linux-imx

// SPDX-License-Identifier: GPL-2.0

/*

 * Copyright (c) 2016-present, Facebook, Inc.

 * All rights reserved.

 *

 */

​

#include <linux/bio.h>

#include <linux/bitmap.h>

#include <linux/err.h>

#include <linux/init.h>

#include <linux/kernel.h>

#include <linux/mm.h>

#include <linux/sched/mm.h>

#include <linux/pagemap.h>

#include <linux/refcount.h>

#include <linux/sched.h>

#include <linux/slab.h>

#include <linux/zstd.h>

#include "compression.h"

#include "ctree.h"

​

#define ZSTD_BTRFS_MAX_WINDOWLOG 17

#define ZSTD_BTRFS_MAX_INPUT (1 << ZSTD_BTRFS_MAX_WINDOWLOG)

#define ZSTD_BTRFS_DEFAULT_LEVEL 3

#define ZSTD_BTRFS_MAX_LEVEL 15

/* 307s to avoid pathologically clashing with transaction commit */

#define ZSTD_BTRFS_RECLAIM_JIFFIES (307 * HZ)

​

static ZSTD_parameters zstd_get_btrfs_parameters(unsigned int level,

                         size_t src_len)

{

    ZSTD_parameters params = ZSTD_getParams(level, src_len, 0);

​

    if (params.cParams.windowLog > ZSTD_BTRFS_MAX_WINDOWLOG)

        params.cParams.windowLog = ZSTD_BTRFS_MAX_WINDOWLOG;

    WARN_ON(src_len > ZSTD_BTRFS_MAX_INPUT);

    return params;

}

​

struct workspace {

    void *mem;

    size_t size;

    char *buf;

    unsigned int level;

    unsigned int req_level;

    unsigned long last_used; /* jiffies */

    struct list_head list;

    struct list_head lru_list;

    ZSTD_inBuffer in_buf;

    ZSTD_outBuffer out_buf;

};

​

/*

 * Zstd Workspace Management

 *

 * Zstd workspaces have different memory requirements depending on the level.

 * The zstd workspaces are managed by having individual lists for each level

 * and a global lru.  Forward progress is maintained by protecting a max level

 * workspace.

 *

 * Getting a workspace is done by using the bitmap to identify the levels that

 * have available workspaces and scans up.  This lets us recycle higher level

 * workspaces because of the monotonic memory guarantee.  A workspace's

 * last_used is only updated if it is being used by the corresponding memory

 * level.  Putting a workspace involves adding it back to the appropriate places

 * and adding it back to the lru if necessary.

 *

 * A timer is used to reclaim workspaces if they have not been used for

 * ZSTD_BTRFS_RECLAIM_JIFFIES.  This helps keep only active workspaces around.

 * The upper bound is provided by the workqueue limit which is 2 (percpu limit).

 */

​

struct zstd_workspace_manager {

    const struct btrfs_compress_op *ops;

    spinlock_t lock;

    struct list_head lru_list;

    struct list_head idle_ws[ZSTD_BTRFS_MAX_LEVEL];

    unsigned long active_map;

    wait_queue_head_t wait;

    struct timer_list timer;

};

​

static struct zstd_workspace_manager wsm;

​

static size_t zstd_ws_mem_sizes[ZSTD_BTRFS_MAX_LEVEL];

​

static inline struct workspace *list_to_workspace(struct list_head *list)

{

    return container_of(list, struct workspace, list);

}

​