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block: lift setting the readahead size into the block layer 

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
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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);
@ -8111,17 +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);
}
}
}

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);