// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2017 Western Digital Corporation or its affiliates.
 *
 * This file is released under the GPL.
 */

#include "dm-zoned.h"

#include <linux/module.h>

#define DM_MSG_PREFIX           "zoned"

#define DMZ_MIN_BIOS            8192

/*
 * Zone BIO context.
 */
struct dmz_bioctx {
        struct dmz_dev          *dev;
        struct dm_zone          *zone;
        struct bio              *bio;
        refcount_t              ref;
};

/*
 * Chunk work descriptor.
 */
struct dm_chunk_work {
        struct work_struct      work;
        refcount_t              refcount;
        struct dmz_target       *target;
        unsigned int            chunk;
        struct bio_list         bio_list;
};

/*
 * Target descriptor.
 */
struct dmz_target {
        struct dm_dev           **ddev;
        unsigned int            nr_ddevs;

        unsigned int            flags;

        /* Zoned block device information */
        struct dmz_dev          *dev;

        /* For metadata handling */
        struct dmz_metadata     *metadata;

        /* For chunk work */
        struct radix_tree_root  chunk_rxtree;
        struct workqueue_struct *chunk_wq;
        struct mutex            chunk_lock;

        /* For cloned BIOs to zones */
        struct bio_set          bio_set;

        /* For flush */
        spinlock_t              flush_lock;
        struct bio_list         flush_list;
        struct delayed_work     flush_work;
        struct workqueue_struct *flush_wq;
};

/*
 * Flush intervals (seconds).
 */
#define DMZ_FLUSH_PERIOD        (10 * HZ)

/*
 * Target BIO completion.
 */
static inline void dmz_bio_endio(struct bio *bio, blk_status_t status)
{
        struct dmz_bioctx *bioctx =
                dm_per_bio_data(bio, sizeof(struct dmz_bioctx));

        if (status != BLK_STS_OK && bio->bi_status == BLK_STS_OK)
                bio->bi_status = status;
        if (bioctx->dev && bio->bi_status != BLK_STS_OK)
                bioctx->dev->flags |= DMZ_CHECK_BDEV;

        if (refcount_dec_and_test(&bioctx->ref)) {
                struct dm_zone *zone = bioctx->zone;

                if (zone) {
                        if (bio->bi_status != BLK_STS_OK &&
                            bio_op(bio) == REQ_OP_WRITE &&
                            dmz_is_seq(zone))
                                set_bit(DMZ_SEQ_WRITE_ERR, &zone->flags);
                        dmz_deactivate_zone(zone);
                }
                bio_endio(bio);
        }
}

/*
 * Completion callback for an internally cloned target BIO. This terminates the
 * target BIO when there are no more references to its context.
 */
static void dmz_clone_endio(struct bio *clone)
{
        struct dmz_bioctx *bioctx = clone->bi_private;
        blk_status_t status = clone->bi_status;

        bio_put(clone);
        dmz_bio_endio(bioctx->bio, status);
}

/*
 * Issue a clone of a target BIO. The clone may only partially process the
 * original target BIO.
 */
static int dmz_submit_bio(struct dmz_target *dmz, struct dm_zone *zone,
                          struct bio *bio, sector_t chunk_block,
                          unsigned int nr_blocks)
{
        struct dmz_bioctx *bioctx =
                dm_per_bio_data(bio, sizeof(struct dmz_bioctx));
        struct dmz_dev *dev = zone->dev;
        struct bio *clone;

        if (dev->flags & DMZ_BDEV_DYING)
                return -EIO;

        clone = bio_alloc_clone(dev->bdev, bio, GFP_NOIO, &dmz->bio_set);
        if (!clone)
                return -ENOMEM;

        bioctx->dev = dev;
        clone->bi_iter.bi_sector =
                dmz_start_sect(dmz->metadata, zone) + dmz_blk2sect(chunk_block);
        clone->bi_iter.bi_size = dmz_blk2sect(nr_blocks) << SECTOR_SHIFT;
        clone->bi_end_io = dmz_clone_endio;
        clone->bi_private = bioctx;

        bio_advance(bio, clone->bi_iter.bi_size);

        refcount_inc(&bioctx->ref);
        submit_bio_noacct(clone);

        if (bio_op(bio) == REQ_OP_WRITE && dmz_is_seq(zone))
                zone->wp_block += nr_blocks;

        return 0;
}

/*
 * Zero out pages of discarded blocks accessed by a read BIO.
 */
static void dmz_handle_read_zero(struct dmz_target *dmz, struct bio *bio,
                                 sector_t chunk_block, unsigned int nr_blocks)
{
        unsigned int size = nr_blocks << DMZ_BLOCK_SHIFT;

