blk-sysfs.c

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/*
 * Functions related to sysfs handling
 */
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/bio.h>
#include <linux/blkdev.h>
#include <linux/blktrace_api.h>

#include "blk.h"
#include "blk-cgroup.h"

struct queue_sysfs_entry {
    struct attribute attr;
    ssize_t (*show)(struct request_queue *, char *);
    ssize_t (*store)(struct request_queue *, const char *, size_t);
};

static ssize_t
queue_var_show(unsigned long var, char *page)
{
    return sprintf(page, "%lu\n", var);
}

static ssize_t
queue_var_store(unsigned long *var, const char *page, size_t count)
{
    int err;
    unsigned long v;

    err = strict_strtoul(page, 10, &v);
    if (err || v > UINT_MAX)
        return -EINVAL;

    *var = v;

    return count;
}

static ssize_t queue_requests_show(struct request_queue *q, char *page)
{
    return queue_var_show(q->nr_requests, (page));
}

static ssize_t
queue_requests_store(struct request_queue *q, const char *page, size_t count)
{
    struct request_list *rl;
    unsigned long nr;
    int ret;

    if (!q->request_fn)
        return -EINVAL;

    ret = queue_var_store(&nr, page, count);
    if (ret < 0)
        return ret;

    if (nr < BLKDEV_MIN_RQ)
        nr = BLKDEV_MIN_RQ;

    spin_lock_irq(q->queue_lock);
    q->nr_requests = nr;
    blk_queue_congestion_threshold(q);

    /* congestion isn't cgroup aware and follows root blkcg for now */
    rl = &q->root_rl;

    if (rl->count[BLK_RW_SYNC] >= queue_congestion_on_threshold(q))
        blk_set_queue_congested(q, BLK_RW_SYNC);
    else if (rl->count[BLK_RW_SYNC] < queue_congestion_off_threshold(q))
        blk_clear_queue_congested(q, BLK_RW_SYNC);

    if (rl->count[BLK_RW_ASYNC] >= queue_congestion_on_threshold(q))
        blk_set_queue_congested(q, BLK_RW_ASYNC);
    else if (rl->count[BLK_RW_ASYNC] < queue_congestion_off_threshold(q))
        blk_clear_queue_congested(q, BLK_RW_ASYNC);

    blk_queue_for_each_rl(rl, q) {
        if (rl->count[BLK_RW_SYNC] >= q->nr_requests) {
            blk_set_rl_full(rl, BLK_RW_SYNC);
        } else {
            blk_clear_rl_full(rl, BLK_RW_SYNC);
            wake_up(&rl->wait[BLK_RW_SYNC]);
        }

        if (rl->count[BLK_RW_ASYNC] >= q->nr_requests) {
            blk_set_rl_full(rl, BLK_RW_ASYNC);
        } else {
            blk_clear_rl_full(rl, BLK_RW_ASYNC);
            wake_up(&rl->wait[BLK_RW_ASYNC]);
        }
    }

    spin_unlock_irq(q->queue_lock);
    return ret;
}

static ssize_t queue_ra_show(struct request_queue *q, char *page)
{
    unsigned long ra_kb = q->backing_dev_info.ra_pages <<
                    (PAGE_CACHE_SHIFT - 10);

    return queue_var_show(ra_kb, (page));
}

static ssize_t
queue_ra_store(struct request_queue *q, const char *page, size_t count)
{
    unsigned long ra_kb;
    ssize_t ret = queue_var_store(&ra_kb, page, count);

    if (ret < 0)
        return ret;

    q->backing_dev_info.ra_pages = ra_kb >> (PAGE_CACHE_SHIFT - 10);

    return ret;
}

static ssize_t queue_max_sectors_show(struct request_queue *q, char *page)
{
    int max_sectors_kb = queue_max_sectors(q) >> 1;

    return queue_var_show(max_sectors_kb, (page));
}

static ssize_t queue_max_segments_show(struct request_queue *q, char *page)
{
    return queue_var_show(queue_max_segments(q), (page));
}

