Message-ID: <CALZtONDX3Scxtv3=Vhixnov2E6EEormqXL_kFufqL4SGxFK6DQ@mail.gmail.com>
Date:	Sat, 10 May 2014 12:06:58 -0400
From:	Dan Streetman <ddstreet@...e.org>
To:	Seth Jennings <sjennings@...iantweb.net>
Cc:	Minchan Kim <minchan@...nel.org>, Nitin Gupta <ngupta@...are.org>,
	Weijie Yang <weijie.yang@...sung.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Bob Liu <bob.liu@...cle.com>, Hugh Dickins <hughd@...gle.com>,
	Mel Gorman <mgorman@...e.de>, Rik van Riel <riel@...hat.com>,
	Johannes Weiner <hannes@...xchg.org>,
	Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
	Linux-MM <linux-mm@...ck.org>,
	linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCHv2 3/4] mm/zpool: implement common zpool api to zbud/zsmalloc

On Fri, May 9, 2014 at 12:13 AM, Seth Jennings <sjennings@...iantweb.net> wrote:
> On Wed, May 07, 2014 at 05:51:35PM -0400, Dan Streetman wrote:
>> Add zpool api.
>>
>> zpool provides an interface for memory storage, typically of compressed
>> memory.  Users can select what backend to use; currently the only
>> implementations are zbud, a low density implementation with up to
>> two compressed pages per storage page, and zsmalloc, a higher density
>> implementation with multiple compressed pages per storage page.
>
> This is the wrong design methinks.  There are a bunch of #ifdefs for each
> driver in the zpool.c code.  Available drivers (zbud, zsmalloc) should
> register _up_ to the zpool layer.  That way the zpool layer doesn't have
> to add a bunch of new code for each driver.
>
> This zpool layer should be _really_ thin, stateless from the user point
> of view, basically just wrapping the driver ops call.

Ok, yeah that does make sense.  The ops param and evict callback might
be a bit difficult but i'll get to that last :-)


>
> New functions for driver registration:
> zpool_register_driver()
> zpool_unregister_driver()
>
> Something like this (note the "void *" type of the pool):
>
> struct zpool_driver_ops {
>         void (*destroy)(void *pool);
>         int (*malloc)(void *pool, size_t size, unsigned long *handle);
>         ....
> }
>
> Each driver can cast the void *pool to the driver pool type on the
> driver side.
>
> struct zpool_driver {
>         char *driver_name;
>         struct zpool_driver *ops;
> }
>
> Then drivers create a struct zpool_driver suitable for them and register
> with zpool_register_driver().
>
> struct zpool {
>         void *driver_pool;
>         struct zpool_driver *driver;
> }
>
> zpool_create() is:
>
> struct zpool *zpool_create(char *driver_name, gfp_t flags, void *ops)
> {
>         [search for backend driver with name driver_name]
>         [alloc new zpool]
>         zpool->driver = driver;
>         zpool->driver_pool = driver->ops->create(flags, ops);
>         return zpool;
> }
>
> A user function like zpool_free() is just:
>
> void zpool_free(struct zpool *pool, unsigned long handle)
> {
>         pool->driver->free(pool->driver_pool, handle);
> }
>
> Hopefully this makes sense.  Obviously, I didn't rewrite this whole
> thing to see how it works end to end so there may be some pitfalls I'm
> not considering.
