// 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 <linux/mm.h>
#include <linux/vmalloc.h>
#include <linux/sched/mm.h>

#include "blk.h"

#define ZONE_COND_NAME(name) [BLK_ZONE_COND_##name] = #name
static const char *const zone_cond_name[] = {
        ZONE_COND_NAME(NOT_WP),
        ZONE_COND_NAME(EMPTY),
        ZONE_COND_NAME(IMP_OPEN),
        ZONE_COND_NAME(EXP_OPEN),
        ZONE_COND_NAME(CLOSED),
        ZONE_COND_NAME(READONLY),
        ZONE_COND_NAME(FULL),
        ZONE_COND_NAME(OFFLINE),
};
#undef ZONE_COND_NAME

/**
 * blk_zone_cond_str - Return string XXX in BLK_ZONE_COND_XXX.
 * @zone_cond: BLK_ZONE_COND_XXX.
 *
 * Description: Centralize block layer function to convert BLK_ZONE_COND_XXX
 * into string format. Useful in the debugging and tracing zone conditions. For
 * invalid BLK_ZONE_COND_XXX it returns string "UNKNOWN".
 */
const char *blk_zone_cond_str(enum blk_zone_cond zone_cond)
{
        static const char *zone_cond_str = "UNKNOWN";

        if (zone_cond < ARRAY_SIZE(zone_cond_name) && zone_cond_name[zone_cond])
                zone_cond_str = zone_cond_name[zone_cond];

        return zone_cond_str;
}
EXPORT_SYMBOL_GPL(blk_zone_cond_str);

/*
 * 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);

bool blk_req_zone_write_trylock(struct request *rq)
{
        unsigned int zno = blk_rq_zone_no(rq);

        if (test_and_set_bit(zno, rq->q->seq_zones_wlock))
                return false;

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

        return true;
}
EXPORT_SYMBOL_GPL(blk_req_zone_write_trylock);

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);

/**
 * blkdev_nr_zones - Get number of zones
 * @disk:       Target gendisk
 *
 * Return the total number of zones of a zoned block device.  For a block
 * device without zone capabilities, the number of zones is always 0.
 */
unsigned int blkdev_nr_zones(struct gendisk *disk)
{
        sector_t zone_sectors = blk_queue_zone_sectors(disk->queue);

        if (!blk_queue_is_zoned(disk->queue))
                return 0;
        return (get_capacity(disk) + zone_sectors - 1) >> ilog2(zone_sectors);
}
EXPORT_SYMBOL_GPL(blkdev_nr_zones);

/**
 * blkdev_report_zones - Get zones information
 * @bdev:       Target block device
 * @sector:     Sector from which to report zones
 * @nr_zones:   Maximum number of zones to report
 * @cb:         Callback function called for each reported zone
 * @data:       Private data for the callback
 *
 * Description:
 *    Get zone information starting from the zone containing @sector for at most
 *    @nr_zones, and call @cb for each zone reported by the device.
 *    To report all zones in a device starting from @sector, the BLK_ALL_ZONES
 *    constant can be passed to @nr_zones.
 *    Returns the number of zones reported by the device, or a negative errno
 *    value in case of failure.
 *
 *    Note: The caller must use memalloc_noXX_save/restore() calls to control
 *    memory allocations done within this function.
 */
int blkdev_report_zones(struct block_device *bdev, sector_t sector,
                        unsigned int nr_zones, report_zones_cb cb, void *data)
{
        struct gendisk *disk = bdev->bd_disk;
        sector_t capacity = get_capacity(disk);

        if (!blk_queue_is_zoned(bdev_get_queue(bdev)) ||
            WARN_ON_ONCE(!disk->fops->report_zones))
                return -EOPNOTSUPP;

        if (!nr_zones || sector >= capacity)
                return 0;

        return disk->fops->report_zones(disk, sector, nr_zones, cb, data);
}
EXPORT_SYMBOL_GPL(blkdev_report_zones);

