[RFC PATCH v2 5/7] mm: zswap: remove shrink from zpool interface

Domenico Cerasuolo
2023-06-06T14:57:45Z

Now that all three zswap backends have removed their shrink code, it is
no longer necessary for the zpool interface to include shrink/writeback
endpoints.

Signed-off-by: Domenico Cerasuolo <cerasuolodomenico@gmail.com>
---
include/linux/zpool.h | 19 ++---------------
mm/z3fold.c | 5 +----
mm/zbud.c | 5 +----
mm/zpool.c | 48 ++-----------------------------------------
mm/zsmalloc.c | 5 +----
mm/zswap.c | 27 +++++++-----------------
6 files changed, 14 insertions(+), 95 deletions(-)

diff --git a/include/linux/zpool.h b/include/linux/zpool.h
index e8997010612a..6b15a4213de5 100644
--- a/include/linux/zpool.h
+++ b/include/linux/zpool.h
@@ -14,10 +14,6 @@

struct zpool;

-struct zpool_ops {
- int (*evict)(struct zpool *pool, unsigned long handle);
-};
-
/*
* Control how a handle is mapped. It will be ignored if the
* implementation does not support it. Its use is optional.
@@ -40,7 +36,7 @@ enum zpool_mapmode {
bool zpool_has_pool(char *type);

struct zpool *zpool_create_pool(const char *type, const char *name,
- gfp_t gfp, const struct zpool_ops *ops);
+ gfp_t gfp);

const char *zpool_get_type(struct zpool *pool);

@@ -53,9 +49,6 @@ int zpool_malloc(struct zpool *pool, size_t size, gfp_t gfp,

void zpool_free(struct zpool *pool, unsigned long handle);

-int zpool_shrink(struct zpool *pool, unsigned int pages,
- unsigned int *reclaimed);
-
void *zpool_map_handle(struct zpool *pool, unsigned long handle,
enum zpool_mapmode mm);

@@ -72,7 +65,6 @@ u64 zpool_get_total_size(struct zpool *pool);
* @destroy: destroy a pool.
* @malloc: allocate mem from a pool.
* @free: free mem from a pool.
- * @shrink: shrink the pool.
* @sleep_mapped: whether zpool driver can sleep during map.
* @map: map a handle.
* @unmap: unmap a handle.
@@ -87,10 +79,7 @@ struct zpool_driver {
atomic_t refcount;
struct list_head list;

- void *(*create)(const char *name,
- gfp_t gfp,
- const struct zpool_ops *ops,
- struct zpool *zpool);
+ void *(*create)(const char *name, gfp_t gfp);
void (*destroy)(void *pool);

bool malloc_support_movable;
@@ -98,9 +87,6 @@ struct zpool_driver {
unsigned long *handle);
void (*free)(void *pool, unsigned long handle);

- int (*shrink)(void *pool, unsigned int pages,
- unsigned int *reclaimed);
-
bool sleep_mapped;
void *(*map)(void *pool, unsigned long handle,
enum zpool_mapmode mm);
@@ -113,7 +99,6 @@ void zpool_register_driver(struct zpool_driver *driver);

int zpool_unregister_driver(struct zpool_driver *driver);

-bool zpool_evictable(struct zpool *pool);
bool zpool_can_sleep_mapped(struct zpool *pool);

#endif
diff --git a/mm/z3fold.c b/mm/z3fold.c
index 4af8741553ac..e84de91ecccb 100644
--- a/mm/z3fold.c
+++ b/mm/z3fold.c
@@ -1364,9 +1364,7 @@ static const struct movable_operations z3fold_mops = {
* zpool
****************/

-static void *z3fold_zpool_create(const char *name, gfp_t gfp,
- const struct zpool_ops *zpool_ops,
- struct zpool *zpool)
+static void *z3fold_zpool_create(const char *name, gfp_t gfp)
{
return z3fold_create_pool(name, gfp);
}
@@ -1409,7 +1407,6 @@ static struct zpool_driver z3fold_zpool_driver = {
.destroy = z3fold_zpool_destroy,
.malloc = z3fold_zpool_malloc,
.free = z3fold_zpool_free,
- .shrink = NULL,
.map = z3fold_zpool_map,
.unmap = z3fold_zpool_unmap,
.total_size = z3fold_zpool_total_size,
diff --git a/mm/zbud.c b/mm/zbud.c
index 19bc662ef5e9..2190cc1f37b3 100644
--- a/mm/zbud.c
+++ b/mm/zbud.c
@@ -380,9 +380,7 @@ static u64 zbud_get_pool_size(struct zbud_pool *pool)
* zpool
****************/