>
> Seth
>
>>
>> Signed-off-by: Dan Streetman <ddstreet@...e.org>
>> Cc: Seth Jennings <sjennings@...iantweb.net>
>> Cc: Minchan Kim <minchan@...nel.org>
>> Cc: Nitin Gupta <ngupta@...are.org>
>> Cc: Weijie Yang <weijie.yang@...sung.com>
>> ---
>>
>> Changes since v1 https://lkml.org/lkml/2014/4/19/101
>>  -add some pr_info() during creation and pr_err() on errors
>>  -remove zpool code to call zs_shrink(), since zsmalloc shrinking
>>   was removed from this patchset
>>  -remove fallback; only specified pool type will be tried
>>  -pr_fmt() is defined in zpool to prefix zpool: in any pr_XXX() calls
>>
>>  include/linux/zpool.h | 160 +++++++++++++++++++++++
>>  mm/Kconfig            |  43 ++++---
>>  mm/Makefile           |   1 +
>>  mm/zpool.c            | 349 ++++++++++++++++++++++++++++++++++++++++++++++++++
>>  4 files changed, 535 insertions(+), 18 deletions(-)
>>  create mode 100644 include/linux/zpool.h
>>  create mode 100644 mm/zpool.c
>>
>> diff --git a/include/linux/zpool.h b/include/linux/zpool.h
>> new file mode 100644
>> index 0000000..08f5468
>> --- /dev/null
>> +++ b/include/linux/zpool.h
>> @@ -0,0 +1,160 @@
>> +/*
>> + * zpool memory storage api
>> + *
>> + * Copyright (C) 2014 Dan Streetman
>> + *
>> + * This is a common frontend for the zbud and zsmalloc memory
>> + * storage pool implementations.  Typically, this is used to
>> + * store compressed memory.
>> + */
>> +
>> +#ifndef _ZPOOL_H_
>> +#define _ZPOOL_H_
>> +
>> +struct zpool;
>> +
>> +struct zpool_ops {
>> +     int (*evict)(struct zpool *pool, unsigned long handle);
>> +};
>> +
>> +#define ZPOOL_TYPE_ZSMALLOC "zsmalloc"
>> +#define ZPOOL_TYPE_ZBUD "zbud"
>> +
>> +/*
>> + * Control how a handle is mapped.  It will be ignored if the
>> + * implementation does not support it.  Its use is optional.
>> + * Note that this does not refer to memory protection, it
>> + * refers to how the memory will be copied in/out if copying
>> + * is necessary during mapping; read-write is the safest as
>> + * it copies the existing memory in on map, and copies the
>> + * changed memory back out on unmap.  Write-only does not copy
>> + * in the memory and should only be used for initialization.
>> + * If in doubt, use ZPOOL_MM_DEFAULT which is read-write.
>> + */
>> +enum zpool_mapmode {
>> +     ZPOOL_MM_RW, /* normal read-write mapping */
>> +     ZPOOL_MM_RO, /* read-only (no copy-out at unmap time) */
>> +     ZPOOL_MM_WO, /* write-only (no copy-in at map time) */
>> +
>> +     ZPOOL_MM_DEFAULT = ZPOOL_MM_RW
>> +};
>> +
>> +/**
>> + * zpool_create_pool() - Create a new zpool
>> + * @type     The type of the zpool to create (e.g. zbud, zsmalloc)
>> + * @flags    What GFP flags should be used when the zpool allocates memory.
>> + * @ops              The optional ops callback.
>> + *
>> + * This creates a new zpool of the specified type.  The zpool will use the
>> + * given flags when allocating any memory.  If the ops param is NULL, then
>> + * the created zpool will not be shrinkable.
>> + *
>> + * Returns: New zpool on success, NULL on failure.
>> + */
>> +struct zpool *zpool_create_pool(char *type, gfp_t flags,
>> +                     struct zpool_ops *ops);
>> +
>> +/**
>> + * zpool_get_type() - Get the type of the zpool
>> + * @pool     The zpool to check
>> + *
>> + * This returns the type of the pool, which will match one of the
>> + * ZPOOL_TYPE_* defined values.
>> + *
>> + * Returns: The type of zpool.
>> + */
>> +char *zpool_get_type(struct zpool *pool);
>> +
>> +/**
>> + * zpool_destroy_pool() - Destroy a zpool
>> + * @pool     The zpool to destroy.
>> + *
>> + * This destroys an existing zpool.  The zpool should not be in use.
>> + */
>> +void zpool_destroy_pool(struct zpool *pool);
>> +
>> +/**
>> + * zpool_malloc() - Allocate memory
>> + * @pool     The zpool to allocate from.
>> + * @size     The amount of memory to allocate.
>> + * @handle   Pointer to the handle to set
>> + *
>> + * This allocates the requested amount of memory from the pool.
