/*
   * Copyright (C) 2015 IT University of Copenhagen
   * Initial release: Matias Bjorling <m@bjorling.me>
   *
   * This program is free software; you can redistribute it and/or
   * modify it under the terms of the GNU General Public License version
   * 2 as published by the Free Software Foundation.
   *
   * This program is distributed in the hope that it will be useful, but
   * WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   * General Public License for more details.
   *
   * Implementation of a Round-robin page-based Hybrid FTL for Open-channel SSDs.
   */
  
  #include "rrpc.h"
  
  static struct kmem_cache *rrpc_gcb_cache, *rrpc_rq_cache;
  static DECLARE_RWSEM(rrpc_lock);
  
  static int rrpc_submit_io(struct rrpc *rrpc, struct bio *bio,
  				struct nvm_rq *rqd, unsigned long flags);
  
  #define rrpc_for_each_lun(rrpc, rlun, i) \
  		for ((i) = 0, rlun = &(rrpc)->luns[0]; \
  			(i) < (rrpc)->nr_luns; (i)++, rlun = &(rrpc)->luns[(i)])
  
  static void rrpc_page_invalidate(struct rrpc *rrpc, struct rrpc_addr *a)
  {
  	struct rrpc_block *rblk = a->rblk;
  	unsigned int pg_offset;
  
  	lockdep_assert_held(&rrpc->rev_lock);
  
  	if (a->addr == ADDR_EMPTY || !rblk)
  		return;
  
  	spin_lock(&rblk->lock);

  	div_u64_rem(a->addr, rrpc->dev->sec_per_blk, &pg_offset);

  	WARN_ON(test_and_set_bit(pg_offset, rblk->invalid_pages));
  	rblk->nr_invalid_pages++;
  
  	spin_unlock(&rblk->lock);
  
  	rrpc->rev_trans_map[a->addr - rrpc->poffset].addr = ADDR_EMPTY;
  }
  
  static void rrpc_invalidate_range(struct rrpc *rrpc, sector_t slba,

  							unsigned int len)

  {
  	sector_t i;
  
  	spin_lock(&rrpc->rev_lock);
  	for (i = slba; i < slba + len; i++) {
  		struct rrpc_addr *gp = &rrpc->trans_map[i];
  
  		rrpc_page_invalidate(rrpc, gp);
  		gp->rblk = NULL;
  	}
  	spin_unlock(&rrpc->rev_lock);
  }
  
  static struct nvm_rq *rrpc_inflight_laddr_acquire(struct rrpc *rrpc,
  					sector_t laddr, unsigned int pages)
  {
  	struct nvm_rq *rqd;
  	struct rrpc_inflight_rq *inf;
  
  	rqd = mempool_alloc(rrpc->rq_pool, GFP_ATOMIC);
  	if (!rqd)
  		return ERR_PTR(-ENOMEM);
  
  	inf = rrpc_get_inflight_rq(rqd);
  	if (rrpc_lock_laddr(rrpc, laddr, pages, inf)) {
  		mempool_free(rqd, rrpc->rq_pool);
  		return NULL;
  	}
  
  	return rqd;
  }
  
  static void rrpc_inflight_laddr_release(struct rrpc *rrpc, struct nvm_rq *rqd)
  {
  	struct rrpc_inflight_rq *inf = rrpc_get_inflight_rq(rqd);
  
  	rrpc_unlock_laddr(rrpc, inf);
  
  	mempool_free(rqd, rrpc->rq_pool);
  }
  
  static void rrpc_discard(struct rrpc *rrpc, struct bio *bio)
  {
  	sector_t slba = bio->bi_iter.bi_sector / NR_PHY_IN_LOG;
  	sector_t len = bio->bi_iter.bi_size / RRPC_EXPOSED_PAGE_SIZE;
  	struct nvm_rq *rqd;

  	while (1) {

  		rqd = rrpc_inflight_laddr_acquire(rrpc, slba, len);

  		if (rqd)
  			break;

  		schedule();

