Merge tag 'trace-printf-v6.13' of git://git.kernel.org/pub/scm/linux/kernel/git/trace...

[drm/drm-misc.git] / 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/blk-integrity.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_hw_zone_append_sectors = UINT_MAX;
        lim->max_user_discard_sectors = UINT_MAX;
}
EXPORT_SYMBOL(blk_set_stacking_limits);

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->features & BLK_FEAT_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;

        /*
         * Given that active zones include open zones, the maximum number of
         * open zones cannot be larger than the maximum number of active zones.
         */
        if (lim->max_active_zones &&
            lim->max_open_zones > lim->max_active_zones)
                return -EINVAL;

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

        /*
         * The Zone Append size is limited by the maximum I/O size and the zone
         * size given that it can't span zones.
         *
         * If no max_hw_zone_append_sectors limit is provided, the block layer
         * will emulated it, else we're also bound by the hardware limit.
         */
        lim->max_zone_append_sectors =
                min_not_zero(lim->max_hw_zone_append_sectors,
                        min(lim->chunk_sectors, lim->max_hw_sectors));
        return 0;
}

static int blk_validate_integrity_limits(struct queue_limits *lim)
{
        struct blk_integrity *bi = &lim->integrity;

        if (!bi->tuple_size) {
                if (bi->csum_type != BLK_INTEGRITY_CSUM_NONE ||
                    bi->tag_size || ((bi->flags & BLK_INTEGRITY_REF_TAG))) {
                        pr_warn("invalid PI settings.\n");
                        return -EINVAL;
                }
                return 0;
        }

        if (!IS_ENABLED(CONFIG_BLK_DEV_INTEGRITY)) {
                pr_warn("integrity support disabled.\n");
                return -EINVAL;
        }

        if (bi->csum_type == BLK_INTEGRITY_CSUM_NONE &&
            (bi->flags & BLK_INTEGRITY_REF_TAG)) {
                pr_warn("ref tag not support without checksum.\n");
                return -EINVAL;
        }

        if (!bi->interval_exp)
                bi->interval_exp = ilog2(lim->logical_block_size);

        return 0;
}

/*
 * Returns max guaranteed bytes which we can fit in a bio.
 *
 * We request that an atomic_write is ITER_UBUF iov_iter (so a single vector),
 * so we assume that we can fit in at least PAGE_SIZE in a segment, apart from
 * the first and last segments.
 */
static unsigned int blk_queue_max_guaranteed_bio(struct queue_limits *lim)
{
        unsigned int max_segments = min(BIO_MAX_VECS, lim->max_segments);
        unsigned int length;

        length = min(max_segments, 2) * lim->logical_block_size;
        if (max_segments > 2)
                length += (max_segments - 2) * PAGE_SIZE;

        return length;
}

static void blk_atomic_writes_update_limits(struct queue_limits *lim)
{
        unsigned int unit_limit = min(lim->max_hw_sectors << SECTOR_SHIFT,
                                        blk_queue_max_guaranteed_bio(lim));

        unit_limit = rounddown_pow_of_two(unit_limit);

        lim->atomic_write_max_sectors =
                min(lim->atomic_write_hw_max >> SECTOR_SHIFT,
                        lim->max_hw_sectors);
        lim->atomic_write_unit_min =
                min(lim->atomic_write_hw_unit_min, unit_limit);
        lim->atomic_write_unit_max =
                min(lim->atomic_write_hw_unit_max, unit_limit);
        lim->atomic_write_boundary_sectors =
                lim->atomic_write_hw_boundary >> SECTOR_SHIFT;
}

static void blk_validate_atomic_write_limits(struct queue_limits *lim)
{
        unsigned int boundary_sectors;

        if (!lim->atomic_write_hw_max)
                goto unsupported;

        if (WARN_ON_ONCE(!is_power_of_2(lim->atomic_write_hw_unit_min)))
                goto unsupported;

        if (WARN_ON_ONCE(!is_power_of_2(lim->atomic_write_hw_unit_max)))
                goto unsupported;

        if (WARN_ON_ONCE(lim->atomic_write_hw_unit_min >
                         lim->atomic_write_hw_unit_max))
                goto unsupported;

        if (WARN_ON_ONCE(lim->atomic_write_hw_unit_max >
                         lim->atomic_write_hw_max))
                goto unsupported;

