path: root/block/blk-settings.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Functions related to setting various queue properties from drivers
 */
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/bio.h>
#include <linux/blkdev.h>
#include <linux/pagemap.h>
#include <linux/backing-dev-defs.h>
#include <linux/gcd.h>
#include <linux/lcm.h>
#include <linux/jiffies.h>
#include <linux/gfp.h>
#include <linux/dma-mapping.h>

#include "blk.h"
#include "blk-rq-qos.h"
#include "blk-wbt.h"

void blk_queue_rq_timeout(struct request_queue *q, unsigned int timeout)
{
	q->rq_timeout = timeout;
}
EXPORT_SYMBOL_GPL(blk_queue_rq_timeout);

/**
 * blk_set_stacking_limits - set default limits for stacking devices
 * @lim:  the queue_limits structure to reset
 *
 * Prepare queue limits for applying limits from underlying devices using
 * blk_stack_limits().
 */
void blk_set_stacking_limits(struct queue_limits *lim)
{
	memset(lim, 0, sizeof(*lim));
	lim->logical_block_size = SECTOR_SIZE;
	lim->physical_block_size = SECTOR_SIZE;
	lim->io_min = SECTOR_SIZE;
	lim->discard_granularity = SECTOR_SIZE;
	lim->dma_alignment = SECTOR_SIZE - 1;
	lim->seg_boundary_mask = BLK_SEG_BOUNDARY_MASK;

	/* Inherit limits from component devices */
	lim->max_segments = USHRT_MAX;
	lim->max_discard_segments = USHRT_MAX;
	lim->max_hw_sectors = UINT_MAX;
	lim->max_segment_size = UINT_MAX;
	lim->max_sectors = UINT_MAX;
	lim->max_dev_sectors = UINT_MAX;
	lim->max_write_zeroes_sectors = UINT_MAX;
	lim->max_zone_append_sectors = UINT_MAX;
	lim->max_user_discard_sectors = UINT_MAX;
}
EXPORT_SYMBOL(blk_set_stacking_limits);

static void blk_apply_bdi_limits(struct backing_dev_info *bdi,
		struct queue_limits *lim)
{
	/*
	 * For read-ahead of large files to be effective, we need to read ahead
	 * at least twice the optimal I/O size.
	 */
	bdi->ra_pages = max(lim->io_opt * 2 / PAGE_SIZE, VM_READAHEAD_PAGES);
	bdi->io_pages = lim->max_sectors >> PAGE_SECTORS_SHIFT;
}

static int blk_validate_zoned_limits(struct queue_limits *lim)
{
	if (!lim->zoned) {
		if (WARN_ON_ONCE(lim->max_open_zones) ||
		    WARN_ON_ONCE(lim->max_active_zones) ||
		    WARN_ON_ONCE(lim->zone_write_granularity) ||
		    WARN_ON_ONCE(lim->max_zone_append_sectors))
			return -EINVAL;
		return 0;
	}

	if (WARN_ON_ONCE(!IS_ENABLED(CONFIG_BLK_DEV_ZONED)))
		return -EINVAL;

	if (lim->zone_write_granularity < lim->logical_block_size)
		lim->zone_write_granularity = lim->logical_block_size;

	if (lim->max_zone_append_sectors) {
		/*
		 * The Zone Append size is limited by the maximum I/O size
		 * and the zone size given that it can't span zones.
		 */
		lim->max_zone_append_sectors =
			min3(lim->max_hw_sectors,
			     lim->max_zone_append_sectors,
			     lim->chunk_sectors);
	}

	return 0;
}

/*
 * Check that the limits in lim are valid, initialize defaults for unset
 * values, and cap values based on others where needed.
 */
static int blk_validate_limits(struct queue_limits *lim)
{
	unsigned int max_hw_sectors;
	unsigned int logical_block_sectors;

	/*
	 * Unless otherwise specified, default to 512 byte logical blocks and a
	 * physical block size equal to the logical block size.
	 */
	if (!lim->logical_block_size)
		lim->logical_block_size = SECTOR_SIZE;
	if (lim->physical_block_size < lim->logical_block_size)
		lim->physical_block_size = lim->logical_block_size;

	/*
	 * The minimum I/O size defaults to the physical block size unless
	 * explicitly overridden.
	 */
	if (lim->io_min < lim->physical_block_size)
		lim->io_min = lim->physical_block_size;