-static void *zbud_zpool_create(const char *name, gfp_t gfp,
- const struct zpool_ops *zpool_ops,
- struct zpool *zpool)
+static void *zbud_zpool_create(const char *name, gfp_t gfp)
{
return zbud_create_pool(gfp);
}
@@ -425,7 +423,6 @@ static struct zpool_driver zbud_zpool_driver = {
.destroy = zbud_zpool_destroy,
.malloc = zbud_zpool_malloc,
.free = zbud_zpool_free,
- .shrink = NULL,
.map = zbud_zpool_map,
.unmap = zbud_zpool_unmap,
.total_size = zbud_zpool_total_size,
diff --git a/mm/zpool.c b/mm/zpool.c
index 6a19c4a58f77..846410479c2f 100644
--- a/mm/zpool.c
+++ b/mm/zpool.c
@@ -133,7 +133,6 @@ EXPORT_SYMBOL(zpool_has_pool);
* @type: The type of the zpool to create (e.g. zbud, zsmalloc)
* @name: The name of the zpool (e.g. zram0, zswap)
* @gfp: The GFP flags to use when allocating the pool.
- * @ops: The optional ops callback.
*
* This creates a new zpool of the specified type. The gfp flags will be
* used when allocating memory, if the implementation supports it. If the
@@ -145,8 +144,7 @@ EXPORT_SYMBOL(zpool_has_pool);
*
* Returns: New zpool on success, NULL on failure.
*/
-struct zpool *zpool_create_pool(const char *type, const char *name, gfp_t gfp,
- const struct zpool_ops *ops)
+struct zpool *zpool_create_pool(const char *type, const char *name, gfp_t gfp)
{
struct zpool_driver *driver;
struct zpool *zpool;
@@ -173,7 +171,7 @@ struct zpool *zpool_create_pool(const char *type, const char *name, gfp_t gfp,
}

zpool->driver = driver;
- zpool->pool = driver->create(name, gfp, ops, zpool);
+ zpool->pool = driver->create(name, gfp);

if (!zpool->pool) {
pr_err("couldn't create %s pool\n", type);
@@ -279,30 +277,6 @@ void zpool_free(struct zpool *zpool, unsigned long handle)
zpool->driver->free(zpool->pool, handle);
}

-/**
- * zpool_shrink() - Shrink the pool size
- * @zpool: The zpool to shrink.
- * @pages: The number of pages to shrink the pool.
- * @reclaimed: The number of pages successfully evicted.
- *
- * This attempts to shrink the actual memory size of the pool
- * by evicting currently used handle(s). If the pool was
- * created with no zpool_ops, or the evict call fails for any
- * of the handles, this will fail. If non-NULL, the @reclaimed
- * parameter will be set to the number of pages reclaimed,
- * which may be more than the number of pages requested.
- *
- * Implementations must guarantee this to be thread-safe.
- *
- * Returns: 0 on success, negative value on error/failure.
- */
-int zpool_shrink(struct zpool *zpool, unsigned int pages,
- unsigned int *reclaimed)
-{
- return zpool->driver->shrink ?
- zpool->driver->shrink(zpool->pool, pages, reclaimed) : -EINVAL;
-}
-
/**
* zpool_map_handle() - Map a previously allocated handle into memory
* @zpool: The zpool that the handle was allocated from
@@ -359,24 +333,6 @@ u64 zpool_get_total_size(struct zpool *zpool)
return zpool->driver->total_size(zpool->pool);
}

-/**
- * zpool_evictable() - Test if zpool is potentially evictable
- * @zpool: The zpool to test
- *
- * Zpool is only potentially evictable when it's created with struct
- * zpool_ops.evict and its driver implements struct zpool_driver.shrink.
- *
- * However, it doesn't necessarily mean driver will use zpool_ops.evict
- * in its implementation of zpool_driver.shrink. It could do internal
- * defragmentation instead.
- *
- * Returns: true if potentially evictable; false otherwise.
- */
-bool zpool_evictable(struct zpool *zpool)
-{
- return zpool->driver->shrink;
-}
-
/**
* zpool_can_sleep_mapped - Test if zpool can sleep when do mapped.
* @zpool: The zpool to test
diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index 75386283dba0..634daa19b6c2 100644
--- a/mm/zsmalloc.c
+++ b/mm/zsmalloc.c
@@ -351,9 +351,7 @@ static void record_obj(unsigned long handle, unsigned long obj)