>> + * The provided @handle will be set to the allocated object handle.
>> + *
>> + * Returns: 0 on success, negative value on error.
>> + */
>> +int zpool_malloc(struct zpool *pool, size_t size, unsigned long *handle);
>> +
>> +/**
>> + * zpool_free() - Free previously allocated memory
>> + * @pool     The zpool that allocated the memory.
>> + * @handle   The handle to the memory to free.
>> + *
>> + * This frees previously allocated memory.  This does not guarantee
>> + * that the pool will actually free memory, only that the memory
>> + * in the pool will become available for use by the pool.
>> + */
>> +void zpool_free(struct zpool *pool, unsigned long handle);
>> +
>> +/**
>> + * zpool_shrink() - Shrink the pool size
>> + * @pool     The zpool to shrink.
>> + * @size     The minimum amount to shrink the pool.
>> + *
>> + * 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.
>> + *
>> + * Returns: 0 on success, negative value on error/failure.
>> + */
>> +int zpool_shrink(struct zpool *pool, size_t size);
>> +
>> +/**
>> + * zpool_map_handle() - Map a previously allocated handle into memory
>> + * @pool     The zpool that the handle was allocated from
>> + * @handle   The handle to map
>> + * @mm       How the memory should be mapped
>> + *
>> + * This maps a previously allocated handle into memory.  The @mm
>> + * param indicates to the implemenation how the memory will be
>> + * used, i.e. read-only, write-only, read-write.  If the
>> + * implementation does not support it, the memory will be treated
>> + * as read-write.
>> + *
>> + * This may hold locks, disable interrupts, and/or preemption,
>> + * and the zpool_unmap_handle() must be called to undo those
>> + * actions.  The code that uses the mapped handle should complete
>> + * its operatons on the mapped handle memory quickly and unmap
>> + * as soon as possible.  Multiple handles should not be mapped
>> + * concurrently on a cpu.
>> + *
>> + * Returns: A pointer to the handle's mapped memory area.
>> + */
>> +void *zpool_map_handle(struct zpool *pool, unsigned long handle,
>> +                     enum zpool_mapmode mm);
>> +
>> +/**
>> + * zpool_unmap_handle() - Unmap a previously mapped handle
>> + * @pool     The zpool that the handle was allocated from
>> + * @handle   The handle to unmap
>> + *
>> + * This unmaps a previously mapped handle.  Any locks or other
>> + * actions that the implemenation took in zpool_map_handle()
>> + * will be undone here.  The memory area returned from
>> + * zpool_map_handle() should no longer be used after this.
>> + */
>> +void zpool_unmap_handle(struct zpool *pool, unsigned long handle);
>> +
>> +/**
>> + * zpool_get_total_size() - The total size of the pool
>> + * @pool     The zpool to check
>> + *
>> + * This returns the total size in bytes of the pool.
>> + *
>> + * Returns: Total size of the zpool in bytes.
>> + */
>> +u64 zpool_get_total_size(struct zpool *pool);
>> +
>> +#endif
>> diff --git a/mm/Kconfig b/mm/Kconfig
>> index 30cb6cb..bdb4cb2 100644
>> --- a/mm/Kconfig
>> +++ b/mm/Kconfig
>> @@ -515,21 +515,23 @@ config CMA_DEBUG
>>         processing calls such as dma_alloc_from_contiguous().
>>         This option does not affect warning and error messages.
>>
>> -config ZBUD
>> -     tristate
>> -     default n
>> +config MEM_SOFT_DIRTY
>> +     bool "Track memory changes"
>> +     depends on CHECKPOINT_RESTORE && HAVE_ARCH_SOFT_DIRTY && PROC_FS
>> +     select PROC_PAGE_MONITOR
>>       help
>> -       A special purpose allocator for storing compressed pages.
>> -       It is designed to store up to two compressed pages per physical
>> -       page.  While this design limits storage density, it has simple and
>> -       deterministic reclaim properties that make it preferable to a higher
>> -       density approach when reclaim will be used.