static ssize_t queue_max_integrity_segments_show(struct request_queue *q, char *page)
{
    return queue_var_show(q->limits.max_integrity_segments, (page));
}

static ssize_t queue_max_segment_size_show(struct request_queue *q, char *page)
{
    if (blk_queue_cluster(q))
        return queue_var_show(queue_max_segment_size(q), (page));

    return queue_var_show(PAGE_CACHE_SIZE, (page));
}

static ssize_t queue_logical_block_size_show(struct request_queue *q, char *page)
{
    return queue_var_show(queue_logical_block_size(q), page);
}

static ssize_t queue_physical_block_size_show(struct request_queue *q, char *page)
{
    return queue_var_show(queue_physical_block_size(q), page);
}

static ssize_t queue_io_min_show(struct request_queue *q, char *page)
{
    return queue_var_show(queue_io_min(q), page);
}

static ssize_t queue_io_opt_show(struct request_queue *q, char *page)
{
    return queue_var_show(queue_io_opt(q), page);
}

static ssize_t queue_discard_granularity_show(struct request_queue *q, char *page)
{
    return queue_var_show(q->limits.discard_granularity, page);
}

static ssize_t queue_discard_max_show(struct request_queue *q, char *page)
{
    return sprintf(page, "%llu\n",
               (unsigned long long)q->limits.max_discard_sectors << 9);
}

static ssize_t queue_discard_zeroes_data_show(struct request_queue *q, char *page)
{
    return queue_var_show(queue_discard_zeroes_data(q), page);
}

static ssize_t queue_write_same_max_show(struct request_queue *q, char *page)
{
    return sprintf(page, "%llu\n",
        (unsigned long long)q->limits.max_write_same_sectors << 9);
}


static ssize_t
queue_max_sectors_store(struct request_queue *q, const char *page, size_t count)
{
    unsigned long max_sectors_kb,
        max_hw_sectors_kb = queue_max_hw_sectors(q) >> 1,
            page_kb = 1 << (PAGE_CACHE_SHIFT - 10);
    ssize_t ret = queue_var_store(&max_sectors_kb, page, count);

    if (ret < 0)
        return ret;

    if (max_sectors_kb > max_hw_sectors_kb || max_sectors_kb < page_kb)
        return -EINVAL;

    spin_lock_irq(q->queue_lock);
    q->limits.max_sectors = max_sectors_kb << 1;
    spin_unlock_irq(q->queue_lock);

    return ret;
}

static ssize_t queue_max_hw_sectors_show(struct request_queue *q, char *page)
{
    int max_hw_sectors_kb = queue_max_hw_sectors(q) >> 1;

    return queue_var_show(max_hw_sectors_kb, (page));
}

#define QUEUE_SYSFS_BIT_FNS(name, flag, neg)                \
static ssize_t                              \
queue_show_##name(struct request_queue *q, char *page)          \
{                                   \
    int bit;                            \
    bit = test_bit(QUEUE_FLAG_##flag, &q->queue_flags);     \
    return queue_var_show(neg ? !bit : bit, page);          \
}                                   \
static ssize_t                              \
queue_store_##name(struct request_queue *q, const char *page, size_t count) \
{                                   \
    unsigned long val;                      \
    ssize_t ret;                            \
    ret = queue_var_store(&val, page, count);           \
    if (neg)                            \
        val = !val;                     \
                                    \
    spin_lock_irq(q->queue_lock);                   \
    if (val)                            \
        queue_flag_set(QUEUE_FLAG_##flag, q);           \
    else                                \
        queue_flag_clear(QUEUE_FLAG_##flag, q);         \
    spin_unlock_irq(q->queue_lock);                 \
    return ret;                         \
}

