// SPDX-License-Identifier: GPL-2.0
/*
 * Zoned block device handling
 *
 * Copyright (c) 2015, Hannes Reinecke
 * Copyright (c) 2015, SUSE Linux GmbH
 *
 * Copyright (c) 2016, Damien Le Moal
 * Copyright (c) 2016, Western Digital
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/rbtree.h>
#include <linux/blkdev.h>
#include <linux/blk-mq.h>

#include "blk.h"

static inline sector_t blk_zone_start(struct request_queue *q,
                                      sector_t sector)
{
        sector_t zone_mask = blk_queue_zone_sectors(q) - 1;

        return sector & ~zone_mask;
}

/*
 * Return true if a request is a write requests that needs zone write locking.
 */
bool blk_req_needs_zone_write_lock(struct request *rq)
{
        if (!rq->q->seq_zones_wlock)
                return false;

        if (blk_rq_is_passthrough(rq))
                return false;

        switch (req_op(rq)) {
        case REQ_OP_WRITE_ZEROES:
        case REQ_OP_WRITE_SAME:
        case REQ_OP_WRITE:
                return blk_rq_zone_is_seq(rq);
        default:
                return false;
        }
}
EXPORT_SYMBOL_GPL(blk_req_needs_zone_write_lock);

void __blk_req_zone_write_lock(struct request *rq)
{
        if (WARN_ON_ONCE(test_and_set_bit(blk_rq_zone_no(rq),
                                          rq->q->seq_zones_wlock)))
                return;

        WARN_ON_ONCE(rq->rq_flags & RQF_ZONE_WRITE_LOCKED);
        rq->rq_flags |= RQF_ZONE_WRITE_LOCKED;
}
EXPORT_SYMBOL_GPL(__blk_req_zone_write_lock);

void __blk_req_zone_write_unlock(struct request *rq)
{
        rq->rq_flags &= ~RQF_ZONE_WRITE_LOCKED;
        if (rq->q->seq_zones_wlock)
                WARN_ON_ONCE(!test_and_clear_bit(blk_rq_zone_no(rq),
                                                 rq->q->seq_zones_wlock));
}
EXPORT_SYMBOL_GPL(__blk_req_zone_write_unlock);

static inline unsigned int __blkdev_nr_zones(struct request_queue *q,
                                             sector_t nr_sectors)
{
        unsigned long zone_sectors = blk_queue_zone_sectors(q);

        return (nr_sectors + zone_sectors - 1) >> ilog2(zone_sectors);
}

/**
 * blkdev_nr_zones - Get number of zones
 * @bdev:       Target block device
 *
 * Description:
 *    Return the total number of zones of a zoned block device.
 *    For a regular block device, the number of zones is always 0.
 */
unsigned int blkdev_nr_zones(struct block_device *bdev)
{
        struct request_queue *q = bdev_get_queue(bdev);

        if (!blk_queue_is_zoned(q))
                return 0;

        return __blkdev_nr_zones(q, bdev->bd_part->nr_sects);
}
EXPORT_SYMBOL_GPL(blkdev_nr_zones);

/*
 * Check that a zone report belongs to this partition, and if yes, fix its start
 * sector and write pointer and return true. Return false otherwise.
 */
static bool blkdev_report_zone(struct block_device *bdev, struct blk_zone *rep)
{
        sector_t offset = get_start_sect(bdev);

        if (rep->start < offset)
                return false;

        rep->start -= offset;
        if (rep->start + rep->len > bdev->bd_part->nr_sects)
                return false;

        if (rep->type == BLK_ZONE_TYPE_CONVENTIONAL)
                rep->wp = rep->start + rep->len;
        else
                rep->wp -= offset;
        return true;
}

static int blk_report_zones(struct gendisk *disk, sector_t sector,
                            struct blk_zone *zones, unsigned int *nr_zones,
                            gfp_t gfp_mask)
{
        struct request_queue *q = disk->queue;
        unsigned int z = 0, n, nrz = *nr_zones;
        sector_t capacity = get_capacity(disk);
        int ret;

        while (z < nrz && sector < capacity) {
                n = nrz - z;
                ret = disk->fops->report_zones(disk, sector, &zones[z], &n,
                                               gfp_mask);
                if (ret)
                        return ret;
                if (!n)
                        break;
                sector += blk_queue_zone_sectors(q) * n;
                z += n;
        }