        boundary_sectors = lim->atomic_write_hw_boundary >> SECTOR_SHIFT;

        if (boundary_sectors) {
                if (WARN_ON_ONCE(lim->atomic_write_hw_max >
                                 lim->atomic_write_hw_boundary))
                        goto unsupported;
                /*
                 * A feature of boundary support is that it disallows bios to
                 * be merged which would result in a merged request which
                 * crosses either a chunk sector or atomic write HW boundary,
                 * even though chunk sectors may be just set for performance.
                 * For simplicity, disallow atomic writes for a chunk sector
                 * which is non-zero and smaller than atomic write HW boundary.
                 * Furthermore, chunk sectors must be a multiple of atomic
                 * write HW boundary. Otherwise boundary support becomes
                 * complicated.
                 * Devices which do not conform to these rules can be dealt
                 * with if and when they show up.
                 */
                if (WARN_ON_ONCE(lim->chunk_sectors % boundary_sectors))
                        goto unsupported;

                /*
                 * The boundary size just needs to be a multiple of unit_max
                 * (and not necessarily a power-of-2), so this following check
                 * could be relaxed in future.
                 * Furthermore, if needed, unit_max could even be reduced so
                 * that it is compliant with a !power-of-2 boundary.
                 */
                if (!is_power_of_2(boundary_sectors))
                        goto unsupported;
        }

        blk_atomic_writes_update_limits(lim);
        return;

unsupported:
        lim->atomic_write_max_sectors = 0;
        lim->atomic_write_boundary_sectors = 0;
        lim->atomic_write_unit_min = 0;
        lim->atomic_write_unit_max = 0;
}

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

        /*
         * 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;
        else if (blk_validate_block_size(lim->logical_block_size)) {
                pr_warn("Invalid logical block size (%d)\n", lim->logical_block_size);
                return -EINVAL;
        }
        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;

        /*
         * The optimal I/O size may not be aligned to physical block size
         * (because it may be limited by dma engines which have no clue about
         * block size of the disks attached to them), so we round it down here.
         */
        lim->io_opt = round_down(lim->io_opt, 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 if (lim->io_opt > (BLK_DEF_MAX_SECTORS_CAP << SECTOR_SHIFT)) {
                lim->max_sectors =
                        min(max_hw_sectors, lim->io_opt >> SECTOR_SHIFT);
        } else if (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);
        }
        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->flags &= ~BLK_FLAG_MISALIGNED;
        }

        if (!(lim->features & BLK_FEAT_WRITE_CACHE))
                lim->features &= ~BLK_FEAT_FUA;

        blk_validate_atomic_write_limits(lim);

        err = blk_validate_integrity_limits(lim);
        if (err)
                return err;
        return blk_validate_zoned_limits(lim);
}
EXPORT_SYMBOL_GPL(blk_validate_limits);

/*
 * 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 here.
         */
        lim->max_user_discard_sectors = UINT_MAX;
        return blk_validate_limits(lim);
}

/**
 * queue_limits_commit_update - commit an atomic update of queue limits
 * @q:          queue to update
 * @lim:        limits to apply
 *
 * Apply the limits in @lim that were obtained from queue_limits_start_update()
 * and updated by the caller to @q.
 *
 * Returns 0 if successful, else a negative error code.
 */
int queue_limits_commit_update(struct request_queue *q,
                struct queue_limits *lim)
{
        int error;

        error = blk_validate_limits(lim);
        if (error)
                goto out_unlock;

#ifdef CONFIG_BLK_INLINE_ENCRYPTION
        if (q->crypto_profile && lim->integrity.tag_size) {
                pr_warn("blk-integrity: Integrity and hardware inline encryption are not supported together.\n");
                error = -EINVAL;
                goto out_unlock;
        }
#endif

        q->limits = *lim;
        if (q->disk)
                blk_apply_bdi_limits(q->disk->bdi, lim);
out_unlock:
        mutex_unlock(&q->limits_lock);
        return error;
}
EXPORT_SYMBOL_GPL(queue_limits_commit_update);