  	}

  
  	if (IS_ERR(rqd)) {
  		pr_err("rrpc: unable to acquire inflight IO
  ");
  		bio_io_error(bio);
  		return;
  	}
  
  	rrpc_invalidate_range(rrpc, slba, len);
  	rrpc_inflight_laddr_release(rrpc, rqd);
  }
  
  static int block_is_full(struct rrpc *rrpc, struct rrpc_block *rblk)
  {

  	return (rblk->next_page == rrpc->dev->sec_per_blk);

  }

  /* Calculate relative addr for the given block, considering instantiated LUNs */
  static u64 block_to_rel_addr(struct rrpc *rrpc, struct rrpc_block *rblk)
  {
  	struct nvm_block *blk = rblk->parent;
  	int lun_blk = blk->id % (rrpc->dev->blks_per_lun * rrpc->nr_luns);
  
  	return lun_blk * rrpc->dev->sec_per_blk;
  }
  
  /* Calculate global addr for the given block */

  static u64 block_to_addr(struct rrpc *rrpc, struct rrpc_block *rblk)

  {
  	struct nvm_block *blk = rblk->parent;

  	return blk->id * rrpc->dev->sec_per_blk;

  }

  static struct ppa_addr linear_to_generic_addr(struct nvm_dev *dev,
  							struct ppa_addr r)
  {
  	struct ppa_addr l;
  	int secs, pgs, blks, luns;
  	sector_t ppa = r.ppa;
  
  	l.ppa = 0;
  
  	div_u64_rem(ppa, dev->sec_per_pg, &secs);
  	l.g.sec = secs;
  
  	sector_div(ppa, dev->sec_per_pg);

  	div_u64_rem(ppa, dev->pgs_per_blk, &pgs);

  	l.g.pg = pgs;
  
  	sector_div(ppa, dev->pgs_per_blk);
  	div_u64_rem(ppa, dev->blks_per_lun, &blks);
  	l.g.blk = blks;
  
  	sector_div(ppa, dev->blks_per_lun);
  	div_u64_rem(ppa, dev->luns_per_chnl, &luns);
  	l.g.lun = luns;
  
  	sector_div(ppa, dev->luns_per_chnl);
  	l.g.ch = ppa;
  
  	return l;
  }

  static struct ppa_addr rrpc_ppa_to_gaddr(struct nvm_dev *dev, u64 addr)

  {
  	struct ppa_addr paddr;
  
  	paddr.ppa = addr;

  	return linear_to_generic_addr(dev, paddr);

  }
  
  /* requires lun->lock taken */

  static void rrpc_set_lun_cur(struct rrpc_lun *rlun, struct rrpc_block *new_rblk,
  						struct rrpc_block **cur_rblk)

  {
  	struct rrpc *rrpc = rlun->rrpc;

  	if (*cur_rblk) {
  		spin_lock(&(*cur_rblk)->lock);
  		WARN_ON(!block_is_full(rrpc, *cur_rblk));
  		spin_unlock(&(*cur_rblk)->lock);

  	}

  	*cur_rblk = new_rblk;

  }
  
  static struct rrpc_block *rrpc_get_blk(struct rrpc *rrpc, struct rrpc_lun *rlun,
  							unsigned long flags)
  {
  	struct nvm_block *blk;
  	struct rrpc_block *rblk;

  	blk = nvm_get_blk(rrpc->dev, rlun->parent, flags);

  	if (!blk) {
  		pr_err("nvm: rrpc: cannot get new block from media manager
  ");

  		return NULL;

  	}

  	rblk = rrpc_get_rblk(rlun, blk->id);

  	blk->priv = rblk;

  	bitmap_zero(rblk->invalid_pages, rrpc->dev->sec_per_blk);

  	rblk->next_page = 0;
  	rblk->nr_invalid_pages = 0;
  	atomic_set(&rblk->data_cmnt_size, 0);
  
  	return rblk;
  }
  
  static void rrpc_put_blk(struct rrpc *rrpc, struct rrpc_block *rblk)
  {

  	nvm_put_blk(rrpc->dev, rblk->parent);