        /* Clear nr_blocks */
        swap(bio->bi_iter.bi_size, size);
        zero_fill_bio(bio);
        swap(bio->bi_iter.bi_size, size);

        bio_advance(bio, size);
}

/*
 * Process a read BIO.
 */
static int dmz_handle_read(struct dmz_target *dmz, struct dm_zone *zone,
                           struct bio *bio)
{
        struct dmz_metadata *zmd = dmz->metadata;
        sector_t chunk_block = dmz_chunk_block(zmd, dmz_bio_block(bio));
        unsigned int nr_blocks = dmz_bio_blocks(bio);
        sector_t end_block = chunk_block + nr_blocks;
        struct dm_zone *rzone, *bzone;
        int ret;

        /* Read into unmapped chunks need only zeroing the BIO buffer */
        if (!zone) {
                zero_fill_bio(bio);
                return 0;
        }

        DMDEBUG("(%s): READ chunk %llu -> %s zone %u, block %llu, %u blocks",
                dmz_metadata_label(zmd),
                (unsigned long long)dmz_bio_chunk(zmd, bio),
                (dmz_is_rnd(zone) ? "RND" :
                 (dmz_is_cache(zone) ? "CACHE" : "SEQ")),
                zone->id,
                (unsigned long long)chunk_block, nr_blocks);

        /* Check block validity to determine the read location */
        bzone = zone->bzone;
        while (chunk_block < end_block) {
                nr_blocks = 0;
                if (dmz_is_rnd(zone) || dmz_is_cache(zone) ||
                    chunk_block < zone->wp_block) {
                        /* Test block validity in the data zone */
                        ret = dmz_block_valid(zmd, zone, chunk_block);
                        if (ret < 0)
                                return ret;
                        if (ret > 0) {
                                /* Read data zone blocks */
                                nr_blocks = ret;
                                rzone = zone;
                        }
                }

                /*
                 * No valid blocks found in the data zone.
                 * Check the buffer zone, if there is one.
                 */
                if (!nr_blocks && bzone) {
                        ret = dmz_block_valid(zmd, bzone, chunk_block);
                        if (ret < 0)
                                return ret;
                        if (ret > 0) {
                                /* Read buffer zone blocks */
                                nr_blocks = ret;
                                rzone = bzone;
                        }
                }

                if (nr_blocks) {
                        /* Valid blocks found: read them */
                        nr_blocks = min_t(unsigned int, nr_blocks,
                                          end_block - chunk_block);
                        ret = dmz_submit_bio(dmz, rzone, bio,
                                             chunk_block, nr_blocks);
                        if (ret)
                                return ret;
                        chunk_block += nr_blocks;
                } else {
                        /* No valid block: zeroout the current BIO block */
                        dmz_handle_read_zero(dmz, bio, chunk_block, 1);
                        chunk_block++;
                }
        }

        return 0;
}

/*
 * Write blocks directly in a data zone, at the write pointer.
 * If a buffer zone is assigned, invalidate the blocks written
 * in place.
 */
static int dmz_handle_direct_write(struct dmz_target *dmz,
                                   struct dm_zone *zone, struct bio *bio,
                                   sector_t chunk_block,
                                   unsigned int nr_blocks)
{
        struct dmz_metadata *zmd = dmz->metadata;
        struct dm_zone *bzone = zone->bzone;
        int ret;

        if (dmz_is_readonly(zone))
                return -EROFS;

        /* Submit write */
        ret = dmz_submit_bio(dmz, zone, bio, chunk_block, nr_blocks);
        if (ret)
                return ret;

        /*
         * Validate the blocks in the data zone and invalidate
         * in the buffer zone, if there is one.
         */
        ret = dmz_validate_blocks(zmd, zone, chunk_block, nr_blocks);
        if (ret == 0 && bzone)
                ret = dmz_invalidate_blocks(zmd, bzone, chunk_block, nr_blocks);

        return ret;
}

/*
 * Write blocks in the buffer zone of @zone.
 * If no buffer zone is assigned yet, get one.
 * Called with @zone write locked.
 */
static int dmz_handle_buffered_write(struct dmz_target *dmz,
                                     struct dm_zone *zone, struct bio *bio,
                                     sector_t chunk_block,
                                     unsigned int nr_blocks)
{
        struct dmz_metadata *zmd = dmz->metadata;
        struct dm_zone *bzone;
        int ret;

        /* Get the buffer zone. One will be allocated if needed */
        bzone = dmz_get_chunk_buffer(zmd, zone);
        if (IS_ERR(bzone))
                return PTR_ERR(bzone);

        if (dmz_is_readonly(bzone))
                return -EROFS;

        /* Submit write */
        ret = dmz_submit_bio(dmz, bzone, bio, chunk_block, nr_blocks);
        if (ret)
                return ret;

