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 <h...@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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