        WARN_ON(z > *nr_zones);
        *nr_zones = z;

        return 0;
}

/**
 * blkdev_report_zones - Get zones information
 * @bdev:       Target block device
 * @sector:     Sector from which to report zones
 * @zones:      Array of zone structures where to return the zones information
 * @nr_zones:   Number of zone structures in the zone array
 * @gfp_mask:   Memory allocation flags (for bio_alloc)
 *
 * Description:
 *    Get zone information starting from the zone containing @sector.
 *    The number of zone information reported may be less than the number
 *    requested by @nr_zones. The number of zones actually reported is
 *    returned in @nr_zones.
 */
int blkdev_report_zones(struct block_device *bdev, sector_t sector,
                        struct blk_zone *zones, unsigned int *nr_zones,
                        gfp_t gfp_mask)
{
        struct request_queue *q = bdev_get_queue(bdev);
        unsigned int i, nrz;
        int ret;

        if (!blk_queue_is_zoned(q))
                return -EOPNOTSUPP;

        /*
         * A block device that advertized itself as zoned must have a
         * report_zones method. If it does not have one defined, the device
         * driver has a bug. So warn about that.
         */
        if (WARN_ON_ONCE(!bdev->bd_disk->fops->report_zones))
                return -EOPNOTSUPP;

        if (!*nr_zones || sector >= bdev->bd_part->nr_sects) {
                *nr_zones = 0;
                return 0;
        }

        nrz = min(*nr_zones,
                  __blkdev_nr_zones(q, bdev->bd_part->nr_sects - sector));
        ret = blk_report_zones(bdev->bd_disk, get_start_sect(bdev) + sector,
                               zones, &nrz, gfp_mask);
        if (ret)
                return ret;

        for (i = 0; i < nrz; i++) {
                if (!blkdev_report_zone(bdev, zones))
                        break;
                zones++;
        }

        *nr_zones = i;

        return 0;
}
EXPORT_SYMBOL_GPL(blkdev_report_zones);

/**
 * blkdev_reset_zones - Reset zones write pointer
 * @bdev:       Target block device
 * @sector:     Start sector of the first zone to reset
 * @nr_sectors: Number of sectors, at least the length of one zone
 * @gfp_mask:   Memory allocation flags (for bio_alloc)
 *
 * Description:
 *    Reset the write pointer of the zones contained in the range
 *    @sector..@sector+@nr_sectors. Specifying the entire disk sector range
 *    is valid, but the specified range should not contain conventional zones.
 */
int blkdev_reset_zones(struct block_device *bdev,
                       sector_t sector, sector_t nr_sectors,
                       gfp_t gfp_mask)
{
        struct request_queue *q = bdev_get_queue(bdev);
        sector_t zone_sectors;
        sector_t end_sector = sector + nr_sectors;
        struct bio *bio = NULL;
        struct blk_plug plug;
        int ret;

        if (!blk_queue_is_zoned(q))
                return -EOPNOTSUPP;

        if (bdev_read_only(bdev))
                return -EPERM;

        if (!nr_sectors || end_sector > bdev->bd_part->nr_sects)
                /* Out of range */
                return -EINVAL;

        /* Check alignment (handle eventual smaller last zone) */
        zone_sectors = blk_queue_zone_sectors(q);
        if (sector & (zone_sectors - 1))
                return -EINVAL;

        if ((nr_sectors & (zone_sectors - 1)) &&
            end_sector != bdev->bd_part->nr_sects)
                return -EINVAL;

        blk_start_plug(&plug);
        while (sector < end_sector) {

                bio = blk_next_bio(bio, 0, gfp_mask);
                bio->bi_iter.bi_sector = sector;
                bio_set_dev(bio, bdev);
                bio_set_op_attrs(bio, REQ_OP_ZONE_RESET, 0);

                sector += zone_sectors;

