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. To ensure the limits work well for stacking drivers a
new helper is added to update the readahead limits from the block
limits, which is also called from disk_stack_limits.
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
Acked-by: Coly Li <colyli@xxxxxxx>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@xxxxxxx>
---
block/blk-settings.c | 18 ++++++++++++++++--
block/blk-sysfs.c | 2 ++
drivers/block/aoe/aoeblk.c | 1 -
drivers/block/drbd/drbd_nl.c | 10 +---------
drivers/md/bcache/super.c | 3 ---
drivers/md/dm-table.c | 3 +--
drivers/md/raid0.c | 16 ----------------
drivers/md/raid10.c | 24 +-----------------------
drivers/md/raid5.c | 13 +------------
drivers/nvme/host/core.c | 1 +
include/linux/blkdev.h | 1 +
11 files changed, 24 insertions(+), 68 deletions(-)
diff --git a/block/blk-settings.c b/block/blk-settings.c
index 5ea3de48afba22..4f6eb4bb17236a 100644
--- a/block/blk-settings.c
+++ b/block/blk-settings.c
@@ -372,6 +372,19 @@ void blk_queue_alignment_offset(struct request_queue *q, unsigned int offset)
}
EXPORT_SYMBOL(blk_queue_alignment_offset);
+void blk_queue_update_readahead(struct request_queue *q)
+{
+ /*
+ * For read-ahead of large files to be effective, we need to read ahead
+ * at least twice the optimal I/O size.
+ */
+ q->backing_dev_info->ra_pages =
+ max(queue_io_opt(q) * 2 / PAGE_SIZE, VM_READAHEAD_PAGES);
+ q->backing_dev_info->io_pages =
+ queue_max_sectors(q) >> (PAGE_SHIFT - 9);
+}
+EXPORT_SYMBOL_GPL(blk_queue_update_readahead);
+
/**
* blk_limits_io_min - set minimum request size for a device
* @limits: the queue limits
@@ -450,6 +463,8 @@ 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);
@@ -631,8 +646,7 @@ void disk_stack_limits(struct gendisk *disk, struct block_device *bdev,
top, bottom);
}
- t->backing_dev_info->io_pages =
- t->limits.max_sectors >> (PAGE_SHIFT - 9);
+ blk_queue_update_readahead(disk->queue);
}
EXPORT_SYMBOL(disk_stack_limits);
diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index 81722cdcf0cb21..869ed21a9edcab 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -854,6 +854,8 @@ int blk_register_queue(struct gendisk *disk)
percpu_ref_switch_to_percpu(&q->q_usage_counter);
}
+ blk_queue_update_readahead(q);
+
ret = blk_trace_init_sysfs(dev);
if (ret)
return ret;
diff --git a/drivers/block/aoe/aoeblk.c b/drivers/block/aoe/aoeblk.c
index d8cfc233e64b93..c34e71b0c4a98c 100644
--- a/drivers/block/aoe/aoeblk.c
+++ b/drivers/block/aoe/aoeblk.c
@@ -406,7 +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 = SZ_2M / PAGE_SIZE;
blk_queue_io_opt(q, SZ_2M);
d->bufpool = mp;
d->blkq = gd->queue = q;
diff --git a/drivers/block/drbd/drbd_nl.c b/drivers/block/drbd/drbd_nl.c
index aaff5bde391506..54a4930c04fe07 100644
--- a/drivers/block/drbd/drbd_nl.c
+++ b/drivers/block/drbd/drbd_nl.c
@@ -1362,15 +1362,7 @@ static void drbd_setup_queue_param(struct drbd_device *device, struct drbd_backi
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;
- }
+ blk_queue_update_readahead(q);
}
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 48113005ed86ad..6bfa771673623e 100644
--- a/drivers/md/bcache/super.c
+++ b/drivers/md/bcache/super.c
@@ -1427,9 +1427,6 @@ 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);
blk_queue_io_opt(dc->disk.disk->queue,
max(queue_io_opt(dc->disk.disk->queue), queue_io_opt(q)));
diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index 5edc3079e7c199..ef2757012f59d5 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -1925,8 +1925,7 @@ void dm_table_set_restrictions(struct dm_table *t, struct request_queue *q,
}
#endif
- /* Allow reads to exceed readahead limits */
- q->backing_dev_info->io_pages = limits->max_sectors >> (PAGE_SHIFT - 9);
+ blk_queue_update_readahead(q);
}
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 9956a04ac13bd6..5d1bdee313ec33 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -3873,19 +3873,6 @@ 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;
@@ -4723,17 +4710,8 @@ 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 9a7d1250894ef1..7ace1f76b14736 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -7522,8 +7522,6 @@ 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);
@@ -8111,17 +8109,8 @@ 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);
- }
}
}
diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index ea1fa41fbba8df..741c9bfa8e14c7 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -2147,6 +2147,7 @@ static int __nvme_revalidate_disk(struct gendisk *disk, struct nvme_id_ns *id)
nvme_update_disk_info(ns->head->disk, ns, id);
blk_stack_limits(&ns->head->disk->queue->limits,
&ns->queue->limits, 0);
+ blk_queue_update_readahead(ns->head->disk->queue);
nvme_update_bdev_size(ns->head->disk);
}
#endif
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index be5ef6f4ba1905..282f5ca424f14a 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -1140,6 +1140,7 @@ extern void blk_queue_max_zone_append_sectors(struct request_queue *q,
extern void blk_queue_physical_block_size(struct request_queue *, unsigned int);
extern void blk_queue_alignment_offset(struct request_queue *q,
unsigned int alignment);
+void blk_queue_update_readahead(struct request_queue *q);
extern void blk_limits_io_min(struct queue_limits *limits, unsigned int min);
extern void blk_queue_io_min(struct request_queue *q, unsigned int min);
extern void blk_limits_io_opt(struct queue_limits *limits, unsigned int opt);
--
2.28.0
