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    Subject[PATCH 06/14] block: lift setting the readahead size into the block layer
    Date
    Drivers shouldn't really mess with the readahead size, as that is a VM
    concept. Instead set it based on the optimal I/O size by lifting the
    algorithm from the md driver when registering the disk. Also set
    bdi->io_pages there as well by applying the same scheme based on
    max_sectors.

    Signed-off-by: Christoph Hellwig <hch@lst.de>
    ---
    block/blk-settings.c | 5 ++---
    block/blk-sysfs.c | 1 -
    block/genhd.c | 13 +++++++++++--
    drivers/block/aoe/aoeblk.c | 2 --
    drivers/block/drbd/drbd_nl.c | 12 +-----------
    drivers/md/bcache/super.c | 4 ----
    drivers/md/dm-table.c | 3 ---
    drivers/md/raid0.c | 16 ----------------
    drivers/md/raid10.c | 24 +-----------------------
    drivers/md/raid5.c | 13 +------------
    10 files changed, 16 insertions(+), 77 deletions(-)

    diff --git a/block/blk-settings.c b/block/blk-settings.c
    index 76a7e03bcd6cac..01049e9b998f1d 100644
    --- a/block/blk-settings.c
    +++ b/block/blk-settings.c
    @@ -452,6 +452,8 @@ EXPORT_SYMBOL(blk_limits_io_opt);
    void blk_queue_io_opt(struct request_queue *q, unsigned int opt)
    {
    blk_limits_io_opt(&q->limits, opt);
    + q->backing_dev_info->ra_pages =
    + max(queue_io_opt(q) * 2 / PAGE_SIZE, VM_READAHEAD_PAGES);
    }
    EXPORT_SYMBOL(blk_queue_io_opt);

    @@ -628,9 +630,6 @@ void disk_stack_limits(struct gendisk *disk, struct block_device *bdev,
    printk(KERN_NOTICE "%s: Warning: Device %s is misaligned\n",
    top, bottom);
    }
    -
    - t->backing_dev_info->io_pages =
    - t->limits.max_sectors >> (PAGE_SHIFT - 9);
    }
    EXPORT_SYMBOL(disk_stack_limits);

    diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
    index 7dda709f3ccb6f..ce418d9128a0b2 100644
    --- a/block/blk-sysfs.c
    +++ b/block/blk-sysfs.c
    @@ -245,7 +245,6 @@ queue_max_sectors_store(struct request_queue *q, const char *page, size_t count)

    spin_lock_irq(&q->queue_lock);
    q->limits.max_sectors = max_sectors_kb << 1;
    - q->backing_dev_info->io_pages = max_sectors_kb >> (PAGE_SHIFT - 10);
    spin_unlock_irq(&q->queue_lock);

    return ret;
    diff --git a/block/genhd.c b/block/genhd.c
    index 8b1e9f48957cb5..097d4e4bc0b8a2 100644
    --- a/block/genhd.c
    +++ b/block/genhd.c
    @@ -775,6 +775,7 @@ static void __device_add_disk(struct device *parent, struct gendisk *disk,
    const struct attribute_group **groups,
    bool register_queue)
    {
    + struct request_queue *q = disk->queue;
    dev_t devt;
    int retval;

    @@ -785,7 +786,7 @@ static void __device_add_disk(struct device *parent, struct gendisk *disk,
    * registration.
    */
    if (register_queue)
    - elevator_init_mq(disk->queue);
    + elevator_init_mq(q);

    /* minors == 0 indicates to use ext devt from part0 and should
    * be accompanied with EXT_DEVT flag. Make sure all
    @@ -815,10 +816,18 @@ static void __device_add_disk(struct device *parent, struct gendisk *disk,
    disk->flags |= GENHD_FL_SUPPRESS_PARTITION_INFO;
    disk->flags |= GENHD_FL_NO_PART_SCAN;
    } else {
    - struct backing_dev_info *bdi = disk->queue->backing_dev_info;
    + struct backing_dev_info *bdi = q->backing_dev_info;
    struct device *dev = disk_to_dev(disk);
    int ret;