/**
 * queue_limits_set - apply queue limits to queue
 * @q:          queue to update
 * @lim:        limits to apply
 *
 * Apply the limits in @lim that were freshly initialized to @q.
 * To update existing limits use queue_limits_start_update() and
 * queue_limits_commit_update() instead.
 *
 * Returns 0 if successful, else a negative error code.
 */
int queue_limits_set(struct request_queue *q, struct queue_limits *lim)
{
        mutex_lock(&q->limits_lock);
        return queue_limits_commit_update(q, lim);
}
EXPORT_SYMBOL_GPL(queue_limits_set);

static int queue_limit_alignment_offset(const struct queue_limits *lim,
                sector_t sector)
{
        unsigned int granularity = max(lim->physical_block_size, lim->io_min);
        unsigned int alignment = sector_div(sector, granularity >> SECTOR_SHIFT)
                << SECTOR_SHIFT;

        return (granularity + lim->alignment_offset - alignment) % granularity;
}

static unsigned int queue_limit_discard_alignment(
                const struct queue_limits *lim, sector_t sector)
{
        unsigned int alignment, granularity, offset;

        if (!lim->max_discard_sectors)
                return 0;

        /* Why are these in bytes, not sectors? */
        alignment = lim->discard_alignment >> SECTOR_SHIFT;
        granularity = lim->discard_granularity >> SECTOR_SHIFT;

        /* Offset of the partition start in 'granularity' sectors */
        offset = sector_div(sector, granularity);

        /* And why do we do this modulus *again* in blkdev_issue_discard()? */
        offset = (granularity + alignment - offset) % granularity;

        /* Turn it back into bytes, gaah */
        return offset << SECTOR_SHIFT;
}

static unsigned int blk_round_down_sectors(unsigned int sectors, unsigned int lbs)
{
        sectors = round_down(sectors, lbs >> SECTOR_SHIFT);
        if (sectors < PAGE_SIZE >> SECTOR_SHIFT)
                sectors = PAGE_SIZE >> SECTOR_SHIFT;
        return sectors;
}

/* Check if second and later bottom devices are compliant */
static bool blk_stack_atomic_writes_tail(struct queue_limits *t,
                                struct queue_limits *b)
{
        /* We're not going to support different boundary sizes.. yet */
        if (t->atomic_write_hw_boundary != b->atomic_write_hw_boundary)
                return false;

        /* Can't support this */
        if (t->atomic_write_hw_unit_min > b->atomic_write_hw_unit_max)
                return false;

        /* Or this */
        if (t->atomic_write_hw_unit_max < b->atomic_write_hw_unit_min)
                return false;

        t->atomic_write_hw_max = min(t->atomic_write_hw_max,
                                b->atomic_write_hw_max);
        t->atomic_write_hw_unit_min = max(t->atomic_write_hw_unit_min,
                                b->atomic_write_hw_unit_min);
        t->atomic_write_hw_unit_max = min(t->atomic_write_hw_unit_max,
                                b->atomic_write_hw_unit_max);
        return true;
}

/* Check for valid boundary of first bottom device */
static bool blk_stack_atomic_writes_boundary_head(struct queue_limits *t,
                                struct queue_limits *b)
{
        /*
         * Ensure atomic write boundary is aligned with chunk sectors. Stacked
         * devices store chunk sectors in t->io_min.
         */
        if (b->atomic_write_hw_boundary > t->io_min &&
            b->atomic_write_hw_boundary % t->io_min)
                return false;
        if (t->io_min > b->atomic_write_hw_boundary &&
            t->io_min % b->atomic_write_hw_boundary)
                return false;

        t->atomic_write_hw_boundary = b->atomic_write_hw_boundary;
        return true;
}


/* Check stacking of first bottom device */
static bool blk_stack_atomic_writes_head(struct queue_limits *t,
                                struct queue_limits *b)
{
        if (b->atomic_write_hw_boundary &&
            !blk_stack_atomic_writes_boundary_head(t, b))
                return false;

        if (t->io_min <= SECTOR_SIZE) {
                /* No chunk sectors, so use bottom device values directly */
                t->atomic_write_hw_unit_max = b->atomic_write_hw_unit_max;
                t->atomic_write_hw_unit_min = b->atomic_write_hw_unit_min;
                t->atomic_write_hw_max = b->atomic_write_hw_max;
                return true;
        }

