Change ZRAM into using zpool API. This patch allows to use any
zpool compatible allocation backend with ZRAM. It is meant to make
no functional changes to ZRAM.

zpool-registered backend can be selected via the module parameter
or kernel boot string. 'zsmalloc' is taken by default.

Signed-off-by: Vitaly Wool <[email protected]>
---
 drivers/block/zram/Kconfig    |  3 ++-
 drivers/block/zram/zram_drv.c | 64 +++++++++++++++++++----------------
 drivers/block/zram/zram_drv.h |  4 +--
 3 files changed, 39 insertions(+), 32 deletions(-)

diff --git a/drivers/block/zram/Kconfig b/drivers/block/zram/Kconfig
index fe7a4b7d30cf..7248d5aa3468 100644
--- a/drivers/block/zram/Kconfig
+++ b/drivers/block/zram/Kconfig
@@ -1,8 +1,9 @@
 # SPDX-License-Identifier: GPL-2.0
 config ZRAM
        tristate "Compressed RAM block device support"
-       depends on BLOCK && SYSFS && ZSMALLOC && CRYPTO
+       depends on BLOCK && SYSFS && CRYPTO
        select CRYPTO_LZO
+       select ZPOOL
        help
          Creates virtual block devices called /dev/zramX (X = 0, 1, ...).
          Pages written to these disks are compressed and stored in memory
diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index d58a359a6622..881f10f99a5d 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -43,6 +43,9 @@ static DEFINE_MUTEX(zram_index_mutex);
 static int zram_major;
 static const char *default_compressor = "lzo-rle";
 
+#define BACKEND_PAR_BUF_SIZE   32
+static char backend_par_buf[BACKEND_PAR_BUF_SIZE];
+
 /* Module params (documentation at end) */
 static unsigned int num_devices = 1;
 /*
@@ -277,7 +280,7 @@ static ssize_t mem_used_max_store(struct device *dev,
        down_read(&zram->init_lock);
        if (init_done(zram)) {
                atomic_long_set(&zram->stats.max_used_pages,
-                               zs_get_total_pages(zram->mem_pool));
+                       zpool_get_total_size(zram->mem_pool) >> PAGE_SHIFT);
        }
        up_read(&zram->init_lock);
 
@@ -1020,7 +1023,7 @@ static ssize_t compact_store(struct device *dev,
                return -EINVAL;
        }
 
-       zs_compact(zram->mem_pool);
+       zpool_compact(zram->mem_pool);
        up_read(&zram->init_lock);
 
        return len;
@@ -1048,17 +1051,14 @@ static ssize_t mm_stat_show(struct device *dev,
                struct device_attribute *attr, char *buf)
 {
        struct zram *zram = dev_to_zram(dev);
-       struct zs_pool_stats pool_stats;
        u64 orig_size, mem_used = 0;
-       long max_used;
+       long max_used, num_compacted = 0;
        ssize_t ret;
 
-       memset(&pool_stats, 0x00, sizeof(struct zs_pool_stats));
-
        down_read(&zram->init_lock);
        if (init_done(zram)) {
-               mem_used = zs_get_total_pages(zram->mem_pool);
-               zs_pool_stats(zram->mem_pool, &pool_stats);
+               mem_used = zpool_get_total_size(zram->mem_pool);
+               num_compacted = zpool_get_num_compacted(zram->mem_pool);
        }
 
        orig_size = atomic64_read(&zram->stats.pages_stored);
@@ -1068,11 +1068,11 @@ static ssize_t mm_stat_show(struct device *dev,
                        "%8llu %8llu %8llu %8lu %8ld %8llu %8lu %8llu\n",
                        orig_size << PAGE_SHIFT,
                        (u64)atomic64_read(&zram->stats.compr_data_size),
-                       mem_used << PAGE_SHIFT,
+                       mem_used,
                        zram->limit_pages << PAGE_SHIFT,
                        max_used << PAGE_SHIFT,
                        (u64)atomic64_read(&zram->stats.same_pages),
-                       pool_stats.pages_compacted,
+                       num_compacted,
                        (u64)atomic64_read(&zram->stats.huge_pages));
        up_read(&zram->init_lock);
 
@@ -1133,27 +1133,30 @@ static void zram_meta_free(struct zram *zram, u64 
disksize)
        for (index = 0; index < num_pages; index++)
                zram_free_page(zram, index);
 
-       zs_destroy_pool(zram->mem_pool);
+       zpool_destroy_pool(zram->mem_pool);
        vfree(zram->table);
 }
 
 static bool zram_meta_alloc(struct zram *zram, u64 disksize)
 {
        size_t num_pages;
+       char *backend;
 
        num_pages = disksize >> PAGE_SHIFT;
        zram->table = vzalloc(array_size(num_pages, sizeof(*zram->table)));
        if (!zram->table)
                return false;
 
-       zram->mem_pool = zs_create_pool(zram->disk->disk_name);
+       backend = strlen(backend_par_buf) ? backend_par_buf : "zsmalloc";
+       zram->mem_pool = zpool_create_pool(backend, zram->disk->disk_name,
+                                       GFP_NOIO, NULL);
        if (!zram->mem_pool) {
                vfree(zram->table);
                return false;
        }
 
        if (!huge_class_size)
-               huge_class_size = zs_huge_class_size(zram->mem_pool);
+               huge_class_size = zpool_huge_class_size(zram->mem_pool);
        return true;
 }
 
@@ -1197,7 +1200,7 @@ static void zram_free_page(struct zram *zram, size_t 
index)
        if (!handle)
                return;
 