        /*
         * Validate the blocks in the buffer zone
         * and invalidate in the data zone.
         */
        ret = dmz_validate_blocks(zmd, bzone, chunk_block, nr_blocks);
        if (ret == 0 && chunk_block < zone->wp_block)
                ret = dmz_invalidate_blocks(zmd, zone, chunk_block, nr_blocks);

        return ret;
}

/*
 * Process a write BIO.
 */
static int dmz_handle_write(struct dmz_target *dmz, struct dm_zone *zone,
                            struct bio *bio)
{
        struct dmz_metadata *zmd = dmz->metadata;
        sector_t chunk_block = dmz_chunk_block(zmd, dmz_bio_block(bio));
        unsigned int nr_blocks = dmz_bio_blocks(bio);

        if (!zone)
                return -ENOSPC;

        DMDEBUG("(%s): WRITE chunk %llu -> %s zone %u, block %llu, %u blocks",
                dmz_metadata_label(zmd),
                (unsigned long long)dmz_bio_chunk(zmd, bio),
                (dmz_is_rnd(zone) ? "RND" :
                 (dmz_is_cache(zone) ? "CACHE" : "SEQ")),
                zone->id,
                (unsigned long long)chunk_block, nr_blocks);

        if (dmz_is_rnd(zone) || dmz_is_cache(zone) ||
            chunk_block == zone->wp_block) {
                /*
                 * zone is a random zone or it is a sequential zone
                 * and the BIO is aligned to the zone write pointer:
                 * direct write the zone.
                 */
                return dmz_handle_direct_write(dmz, zone, bio,
                                               chunk_block, nr_blocks);
        }

        /*
         * This is an unaligned write in a sequential zone:
         * use buffered write.
         */
        return dmz_handle_buffered_write(dmz, zone, bio, chunk_block, nr_blocks);
}

/*
 * Process a discard BIO.
 */
static int dmz_handle_discard(struct dmz_target *dmz, struct dm_zone *zone,
                              struct bio *bio)
{
        struct dmz_metadata *zmd = dmz->metadata;
        sector_t block = dmz_bio_block(bio);
        unsigned int nr_blocks = dmz_bio_blocks(bio);
        sector_t chunk_block = dmz_chunk_block(zmd, block);
        int ret = 0;

        /* For unmapped chunks, there is nothing to do */
        if (!zone)
                return 0;

        if (dmz_is_readonly(zone))
                return -EROFS;

        DMDEBUG("(%s): DISCARD chunk %llu -> zone %u, block %llu, %u blocks",
                dmz_metadata_label(dmz->metadata),
                (unsigned long long)dmz_bio_chunk(zmd, bio),
                zone->id,
                (unsigned long long)chunk_block, nr_blocks);

        /*
         * Invalidate blocks in the data zone and its
         * buffer zone if one is mapped.
         */
        if (dmz_is_rnd(zone) || dmz_is_cache(zone) ||
            chunk_block < zone->wp_block)
                ret = dmz_invalidate_blocks(zmd, zone, chunk_block, nr_blocks);
        if (ret == 0 && zone->bzone)
                ret = dmz_invalidate_blocks(zmd, zone->bzone,
                                            chunk_block, nr_blocks);
        return ret;
}

/*
 * Process a BIO.
 */
static void dmz_handle_bio(struct dmz_target *dmz, struct dm_chunk_work *cw,
                           struct bio *bio)
{
        struct dmz_bioctx *bioctx =
                dm_per_bio_data(bio, sizeof(struct dmz_bioctx));
        struct dmz_metadata *zmd = dmz->metadata;
        struct dm_zone *zone;
        int ret;

        dmz_lock_metadata(zmd);

        /*
         * Get the data zone mapping the chunk. There may be no
         * mapping for read and discard. If a mapping is obtained,
         + the zone returned will be set to active state.
         */
        zone = dmz_get_chunk_mapping(zmd, dmz_bio_chunk(zmd, bio),
                                     bio_op(bio));
        if (IS_ERR(zone)) {
                ret = PTR_ERR(zone);
                goto out;
        }

        /* Process the BIO */
        if (zone) {
                dmz_activate_zone(zone);
                bioctx->zone = zone;
                dmz_reclaim_bio_acc(zone->dev->reclaim);
        }

        switch (bio_op(bio)) {
        case REQ_OP_READ:
                ret = dmz_handle_read(dmz, zone, bio);
                break;
        case REQ_OP_WRITE:
                ret = dmz_handle_write(dmz, zone, bio);
                break;
        case REQ_OP_DISCARD:
        case REQ_OP_WRITE_ZEROES:
                ret = dmz_handle_discard(dmz, zone, bio);
                break;
        default:
                DMERR("(%s): Unsupported BIO operation 0x%x",
                      dmz_metadata_label(dmz->metadata), bio_op(bio));
                ret = -EIO;
        }

        /*
         * Release the chunk mapping. This will check that the mapping
         * is still valid, that is, that the zone used still has valid blocks.
         */
        if (zone)
                dmz_put_chunk_mapping(zmd, zone);
out:
        dmz_bio_endio(bio, errno_to_blk_status(ret));

        dmz_unlock_metadata(zmd);
}

/*
 * Increment a chunk reference counter.
 */
static inline void dmz_get_chunk_work(struct dm_chunk_work *cw)
{
        refcount_inc(&cw->refcount);
}

