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block: lift setting the readahead size into the block layer

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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@lst.de>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Mike Snitzer <snitzer@redhat.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Acked-by: Coly Li <colyli@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Christoph Hellwig 2020-09-24 08:51:34 +02:00 committed by Jens Axboe
parent 16ef510139
commit c2e4cd57cf
11 changed files with 24 additions and 68 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

18
block/blk-settings.c
View File

@ -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);

2
block/blk-sysfs.c
View File

@ -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;

1
drivers/block/aoe/aoeblk.c
View File

@ -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;

10
drivers/block/drbd/drbd_nl.c
View File

@ -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);

3
drivers/md/bcache/super.c
View File

@ -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)));

3
drivers/md/dm-table.c
View File

@ -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)

16
drivers/md/raid0.c
View File

@ -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);

24
drivers/md/raid10.c
View File

@ -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;
}

13
drivers/md/raid5.c
View File

@ -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);
@ -8111,18 +8109,9 @@ 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);
}
}
}
/* This is called from the raid5d thread with mddev_lock held.

1
drivers/nvme/host/core.c
View File

@ -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

1
include/linux/blkdev.h
View File

@ -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);