-       zs_free(zram->mem_pool, handle);
+       zpool_free(zram->mem_pool, handle);
 
        atomic64_sub(zram_get_obj_size(zram, index),
                        &zram->stats.compr_data_size);
@@ -1246,7 +1249,7 @@ static int __zram_bvec_read(struct zram *zram, struct 
page *page, u32 index,
 
        size = zram_get_obj_size(zram, index);
 
-       src = zs_map_object(zram->mem_pool, handle, ZS_MM_RO);
+       src = zpool_map_handle(zram->mem_pool, handle, ZPOOL_MM_RO);
        if (size == PAGE_SIZE) {
                dst = kmap_atomic(page);
                memcpy(dst, src, PAGE_SIZE);
@@ -1260,7 +1263,7 @@ static int __zram_bvec_read(struct zram *zram, struct 
page *page, u32 index,
                kunmap_atomic(dst);
                zcomp_stream_put(zram->comp);
        }
-       zs_unmap_object(zram->mem_pool, handle);
+       zpool_unmap_handle(zram->mem_pool, handle);
        zram_slot_unlock(zram, index);
 
        /* Should NEVER happen. Return bio error if it does. */
@@ -1335,7 +1338,7 @@ static int __zram_bvec_write(struct zram *zram, struct 
bio_vec *bvec,
        if (unlikely(ret)) {
                zcomp_stream_put(zram->comp);
                pr_err("Compression failed! err=%d\n", ret);
-               zs_free(zram->mem_pool, handle);
+               zpool_free(zram->mem_pool, handle);
                return ret;
        }
 
@@ -1354,33 +1357,34 @@ static int __zram_bvec_write(struct zram *zram, struct 
bio_vec *bvec,
         * if we have a 'non-null' handle here then we are coming
         * from the slow path and handle has already been allocated.
         */
-       if (!handle)
-               handle = zs_malloc(zram->mem_pool, comp_len,
+       if (handle == 0)
+               ret = zpool_malloc(zram->mem_pool, comp_len,
                                __GFP_KSWAPD_RECLAIM |
                                __GFP_NOWARN |
                                __GFP_HIGHMEM |
-                               __GFP_MOVABLE);
-       if (!handle) {
+                               __GFP_MOVABLE,
+                               &handle);
+       if (ret) {
                zcomp_stream_put(zram->comp);
                atomic64_inc(&zram->stats.writestall);
-               handle = zs_malloc(zram->mem_pool, comp_len,
-                               GFP_NOIO | __GFP_HIGHMEM |
-                               __GFP_MOVABLE);
-               if (handle)
+               ret = zpool_malloc(zram->mem_pool, comp_len,
+                               GFP_NOIO | __GFP_HIGHMEM | __GFP_MOVABLE,
+                               &handle);
+               if (ret == 0)
                        goto compress_again;
                return -ENOMEM;
        }
 
-       alloced_pages = zs_get_total_pages(zram->mem_pool);
+       alloced_pages = zpool_get_total_size(zram->mem_pool) >> PAGE_SHIFT;
        update_used_max(zram, alloced_pages);
 
        if (zram->limit_pages && alloced_pages > zram->limit_pages) {
                zcomp_stream_put(zram->comp);
-               zs_free(zram->mem_pool, handle);
+               zpool_free(zram->mem_pool, handle);
                return -ENOMEM;
        }
 
-       dst = zs_map_object(zram->mem_pool, handle, ZS_MM_WO);
+       dst = zpool_map_handle(zram->mem_pool, handle, ZPOOL_MM_WO);
 
        src = zstrm->buffer;
        if (comp_len == PAGE_SIZE)
@@ -1390,7 +1394,7 @@ static int __zram_bvec_write(struct zram *zram, struct 
bio_vec *bvec,
                kunmap_atomic(src);
 
        zcomp_stream_put(zram->comp);
-       zs_unmap_object(zram->mem_pool, handle);
+       zpool_unmap_handle(zram->mem_pool, handle);
        atomic64_add(comp_len, &zram->stats.compr_data_size);
 out:
        /*
@@ -2136,6 +2140,8 @@ module_exit(zram_exit);
 
 module_param(num_devices, uint, 0);
 MODULE_PARM_DESC(num_devices, "Number of pre-created zram devices");
+module_param_string(backend, backend_par_buf, BACKEND_PAR_BUF_SIZE, S_IRUGO);
+MODULE_PARM_DESC(backend, "Compression storage (backend) name");
 
 MODULE_LICENSE("Dual BSD/GPL");
 MODULE_AUTHOR("Nitin Gupta <[email protected]>");
diff --git a/drivers/block/zram/zram_drv.h b/drivers/block/zram/zram_drv.h
index f2fd46daa760..f4f51c6489ba 100644
--- a/drivers/block/zram/zram_drv.h
+++ b/drivers/block/zram/zram_drv.h
@@ -16,7 +16,7 @@
 #define _ZRAM_DRV_H_
 
 #include <linux/rwsem.h>
-#include <linux/zsmalloc.h>
+#include <linux/zpool.h>
 #include <linux/crypto.h>
 
 #include "zcomp.h"
@@ -91,7 +91,7 @@ struct zram_stats {
 
 struct zram {
        struct zram_table_entry *table;
-       struct zs_pool *mem_pool;
+       struct zpool *mem_pool;
        struct zcomp *comp;
        struct gendisk *disk;
        /* Prevent concurrent execution of device init */
-- 
2.20.1

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