    + /*
    + * For read-ahead of large files to be effective, we need to
    + * readahead at least twice the optimal I/O size.
    + */
    + bdi->ra_pages = max(queue_io_opt(q) * 2 / PAGE_SIZE,
    + VM_READAHEAD_PAGES);
    + bdi->io_pages = queue_max_sectors(q) >> (PAGE_SHIFT - 9);
    +
    /* Register BDI before referencing it from bdev */
    dev->devt = devt;
    ret = bdi_register(bdi, "%u:%u", MAJOR(devt), MINOR(devt));
    diff --git a/drivers/block/aoe/aoeblk.c b/drivers/block/aoe/aoeblk.c
    index 5ca7216e9e01f3..89b33b402b4e52 100644
    --- a/drivers/block/aoe/aoeblk.c
    +++ b/drivers/block/aoe/aoeblk.c
    @@ -347,7 +347,6 @@ aoeblk_gdalloc(void *vp)
    mempool_t *mp;
    struct request_queue *q;
    struct blk_mq_tag_set *set;
    - enum { KB = 1024, MB = KB * KB, READ_AHEAD = 2 * MB, };
    ulong flags;
    int late = 0;
    int err;
    @@ -407,7 +406,6 @@ aoeblk_gdalloc(void *vp)
    WARN_ON(d->gd);
    WARN_ON(d->flags & DEVFL_UP);
    blk_queue_max_hw_sectors(q, BLK_DEF_MAX_SECTORS);
    - q->backing_dev_info->ra_pages = READ_AHEAD / PAGE_SIZE;
    d->bufpool = mp;
    d->blkq = gd->queue = q;
    q->queuedata = d;
    diff --git a/drivers/block/drbd/drbd_nl.c b/drivers/block/drbd/drbd_nl.c
    index 650372ee2c7822..212bf711fb6b41 100644
    --- a/drivers/block/drbd/drbd_nl.c
    +++ b/drivers/block/drbd/drbd_nl.c
    @@ -1360,18 +1360,8 @@ static void drbd_setup_queue_param(struct drbd_device *device, struct drbd_backi
    decide_on_discard_support(device, q, b, discard_zeroes_if_aligned);
    decide_on_write_same_support(device, q, b, o, disable_write_same);

    - if (b) {
    + if (b)
    blk_stack_limits(&q->limits, &b->limits, 0);
    -
    - if (q->backing_dev_info->ra_pages !=
    - b->backing_dev_info->ra_pages) {
    - drbd_info(device, "Adjusting my ra_pages to backing device's (%lu -> %lu)\n",
    - q->backing_dev_info->ra_pages,
    - b->backing_dev_info->ra_pages);
    - q->backing_dev_info->ra_pages =
    - b->backing_dev_info->ra_pages;
    - }
    - }
    fixup_discard_if_not_supported(q);
    fixup_write_zeroes(device, q);
    }
    diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
    index 9e45faa054b6f4..9d3f0711be030f 100644
    --- a/drivers/md/bcache/super.c
    +++ b/drivers/md/bcache/super.c
    @@ -1367,10 +1367,6 @@ static int cached_dev_init(struct cached_dev *dc, unsigned int block_size)
    if (ret)
    return ret;

    - dc->disk.disk->queue->backing_dev_info->ra_pages =
    - max(dc->disk.disk->queue->backing_dev_info->ra_pages,
    - q->backing_dev_info->ra_pages);
    -
    atomic_set(&dc->io_errors, 0);
    dc->io_disable = false;
    dc->error_limit = DEFAULT_CACHED_DEV_ERROR_LIMIT;
    diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
    index aac4c31cfc8498..324a42ed2f8894 100644
    --- a/drivers/md/dm-table.c
    +++ b/drivers/md/dm-table.c
    @@ -1924,9 +1924,6 @@ void dm_table_set_restrictions(struct dm_table *t, struct request_queue *q,
    q->nr_zones = blkdev_nr_zones(t->md->disk);
    }
    #endif
    -
    - /* Allow reads to exceed readahead limits */
    - q->backing_dev_info->io_pages = limits->max_sectors >> (PAGE_SHIFT - 9);
    }

    unsigned int dm_table_get_num_targets(struct dm_table *t)
    diff --git a/drivers/md/raid0.c b/drivers/md/raid0.c
    index f54a449f97aa79..aa2d7279176880 100644
    --- a/drivers/md/raid0.c
    +++ b/drivers/md/raid0.c
    @@ -410,22 +410,6 @@ static int raid0_run(struct mddev *mddev)
    mdname(mddev),
    (unsigned long long)mddev->array_sectors);