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);
}

static int blk_zone_need_reset_cb(struct blk_zone *zone, unsigned int idx,
                                  void *data)
{
        /*
         * For an all-zones reset, ignore conventional, empty, read-only
         * and offline zones.
         */
        switch (zone->cond) {
        case BLK_ZONE_COND_NOT_WP:
        case BLK_ZONE_COND_EMPTY:
        case BLK_ZONE_COND_READONLY:
        case BLK_ZONE_COND_OFFLINE:
                return 0;
        default:
                set_bit(idx, (unsigned long *)data);
                return 0;
        }
}

static int blkdev_zone_reset_all_emulated(struct block_device *bdev,
                                          gfp_t gfp_mask)
{
        struct request_queue *q = bdev_get_queue(bdev);
        sector_t capacity = get_capacity(bdev->bd_disk);
        sector_t zone_sectors = blk_queue_zone_sectors(q);
        unsigned long *need_reset;
        struct bio *bio = NULL;
        sector_t sector = 0;
        int ret;

        need_reset = blk_alloc_zone_bitmap(q->node, q->nr_zones);
        if (!need_reset)
                return -ENOMEM;

        ret = bdev->bd_disk->fops->report_zones(bdev->bd_disk, 0,
                                q->nr_zones, blk_zone_need_reset_cb,
                                need_reset);
        if (ret < 0)
                goto out_free_need_reset;

        ret = 0;
        while (sector < capacity) {
                if (!test_bit(blk_queue_zone_no(q, sector), need_reset)) {
                        sector += zone_sectors;
                        continue;
                }

                bio = blk_next_bio(bio, 0, gfp_mask);
                bio_set_dev(bio, bdev);
                bio->bi_opf = REQ_OP_ZONE_RESET | REQ_SYNC;
                bio->bi_iter.bi_sector = sector;
                sector += zone_sectors;

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

        if (bio) {
                ret = submit_bio_wait(bio);
                bio_put(bio);
        }

out_free_need_reset:
        kfree(need_reset);
        return ret;
}

static int blkdev_zone_reset_all(struct block_device *bdev, gfp_t gfp_mask)
{
        struct bio bio;

        bio_init(&bio, NULL, 0);
        bio_set_dev(&bio, bdev);
        bio.bi_opf = REQ_OP_ZONE_RESET_ALL | REQ_SYNC;

        return submit_bio_wait(&bio);
}

/**
 * blkdev_zone_mgmt - Execute a zone management operation on a range of zones
 * @bdev:       Target block device
 * @op:         Operation to be performed on the zones
 * @sector:     Start sector of the first zone to operate on
 * @nr_sectors: Number of sectors, should be at least the length of one zone and
 *              must be zone size aligned.
 * @gfp_mask:   Memory allocation flags (for bio_alloc)
 *
 * Description:
 *    Perform the specified operation on the range of zones specified by
 *    @sector..@sector+@nr_sectors. Specifying the entire disk sector range
 *    is valid, but the specified range should not contain conventional zones.
 *    The operation to execute on each zone can be a zone reset, open, close
 *    or finish request.
 */
int blkdev_zone_mgmt(struct block_device *bdev, enum req_opf op,
                     sector_t sector, sector_t nr_sectors,
                     gfp_t gfp_mask)
{
        struct request_queue *q = bdev_get_queue(bdev);
        sector_t zone_sectors = blk_queue_zone_sectors(q);
        sector_t capacity = get_capacity(bdev->bd_disk);
        sector_t end_sector = sector + nr_sectors;
        struct bio *bio = NULL;
        int ret = 0;

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

        if (bdev_read_only(bdev))
                return -EPERM;

        if (!op_is_zone_mgmt(op))
                return -EOPNOTSUPP;

        if (end_sector <= sector || end_sector > capacity)
                /* Out of range */
                return -EINVAL;

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

        if ((nr_sectors & (zone_sectors - 1)) && end_sector != capacity)
                return -EINVAL;

        /*
         * In the case of a zone reset operation over all zones,
         * REQ_OP_ZONE_RESET_ALL can be used with devices supporting this
         * command. For other devices, we emulate this command behavior by
         * identifying the zones needing a reset.
         */
        if (op == REQ_OP_ZONE_RESET && sector == 0 && nr_sectors == capacity) {
                if (!blk_queue_zone_resetall(q))
                        return blkdev_zone_reset_all_emulated(bdev, gfp_mask);
                return blkdev_zone_reset_all(bdev, gfp_mask);
        }

        while (sector < end_sector) {
                bio = blk_next_bio(bio, 0, gfp_mask);
                bio_set_dev(bio, bdev);
                bio->bi_opf = op | REQ_SYNC;
                bio->bi_iter.bi_sector = sector;
                sector += zone_sectors;

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

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

        return ret;
}
EXPORT_SYMBOL_GPL(blkdev_zone_mgmt);

struct zone_report_args {
        struct blk_zone __user *zones;
};

static int blkdev_copy_zone_to_user(struct blk_zone *zone, unsigned int idx,
                                    void *data)
{
        struct zone_report_args *args = data;

        if (copy_to_user(&args->zones[idx], zone, sizeof(struct blk_zone)))
                return -EFAULT;
        return 0;
}