	/*
	 * max_hw_sectors has a somewhat weird default for historical reason,
	 * but driver really should set their own instead of relying on this
	 * value.
	 *
	 * The block layer relies on the fact that every driver can
	 * handle at lest a page worth of data per I/O, and needs the value
	 * aligned to the logical block size.
	 */
	if (!lim->max_hw_sectors)
		lim->max_hw_sectors = BLK_SAFE_MAX_SECTORS;
	if (WARN_ON_ONCE(lim->max_hw_sectors < PAGE_SECTORS))
		return -EINVAL;
	logical_block_sectors = lim->logical_block_size >> SECTOR_SHIFT;
	if (WARN_ON_ONCE(logical_block_sectors > lim->max_hw_sectors))
		return -EINVAL;
	lim->max_hw_sectors = round_down(lim->max_hw_sectors,
			logical_block_sectors);

	/*
	 * The actual max_sectors value is a complex beast and also takes the
	 * max_dev_sectors value (set by SCSI ULPs) and a user configurable
	 * value into account.  The ->max_sectors value is always calculated
	 * from these, so directly setting it won't have any effect.
	 */
	max_hw_sectors = min_not_zero(lim->max_hw_sectors,
				lim->max_dev_sectors);
	if (lim->max_user_sectors) {
		if (lim->max_user_sectors < PAGE_SIZE / SECTOR_SIZE)
			return -EINVAL;
		lim->max_sectors = min(max_hw_sectors, lim->max_user_sectors);
	} else {
		lim->max_sectors = min(max_hw_sectors, BLK_DEF_MAX_SECTORS_CAP);
	}
	lim->max_sectors = round_down(lim->max_sectors,
			logical_block_sectors);

	/*
	 * Random default for the maximum number of segments.  Driver should not
	 * rely on this and set their own.
	 */
	if (!lim->max_segments)
		lim->max_segments = BLK_MAX_SEGMENTS;

	lim->max_discard_sectors =
		min(lim->max_hw_discard_sectors, lim->max_user_discard_sectors);

	if (!lim->max_discard_segments)
		lim->max_discard_segments = 1;

	if (lim->discard_granularity < lim->physical_block_size)
		lim->discard_granularity = lim->physical_block_size;

	/*
	 * By default there is no limit on the segment boundary alignment,
	 * but if there is one it can't be smaller than the page size as
	 * that would break all the normal I/O patterns.
	 */
	if (!lim->seg_boundary_mask)
		lim->seg_boundary_mask = BLK_SEG_BOUNDARY_MASK;
	if (WARN_ON_ONCE(lim->seg_boundary_mask < PAGE_SIZE - 1))
		return -EINVAL;

	/*
	 * Stacking device may have both virtual boundary and max segment
	 * size limit, so allow this setting now, and long-term the two
	 * might need to move out of stacking limits since we have immutable
	 * bvec and lower layer bio splitting is supposed to handle the two
	 * correctly.
	 */
	if (lim->virt_boundary_mask) {
		if (!lim->max_segment_size)
			lim->max_segment_size = UINT_MAX;
	} else {
		/*
		 * The maximum segment size has an odd historic 64k default that
		 * drivers probably should override.  Just like the I/O size we
		 * require drivers to at least handle a full page per segment.
		 */
		if (!lim->max_segment_size)
			lim->max_segment_size = BLK_MAX_SEGMENT_SIZE;
		if (WARN_ON_ONCE(lim->max_segment_size < PAGE_SIZE))
			return -EINVAL;
	}

	/*
	 * We require drivers to at least do logical block aligned I/O, but
	 * historically could not check for that due to the separate calls
	 * to set the limits.  Once the transition is finished the check
	 * below should be narrowed down to check the logical block size.
	 */
	if (!lim->dma_alignment)
		lim->dma_alignment = SECTOR_SIZE - 1;
	if (WARN_ON_ONCE(lim->dma_alignment > PAGE_SIZE))
		return -EINVAL;

	if (lim->alignment_offset) {
		lim->alignment_offset &= (lim->physical_block_size - 1);
		lim->misaligned = 0;
	}

	return blk_validate_zoned_limits(lim);
}

/*
 * Set the default limits for a newly allocated queue.  @lim contains the
 * initial limits set by the driver, which could be no limit in which case
 * all fields are cleared to zero.
 */
int blk_set_default_limits(struct queue_limits *lim)
{
	/*
	 * Most defaults are set by capping the bounds in blk_validate_limits,
	 * but max_user_discard_sectors is special and needs an explicit
	 * initialization to the max value her