QUEUE_SYSFS_BIT_FNS(nonrot, NONROT, 1);
QUEUE_SYSFS_BIT_FNS(random, ADD_RANDOM, 0);
QUEUE_SYSFS_BIT_FNS(iostats, IO_STAT, 0);
#undef QUEUE_SYSFS_BIT_FNS

static ssize_t queue_nomerges_show(struct request_queue *q, char *page)
{
    return queue_var_show((blk_queue_nomerges(q) << 1) |
                   blk_queue_noxmerges(q), page);
}

static ssize_t queue_nomerges_store(struct request_queue *q, const char *page,
                    size_t count)
{
    unsigned long nm;
    ssize_t ret = queue_var_store(&nm, page, count);

    if (ret < 0)
        return ret;

    spin_lock_irq(q->queue_lock);
    queue_flag_clear(QUEUE_FLAG_NOMERGES, q);
    queue_flag_clear(QUEUE_FLAG_NOXMERGES, q);
    if (nm == 2)
        queue_flag_set(QUEUE_FLAG_NOMERGES, q);
    else if (nm)
        queue_flag_set(QUEUE_FLAG_NOXMERGES, q);
    spin_unlock_irq(q->queue_lock);

    return ret;
}

static ssize_t queue_rq_affinity_show(struct request_queue *q, char *page)
{
    bool set = test_bit(QUEUE_FLAG_SAME_COMP, &q->queue_flags);
    bool force = test_bit(QUEUE_FLAG_SAME_FORCE, &q->queue_flags);

    return queue_var_show(set << force, page);
}

static ssize_t
queue_rq_affinity_store(struct request_queue *q, const char *page, size_t count)
{
    ssize_t ret = -EINVAL;
#if defined(CONFIG_USE_GENERIC_SMP_HELPERS)
    unsigned long val;

    ret = queue_var_store(&val, page, count);
    if (ret < 0)
        return ret;

    spin_lock_irq(q->queue_lock);
    if (val == 2) {
        queue_flag_set(QUEUE_FLAG_SAME_COMP, q);
        queue_flag_set(QUEUE_FLAG_SAME_FORCE, q);
    } else if (val == 1) {
        queue_flag_set(QUEUE_FLAG_SAME_COMP, q);
        queue_flag_clear(QUEUE_FLAG_SAME_FORCE, q);
    } else if (val == 0) {
        queue_flag_clear(QUEUE_FLAG_SAME_COMP, q);
        queue_flag_clear(QUEUE_FLAG_SAME_FORCE, q);
    }
    spin_unlock_irq(q->queue_lock);
#endif
    return ret;
}

static struct queue_sysfs_entry queue_requests_entry = {
    .attr = {.name = "nr_requests", .mode = S_IRUGO | S_IWUSR },
    .show = queue_requests_show,
    .store = queue_requests_store,
};

static struct queue_sysfs_entry queue_ra_entry = {
    .attr = {.name = "read_ahead_kb", .mode = S_IRUGO | S_IWUSR },
    .show = queue_ra_show,
    .store = queue_ra_store,
};

static struct queue_sysfs_entry queue_max_sectors_entry = {
    .attr = {.name = "max_sectors_kb", .mode = S_IRUGO | S_IWUSR },
    .show = queue_max_sectors_show,
    .store = queue_max_sectors_store,
};

static struct queue_sysfs_entry queue_max_hw_sectors_entry = {
    .attr = {.name = "max_hw_sectors_kb", .mode = S_IRUGO },
    .show = queue_max_hw_sectors_show,
};

static struct queue_sysfs_entry queue_max_segments_entry = {
    .attr = {.name = "max_segments", .mode = S_IRUGO },
    .show = queue_max_segments_show,
};

static struct queue_sysfs_entry queue_max_integrity_segments_entry = {
    .attr = {.name = "max_integrity_segments", .mode = S_IRUGO },
    .show = queue_max_integrity_segments_show,
};

static struct queue_sysfs_entry queue_max_segment_size_entry = {
    .attr = {.name = "max_segment_size", .mode = S_IRUGO },
    .show = queue_max_segment_size_show,
};

static struct queue_sysfs_entry queue_iosched_entry = {
    .attr = {.name = "scheduler", .mode = S_IRUGO | S_IWUSR },
    .show = elv_iosched_show,
    .store = elv_iosched_store,
};