>> +       This option enables memory changes tracking by introducing a
>> +       soft-dirty bit on pte-s. This bit it set when someone writes
>> +       into a page just as regular dirty bit, but unlike the latter
>> +       it can be cleared by hands.
>> +
>> +       See Documentation/vm/soft-dirty.txt for more details.
>>
>>  config ZSWAP
>>       bool "Compressed cache for swap pages (EXPERIMENTAL)"
>>       depends on FRONTSWAP && CRYPTO=y
>>       select CRYPTO_LZO
>> -     select ZBUD
>> +     select ZPOOL
>>       default n
>>       help
>>         A lightweight compressed cache for swap pages.  It takes
>> @@ -545,17 +547,22 @@ config ZSWAP
>>         they have not be fully explored on the large set of potential
>>         configurations and workloads that exist.
>>
>> -config MEM_SOFT_DIRTY
>> -     bool "Track memory changes"
>> -     depends on CHECKPOINT_RESTORE && HAVE_ARCH_SOFT_DIRTY && PROC_FS
>> -     select PROC_PAGE_MONITOR
>> +config ZPOOL
>> +     tristate "Common API for compressed memory storage"
>> +     default n
>>       help
>> -       This option enables memory changes tracking by introducing a
>> -       soft-dirty bit on pte-s. This bit it set when someone writes
>> -       into a page just as regular dirty bit, but unlike the latter
>> -       it can be cleared by hands.
>> +       Compressed memory storage API.  This allows using either zbud or
>> +       zsmalloc.
>>
>> -       See Documentation/vm/soft-dirty.txt for more details.
>> +config ZBUD
>> +     tristate "Low density storage for compressed pages"
>> +     default n
>> +     help
>> +       A special purpose allocator for storing compressed pages.
>> +       It is designed to store up to two compressed pages per physical
>> +       page.  While this design limits storage density, it has simple and
>> +       deterministic reclaim properties that make it preferable to a higher
>> +       density approach when reclaim will be used.
>>
>>  config ZSMALLOC
>>       bool "Memory allocator for compressed pages"
>> diff --git a/mm/Makefile b/mm/Makefile
>> index 9b75a4d..f64a5d4 100644
>> --- a/mm/Makefile
>> +++ b/mm/Makefile
>> @@ -61,6 +61,7 @@ obj-$(CONFIG_DEBUG_KMEMLEAK_TEST) += kmemleak-test.o
>>  obj-$(CONFIG_CLEANCACHE) += cleancache.o
>>  obj-$(CONFIG_MEMORY_ISOLATION) += page_isolation.o
>>  obj-$(CONFIG_PAGE_OWNER) += pageowner.o
>> +obj-$(CONFIG_ZPOOL)  += zpool.o
>>  obj-$(CONFIG_ZBUD)   += zbud.o
>>  obj-$(CONFIG_ZSMALLOC)       += zsmalloc.o
>>  obj-$(CONFIG_GENERIC_EARLY_IOREMAP) += early_ioremap.o
>> diff --git a/mm/zpool.c b/mm/zpool.c
>> new file mode 100644
>> index 0000000..2bda300
>> --- /dev/null
>> +++ b/mm/zpool.c
>> @@ -0,0 +1,349 @@
>> +/*
>> + * zpool memory storage api
>> + *
>> + * Copyright (C) 2014 Dan Streetman
>> + *
>> + * This is a common frontend for the zbud and zsmalloc memory
>> + * storage pool implementations.  Typically, this is used to
>> + * store compressed memory.
