linux-imx

/*

 * Add configfs and memory store: Kyungchan Koh <kkc6196@fb.com> and

 * Shaohua Li <shli@fb.com>

 */

#include <linux/module.h>

​

#include <linux/moduleparam.h>

#include <linux/sched.h>

#include <linux/fs.h>

#include <linux/init.h>

#include "null_blk.h"

​

#define PAGE_SECTORS_SHIFT  (PAGE_SHIFT - SECTOR_SHIFT)

#define PAGE_SECTORS        (1 << PAGE_SECTORS_SHIFT)

#define SECTOR_MASK     (PAGE_SECTORS - 1)

​

#define FREE_BATCH      16

​

#define TICKS_PER_SEC       50ULL

#define TIMER_INTERVAL      (NSEC_PER_SEC / TICKS_PER_SEC)

​

#ifdef CONFIG_BLK_DEV_NULL_BLK_FAULT_INJECTION

static DECLARE_FAULT_ATTR(null_timeout_attr);

static DECLARE_FAULT_ATTR(null_requeue_attr);

#endif

​

static inline u64 mb_per_tick(int mbps)

{

    return (1 << 20) / TICKS_PER_SEC * ((u64) mbps);

}

​

/*

 * Status flags for nullb_device.

 *

 * CONFIGURED:  Device has been configured and turned on. Cannot reconfigure.

 * UP:      Device is currently on and visible in userspace.

 * THROTTLED:   Device is being throttled.

 * CACHE:   Device is using a write-back cache.

 */

enum nullb_device_flags {

    NULLB_DEV_FL_CONFIGURED = 0,

    NULLB_DEV_FL_UP     = 1,

    NULLB_DEV_FL_THROTTLED  = 2,

    NULLB_DEV_FL_CACHE  = 3,

};

​

#define MAP_SZ      ((PAGE_SIZE >> SECTOR_SHIFT) + 2)

/*

 * nullb_page is a page in memory for nullb devices.

 *

 * @page:   The page holding the data.

 * @bitmap: The bitmap represents which sector in the page has data.

 *      Each bit represents one block size. For example, sector 8

 *      will use the 7th bit

 * The highest 2 bits of bitmap are for special purpose. LOCK means the cache

 * page is being flushing to storage. FREE means the cache page is freed and

 * should be skipped from flushing to storage. Please see

 * null_make_cache_space

 */

struct nullb_page {

    struct page *page;

    DECLARE_BITMAP(bitmap, MAP_SZ);

};

#define NULLB_PAGE_LOCK (MAP_SZ - 1)

#define NULLB_PAGE_FREE (MAP_SZ - 2)

​

static LIST_HEAD(nullb_list);

static struct mutex lock;

static int null_major;

static DEFINE_IDA(nullb_indexes);

static struct blk_mq_tag_set tag_set;

​

enum {

    NULL_IRQ_NONE       = 0,

    NULL_IRQ_SOFTIRQ    = 1,

    NULL_IRQ_TIMER      = 2,

};

​

enum {

    NULL_Q_BIO      = 0,

    NULL_Q_RQ       = 1,

    NULL_Q_MQ       = 2,

};

​

static int g_no_sched;

module_param_named(no_sched, g_no_sched, int, 0444);

MODULE_PARM_DESC(no_sched, "No io scheduler");

​

static int g_submit_queues = 1;

module_param_named(submit_queues, g_submit_queues, int, 0444);

MODULE_PARM_DESC(submit_queues, "Number of submission queues");

​