On 12/23/22 02:52, Keith Busch wrote:
> From: Keith Busch <kbusch@xxxxxxxxxx>
>
> 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 kernel defined
> BLK_DEF_MAX_SECTORS limit.
>
> Preserve the user's setting for the max_sectors limit as long as it's
> valid. The user can reset back to defaults by writing 0 to the sysfs
> file.
Updating Documentation/ABI/stable/sysfs-block about this change would be
nice too.
>
> Signed-off-by: Keith Busch <kbusch@xxxxxxxxxx>
> ---
> block/blk-settings.c | 9 +++++++--
> block/blk-sysfs.c | 10 +++++++++-
> include/linux/blkdev.h | 1 +
> 3 files changed, 17 insertions(+), 3 deletions(-)
>
> diff --git a/block/blk-settings.c b/block/blk-settings.c
> index 0477c4d527fee..e75304f853bd5 100644
> --- a/block/blk-settings.c
> +++ b/block/blk-settings.c
> @@ -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_t(unsigned int, max_sectors, BLK_DEF_MAX_SECTORS);
> +
> + if (limits->max_user_sectors)
> + max_sectors = min_not_zero(max_sectors, limits->max_user_sectors);
> + else
> + max_sectors = min_t(unsigned int, max_sectors, BLK_DEF_MAX_SECTORS);
> +
> max_sectors = round_down(max_sectors,
> limits->logical_block_size >> SECTOR_SHIFT);
> limits->max_sectors = max_sectors;
> diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
> index 93d9e9c9a6ea8..db5d1d908f5d9 100644
> --- a/block/blk-sysfs.c
> +++ b/block/blk-sysfs.c
> @@ -250,8 +250,16 @@ queue_max_sectors_store(struct request_queue *q, const char *page, size_t count)
> max_hw_sectors_kb = min_not_zero(max_hw_sectors_kb, (unsigned long)
> q->limits.max_dev_sectors >> 1);
>
> - if (max_sectors_kb > max_hw_sectors_kb || max_sectors_kb < page_kb)
> + if (max_sectors_kb == 0) {
> + q->limits.max_user_sectors = 0;
> + max_sectors_kb = min_t(unsigned int, 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;
> + } else {
> + q->limits.max_user_sectors = max_sectors_kb << 1;
> + }
>
> spin_lock_irq(&q->queue_lock);
> q->limits.max_sectors = max_sectors_kb << 1;
> diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
> index 301cf1cf4f2fa..71e97f0a87264 100644
> --- a/include/linux/blkdev.h
> +++ b/include/linux/blkdev.h
> @@ -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;
--
Damien Le Moal
Western Digital Research