    - if (mddev->queue) {
    - /* calculate the max read-ahead size.
    - * For read-ahead of large files to be effective, we need to
    - * readahead at least twice a whole stripe. i.e. number of devices
    - * multiplied by chunk size times 2.
    - * If an individual device has an ra_pages greater than the
    - * chunk size, then we will not drive that device as hard as it
    - * wants. We consider this a configuration error: a larger
    - * chunksize should be used in that case.
    - */
    - int stripe = mddev->raid_disks *
    - (mddev->chunk_sectors << 9) / PAGE_SIZE;
    - if (mddev->queue->backing_dev_info->ra_pages < 2* stripe)
    - mddev->queue->backing_dev_info->ra_pages = 2* stripe;
    - }
    -
    dump_zones(mddev);

    ret = md_integrity_register(mddev);
    diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
    index 9f88ff9bdee437..23d15acbf457d4 100644
    --- a/drivers/md/raid10.c
    +++ b/drivers/md/raid10.c
    @@ -3865,19 +3865,6 @@ static int raid10_run(struct mddev *mddev)
    mddev->resync_max_sectors = size;
    set_bit(MD_FAILFAST_SUPPORTED, &mddev->flags);

    - if (mddev->queue) {
    - int stripe = conf->geo.raid_disks *
    - ((mddev->chunk_sectors << 9) / PAGE_SIZE);
    -
    - /* Calculate max read-ahead size.
    - * We need to readahead at least twice a whole stripe....
    - * maybe...
    - */
    - stripe /= conf->geo.near_copies;
    - if (mddev->queue->backing_dev_info->ra_pages < 2 * stripe)
    - mddev->queue->backing_dev_info->ra_pages = 2 * stripe;
    - }
    -
    if (md_integrity_register(mddev))
    goto out_free_conf;

    @@ -4715,17 +4702,8 @@ static void end_reshape(struct r10conf *conf)
    conf->reshape_safe = MaxSector;
    spin_unlock_irq(&conf->device_lock);

    - /* read-ahead size must cover two whole stripes, which is
    - * 2 * (datadisks) * chunksize where 'n' is the number of raid devices
    - */
    - if (conf->mddev->queue) {
    - int stripe = conf->geo.raid_disks *
    - ((conf->mddev->chunk_sectors << 9) / PAGE_SIZE);
    - stripe /= conf->geo.near_copies;
    - if (conf->mddev->queue->backing_dev_info->ra_pages < 2 * stripe)
    - conf->mddev->queue->backing_dev_info->ra_pages = 2 * stripe;
    + if (conf->mddev->queue)
    raid10_set_io_opt(conf);
    - }
    conf->fullsync = 0;
    }

    diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
    index 68e41ce3ca75cc..415ce3cc155698 100644
    --- a/drivers/md/raid5.c
    +++ b/drivers/md/raid5.c
    @@ -7413,8 +7413,6 @@ static int raid5_run(struct mddev *mddev)
    int data_disks = conf->previous_raid_disks - conf->max_degraded;
    int stripe = data_disks *
    ((mddev->chunk_sectors << 9) / PAGE_SIZE);
    - if (mddev->queue->backing_dev_info->ra_pages < 2 * stripe)
    - mddev->queue->backing_dev_info->ra_pages = 2 * stripe;

    chunk_size = mddev->chunk_sectors << 9;
    blk_queue_io_min(mddev->queue, chunk_size);
    @@ -8002,17 +8000,8 @@ static void end_reshape(struct r5conf *conf)
    spin_unlock_irq(&conf->device_lock);
    wake_up(&conf->wait_for_overlap);

    - /* read-ahead size must cover two whole stripes, which is
    - * 2 * (datadisks) * chunksize where 'n' is the number of raid devices
    - */
    - if (conf->mddev->queue) {
    - int data_disks = conf->raid_disks - conf->max_degraded;
    - int stripe = data_disks * ((conf->chunk_sectors << 9)
    - / PAGE_SIZE);
    - if (conf->mddev->queue->backing_dev_info->ra_pages < 2 * stripe)
    - conf->mddev->queue->backing_dev_info->ra_pages = 2 * stripe;
    + if (conf->mddev->queue)
    raid5_set_io_opt(conf);
    - }
    }
    }

    --
    2.27.0
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      Last update: 2020-07-22 08:29    [W:4.518 / U:0.084 seconds]
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