[PATCH v2] mm/zswap: Check all pool pages instead of one pool pages

Cai Liu
2014-01-20T07:51:24Z

zswap can support multiple swapfiles. So we need to check
all zbud pool pages in zswap.

Version 2:
* add *total_zbud_pages* in zbud to record all the pages in pools
* move the updating of pool pages statistics to
alloc_zbud_page/free_zbud_page to hide the details

Signed-off-by: Cai Liu <cai.liu@samsung.com>
---
include/linux/zbud.h | 2 +-
mm/zbud.c | 44 ++++++++++++++++++++++++++++++++------------
mm/zswap.c | 4 ++--
3 files changed, 35 insertions(+), 15 deletions(-)

diff --git a/include/linux/zbud.h b/include/linux/zbud.h
index 2571a5c..1dbc13e 100644
--- a/include/linux/zbud.h
+++ b/include/linux/zbud.h
@@ -17,6 +17,6 @@ void zbud_free(struct zbud_pool *pool, unsigned long handle);
int zbud_reclaim_page(struct zbud_pool *pool, unsigned int retries);
void *zbud_map(struct zbud_pool *pool, unsigned long handle);
void zbud_unmap(struct zbud_pool *pool, unsigned long handle);
-u64 zbud_get_pool_size(struct zbud_pool *pool);
+u64 zbud_get_pool_size(void);

#endif /* _ZBUD_H_ */
diff --git a/mm/zbud.c b/mm/zbud.c
index 9451361..711aaf4 100644
--- a/mm/zbud.c
+++ b/mm/zbud.c
@@ -52,6 +52,13 @@
#include <linux/spinlock.h>
#include <linux/zbud.h>

+/*********************************
+* statistics
+**********************************/
+
+/* zbud pages in all pools */
+static u64 total_zbud_pages;
+
/*****************
* Structures
*****************/
@@ -142,10 +149,28 @@ static struct zbud_header *init_zbud_page(struct page *page)
return zhdr;
}

+static struct page *alloc_zbud_page(struct zbud_pool *pool, gfp_t gfp)
+{
+ struct page *page;
+
+ page = alloc_page(gfp);
+
+ if (page) {
+ pool->pages_nr++;
+ total_zbud_pages++;
+ }
+
+ return page;
+}
+
+
/* Resets the struct page fields and frees the page */
-static void free_zbud_page(struct zbud_header *zhdr)
+static void free_zbud_page(struct zbud_pool *pool, struct zbud_header *zhdr)
{
__free_page(virt_to_page(zhdr));
+
+ pool->pages_nr--;
+ total_zbud_pages--;
}

/*
@@ -279,11 +304,10 @@ int zbud_alloc(struct zbud_pool *pool, int size, gfp_t gfp,

/* Couldn't find unbuddied zbud page, create new one */
spin_unlock(&pool->lock);
- page = alloc_page(gfp);
+ page = alloc_zbud_page(pool, gfp);
if (!page)
return -ENOMEM;
spin_lock(&pool->lock);
- pool->pages_nr++;
zhdr = init_zbud_page(page);
bud = FIRST;

@@ -349,8 +373,7 @@ void zbud_free(struct zbud_pool *pool, unsigned long handle)
if (zhdr->first_chunks == 0 && zhdr->last_chunks == 0) {
/* zbud page is empty, free */
list_del(&zhdr->lru);
- free_zbud_page(zhdr);
- pool->pages_nr--;
+ free_zbud_page(pool, zhdr);
} else {
/* Add to unbuddied list */
freechunks = num_free_chunks(zhdr);
@@ -447,8 +470,7 @@ next:
* Both buddies are now free, free the zbud page and
* return success.
*/
- free_zbud_page(zhdr);
- pool->pages_nr--;
+ free_zbud_page(pool, zhdr);
spin_unlock(&pool->lock);
return 0;
} else if (zhdr->first_chunks == 0 ||
@@ -496,14 +518,12 @@ void zbud_unmap(struct zbud_pool *pool, unsigned long handle)

/**
* zbud_get_pool_size() - gets the zbud pool size in pages
- * @pool: pool whose size is being queried
*
- * Returns: size in pages of the given pool. The pool lock need not be
- * taken to access pages_nr.
+ * Returns: size in pages of all the zbud pools.
*/
-u64 zbud_get_pool_size(struct zbud_pool *pool)
+u64 zbud_get_pool_size(void)
{
- return pool->pages_nr;
+ return total_zbud_pages;
}

static int __init init_zbud(void)
diff --git a/mm/zswap.c b/mm/zswap.c
index 5a63f78..ef44d9d 100644
--- a/mm/zswap.c
+++ b/mm/zswap.c
@@ -291,7 +291,7 @@ static void zswap_free_entry(struct zswap_tree *tree,
zbud_free(tree->pool, entry->handle);
zswap_entry_cache_free(entry);
atomic_dec(&zswap_stored_pages);
- zswap_pool_pages = zbud_get_pool_size(tree->pool);
+ zswap_pool_pages = zbud_get_pool_size();
}

/* caller must hold the tree lock */
@@ -716,7 +716,7 @@ static int zswap_frontswap_store(unsigned type, pgoff_t offset,

/* update stats */
atomic_inc(&zswap_stored_pages);
- zswap_pool_pages = zbud_get_pool_size(tree->pool);
+ zswap_pool_pages = zbud_get_pool_size();

return 0;

--
1.7.10.4