        /*
         * Find values for limits which work for chunk size.
         * b->atomic_write_hw_unit_{min, max} may not be aligned with chunk
         * size (t->io_min), as chunk size is not restricted to a power-of-2.
         * So we need to find highest power-of-2 which works for the chunk
         * size.
         * As an example scenario, we could have b->unit_max = 16K and
         * t->io_min = 24K. For this case, reduce t->unit_max to a value
         * aligned with both limits, i.e. 8K in this example.
         */
        t->atomic_write_hw_unit_max = b->atomic_write_hw_unit_max;
        while (t->io_min % t->atomic_write_hw_unit_max)
                t->atomic_write_hw_unit_max /= 2;

        t->atomic_write_hw_unit_min = min(b->atomic_write_hw_unit_min,
                                          t->atomic_write_hw_unit_max);
        t->atomic_write_hw_max = min(b->atomic_write_hw_max, t->io_min);

        return true;
}

static void blk_stack_atomic_writes_limits(struct queue_limits *t,
                                struct queue_limits *b)
{
        if (!(t->features & BLK_FEAT_ATOMIC_WRITES_STACKED))
                goto unsupported;

        if (!b->atomic_write_unit_min)
                goto unsupported;

        /*
         * If atomic_write_hw_max is set, we have already stacked 1x bottom
         * device, so check for compliance.
         */
        if (t->atomic_write_hw_max) {
                if (!blk_stack_atomic_writes_tail(t, b))
                        goto unsupported;
                return;
        }

        if (!blk_stack_atomic_writes_head(t, b))
                goto unsupported;
        return;

unsupported:
        t->atomic_write_hw_max = 0;
        t->atomic_write_hw_unit_max = 0;
        t->atomic_write_hw_unit_min = 0;
        t->atomic_write_hw_boundary = 0;
        t->features &= ~BLK_FEAT_ATOMIC_WRITES_STACKED;
}

/**
 * blk_stack_limits - adjust queue_limits for stacked devices
 * @t:  the stacking driver limits (top device)
 * @b:  the underlying queue limits (bottom, component device)
 * @start:  first data sector within component device
 *
 * Description:
 *    This function is used by stacking drivers like MD and DM to ensure
 *    that all component devices have compatible block sizes and
 *    alignments.  The stacking driver must provide a queue_limits
 *    struct (top) and then iteratively call the stacking function for
 *    all component (bottom) devices.  The stacking function will
 *    attempt to combine the values and ensure proper alignment.
 *
 *    Returns 0 if the top and bottom queue_limits are compatible.  The
 *    top device's block sizes and alignment offsets may be adjusted to
 *    ensure alignment with the bottom device. If no compatible sizes
 *    and alignments exist, -1 is returned and the resulting top
 *    queue_limits will have the misaligned flag set to indicate that
 *    the alignment_offset is undefined.
 */
int blk_stack_limits(struct queue_limits *t, struct queue_limits *b,
                     sector_t start)
{
        unsigned int top, bottom, alignment, ret = 0;

        t->features |= (b->features & BLK_FEAT_INHERIT_MASK);

        /*
         * Some feaures need to be supported both by the stacking driver and all
         * underlying devices.  The stacking driver sets these flags before
         * stacking the limits, and this will clear the flags if any of the
         * underlying devices does not support it.
         */
        if (!(b->features & BLK_FEAT_NOWAIT))
                t->features &= ~BLK_FEAT_NOWAIT;
        if (!(b->features & BLK_FEAT_POLL))
                t->features &= ~BLK_FEAT_POLL;

        t->flags |= (b->flags & BLK_FLAG_MISALIGNED);

        t->max_sectors = min_not_zero(t->max_sectors, b->max_sectors);
        t->max_user_sectors = min_not_zero(t->max_user_sectors,
                        b->max_user_sectors);
        t->max_hw_sectors = min_not_zero(t->max_hw_sectors, b->max_hw_sectors);
        t->max_dev_sectors = min_not_zero(t->max_dev_sectors, b->max_dev_sectors);
        t->max_write_zeroes_sectors = min(t->max_write_zeroes_sectors,
                                        b->max_write_zeroes_sectors);
        t->max_hw_zone_append_sectors = min(t->max_hw_zone_append_sectors,
                                        b->max_hw_zone_append_sectors);

        t->seg_boundary_mask = min_not_zero(t->seg_boundary_mask,
                                            b->seg_boundary_mask);
        t->virt_boundary_mask = min_not_zero(t->virt_boundary_mask,
                                            b->virt_boundary_mask);

        t->max_segments = min_not_zero(t->max_segments, b->max_segments);
        t->max_discard_segments = min_not_zero(t->max_discard_segments,
                                               b->max_discard_segments);
        t->max_integrity_segments = min_not_zero(t->max_integrity_segments,
                                                 b->max_integrity_segments);

        t->max_segment_size = min_not_zero(t->max_segment_size,
                                           b->max_segment_size);

        alignment = queue_limit_alignment_offset(b, start);