static struct queue_sysfs_entry queue_hw_sector_size_entry = {
    .attr = {.name = "hw_sector_size", .mode = S_IRUGO },
    .show = queue_logical_block_size_show,
};

static struct queue_sysfs_entry queue_logical_block_size_entry = {
    .attr = {.name = "logical_block_size", .mode = S_IRUGO },
    .show = queue_logical_block_size_show,
};

static struct queue_sysfs_entry queue_physical_block_size_entry = {
    .attr = {.name = "physical_block_size", .mode = S_IRUGO },
    .show = queue_physical_block_size_show,
};

static struct queue_sysfs_entry queue_io_min_entry = {
    .attr = {.name = "minimum_io_size", .mode = S_IRUGO },
    .show = queue_io_min_show,
};

static struct queue_sysfs_entry queue_io_opt_entry = {
    .attr = {.name = "optimal_io_size", .mode = S_IRUGO },
    .show = queue_io_opt_show,
};

static struct queue_sysfs_entry queue_discard_granularity_entry = {
    .attr = {.name = "discard_granularity", .mode = S_IRUGO },
    .show = queue_discard_granularity_show,
};

static struct queue_sysfs_entry queue_discard_max_entry = {
    .attr = {.name = "discard_max_bytes", .mode = S_IRUGO },
    .show = queue_discard_max_show,
};

static struct queue_sysfs_entry queue_discard_zeroes_data_entry = {
    .attr = {.name = "discard_zeroes_data", .mode = S_IRUGO },
    .show = queue_discard_zeroes_data_show,
};

static struct queue_sysfs_entry queue_write_same_max_entry = {
    .attr = {.name = "write_same_max_bytes", .mode = S_IRUGO },
    .show = queue_write_same_max_show,
};

static struct queue_sysfs_entry queue_nonrot_entry = {
    .attr = {.name = "rotational", .mode = S_IRUGO | S_IWUSR },
    .show = queue_show_nonrot,
    .store = queue_store_nonrot,
};

static struct queue_sysfs_entry queue_nomerges_entry = {
    .attr = {.name = "nomerges", .mode = S_IRUGO | S_IWUSR },
    .show = queue_nomerges_show,
    .store = queue_nomerges_store,
};

static struct queue_sysfs_entry queue_rq_affinity_entry = {
    .attr = {.name = "rq_affinity", .mode = S_IRUGO | S_IWUSR },
    .show = queue_rq_affinity_show,
    .store = queue_rq_affinity_store,
};

static struct queue_sysfs_entry queue_iostats_entry = {
    .attr = {.name = "iostats", .mode = S_IRUGO | S_IWUSR },
    .show = queue_show_iostats,
    .store = queue_store_iostats,
};

static struct queue_sysfs_entry queue_random_entry = {
    .attr = {.name = "add_random", .mode = S_IRUGO | S_IWUSR },
    .show = queue_show_random,
    .store = queue_store_random,
};

static struct attribute *default_attrs[] = {
    &queue_requests_entry.attr,
    &queue_ra_entry.attr,
    &queue_max_hw_sectors_entry.attr,
    &queue_max_sectors_entry.attr,
    &queue_max_segments_entry.attr,
    &queue_max_integrity_segments_entry.attr,
    &queue_max_segment_size_entry.attr,
    &queue_iosched_entry.attr,
    &queue_hw_sector_size_entry.attr,
    &queue_logical_block_size_entry.attr,
    &queue_physical_block_size_entry.attr,
    &queue_io_min_entry.attr,
    &queue_io_opt_entry.attr,
    &queue_discard_granularity_entry.attr,
    &queue_discard_max_entry.attr,
    &queue_discard_zeroes_data_entry.attr,
    &queue_write_same_max_entry.attr,
    &queue_nonrot_entry.attr,
    &queue_nomerges_entry.attr,
    &queue_rq_affinity_entry.attr,
    &queue_iostats_entry.attr,
    &queue_random_entry.attr,
    NULL,
};

