// 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"

  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)
  {

  	sector_t 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)

  {
  	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);

  		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

   *
   * 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.

   *    The caller must use memalloc_noXX_save/restore() calls to control
   *    memory allocations done within this function (zone array and command
   *    buffer allocation by the device driver).

   */

  int blkdev_report_zones(struct block_device *bdev, sector_t sector,

  			struct blk_zone *zones, unsigned int *nr_zones)

  {
  	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);

  	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);

  	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(unsigned int *nr_zones)

  {

  	struct blk_zone *zones;
  	size_t nrz = min(*nr_zones, BLK_ZONED_REPORT_MAX_ZONES);
  
  	/*
  	 * GFP_KERNEL here is meaningless as the caller task context has
  	 * the PF_MEMALLOC_NOIO flag set in blk_revalidate_disk_zones()
  	 * with memalloc_noio_save().
  	 */
  	zones = kvcalloc(nrz, sizeof(struct blk_zone), GFP_KERNEL);
  	if (!zones) {
  		*nr_zones = 0;
  		return NULL;

  	}

  	*nr_zones = nrz;
  
  	return zones;

  }
  
  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;

  	unsigned int noio_flag;

  	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;
  	}

  	/*
  	 * Ensure that all memory allocations in this context are done as
  	 * if GFP_NOIO was specified.
  	 */
  	noio_flag = memalloc_noio_save();

  	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(&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);

  		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:

  	memalloc_noio_restore(noio_flag);

  	kvfree(zones);

  	kfree(seq_zones_wlock);
  	kfree(seq_zones_bitmap);
  
  	if (ret) {
  		pr_warn("%s: failed to revalidate zones
  ", 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);