/*
 * Decrement a chunk work reference count and
 * free it if it becomes 0.
 */
static void dmz_put_chunk_work(struct dm_chunk_work *cw)
{
        if (refcount_dec_and_test(&cw->refcount)) {
                WARN_ON(!bio_list_empty(&cw->bio_list));
                radix_tree_delete(&cw->target->chunk_rxtree, cw->chunk);
                kfree(cw);
        }
}

/*
 * Chunk BIO work function.
 */
static void dmz_chunk_work(struct work_struct *work)
{
        struct dm_chunk_work *cw = container_of(work, struct dm_chunk_work, work);
        struct dmz_target *dmz = cw->target;
        struct bio *bio;

        mutex_lock(&dmz->chunk_lock);

        /* Process the chunk BIOs */
        while ((bio = bio_list_pop(&cw->bio_list))) {
                mutex_unlock(&dmz->chunk_lock);
                dmz_handle_bio(dmz, cw, bio);
                mutex_lock(&dmz->chunk_lock);
                dmz_put_chunk_work(cw);
        }

        /* Queueing the work incremented the work refcount */
        dmz_put_chunk_work(cw);

        mutex_unlock(&dmz->chunk_lock);
}

/*
 * Flush work.
 */
static void dmz_flush_work(struct work_struct *work)
{
        struct dmz_target *dmz = container_of(work, struct dmz_target, flush_work.work);
        struct bio *bio;
        int ret;

        /* Flush dirty metadata blocks */
        ret = dmz_flush_metadata(dmz->metadata);
        if (ret)
                DMDEBUG("(%s): Metadata flush failed, rc=%d",
                        dmz_metadata_label(dmz->metadata), ret);

        /* Process queued flush requests */
        while (1) {
                spin_lock(&dmz->flush_lock);
                bio = bio_list_pop(&dmz->flush_list);
                spin_unlock(&dmz->flush_lock);

                if (!bio)
                        break;

                dmz_bio_endio(bio, errno_to_blk_status(ret));
        }

        queue_delayed_work(dmz->flush_wq, &dmz->flush_work, DMZ_FLUSH_PERIOD);
}

/*
 * Get a chunk work and start it to process a new BIO.
 * If the BIO chunk has no work yet, create one.
 */
static int dmz_queue_chunk_work(struct dmz_target *dmz, struct bio *bio)
{
        unsigned int chunk = dmz_bio_chunk(dmz->metadata, bio);
        struct dm_chunk_work *cw;
        int ret = 0;

        mutex_lock(&dmz->chunk_lock);

        /* Get the BIO chunk work. If one is not active yet, create one */
        cw = radix_tree_lookup(&dmz->chunk_rxtree, chunk);
        if (cw) {
                dmz_get_chunk_work(cw);
        } else {
                /* Create a new chunk work */
                cw = kmalloc_obj(struct dm_chunk_work, GFP_NOIO);
                if (unlikely(!cw)) {
                        ret = -ENOMEM;
                        goto out;
                }

                INIT_WORK(&cw->work, dmz_chunk_work);
                refcount_set(&cw->refcount, 1);
                cw->target = dmz;
                cw->chunk = chunk;
                bio_list_init(&cw->bio_list);

                ret = radix_tree_insert(&dmz->chunk_rxtree, chunk, cw);
                if (unlikely(ret)) {
                        kfree(cw);
                        goto out;
                }
        }

        bio_list_add(&cw->bio_list, bio);

        if (queue_work(dmz->chunk_wq, &cw->work))
                dmz_get_chunk_work(cw);
out:
        mutex_unlock(&dmz->chunk_lock);
        return ret;
}

/*
 * Check if the backing device is being removed. If it's on the way out,
 * start failing I/O. Reclaim and metadata components also call this
 * function to cleanly abort operation in the event of such failure.
 */
bool dmz_bdev_is_dying(struct dmz_dev *dmz_dev)
{
        if (dmz_dev->flags & DMZ_BDEV_DYING)
                return true;

        if (dmz_dev->flags & DMZ_CHECK_BDEV)
                return !dmz_check_bdev(dmz_dev);

        if (blk_queue_dying(bdev_get_queue(dmz_dev->bdev))) {
                dmz_dev_warn(dmz_dev, "Backing device queue dying");
                dmz_dev->flags |= DMZ_BDEV_DYING;
        }

        return dmz_dev->flags & DMZ_BDEV_DYING;
}

/*
 * Check the backing device availability. This detects such events as
 * backing device going offline due to errors, media removals, etc.
 * This check is less efficient than dmz_bdev_is_dying() and should
 * only be performed as a part of error handling.
 */
bool dmz_check_bdev(struct dmz_dev *dmz_dev)
{
        struct gendisk *disk;

        dmz_dev->flags &= ~DMZ_CHECK_BDEV;