>> + */
>> +
>> +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
>> +
>> +#include <linux/list.h>
>> +#include <linux/types.h>
>> +#include <linux/mm.h>
>> +#include <linux/slab.h>
>> +#include <linux/spinlock.h>
>> +#include <linux/zpool.h>
>> +#include <linux/zbud.h>
>> +#include <linux/zsmalloc.h>
>> +
>> +struct zpool_imp {
>> +     void (*destroy)(struct zpool *pool);
>> +
>> +     int (*malloc)(struct zpool *pool, size_t size, unsigned long *handle);
>> +     void (*free)(struct zpool *pool, unsigned long handle);
>> +
>> +     int (*shrink)(struct zpool *pool, size_t size);
>> +
>> +     void *(*map)(struct zpool *pool, unsigned long handle,
>> +                             enum zpool_mapmode mm);
>> +     void (*unmap)(struct zpool *pool, unsigned long handle);
>> +
>> +     u64 (*total_size)(struct zpool *pool);
>> +};
>> +
>> +struct zpool {
>> +     char *type;
>> +
>> +     union {
>> +#ifdef CONFIG_ZSMALLOC
>> +     struct zs_pool *zsmalloc_pool;
>> +#endif
>> +#ifdef CONFIG_ZBUD
>> +     struct zbud_pool *zbud_pool;
>> +#endif
>> +     };
>> +
>> +     struct zpool_imp *imp;
>> +     struct zpool_ops *ops;
>> +
>> +     struct list_head list;
>> +};
>> +
>> +static LIST_HEAD(zpools);
>> +static DEFINE_SPINLOCK(zpools_lock);
>> +
>> +static int zpool_noop_evict(struct zpool *pool, unsigned long handle)
>> +{
>> +     return -EINVAL;
>> +}
>> +static struct zpool_ops zpool_noop_ops = {
>> +     .evict = zpool_noop_evict
>> +};
>> +
>> +
>> +/* zsmalloc */
>> +
>> +#ifdef CONFIG_ZSMALLOC
>> +
>> +static void zpool_zsmalloc_destroy(struct zpool *zpool)
>> +{
>> +     spin_lock(&zpools_lock);
>> +     list_del(&zpool->list);
>> +     spin_unlock(&zpools_lock);
>> +
>> +     zs_destroy_pool(zpool->zsmalloc_pool);
>> +     kfree(zpool);
>> +}
>> +
>> +static int zpool_zsmalloc_malloc(struct zpool *pool, size_t size,
>> +                     unsigned long *handle)
>> +{
>> +     *handle = zs_malloc(pool->zsmalloc_pool, size);
>> +     return *handle ? 0 : -1;
>> +}
>> +
>> +static void zpool_zsmalloc_free(struct zpool *pool, unsigned long handle)
>> +{
>> +     zs_free(pool->zsmalloc_pool, handle);
>> +}
>> +
>> +static int zpool_zsmalloc_shrink(struct zpool *pool, size_t size)
>> +{
>> +     /* Not yet supported */
>> +     return -EINVAL;
>> +}
>> +
>> +static void *zpool_zsmalloc_map(struct zpool *pool, unsigned long handle,
>> +                     enum zpool_mapmode zpool_mapmode)
>> +{
>> +     enum zs_mapmode zs_mapmode;
>> +
>> +     switch (zpool_mapmode) {
>> +     case ZPOOL_MM_RO:
>> +             zs_mapmode = ZS_MM_RO; break;
>> +     case ZPOOL_MM_WO:
>> +             zs_mapmode = ZS_MM_WO; break;
>> +     case ZPOOL_MM_RW: /* fallthrough */
>> +     default:
>> +             zs_mapmode = ZS_MM_RW; break;
>> +     }
>> +     return zs_map_object(pool->zsmalloc_pool, handle, zs_mapmode);
>> +}
>> +
>> +static void zpool_zsmalloc_unmap(struct zpool *pool, unsigned long handle)
>> +{
>> +     zs_unmap_object(pool->zsmalloc_pool, handle);
>> +}
>> +
>> +static u64 zpool_zsmalloc_total_size(struct zpool *pool)
>> +{
>> +     return zs_get_total_size_bytes(pool->zsmalloc_pool);
>> +}
>> +
>> +static struct zpool_imp zpool_zsmalloc_imp = {