#ifdef CONFIG_ZPOOL

-static void *zs_zpool_create(const char *name, gfp_t gfp,
- const struct zpool_ops *zpool_ops,
- struct zpool *zpool)
+static void *zs_zpool_create(const char *name, gfp_t gfp)
{
/*
* Ignore global gfp flags: zs_malloc() may be invoked from
@@ -420,7 +418,6 @@ static struct zpool_driver zs_zpool_driver = {
.malloc_support_movable = true,
.malloc = zs_zpool_malloc,
.free = zs_zpool_free,
- .shrink = NULL,
.map = zs_zpool_map,
.unmap = zs_zpool_unmap,
.total_size = zs_zpool_total_size,
diff --git a/mm/zswap.c b/mm/zswap.c
index c99bafcefecf..2831bf56b168 100644
--- a/mm/zswap.c
+++ b/mm/zswap.c
@@ -254,10 +254,6 @@ static int zswap_writeback_entry(struct zpool *pool, unsigned long handle);
static int zswap_pool_get(struct zswap_pool *pool);
static void zswap_pool_put(struct zswap_pool *pool);

-static const struct zpool_ops zswap_zpool_ops = {
- .evict = zswap_writeback_entry
-};
-
static bool zswap_is_full(void)
{
return totalram_pages() * zswap_max_pool_percent / 100 <
@@ -375,12 +371,9 @@ static void zswap_free_entry(struct zswap_entry *entry)
if (!entry->length)
atomic_dec(&zswap_same_filled_pages);
else {
- /* zpool_evictable will be removed once all 3 backends have migrated */
- if (!zpool_evictable(entry->pool->zpool)) {
- spin_lock(&entry->pool->lru_lock);
- list_del(&entry->lru);
- spin_unlock(&entry->pool->lru_lock);
- }
+ spin_lock(&entry->pool->lru_lock);
+ list_del(&entry->lru);
+ spin_unlock(&entry->pool->lru_lock);
zpool_free(entry->pool->zpool, entry->handle);
zswap_pool_put(entry->pool);
}
@@ -659,12 +652,8 @@ static void shrink_worker(struct work_struct *w)
shrink_work);
int ret, failures = 0;

- /* zpool_evictable will be removed once all 3 backends have migrated */
do {
- if (zpool_evictable(pool->zpool))
- ret = zpool_shrink(pool->zpool, 1, NULL);
- else
- ret = zswap_shrink(pool);
+ ret = zswap_shrink(pool);
if (ret) {
zswap_reject_reclaim_fail++;
if (ret != -EAGAIN)
@@ -702,7 +691,7 @@ static struct zswap_pool *zswap_pool_create(char *type, char *compressor)
/* unique name for each pool specifically required by zsmalloc */
snprintf(name, 38, "zswap%x", atomic_inc_return(&zswap_pools_count));

- pool->zpool = zpool_create_pool(type, name, gfp, &zswap_zpool_ops);
+ pool->zpool = zpool_create_pool(type, name, gfp);
if (!pool->zpool) {
pr_err("%s zpool not available\n", type);
goto error;
@@ -1388,8 +1377,7 @@ static int zswap_frontswap_store(unsigned type, pgoff_t offset,
zswap_entry_put(tree, dupentry);
}
} while (ret == -EEXIST);
- /* zpool_evictable will be removed once all 3 backends have migrated */
- if (entry->length && !zpool_evictable(entry->pool->zpool)) {
+ if (entry->length) {
spin_lock(&entry->pool->lru_lock);
list_add(&entry->lru, &entry->pool->lru);
spin_unlock(&entry->pool->lru_lock);
@@ -1495,8 +1483,7 @@ static int zswap_frontswap_load(unsigned type, pgoff_t offset,
freeentry:
spin_lock(&tree->lock);
zswap_entry_put(tree, entry);
- /* zpool_evictable will be removed once all 3 backends have migrated */
- if (entry->length && !zpool_evictable(entry->pool->zpool)) {
+ if (entry->length) {
spin_lock(&entry->pool->lru_lock);
list_move(&entry->lru, &entry->pool->lru);
spin_unlock(&entry->pool->lru_lock);
--
2.34.1