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block: save user max_sectors limit

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The user can set the max_sectors limit to any valid value via sysfs
/sys/block/<dev>/queue/max_sectors_kb attribute. If the device limits
are ever rescanned, though, the limit reverts back to the potentially
artificially low BLK_DEF_MAX_SECTORS value.

Preserve the user's setting as the max_sectors limit as long as it's
valid. The user can reset back to defaults by writing 0 to the sysfs
file.

Signed-off-by: Keith Busch <kbusch@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Link: https://lore.kernel.org/r/20230105205146.3610282-3-kbusch@meta.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Keith Busch 2023-01-05 12:51:46 -08:00 committed by Jens Axboe
parent 0a26f327e4
commit c9c77418a9
4 changed files with 25 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
Documentation/ABI/stable/sysfs-block
View File

@ -432,7 +432,8 @@ Contact: linux-block@vger.kernel.org
Description:
[RW] This is the maximum number of kilobytes that the block
layer will allow for a filesystem request. Must be smaller than
or equal to the maximum size allowed by the hardware.
or equal to the maximum size allowed by the hardware. Write 0
to use default kernel settings.
What: /sys/block/<disk>/queue/max_segment_size

9
block/blk-settings.c
View File

@ -40,7 +40,7 @@ void blk_set_default_limits(struct queue_limits *lim)
lim->virt_boundary_mask = 0;
lim->max_segment_size = BLK_MAX_SEGMENT_SIZE;
lim->max_sectors = lim->max_hw_sectors = BLK_SAFE_MAX_SECTORS;
lim->max_dev_sectors = 0;
lim->max_user_sectors = lim->max_dev_sectors = 0;
lim->chunk_sectors = 0;
lim->max_write_zeroes_sectors = 0;
lim->max_zone_append_sectors = 0;
@ -135,7 +135,12 @@ void blk_queue_max_hw_sectors(struct request_queue *q, unsigned int max_hw_secto
limits->max_hw_sectors = max_hw_sectors;
max_sectors = min_not_zero(max_hw_sectors, limits->max_dev_sectors);
max_sectors = min(max_sectors, BLK_DEF_MAX_SECTORS);
if (limits->max_user_sectors)
max_sectors = min(max_sectors, limits->max_user_sectors);
else
max_sectors = min(max_sectors, BLK_DEF_MAX_SECTORS);
max_sectors = round_down(max_sectors,
limits->logical_block_size >> SECTOR_SHIFT);
limits->max_sectors = max_sectors;

21
block/blk-sysfs.c
View File

@ -239,19 +239,28 @@ static ssize_t queue_zone_append_max_show(struct request_queue *q, char *page)
static ssize_t
queue_max_sectors_store(struct request_queue *q, const char *page, size_t count)
{
unsigned long max_sectors_kb,
unsigned long var;
unsigned int max_sectors_kb,
max_hw_sectors_kb = queue_max_hw_sectors(q) >> 1,
page_kb = 1 << (PAGE_SHIFT - 10);
ssize_t ret = queue_var_store(&max_sectors_kb, page, count);
ssize_t ret = queue_var_store(&var, page, count);
if (ret < 0)
return ret;
max_hw_sectors_kb = min_not_zero(max_hw_sectors_kb, (unsigned long)
max_sectors_kb = (unsigned int)var;
max_hw_sectors_kb = min_not_zero(max_hw_sectors_kb,
q->limits.max_dev_sectors >> 1);
if (max_sectors_kb > max_hw_sectors_kb || max_sectors_kb < page_kb)
return -EINVAL;
if (max_sectors_kb == 0) {
q->limits.max_user_sectors = 0;
max_sectors_kb = min(max_hw_sectors_kb,
BLK_DEF_MAX_SECTORS >> 1);
} else {
if (max_sectors_kb > max_hw_sectors_kb ||
max_sectors_kb < page_kb)
return -EINVAL;
q->limits.max_user_sectors = max_sectors_kb << 1;
}
spin_lock_irq(&q->queue_lock);
q->limits.max_sectors = max_sectors_kb << 1;

1
include/linux/blkdev.h
View File

@ -288,6 +288,7 @@ struct queue_limits {
unsigned int max_dev_sectors;
unsigned int chunk_sectors;
unsigned int max_sectors;
unsigned int max_user_sectors;
unsigned int max_segment_size;
unsigned int physical_block_size;
unsigned int logical_block_size;