/*
 * 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 zone_report_args args;
        struct request_queue *q;
        struct blk_zone_report rep;
        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;

        args.zones = argp + sizeof(struct blk_zone_report);
        ret = blkdev_report_zones(bdev, rep.sector, rep.nr_zones,
                                  blkdev_copy_zone_to_user, &args);
        if (ret < 0)
                return ret;

        rep.nr_zones = ret;
        rep.flags = BLK_ZONE_REP_CAPACITY;
        if (copy_to_user(argp, &rep, sizeof(struct blk_zone_report)))
                return -EFAULT;
        return 0;
}

static int blkdev_truncate_zone_range(struct block_device *bdev, fmode_t mode,
                                      const struct blk_zone_range *zrange)
{
        loff_t start, end;

        if (zrange->sector + zrange->nr_sectors <= zrange->sector ||
            zrange->sector + zrange->nr_sectors > get_capacity(bdev->bd_disk))
                /* Out of range */
                return -EINVAL;

        start = zrange->sector << SECTOR_SHIFT;
        end = ((zrange->sector + zrange->nr_sectors) << SECTOR_SHIFT) - 1;

        return truncate_bdev_range(bdev, mode, start, end);
}

/*
 * BLKRESETZONE, BLKOPENZONE, BLKCLOSEZONE and BLKFINISHZONE ioctl processing.
 * Called from blkdev_ioctl.
 */
int blkdev_zone_mgmt_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;
        enum req_opf op;
        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 (!(mode & FMODE_WRITE))
                return -EBADF;

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

        switch (cmd) {
        case BLKRESETZONE:
                op = REQ_OP_ZONE_RESET;

                /* Invalidate the page cache, including dirty pages. */
                ret = blkdev_truncate_zone_range(bdev, mode, &zrange);
                if (ret)
                        return ret;
                break;
        case BLKOPENZONE:
                op = REQ_OP_ZONE_OPEN;
                break;
        case BLKCLOSEZONE:
                op = REQ_OP_ZONE_CLOSE;
                break;
        case BLKFINISHZONE:
                op = REQ_OP_ZONE_FINISH;
                break;
        default:
                return -ENOTTY;
        }

        ret = blkdev_zone_mgmt(bdev, op, zrange.sector, zrange.nr_sectors,
                               GFP_KERNEL);

        /*
         * Invalidate the page cache again for zone reset: writes can only be
         * direct for zoned devices so concurrent writes would not add any page
         * to the page cache after/during reset. The page cache may be filled
         * again due to concurrent reads though and dropping the pages for
         * these is fine.
         */
        if (!ret && cmd == BLKRESETZONE)
                ret = blkdev_truncate_zone_range(bdev, mode, &zrange);

        return ret;
}

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

struct blk_revalidate_zone_args {
        struct gendisk  *disk;
        unsigned long   *conv_zones_bitmap;
        unsigned long   *seq_zones_wlock;
        unsigned int    nr_zones;
        sector_t        zone_sectors;
        sector_t        sector;
};

/*
 * Helper function to check the validity of zones of a zoned block device.
 */
static int blk_revalidate_zone_cb(struct blk_zone *zone, unsigned int idx,
                                  void *data)
{
        struct blk_revalidate_zone_args *args = data;
        struct gendisk *disk = args->disk;
        struct request_queue *q = disk->queue;
        sector_t capacity = get_capacity(disk);

        /*
         * All zones must have the same size, with the exception on an eventual
         * smaller last zone.
         */
        if (zone->start == 0) {
                if (zone->len == 0 || !is_power_of_2(zone->len)) {
                        pr_warn("%s: Invalid zoned device with non power of two zone size (%llu)\n",
                                disk->disk_name, zone->len);
                        return -ENODEV;
                }

                args->zone_sectors = zone->len;
                args->nr_zones = (capacity + zone->len - 1) >> ilog2(zone->len);
        } else if (zone->start + args->zone_sectors < capacity) {
                if (zone->len != args->zone_sectors) {
                        pr_warn("%s: Invalid zoned device with non constant zone size\n",
                                disk->disk_name);
                        return -ENODEV;
                }
        } else {
                if (zone->len > args->zone_sectors) {
                        pr_warn("%s: Invalid zoned device with larger last zone size\n",
                                disk->disk_name);
                        return -ENODEV;
                }
        }

        /* Check for holes in the zone report */
        if (zone->start != args->sector) {
                pr_warn("%s: Zone gap at sectors %llu..%llu\n",
                        disk->disk_name, args->sector, zone->start);
                return -ENODEV;
        }