                /* This may take a while, so be nice to others */
                cond_resched();

        }

        ret = submit_bio_wait(bio);
        bio_put(bio);

        blk_finish_plug(&plug);

        return ret;
}
EXPORT_SYMBOL_GPL(blkdev_reset_zones);

/*
 * BLKREPORTZONE ioctl processing.
 * Called from blkdev_ioctl.
 */
int blkdev_report_zones_ioctl(struct block_device *bdev, fmode_t mode,
                              unsigned int cmd, unsigned long arg)
{
        void __user *argp = (void __user *)arg;
        struct request_queue *q;
        struct blk_zone_report rep;
        struct blk_zone *zones;
        int ret;

        if (!argp)
                return -EINVAL;

        q = bdev_get_queue(bdev);
        if (!q)
                return -ENXIO;

        if (!blk_queue_is_zoned(q))
                return -ENOTTY;

        if (!capable(CAP_SYS_ADMIN))
                return -EACCES;

        if (copy_from_user(&rep, argp, sizeof(struct blk_zone_report)))
                return -EFAULT;

        if (!rep.nr_zones)
                return -EINVAL;

        rep.nr_zones = min(blkdev_nr_zones(bdev), rep.nr_zones);

        zones = kvmalloc_array(rep.nr_zones, sizeof(struct blk_zone),
                               GFP_KERNEL | __GFP_ZERO);
        if (!zones)
                return -ENOMEM;

        ret = blkdev_report_zones(bdev, rep.sector,
                                  zones, &rep.nr_zones,
                                  GFP_KERNEL);
        if (ret)
                goto out;

        if (copy_to_user(argp, &rep, sizeof(struct blk_zone_report))) {
                ret = -EFAULT;
                goto out;
        }

        if (rep.nr_zones) {
                if (copy_to_user(argp + sizeof(struct blk_zone_report), zones,
                                 sizeof(struct blk_zone) * rep.nr_zones))
                        ret = -EFAULT;
        }

 out:
        kvfree(zones);

        return ret;
}

/*
 * BLKRESETZONE ioctl processing.
 * Called from blkdev_ioctl.
 */
int blkdev_reset_zones_ioctl(struct block_device *bdev, fmode_t mode,
                             unsigned int cmd, unsigned long arg)
{
        void __user *argp = (void __user *)arg;
        struct request_queue *q;
        struct blk_zone_range zrange;

        if (!argp)
                return -EINVAL;

        q = bdev_get_queue(bdev);
        if (!q)
                return -ENXIO;

        if (!blk_queue_is_zoned(q))
                return -ENOTTY;

        if (!capable(CAP_SYS_ADMIN))
                return -EACCES;

        if (!(mode & FMODE_WRITE))
                return -EBADF;

        if (copy_from_user(&zrange, argp, sizeof(struct blk_zone_range)))
                return -EFAULT;

        return blkdev_reset_zones(bdev, zrange.sector, zrange.nr_sectors,
                                  GFP_KERNEL);
}

static inline unsigned long *blk_alloc_zone_bitmap(int node,
                                                   unsigned int nr_zones)
{
        return kcalloc_node(BITS_TO_LONGS(nr_zones), sizeof(unsigned long),
                            GFP_NOIO, node);
}