>> +     .destroy = zpool_zsmalloc_destroy,
>> +     .malloc = zpool_zsmalloc_malloc,
>> +     .free = zpool_zsmalloc_free,
>> +     .shrink = zpool_zsmalloc_shrink,
>> +     .map = zpool_zsmalloc_map,
>> +     .unmap = zpool_zsmalloc_unmap,
>> +     .total_size = zpool_zsmalloc_total_size
>> +};
>> +
>> +static struct zpool *zpool_zsmalloc_create(gfp_t flags, struct zpool_ops *ops)
>> +{
>> +     struct zpool *zpool;
>> +
>> +     zpool = kmalloc(sizeof(*zpool), GFP_KERNEL);
>> +     if (!zpool) {
>> +             pr_err("couldn't create zpool - out of memory\n");
>> +             return NULL;
>> +     }
>> +
>> +     zpool->zsmalloc_pool = zs_create_pool(flags);
>> +     if (!zpool->zsmalloc_pool) {
>> +             kfree(zpool);
>> +             pr_err("zs_create_pool() failed\n");
>> +             return NULL;
>> +     }
>> +
>> +     zpool->type = ZPOOL_TYPE_ZSMALLOC;
>> +     zpool->imp = &zpool_zsmalloc_imp;
>> +     zpool->ops = &zpool_noop_ops;
>> +     spin_lock(&zpools_lock);
>> +     list_add(&zpool->list, &zpools);
>> +     spin_unlock(&zpools_lock);
>> +
>> +     return zpool;
>> +}
>> +
>> +#else
>> +
>> +static struct zpool *zpool_zsmalloc_create(gfp_t flags, struct zpool_ops *ops)
>> +{
>> +     pr_info("no zsmalloc in this kernel\n");
>> +     return NULL;
>> +}
>> +
>> +#endif /* CONFIG_ZSMALLOC */
>> +
>> +
>> +/* zbud */
>> +
>> +#ifdef CONFIG_ZBUD
>> +
>> +static void zpool_zbud_destroy(struct zpool *zpool)
>> +{
>> +     spin_lock(&zpools_lock);
>> +     list_del(&zpool->list);
>> +     spin_unlock(&zpools_lock);
>> +
>> +     zbud_destroy_pool(zpool->zbud_pool);
>> +     kfree(zpool);
>> +}
>> +
>> +static int zpool_zbud_malloc(struct zpool *pool, size_t size,
>> +                     unsigned long *handle)
>> +{
>> +     return zbud_alloc(pool->zbud_pool, size, handle);
>> +}
>> +
>> +static void zpool_zbud_free(struct zpool *pool, unsigned long handle)
>> +{
>> +     zbud_free(pool->zbud_pool, handle);
>> +}
>> +
>> +static int zpool_zbud_shrink(struct zpool *pool, size_t size)
>> +{
>> +     return zbud_reclaim_page(pool->zbud_pool, 3);
>> +}
>> +
>> +static void *zpool_zbud_map(struct zpool *pool, unsigned long handle,
>> +                     enum zpool_mapmode zpool_mapmode)
>> +{
>> +     return zbud_map(pool->zbud_pool, handle);
>> +}
>> +
>> +static void zpool_zbud_unmap(struct zpool *pool, unsigned long handle)
>> +{
>> +     zbud_unmap(pool->zbud_pool, handle);
>> +}
>> +
>> +static u64 zpool_zbud_total_size(struct zpool *pool)
>> +{
>> +     return zbud_get_pool_size(pool->zbud_pool) * PAGE_SIZE;
>> +}
>> +
>> +static int zpool_zbud_evict(struct zbud_pool *zbud_pool, unsigned long handle)
>> +{
>> +     struct zpool *zpool;
>> +
>> +     spin_lock(&zpools_lock);
>> +     list_for_each_entry(zpool, &zpools, list) {
>> +             if (zpool->zbud_pool == zbud_pool) {
>> +                     spin_unlock(&zpools_lock);
>> +                     return zpool->ops->evict(zpool, handle);
>> +             }
>> +     }
>> +     spin_unlock(&zpools_lock);
>> +     return -EINVAL;
>> +}
>> +
>> +static struct zpool_imp zpool_zbud_imp = {
>> +     .destroy = zpool_zbud_destroy,