        /* Check zone type */
        switch (zone->type) {
        case BLK_ZONE_TYPE_CONVENTIONAL:
                if (!args->conv_zones_bitmap) {
                        args->conv_zones_bitmap =
                                blk_alloc_zone_bitmap(q->node, args->nr_zones);
                        if (!args->conv_zones_bitmap)
                                return -ENOMEM;
                }
                set_bit(idx, args->conv_zones_bitmap);
                break;
        case BLK_ZONE_TYPE_SEQWRITE_REQ:
        case BLK_ZONE_TYPE_SEQWRITE_PREF:
                if (!args->seq_zones_wlock) {
                        args->seq_zones_wlock =
                                blk_alloc_zone_bitmap(q->node, args->nr_zones);
                        if (!args->seq_zones_wlock)
                                return -ENOMEM;
                }
                break;
        default:
                pr_warn("%s: Invalid zone type 0x%x at sectors %llu\n",
                        disk->disk_name, (int)zone->type, zone->start);
                return -ENODEV;
        }

        args->sector += zone->len;
        return 0;
}

/**
 * blk_revalidate_disk_zones - (re)allocate and initialize zone bitmaps
 * @disk:       Target disk
 * @update_driver_data: Callback to update driver data on the frozen 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 blk-mq based drivers.  For BIO based
 * drivers only q->nr_zones needs to be updated so that the sysfs exposed value
 * is correct.
 * If the @update_driver_data callback function is not NULL, the callback is
 * executed with the device request queue frozen after all zones have been
 * checked.
 */
int blk_revalidate_disk_zones(struct gendisk *disk,
                              void (*update_driver_data)(struct gendisk *disk))
{
        struct request_queue *q = disk->queue;
        struct blk_revalidate_zone_args args = {
                .disk           = disk,
        };
        unsigned int noio_flag;
        int ret;

        if (WARN_ON_ONCE(!blk_queue_is_zoned(q)))
                return -EIO;
        if (WARN_ON_ONCE(!queue_is_mq(q)))
                return -EIO;

        if (!get_capacity(disk))
                return -EIO;

        /*
         * Ensure that all memory allocations in this context are done as if
         * GFP_NOIO was specified.
         */
        noio_flag = memalloc_noio_save();
        ret = disk->fops->report_zones(disk, 0, UINT_MAX,
                                       blk_revalidate_zone_cb, &args);
        if (!ret) {
                pr_warn("%s: No zones reported\n", disk->disk_name);
                ret = -ENODEV;
        }
        memalloc_noio_restore(noio_flag);

        /*
         * If zones where reported, make sure that the entire disk capacity
         * has been checked.
         */
        if (ret > 0 && args.sector != get_capacity(disk)) {
                pr_warn("%s: Missing zones from sector %llu\n",
                        disk->disk_name, args.sector);
                ret = -ENODEV;
        }

        /*
         * Install the new bitmaps and update nr_zones only once the queue is
         * stopped and all I/Os are completed (i.e. a scheduler is not
         * referencing the bitmaps).
         */
        blk_mq_freeze_queue(q);
        if (ret > 0) {
                blk_queue_chunk_sectors(q, args.zone_sectors);
                q->nr_zones = args.nr_zones;
                swap(q->seq_zones_wlock, args.seq_zones_wlock);
                swap(q->conv_zones_bitmap, args.conv_zones_bitmap);
                if (update_driver_data)
                        update_driver_data(disk);
                ret = 0;
        } else {
                pr_warn("%s: failed to revalidate zones\n", disk->disk_name);
                blk_queue_free_zone_bitmaps(q);
        }
        blk_mq_unfreeze_queue(q);

        kfree(args.seq_zones_wlock);
        kfree(args.conv_zones_bitmap);
        return ret;
}
EXPORT_SYMBOL_GPL(blk_revalidate_disk_zones);

void blk_queue_clear_zone_settings(struct request_queue *q)
{
        blk_mq_freeze_queue(q);

        blk_queue_free_zone_bitmaps(q);
        blk_queue_flag_clear(QUEUE_FLAG_ZONE_RESETALL, q);
        q->required_elevator_features &= ~ELEVATOR_F_ZBD_SEQ_WRITE;
        q->nr_zones = 0;
        q->max_open_zones = 0;
        q->max_active_zones = 0;
        q->limits.chunk_sectors = 0;
        q->limits.zone_write_granularity = 0;
        q->limits.max_zone_append_sectors = 0;

        blk_mq_unfreeze_queue(q);
}