        if (dmz_bdev_is_dying(dmz_dev))
                return false;

        disk = dmz_dev->bdev->bd_disk;
        if (disk->fops->check_events &&
            disk->fops->check_events(disk, 0) & DISK_EVENT_MEDIA_CHANGE) {
                dmz_dev_warn(dmz_dev, "Backing device offline");
                dmz_dev->flags |= DMZ_BDEV_DYING;
        }

        return !(dmz_dev->flags & DMZ_BDEV_DYING);
}

/*
 * Process a new BIO.
 */
static int dmz_map(struct dm_target *ti, struct bio *bio)
{
        struct dmz_target *dmz = ti->private;
        struct dmz_metadata *zmd = dmz->metadata;
        struct dmz_bioctx *bioctx = dm_per_bio_data(bio, sizeof(struct dmz_bioctx));
        sector_t sector = bio->bi_iter.bi_sector;
        unsigned int nr_sectors = bio_sectors(bio);
        sector_t chunk_sector;
        int ret;

        if (dmz_dev_is_dying(zmd))
                return DM_MAPIO_KILL;

        DMDEBUG("(%s): BIO op %d sector %llu + %u => chunk %llu, block %llu, %u blocks",
                dmz_metadata_label(zmd),
                bio_op(bio), (unsigned long long)sector, nr_sectors,
                (unsigned long long)dmz_bio_chunk(zmd, bio),
                (unsigned long long)dmz_chunk_block(zmd, dmz_bio_block(bio)),
                (unsigned int)dmz_bio_blocks(bio));

        if (!nr_sectors && bio_op(bio) != REQ_OP_WRITE)
                return DM_MAPIO_REMAPPED;

        /* The BIO should be block aligned */
        if ((nr_sectors & DMZ_BLOCK_SECTORS_MASK) || (sector & DMZ_BLOCK_SECTORS_MASK))
                return DM_MAPIO_KILL;

        /* Initialize the BIO context */
        bioctx->dev = NULL;
        bioctx->zone = NULL;
        bioctx->bio = bio;
        refcount_set(&bioctx->ref, 1);

        /* Set the BIO pending in the flush list */
        if (!nr_sectors && bio_op(bio) == REQ_OP_WRITE) {
                spin_lock(&dmz->flush_lock);
                bio_list_add(&dmz->flush_list, bio);
                spin_unlock(&dmz->flush_lock);
                mod_delayed_work(dmz->flush_wq, &dmz->flush_work, 0);
                return DM_MAPIO_SUBMITTED;
        }

        /* Split zone BIOs to fit entirely into a zone */
        chunk_sector = sector & (dmz_zone_nr_sectors(zmd) - 1);
        if (chunk_sector + nr_sectors > dmz_zone_nr_sectors(zmd))
                dm_accept_partial_bio(bio, dmz_zone_nr_sectors(zmd) - chunk_sector);

        /* Now ready to handle this BIO */
        ret = dmz_queue_chunk_work(dmz, bio);
        if (ret) {
                DMDEBUG("(%s): BIO op %d, can't process chunk %llu, err %i",
                        dmz_metadata_label(zmd),
                        bio_op(bio), (u64)dmz_bio_chunk(zmd, bio),
                        ret);
                return DM_MAPIO_REQUEUE;
        }

        return DM_MAPIO_SUBMITTED;
}

/*
 * Get zoned device information.
 */
static int dmz_get_zoned_device(struct dm_target *ti, char *path,
                                int idx, int nr_devs)
{
        struct dmz_target *dmz = ti->private;
        struct dm_dev *ddev;
        struct dmz_dev *dev;
        int ret;
        struct block_device *bdev;

        /* Get the target device */
        ret = dm_get_device(ti, path, dm_table_get_mode(ti->table), &ddev);
        if (ret) {
                ti->error = "Get target device failed";
                return ret;
        }

        bdev = ddev->bdev;
        if (!bdev_is_zoned(bdev)) {
                if (nr_devs == 1) {
                        ti->error = "Invalid regular device";
                        goto err;
                }
                if (idx != 0) {
                        ti->error = "First device must be a regular device";
                        goto err;
                }
                if (dmz->ddev[0]) {
                        ti->error = "Too many regular devices";
                        goto err;
                }
                dev = &dmz->dev[idx];
                dev->flags = DMZ_BDEV_REGULAR;
        } else {
                if (dmz->ddev[idx]) {
                        ti->error = "Too many zoned devices";
                        goto err;
                }
                if (nr_devs > 1 && idx == 0) {
                        ti->error = "First device must be a regular device";
                        goto err;
                }
                dev = &dmz->dev[idx];
        }
        dev->bdev = bdev;
        dev->dev_idx = idx;

        dev->capacity = bdev_nr_sectors(bdev);
        if (ti->begin) {
                ti->error = "Partial mapping is not supported";
                goto err;
        }