        /* Bottom device has different alignment.  Check that it is
         * compatible with the current top alignment.
         */
        if (t->alignment_offset != alignment) {

                top = max(t->physical_block_size, t->io_min)
                        + t->alignment_offset;
                bottom = max(b->physical_block_size, b->io_min) + alignment;

                /* Verify that top and bottom intervals line up */
                if (max(top, bottom) % min(top, bottom)) {
                        t->flags |= BLK_FLAG_MISALIGNED;
                        ret = -1;
                }
        }

        t->logical_block_size = max(t->logical_block_size,
                                    b->logical_block_size);

        t->physical_block_size = max(t->physical_block_size,
                                     b->physical_block_size);

        t->io_min = max(t->io_min, b->io_min);
        t->io_opt = lcm_not_zero(t->io_opt, b->io_opt);
        t->dma_alignment = max(t->dma_alignment, b->dma_alignment);

        /* Set non-power-of-2 compatible chunk_sectors boundary */
        if (b->chunk_sectors)
                t->chunk_sectors = gcd(t->chunk_sectors, b->chunk_sectors);

        /* Physical block size a multiple of the logical block size? */
        if (t->physical_block_size & (t->logical_block_size - 1)) {
                t->physical_block_size = t->logical_block_size;
                t->flags |= BLK_FLAG_MISALIGNED;
                ret = -1;
        }

        /* Minimum I/O a multiple of the physical block size? */
        if (t->io_min & (t->physical_block_size - 1)) {
                t->io_min = t->physical_block_size;
                t->flags |= BLK_FLAG_MISALIGNED;
                ret = -1;
        }

        /* Optimal I/O a multiple of the physical block size? */
        if (t->io_opt & (t->physical_block_size - 1)) {
                t->io_opt = 0;
                t->flags |= BLK_FLAG_MISALIGNED;
                ret = -1;
        }

        /* chunk_sectors a multiple of the physical block size? */
        if ((t->chunk_sectors << 9) & (t->physical_block_size - 1)) {
                t->chunk_sectors = 0;
                t->flags |= BLK_FLAG_MISALIGNED;
                ret = -1;
        }

        /* Find lowest common alignment_offset */
        t->alignment_offset = lcm_not_zero(t->alignment_offset, alignment)
                % max(t->physical_block_size, t->io_min);

        /* Verify that new alignment_offset is on a logical block boundary */
        if (t->alignment_offset & (t->logical_block_size - 1)) {
                t->flags |= BLK_FLAG_MISALIGNED;
                ret = -1;
        }

        t->max_sectors = blk_round_down_sectors(t->max_sectors, t->logical_block_size);
        t->max_hw_sectors = blk_round_down_sectors(t->max_hw_sectors, t->logical_block_size);
        t->max_dev_sectors = blk_round_down_sectors(t->max_dev_sectors, t->logical_block_size);

        /* Discard alignment and granularity */
        if (b->discard_granularity) {
                alignment = queue_limit_discard_alignment(b, start);

                t->max_discard_sectors = min_not_zero(t->max_discard_sectors,
                                                      b->max_discard_sectors);
                t->max_hw_discard_sectors = min_not_zero(t->max_hw_discard_sectors,
                                                         b->max_hw_discard_sectors);
                t->discard_granularity = max(t->discard_granularity,
                                             b->discard_granularity);
                t->discard_alignment = lcm_not_zero(t->discard_alignment, alignment) %
                        t->discard_granularity;
        }
        t->max_secure_erase_sectors = min_not_zero(t->max_secure_erase_sectors,
                                                   b->max_secure_erase_sectors);
        t->zone_write_granularity = max(t->zone_write_granularity,
                                        b->zone_write_granularity);
        if (!(t->features & BLK_FEAT_ZONED)) {
                t->zone_write_granularity = 0;
                t->max_zone_append_sectors = 0;
        }
        blk_stack_atomic_writes_limits(t, b);

        return ret;
}
EXPORT_SYMBOL(blk_stack_limits);