>> +     .malloc = zpool_zbud_malloc,
>> +     .free = zpool_zbud_free,
>> +     .shrink = zpool_zbud_shrink,
>> +     .map = zpool_zbud_map,
>> +     .unmap = zpool_zbud_unmap,
>> +     .total_size = zpool_zbud_total_size
>> +};
>> +
>> +static struct zbud_ops zpool_zbud_ops = {
>> +     .evict = zpool_zbud_evict
>> +};
>> +
>> +static struct zpool *zpool_zbud_create(gfp_t flags, struct zpool_ops *ops)
>> +{
>> +     struct zpool *zpool;
>> +     struct zbud_ops *zbud_ops = (ops ? &zpool_zbud_ops : NULL);
>> +
>> +     zpool = kmalloc(sizeof(*zpool), GFP_KERNEL);
>> +     if (!zpool) {
>> +             pr_err("couldn't create zpool - out of memory\n");
>> +             return NULL;
>> +     }
>> +
>> +     zpool->zbud_pool = zbud_create_pool(flags, zbud_ops);
>> +     if (!zpool->zbud_pool) {
>> +             kfree(zpool);
>> +             pr_err("zbud_create_pool() failed\n");
>> +             return NULL;
>> +     }
>> +
>> +     zpool->type = ZPOOL_TYPE_ZBUD;
>> +     zpool->imp = &zpool_zbud_imp;
>> +     zpool->ops = (ops ? ops : &zpool_noop_ops);
>> +     spin_lock(&zpools_lock);
>> +     list_add(&zpool->list, &zpools);
>> +     spin_unlock(&zpools_lock);
>> +
>> +     return zpool;
>> +}
>> +
>> +#else
>> +
>> +static struct zpool *zpool_zbud_create(gfp_t flags, struct zpool_ops *ops)
>> +{
>> +     pr_info("no zbud in this kernel\n");
>> +     return NULL;
>> +}
>> +
>> +#endif /* CONFIG_ZBUD */
>> +
>> +
>> +struct zpool *zpool_create_pool(char *type, gfp_t flags,
>> +                     struct zpool_ops *ops)
>> +{
>> +     struct zpool *pool = NULL;
>> +
>> +     pr_info("creating pool type %s\n", type);
>> +
>> +     if (!strcmp(type, ZPOOL_TYPE_ZSMALLOC))
>> +             pool = zpool_zsmalloc_create(flags, ops);
>> +     else if (!strcmp(type, ZPOOL_TYPE_ZBUD))
>> +             pool = zpool_zbud_create(flags, ops);
>> +     else
>> +             pr_err("unknown type %s\n", type);
>> +
>> +     if (pool)
>> +             pr_info("created %s pool\n", type);
>> +     else
>> +             pr_err("couldn't create %s pool\n", type);
>> +
>> +     return pool;
>> +}
>> +
>> +char *zpool_get_type(struct zpool *pool)
>> +{
>> +     return pool->type;
>> +}
>> +
>> +void zpool_destroy_pool(struct zpool *pool)
>> +{
>> +     pool->imp->destroy(pool);
>> +}
>> +
>> +int zpool_malloc(struct zpool *pool, size_t size, unsigned long *handle)
>> +{
>> +     return pool->imp->malloc(pool, size, handle);
>> +}
>> +
>> +void zpool_free(struct zpool *pool, unsigned long handle)
>> +{
>> +     pool->imp->free(pool, handle);
>> +}
>> +
>> +int zpool_shrink(struct zpool *pool, size_t size)
>> +{
>> +     return pool->imp->shrink(pool, size);
>> +}
>> +
>> +void *zpool_map_handle(struct zpool *pool, unsigned long handle,
>> +                     enum zpool_mapmode mapmode)
>> +{
>> +     return pool->imp->map(pool, handle, mapmode);
>> +}
>> +
>> +void zpool_unmap_handle(struct zpool *pool, unsigned long handle)
>> +{
>> +     pool->imp->unmap(pool, handle);
>> +}
>> +
>> +u64 zpool_get_total_size(struct zpool *pool)
>> +{
>> +     return pool->imp->total_size(pool);
>> +}
>> --
>> 1.8.3.1
>>
--
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