        dmz->ddev[idx] = ddev;

        return 0;
err:
        dm_put_device(ti, ddev);
        return -EINVAL;
}

/*
 * Cleanup zoned device information.
 */
static void dmz_put_zoned_devices(struct dm_target *ti)
{
        struct dmz_target *dmz = ti->private;
        int i;

        for (i = 0; i < dmz->nr_ddevs; i++)
                if (dmz->ddev[i])
                        dm_put_device(ti, dmz->ddev[i]);

        kfree(dmz->ddev);
}

static int dmz_fixup_devices(struct dm_target *ti)
{
        struct dmz_target *dmz = ti->private;
        struct dmz_dev *reg_dev = NULL;
        sector_t zone_nr_sectors = 0;
        int i;

        /*
         * When we have more than on devices, the first one must be a
         * regular block device and the others zoned block devices.
         */
        if (dmz->nr_ddevs > 1) {
                reg_dev = &dmz->dev[0];
                if (!(reg_dev->flags & DMZ_BDEV_REGULAR)) {
                        ti->error = "Primary disk is not a regular device";
                        return -EINVAL;
                }
                for (i = 1; i < dmz->nr_ddevs; i++) {
                        struct dmz_dev *zoned_dev = &dmz->dev[i];
                        struct block_device *bdev = zoned_dev->bdev;

                        if (zoned_dev->flags & DMZ_BDEV_REGULAR) {
                                ti->error = "Secondary disk is not a zoned device";
                                return -EINVAL;
                        }
                        if (zone_nr_sectors &&
                            zone_nr_sectors != bdev_zone_sectors(bdev)) {
                                ti->error = "Zone nr sectors mismatch";
                                return -EINVAL;
                        }
                        zone_nr_sectors = bdev_zone_sectors(bdev);
                        zoned_dev->zone_nr_sectors = zone_nr_sectors;
                        zoned_dev->nr_zones = bdev_nr_zones(bdev);
                }
        } else {
                struct dmz_dev *zoned_dev = &dmz->dev[0];
                struct block_device *bdev = zoned_dev->bdev;

                if (zoned_dev->flags & DMZ_BDEV_REGULAR) {
                        ti->error = "Disk is not a zoned device";
                        return -EINVAL;
                }
                zoned_dev->zone_nr_sectors = bdev_zone_sectors(bdev);
                zoned_dev->nr_zones = bdev_nr_zones(bdev);
        }

        if (reg_dev) {
                sector_t zone_offset;

                reg_dev->zone_nr_sectors = zone_nr_sectors;
                reg_dev->nr_zones =
                        DIV_ROUND_UP_SECTOR_T(reg_dev->capacity,
                                              reg_dev->zone_nr_sectors);
                reg_dev->zone_offset = 0;
                zone_offset = reg_dev->nr_zones;
                for (i = 1; i < dmz->nr_ddevs; i++) {
                        dmz->dev[i].zone_offset = zone_offset;
                        zone_offset += dmz->dev[i].nr_zones;
                }
        }
        return 0;
}

/*
 * Setup target.
 */
static int dmz_ctr(struct dm_target *ti, unsigned int argc, char **argv)
{
        struct dmz_target *dmz;
        int ret, i;

        /* Check arguments */
        if (argc < 1) {
                ti->error = "Invalid argument count";
                return -EINVAL;
        }

        /* Allocate and initialize the target descriptor */
        dmz = kzalloc_obj(struct dmz_target);
        if (!dmz) {
                ti->error = "Unable to allocate the zoned target descriptor";
                return -ENOMEM;
        }
        dmz->dev = kzalloc_objs(struct dmz_dev, argc);
        if (!dmz->dev) {
                ti->error = "Unable to allocate the zoned device descriptors";
                kfree(dmz);
                return -ENOMEM;
        }
        dmz->ddev = kzalloc_objs(struct dm_dev *, argc);
        if (!dmz->ddev) {
                ti->error = "Unable to allocate the dm device descriptors";
                ret = -ENOMEM;
                goto err;
        }
        dmz->nr_ddevs = argc;

        ti->private = dmz;

        /* Get the target zoned block device */
        for (i = 0; i < argc; i++) {
                ret = dmz_get_zoned_device(ti, argv[i], i, argc);
                if (ret)
                        goto err_dev;
        }
        ret = dmz_fixup_devices(ti);
        if (ret)
                goto err_dev;

        /* Initialize metadata */
        ret = dmz_ctr_metadata(dmz->dev, argc, &dmz->metadata,
                               dm_table_device_name(ti->table));
        if (ret) {
                ti->error = "Metadata initialization failed";
                goto err_dev;
        }

        /* Set target (no write same support) */
        ti->max_io_len = dmz_zone_nr_sectors(dmz->metadata);
        ti->num_flush_bios = 1;
        ti->num_discard_bios = 1;
        ti->num_write_zeroes_bios = 1;
        ti->per_io_data_size = sizeof(struct dmz_bioctx);
        ti->flush_supported = true;
        ti->discards_supported = true;