/*
 * Allocate an array of struct blk_zone to get nr_zones zone information.
 * The allocated array may be smaller than nr_zones.
 */
static struct blk_zone *blk_alloc_zones(int node, unsigned int *nr_zones)
{
        size_t size = *nr_zones * sizeof(struct blk_zone);
        struct page *page;
        int order;

        for (order = get_order(size); order >= 0; order--) {
                page = alloc_pages_node(node, GFP_NOIO | __GFP_ZERO, order);
                if (page) {
                        *nr_zones = min_t(unsigned int, *nr_zones,
                                (PAGE_SIZE << order) / sizeof(struct blk_zone));
                        return page_address(page);
                }
        }

        return NULL;
}

void blk_queue_free_zone_bitmaps(struct request_queue *q)
{
        kfree(q->seq_zones_bitmap);
        q->seq_zones_bitmap = NULL;
        kfree(q->seq_zones_wlock);
        q->seq_zones_wlock = NULL;
}

/**
 * blk_revalidate_disk_zones - (re)allocate and initialize zone bitmaps
 * @disk:       Target disk
 *
 * Helper function for low-level device drivers to (re) allocate and initialize
 * a disk request queue zone bitmaps. This functions should normally be called
 * within the disk ->revalidate method. For BIO based queues, no zone bitmap
 * is allocated.
 */
int blk_revalidate_disk_zones(struct gendisk *disk)
{
        struct request_queue *q = disk->queue;
        unsigned int nr_zones = __blkdev_nr_zones(q, get_capacity(disk));
        unsigned long *seq_zones_wlock = NULL, *seq_zones_bitmap = NULL;
        unsigned int i, rep_nr_zones = 0, z = 0, nrz;
        struct blk_zone *zones = NULL;
        sector_t sector = 0;
        int ret = 0;

        /*
         * BIO based queues do not use a scheduler so only q->nr_zones
         * needs to be updated so that the sysfs exposed value is correct.
         */
        if (!queue_is_mq(q)) {
                q->nr_zones = nr_zones;
                return 0;
        }

        if (!blk_queue_is_zoned(q) || !nr_zones) {
                nr_zones = 0;
                goto update;
        }

        /* Allocate bitmaps */
        ret = -ENOMEM;
        seq_zones_wlock = blk_alloc_zone_bitmap(q->node, nr_zones);
        if (!seq_zones_wlock)
                goto out;
        seq_zones_bitmap = blk_alloc_zone_bitmap(q->node, nr_zones);
        if (!seq_zones_bitmap)
                goto out;

        /* Get zone information and initialize seq_zones_bitmap */
        rep_nr_zones = nr_zones;
        zones = blk_alloc_zones(q->node, &rep_nr_zones);
        if (!zones)
                goto out;

        while (z < nr_zones) {
                nrz = min(nr_zones - z, rep_nr_zones);
                ret = blk_report_zones(disk, sector, zones, &nrz, GFP_NOIO);
                if (ret)
                        goto out;
                if (!nrz)
                        break;
                for (i = 0; i < nrz; i++) {
                        if (zones[i].type != BLK_ZONE_TYPE_CONVENTIONAL)
                                set_bit(z, seq_zones_bitmap);
                        z++;
                }
                sector += nrz * blk_queue_zone_sectors(q);
        }

        if (WARN_ON(z != nr_zones)) {
                ret = -EIO;
                goto out;
        }

update:
        /*
         * Install the new bitmaps, making sure the queue is stopped and
         * all I/Os are completed (i.e. a scheduler is not referencing the
         * bitmaps).
         */
        blk_mq_freeze_queue(q);
        q->nr_zones = nr_zones;
        swap(q->seq_zones_wlock, seq_zones_wlock);
        swap(q->seq_zones_bitmap, seq_zones_bitmap);
        blk_mq_unfreeze_queue(q);

out:
        free_pages((unsigned long)zones,
                   get_order(rep_nr_zones * sizeof(struct blk_zone)));
        kfree(seq_zones_wlock);
        kfree(seq_zones_bitmap);

        if (ret) {
                pr_warn("%s: failed to revalidate zones\n", disk->disk_name);
                blk_mq_freeze_queue(q);
                blk_queue_free_zone_bitmaps(q);
                blk_mq_unfreeze_queue(q);
        }

        return ret;
}
EXPORT_SYMBOL_GPL(blk_revalidate_disk_zones);