#define to_queue(atr) container_of((atr), struct queue_sysfs_entry, attr)

static ssize_t
queue_attr_show(struct kobject *kobj, struct attribute *attr, char *page)
{
    struct queue_sysfs_entry *entry = to_queue(attr);
    struct request_queue *q =
        container_of(kobj, struct request_queue, kobj);
    ssize_t res;

    if (!entry->show)
        return -EIO;
    mutex_lock(&q->sysfs_lock);
    if (blk_queue_dead(q)) {
        mutex_unlock(&q->sysfs_lock);
        return -ENOENT;
    }
    res = entry->show(q, page);
    mutex_unlock(&q->sysfs_lock);
    return res;
}

static ssize_t
queue_attr_store(struct kobject *kobj, struct attribute *attr,
            const char *page, size_t length)
{
    struct queue_sysfs_entry *entry = to_queue(attr);
    struct request_queue *q;
    ssize_t res;

    if (!entry->store)
        return -EIO;

    q = container_of(kobj, struct request_queue, kobj);
    mutex_lock(&q->sysfs_lock);
    if (blk_queue_dead(q)) {
        mutex_unlock(&q->sysfs_lock);
        return -ENOENT;
    }
    res = entry->store(q, page, length);
    mutex_unlock(&q->sysfs_lock);
    return res;
}

static void blk_release_queue(struct kobject *kobj)
{
    struct request_queue *q =
        container_of(kobj, struct request_queue, kobj);

    blk_sync_queue(q);

    blkcg_exit_queue(q);

    if (q->elevator) {
        spin_lock_irq(q->queue_lock);
        ioc_clear_queue(q);
        spin_unlock_irq(q->queue_lock);
        elevator_exit(q->elevator);
    }

    blk_exit_rl(&q->root_rl);

    if (q->queue_tags)
        __blk_queue_free_tags(q);

    blk_trace_shutdown(q);

    bdi_destroy(&q->backing_dev_info);

    ida_simple_remove(&blk_queue_ida, q->id);
    kmem_cache_free(blk_requestq_cachep, q);
}

static const struct sysfs_ops queue_sysfs_ops = {
    .show   = queue_attr_show,
    .store  = queue_attr_store,
};

struct kobj_type blk_queue_ktype = {
    .sysfs_ops  = &queue_sysfs_ops,
    .default_attrs  = default_attrs,
    .release    = blk_release_queue,
};

int blk_register_queue(struct gendisk *disk)
{
    int ret;
    struct device *dev = disk_to_dev(disk);
    struct request_queue *q = disk->queue;

    if (WARN_ON(!q))
        return -ENXIO;

    /*
     * Initialization must be complete by now.  Finish the initial
     * bypass from queue allocation.
     */
    blk_queue_bypass_end(q);

    ret = blk_trace_init_sysfs(dev);
    if (ret)
        return ret;

    ret = kobject_add(&q->kobj, kobject_get(&dev->kobj), "%s", "queue");
    if (ret < 0) {
        blk_trace_remove_sysfs(dev);
        return ret;
    }

    kobject_uevent(&q->kobj, KOBJ_ADD);

    if (!q->request_fn)
        return 0;

    ret = elv_register_queue(q);
    if (ret) {
        kobject_uevent(&q->kobj, KOBJ_REMOVE);
        kobject_del(&q->kobj);
        blk_trace_remove_sysfs(dev);
        kobject_put(&dev->kobj);
        return ret;
    }

    return 0;
}

void blk_unregister_queue(struct gendisk *disk)
{
    struct request_queue *q = disk->queue;

    if (WARN_ON(!q))
        return;

    if (q->request_fn)
        elv_unregister_queue(q);

    kobject_uevent(&q->kobj, KOBJ_REMOVE);
    kobject_del(&q->kobj);
    blk_trace_remove_sysfs(disk_to_dev(disk));
    kobject_put(&disk_to_dev(disk)->kobj);
}