        /* The exposed capacity is the number of chunks that can be mapped */
        ti->len = (sector_t)dmz_nr_chunks(dmz->metadata) <<
                dmz_zone_nr_sectors_shift(dmz->metadata);

        /* Zone BIO */
        ret = bioset_init(&dmz->bio_set, DMZ_MIN_BIOS, 0, 0);
        if (ret) {
                ti->error = "Create BIO set failed";
                goto err_meta;
        }

        /* Chunk BIO work */
        mutex_init(&dmz->chunk_lock);
        INIT_RADIX_TREE(&dmz->chunk_rxtree, GFP_NOIO);
        dmz->chunk_wq = alloc_workqueue("dmz_cwq_%s",
                                        WQ_MEM_RECLAIM | WQ_UNBOUND, 0,
                                        dmz_metadata_label(dmz->metadata));
        if (!dmz->chunk_wq) {
                ti->error = "Create chunk workqueue failed";
                ret = -ENOMEM;
                goto err_bio;
        }

        /* Flush work */
        spin_lock_init(&dmz->flush_lock);
        bio_list_init(&dmz->flush_list);
        INIT_DELAYED_WORK(&dmz->flush_work, dmz_flush_work);
        dmz->flush_wq = alloc_ordered_workqueue("dmz_fwq_%s", WQ_MEM_RECLAIM,
                                                dmz_metadata_label(dmz->metadata));
        if (!dmz->flush_wq) {
                ti->error = "Create flush workqueue failed";
                ret = -ENOMEM;
                goto err_cwq;
        }
        mod_delayed_work(dmz->flush_wq, &dmz->flush_work, DMZ_FLUSH_PERIOD);

        /* Initialize reclaim */
        for (i = 0; i < dmz->nr_ddevs; i++) {
                ret = dmz_ctr_reclaim(dmz->metadata, &dmz->dev[i].reclaim, i);
                if (ret) {
                        ti->error = "Zone reclaim initialization failed";
                        goto err_fwq;
                }
        }

        DMINFO("(%s): Target device: %llu 512-byte logical sectors (%llu blocks)",
               dmz_metadata_label(dmz->metadata),
               (unsigned long long)ti->len,
               (unsigned long long)dmz_sect2blk(ti->len));

        return 0;
err_fwq:
        destroy_workqueue(dmz->flush_wq);
err_cwq:
        destroy_workqueue(dmz->chunk_wq);
err_bio:
        mutex_destroy(&dmz->chunk_lock);
        bioset_exit(&dmz->bio_set);
err_meta:
        dmz_dtr_metadata(dmz->metadata);
err_dev:
        dmz_put_zoned_devices(ti);
err:
        kfree(dmz->dev);
        kfree(dmz);

        return ret;
}

/*
 * Cleanup target.
 */
static void dmz_dtr(struct dm_target *ti)
{
        struct dmz_target *dmz = ti->private;
        int i;

        destroy_workqueue(dmz->chunk_wq);

        for (i = 0; i < dmz->nr_ddevs; i++)
                dmz_dtr_reclaim(dmz->dev[i].reclaim);

        cancel_delayed_work_sync(&dmz->flush_work);
        destroy_workqueue(dmz->flush_wq);

        (void) dmz_flush_metadata(dmz->metadata);

        dmz_dtr_metadata(dmz->metadata);

        bioset_exit(&dmz->bio_set);

        dmz_put_zoned_devices(ti);

        mutex_destroy(&dmz->chunk_lock);

        kfree(dmz->dev);
        kfree(dmz);
}

/*
 * Setup target request queue limits.
 */
static void dmz_io_hints(struct dm_target *ti, struct queue_limits *limits)
{
        struct dmz_target *dmz = ti->private;
        unsigned int chunk_sectors = dmz_zone_nr_sectors(dmz->metadata);

        limits->logical_block_size = DMZ_BLOCK_SIZE;
        limits->physical_block_size = DMZ_BLOCK_SIZE;

        limits->io_min = DMZ_BLOCK_SIZE;
        limits->io_opt = DMZ_BLOCK_SIZE;

        limits->discard_alignment = 0;
        limits->discard_granularity = DMZ_BLOCK_SIZE;
        limits->max_hw_discard_sectors = chunk_sectors;
        limits->max_write_zeroes_sectors = chunk_sectors;

        /* FS hint to try to align to the device zone size */
        limits->chunk_sectors = chunk_sectors;
        limits->max_sectors = chunk_sectors;

        /* We are exposing a drive-managed zoned block device */
        limits->features &= ~BLK_FEAT_ZONED;
}

/*
 * Pass on ioctl to the backend device.
 */
static int dmz_prepare_ioctl(struct dm_target *ti, struct block_device **bdev,
                             unsigned int cmd, unsigned long arg, bool *forward)
{
        struct dmz_target *dmz = ti->private;
        struct dmz_dev *dev = &dmz->dev[0];

        if (!dmz_check_bdev(dev))
                return -EIO;

