(acomp_ctx->mutex);
+
+	zpool = zswap_find_zpool(entry);
+	src = zpool_map_handle(zpool, entry->handle, ZPOOL_MM_RO);
+	if (!zpool_can_sleep_mapped(zpool)) {
+		memcpy(acomp_ctx->dstmem, src, entry->length);
+		src = acomp_ctx->dstmem;
+		zpool_unmap_handle(zpool, entry->handle);
+	}
+
+	sg_init_one(&input, src, entry->length);
+	sg_init_table(&output, 1);
+	sg_set_page(&output, page, PAGE_SIZE, 0);
+	acomp_request_set_params(acomp_ctx->req, &input, &output, entry->length, dlen);
+	ret = crypto_wait_req(crypto_acomp_decompress(acomp_ctx->req), &acomp_ctx->wait);
+	dlen = acomp_ctx->req->dlen;
+	mutex_unlock(acomp_ctx->mutex);
+
+	if (zpool_can_sleep_mapped(zpool))
+		zpool_unmap_handle(zpool, entry->handle);
+
+	BUG_ON(ret);
+	BUG_ON(dlen != PAGE_SIZE);
+}
+
 /*********************************
 * writeback code
 **********************************/
@@ -1413,23 +1448,12 @@ static int zswap_writeback_entry(struct zswap_entry *entry,
 	swp_entry_t swpentry = entry->swpentry;
 	struct page *page;
 	struct mempolicy *mpol;
-	struct scatterlist input, output;
-	struct crypto_acomp_ctx *acomp_ctx;
-	struct zpool *pool = zswap_find_zpool(entry);
 	bool page_was_allocated;
-	u8 *src, *tmp = NULL;
-	unsigned int dlen;
 	int ret;
 	struct writeback_control wbc = {
 		.sync_mode = WB_SYNC_NONE,
 	};
 
-	if (!zpool_can_sleep_mapped(pool)) {
-		tmp = kmalloc(PAGE_SIZE, GFP_KERNEL);
-		if (!tmp)
-			return -ENOMEM;
-	}
-
 	/* try to allocate swap cache page */
 	mpol = get_task_policy(current);
 	page = __read_swap_cache_async(swpentry, GFP_KERNEL, mpol,
@@ -1462,33 +1486,7 @@ static int zswap_writeback_entry(struct zswap_entry *entry,
 	}
 	spin_unlock(&tree->lock);
 
-	/* decompress */
-	acomp_ctx = raw_cpu_ptr(entry->pool->acomp_ctx);
-	dlen = PAGE_SIZE;
-
-	src = zpool_map_handle(pool, entry->handle, ZPOOL_MM_RO);
-	if (!zpool_can_sleep_mapped(pool)) {
-		memcpy(tmp, src, entry->length);
-		src = tmp;
-		zpool_unmap_handle(pool, entry->handle);
-	}
-
-	mutex_lock(acomp_ctx->mutex);
-	sg_init_one(&input, src, entry->length);
-	sg_init_table(&output, 1);
-	sg_set_page(&output, page, PAGE_SIZE, 0);
-	acomp_request_set_params(acomp_ctx->req, &input, &output, entry->length, dlen);
-	ret = crypto_wait_req(crypto_acomp_decompress(acomp_ctx->req), &acomp_ctx->wait);
-	dlen = acomp_ctx->req->dlen;
-	mutex_unlock(acomp_ctx->mutex);
-
-	if (!zpool_can_sleep_mapped(pool))
-		kfree(tmp);
-	else
-		zpool_unmap_handle(pool, entry->handle);
-
-	BUG_ON(ret);
-	BUG_ON(dlen != PAGE_SIZE);
+	__zswap_load(entry, page);
 
 	/* page is up to date */
 	SetPageUptodate(page);
@@ -1508,9 +1506,6 @@ static int zswap_writeback_entry(struct zswap_entry *entry,
 	return ret;
 
 fail:
-	if (!zpool_can_sleep_mapped(pool))
-		kfree(tmp);
-
 	/*
 	 * If we get here because the page is already in swapcache, a
 	 * load may be happening concurrently. It is safe and okay to
@@ -1769,11 +1764,7 @@ bool zswap_load(struct folio *folio)
 	struct page *page = &folio->page;
 	struct zswap_tree *tree = zswap_trees[type];
 	struct zswap_entry *entry;
-	struct scatterlist input, output;
-	struct crypto_acomp_ctx *acomp_ctx;
-	unsigned int dlen = PAGE_SIZE;
-	u8 *src, *dst;
-	struct zpool *zpool;
+	u8 *dst;
 	bool ret;
 
 	VM_WARN_ON_ONCE(!folio_test_locked(folio));
@@ -1795,29 +1786,7 @@ bool zswap_load(struct folio *folio)
 		goto stats;
 	}
 
-	/* decompress */
-	acomp_ctx = raw_cpu_ptr(entry->pool->acomp_ctx);
-	mutex_lock(acomp_ctx->mutex);
-
-	zpool = zswap_find_zpool(entry);
-	src = zpool_map_handle(zpool, entry->handle, ZPOOL_MM_RO);
-	if (!zpool_can_sleep_mapped(zpool)) {
-		memcpy(acomp_ctx->dstmem, src, entry->length);
-		src = acomp_ctx->dstmem;
-		zpool_unmap_handle(zpool, entry->handle);
-	}
-
-	sg_init_one(&input, src, entry->length);
-	sg_init_table(&output, 1);
-	sg_set_page(&output, page, PAGE_SIZE, 0);
-	acomp_request_set_params(acomp_ctx->req, &input, &output, entry->length, dlen);
-	if (crypto_wait_req(crypto_acomp_decompress(acomp_ctx->req), &acomp_ctx->wait))
-		WARN_ON(1);
-	mutex_unlock(acomp_ctx->mutex);
-
-	if (zpool_can_sleep_mapped(zpool))
-		zpool_unmap_handle(zpool, entry->handle);
-
+	__zswap_load(entry, page);
 	ret = true;
 stats:
 	count_vm_event(ZSWPIN);

-- 
b4 0.10.1