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block: take io_opt and io_min into account for max_sectors

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The soft max_sectors limit is normally capped by the hardware limits and
an arbitrary upper limit enforced by the kernel, but can be modified by
the user.  A few drivers want to increase this limit (nbd, rbd) or
adjust it up or down based on hardware capabilities (sd).

Change blk_validate_limits to default max_sectors to the optimal I/O
size, or upgrade it to the preferred minimal I/O size if that is
larger than the kernel default if no optimal I/O size is provided based
on the logic in the SD driver.

This keeps the existing kernel default for drivers that do not provide
an io_opt or very big io_min value, but picks a much more useful
default for those who provide these hints, and allows to remove the
hacks to set the user max_sectors limit in nbd, rbd and sd.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Acked-by: Ilya Dryomov <idryomov@gmail.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Link: https://lore.kernel.org/r/20240531074837.1648501-5-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Christoph Hellwig 2024-05-31 09:47:59 +02:00 committed by Jens Axboe
parent a00d4bfce7
commit a23634644a
4 changed files with 13 additions and 26 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
block/blk-settings.c
View File

@ -153,6 +153,13 @@ static int blk_validate_limits(struct queue_limits *lim)
if (lim->max_user_sectors < PAGE_SIZE / SECTOR_SIZE)
return -EINVAL;
lim->max_sectors = min(max_hw_sectors, lim->max_user_sectors);
} else if (lim->io_opt) {
lim->max_sectors =
min(max_hw_sectors, lim->io_opt >> SECTOR_SHIFT);
} else if (lim->io_min &&
lim->io_min > (BLK_DEF_MAX_SECTORS_CAP << SECTOR_SHIFT)) {
lim->max_sectors =
min(max_hw_sectors, lim->io_min >> SECTOR_SHIFT);
} else {
lim->max_sectors = min(max_hw_sectors, BLK_DEF_MAX_SECTORS_CAP);
}

2
drivers/block/nbd.c
View File

@ -1808,7 +1808,7 @@ static struct nbd_device *nbd_dev_add(int index, unsigned int refs)
{
struct queue_limits lim = {
.max_hw_sectors = 65536,
.max_user_sectors = 256,
.io_opt = 256 << SECTOR_SHIFT,
.max_segments = USHRT_MAX,
.max_segment_size = UINT_MAX,
};

1
drivers/block/rbd.c
View File

@ -4954,7 +4954,6 @@ static int rbd_init_disk(struct rbd_device *rbd_dev)
rbd_dev->layout.object_size * rbd_dev->layout.stripe_count;
struct queue_limits lim = {
.max_hw_sectors = objset_bytes >> SECTOR_SHIFT,
.max_user_sectors = objset_bytes >> SECTOR_SHIFT,
.io_opt = objset_bytes,
.io_min = rbd_dev->opts->alloc_size,
.max_segments = USHRT_MAX,

29
drivers/scsi/sd.c
View File

@ -3593,7 +3593,7 @@ static int sd_revalidate_disk(struct gendisk *disk)
struct request_queue *q = sdkp->disk->queue;
sector_t old_capacity = sdkp->capacity;
unsigned char *buffer;
unsigned int dev_max, rw_max;
unsigned int dev_max;
SCSI_LOG_HLQUEUE(3, sd_printk(KERN_INFO, sdkp,
"sd_revalidate_disk\n"));
@ -3675,34 +3675,15 @@ static int sd_revalidate_disk(struct gendisk *disk)
else
blk_queue_io_min(sdkp->disk->queue, 0);
if (sd_validate_opt_xfer_size(sdkp, dev_max)) {
q->limits.io_opt = logical_to_bytes(sdp, sdkp->opt_xfer_blocks);
rw_max = logical_to_sectors(sdp, sdkp->opt_xfer_blocks);
} else {
q->limits.io_opt = 0;
rw_max = min_not_zero(logical_to_sectors(sdp, dev_max),
(sector_t)BLK_DEF_MAX_SECTORS_CAP);
}
/*
* Limit default to SCSI host optimal sector limit if set. There may be
* an impact on performance for when the size of a request exceeds this
* host limit.
*/
rw_max = min_not_zero(rw_max, sdp->host->opt_sectors);
/* Do not exceed controller limit */
rw_max = min(rw_max, queue_max_hw_sectors(q));
/*
* Only update max_sectors if previously unset or if the current value
* exceeds the capabilities of the hardware.
*/
if (sdkp->first_scan ||
q->limits.max_sectors > q->limits.max_dev_sectors ||
q->limits.max_sectors > q->limits.max_hw_sectors) {
q->limits.max_sectors = rw_max;
q->limits.max_user_sectors = rw_max;
q->limits.io_opt = sdp->host->opt_sectors << SECTOR_SHIFT;
if (sd_validate_opt_xfer_size(sdkp, dev_max)) {
q->limits.io_opt = min_not_zero(q->limits.io_opt,
logical_to_bytes(sdp, sdkp->opt_xfer_blocks));
}
sdkp->first_scan = 0;