        *bdev = dev->bdev;

        return 0;
}

/*
 * Stop works on suspend.
 */
static void dmz_suspend(struct dm_target *ti)
{
        struct dmz_target *dmz = ti->private;
        int i;

        flush_workqueue(dmz->chunk_wq);
        for (i = 0; i < dmz->nr_ddevs; i++)
                dmz_suspend_reclaim(dmz->dev[i].reclaim);
        cancel_delayed_work_sync(&dmz->flush_work);
}

/*
 * Restart works on resume or if suspend failed.
 */
static void dmz_resume(struct dm_target *ti)
{
        struct dmz_target *dmz = ti->private;
        int i;

        queue_delayed_work(dmz->flush_wq, &dmz->flush_work, DMZ_FLUSH_PERIOD);
        for (i = 0; i < dmz->nr_ddevs; i++)
                dmz_resume_reclaim(dmz->dev[i].reclaim);
}

static int dmz_iterate_devices(struct dm_target *ti,
                               iterate_devices_callout_fn fn, void *data)
{
        struct dmz_target *dmz = ti->private;
        unsigned int zone_nr_sectors = dmz_zone_nr_sectors(dmz->metadata);
        sector_t capacity;
        int i, r = 0;

        for (i = 0; i < dmz->nr_ddevs; i++) {
                capacity = dmz->dev[i].capacity & ~(zone_nr_sectors - 1);
                r = fn(ti, dmz->ddev[i], 0, capacity, data);
                if (r)
                        break;
        }
        return r;
}

static void dmz_status(struct dm_target *ti, status_type_t type,
                       unsigned int status_flags, char *result,
                       unsigned int maxlen)
{
        struct dmz_target *dmz = ti->private;
        ssize_t sz = 0;
        char buf[BDEVNAME_SIZE];
        struct dmz_dev *dev;
        int i;

        switch (type) {
        case STATUSTYPE_INFO:
                DMEMIT("%u zones %u/%u cache",
                       dmz_nr_zones(dmz->metadata),
                       dmz_nr_unmap_cache_zones(dmz->metadata),
                       dmz_nr_cache_zones(dmz->metadata));
                for (i = 0; i < dmz->nr_ddevs; i++) {
                        /*
                         * For a multi-device setup the first device
                         * contains only cache zones.
                         */
                        if ((i == 0) &&
                            (dmz_nr_cache_zones(dmz->metadata) > 0))
                                continue;
                        DMEMIT(" %u/%u random %u/%u sequential",
                               dmz_nr_unmap_rnd_zones(dmz->metadata, i),
                               dmz_nr_rnd_zones(dmz->metadata, i),
                               dmz_nr_unmap_seq_zones(dmz->metadata, i),
                               dmz_nr_seq_zones(dmz->metadata, i));
                }
                break;
        case STATUSTYPE_TABLE:
                dev = &dmz->dev[0];
                format_dev_t(buf, dev->bdev->bd_dev);
                DMEMIT("%s", buf);
                for (i = 1; i < dmz->nr_ddevs; i++) {
                        dev = &dmz->dev[i];
                        format_dev_t(buf, dev->bdev->bd_dev);
                        DMEMIT(" %s", buf);
                }
                break;
        case STATUSTYPE_IMA:
                *result = '\0';
                break;
        }
}

static int dmz_message(struct dm_target *ti, unsigned int argc, char **argv,
                       char *result, unsigned int maxlen)
{
        struct dmz_target *dmz = ti->private;
        int r = -EINVAL;

        if (!strcasecmp(argv[0], "reclaim")) {
                int i;

                for (i = 0; i < dmz->nr_ddevs; i++)
                        dmz_schedule_reclaim(dmz->dev[i].reclaim);
                r = 0;
        } else
                DMERR("unrecognized message %s", argv[0]);
        return r;
}

static struct target_type zoned_target = {
        .name            = "zoned",
        .version         = {2, 0, 0},
        .features        = DM_TARGET_SINGLETON | DM_TARGET_MIXED_ZONED_MODEL,
        .module          = THIS_MODULE,
        .ctr             = dmz_ctr,
        .dtr             = dmz_dtr,
        .map             = dmz_map,
        .io_hints        = dmz_io_hints,
        .prepare_ioctl   = dmz_prepare_ioctl,
        .postsuspend     = dmz_suspend,
        .resume          = dmz_resume,
        .iterate_devices = dmz_iterate_devices,
        .status          = dmz_status,
        .message         = dmz_message,
};
module_dm(zoned);

MODULE_DESCRIPTION(DM_NAME " target for zoned block devices");
MODULE_AUTHOR("Damien Le Moal <damien.lemoal@wdc.com>");
MODULE_LICENSE("GPL");