/**
 * queue_limits_stack_bdev - adjust queue_limits for stacked devices
 * @t:  the stacking driver limits (top device)
 * @bdev:  the underlying block device (bottom)
 * @offset:  offset to beginning of data within component device
 * @pfx: prefix to use for warnings logged
 *
 * Description:
 *    This function is used by stacking drivers like MD and DM to ensure
 *    that all component devices have compatible block sizes and
 *    alignments.  The stacking driver must provide a queue_limits
 *    struct (top) and then iteratively call the stacking function for
 *    all component (bottom) devices.  The stacking function will
 *    attempt to combine the values and ensure proper alignment.
 */
void queue_limits_stack_bdev(struct queue_limits *t, struct block_device *bdev,
                sector_t offset, const char *pfx)
{
        if (blk_stack_limits(t, bdev_limits(bdev),
                        get_start_sect(bdev) + offset))
                pr_notice("%s: Warning: Device %pg is misaligned\n",
                        pfx, bdev);
}
EXPORT_SYMBOL_GPL(queue_limits_stack_bdev);

/**
 * queue_limits_stack_integrity - stack integrity profile
 * @t: target queue limits
 * @b: base queue limits
 *
 * Check if the integrity profile in the @b can be stacked into the
 * target @t.  Stacking is possible if either:
 *
 *   a) does not have any integrity information stacked into it yet
 *   b) the integrity profile in @b is identical to the one in @t
 *
 * If @b can be stacked into @t, return %true.  Else return %false and clear the
 * integrity information in @t.
 */
bool queue_limits_stack_integrity(struct queue_limits *t,
                struct queue_limits *b)
{
        struct blk_integrity *ti = &t->integrity;
        struct blk_integrity *bi = &b->integrity;

        if (!IS_ENABLED(CONFIG_BLK_DEV_INTEGRITY))
                return true;

        if (!ti->tuple_size) {
                /* inherit the settings from the first underlying device */
                if (!(ti->flags & BLK_INTEGRITY_STACKED)) {
                        ti->flags = BLK_INTEGRITY_DEVICE_CAPABLE |
                                (bi->flags & BLK_INTEGRITY_REF_TAG);
                        ti->csum_type = bi->csum_type;
                        ti->tuple_size = bi->tuple_size;
                        ti->pi_offset = bi->pi_offset;
                        ti->interval_exp = bi->interval_exp;
                        ti->tag_size = bi->tag_size;
                        goto done;
                }
                if (!bi->tuple_size)
                        goto done;
        }

        if (ti->tuple_size != bi->tuple_size)
                goto incompatible;
        if (ti->interval_exp != bi->interval_exp)
                goto incompatible;
        if (ti->tag_size != bi->tag_size)
                goto incompatible;
        if (ti->csum_type != bi->csum_type)
                goto incompatible;
        if ((ti->flags & BLK_INTEGRITY_REF_TAG) !=
            (bi->flags & BLK_INTEGRITY_REF_TAG))
                goto incompatible;

done:
        ti->flags |= BLK_INTEGRITY_STACKED;
        return true;

incompatible:
        memset(ti, 0, sizeof(*ti));
        return false;
}
EXPORT_SYMBOL_GPL(queue_limits_stack_integrity);

/**
 * blk_set_queue_depth - tell the block layer about the device queue depth
 * @q:          the request queue for the device
 * @depth:              queue depth
 *
 */
void blk_set_queue_depth(struct request_queue *q, unsigned int depth)
{
        q->queue_depth = depth;
        rq_qos_queue_depth_changed(q);
}
EXPORT_SYMBOL(blk_set_queue_depth);

int bdev_alignment_offset(struct block_device *bdev)
{
        struct request_queue *q = bdev_get_queue(bdev);

        if (q->limits.flags & BLK_FLAG_MISALIGNED)
                return -1;
        if (bdev_is_partition(bdev))
                return queue_limit_alignment_offset(&q->limits,
                                bdev->bd_start_sect);
        return q->limits.alignment_offset;
}
EXPORT_SYMBOL_GPL(bdev_alignment_offset);

unsigned int bdev_discard_alignment(struct block_device *bdev)
{
        struct request_queue *q = bdev_get_queue(bdev);

        if (bdev_is_partition(bdev))
                return queue_limit_discard_alignment(&q->limits,
                                bdev->bd_start_sect);
        return q->limits.discard_alignment;
}
EXPORT_SYMBOL_GPL(bdev_discard_alignment);