  }

  static void rrpc_put_blks(struct rrpc *rrpc)
  {
  	struct rrpc_lun *rlun;
  	int i;
  
  	for (i = 0; i < rrpc->nr_luns; i++) {
  		rlun = &rrpc->luns[i];
  		if (rlun->cur)
  			rrpc_put_blk(rrpc, rlun->cur);
  		if (rlun->gc_cur)
  			rrpc_put_blk(rrpc, rlun->gc_cur);
  	}
  }

  static struct rrpc_lun *get_next_lun(struct rrpc *rrpc)
  {
  	int next = atomic_inc_return(&rrpc->next_lun);
  
  	return &rrpc->luns[next % rrpc->nr_luns];
  }
  
  static void rrpc_gc_kick(struct rrpc *rrpc)
  {
  	struct rrpc_lun *rlun;
  	unsigned int i;
  
  	for (i = 0; i < rrpc->nr_luns; i++) {
  		rlun = &rrpc->luns[i];
  		queue_work(rrpc->krqd_wq, &rlun->ws_gc);
  	}
  }
  
  /*
   * timed GC every interval.
   */
  static void rrpc_gc_timer(unsigned long data)
  {
  	struct rrpc *rrpc = (struct rrpc *)data;
  
  	rrpc_gc_kick(rrpc);
  	mod_timer(&rrpc->gc_timer, jiffies + msecs_to_jiffies(10));
  }
  
  static void rrpc_end_sync_bio(struct bio *bio)
  {
  	struct completion *waiting = bio->bi_private;
  
  	if (bio->bi_error)
  		pr_err("nvm: gc request failed (%u).
  ", bio->bi_error);
  
  	complete(waiting);
  }
  
  /*
   * rrpc_move_valid_pages -- migrate live data off the block
   * @rrpc: the 'rrpc' structure
   * @block: the block from which to migrate live pages
   *
   * Description:
   *   GC algorithms may call this function to migrate remaining live
   *   pages off the block prior to erasing it. This function blocks
   *   further execution until the operation is complete.
   */
  static int rrpc_move_valid_pages(struct rrpc *rrpc, struct rrpc_block *rblk)
  {
  	struct request_queue *q = rrpc->dev->q;
  	struct rrpc_rev_addr *rev;
  	struct nvm_rq *rqd;
  	struct bio *bio;
  	struct page *page;
  	int slot;

  	int nr_sec_per_blk = rrpc->dev->sec_per_blk;

  	u64 phys_addr;

  	DECLARE_COMPLETION_ONSTACK(wait);

  	if (bitmap_full(rblk->invalid_pages, nr_sec_per_blk))

  		return 0;
  
  	bio = bio_alloc(GFP_NOIO, 1);
  	if (!bio) {
  		pr_err("nvm: could not alloc bio to gc
  ");
  		return -ENOMEM;
  	}
  
  	page = mempool_alloc(rrpc->page_pool, GFP_NOIO);

  	if (!page) {
  		bio_put(bio);

  		return -ENOMEM;

  	}

  
  	while ((slot = find_first_zero_bit(rblk->invalid_pages,

  					    nr_sec_per_blk)) < nr_sec_per_blk) {

  
  		/* Lock laddr */

  		phys_addr = rblk->parent->id * nr_sec_per_blk + slot;

  
  try:
  		spin_lock(&rrpc->rev_lock);
  		/* Get logical address from physical to logical table */
  		rev = &rrpc->rev_trans_map[phys_addr - rrpc->poffset];
  		/* already updated by previous regular write */
  		if (rev->addr == ADDR_EMPTY) {
  			spin_unlock(&rrpc->rev_lock);
  			continue;
  		}
  
  		rqd = rrpc_inflight_laddr_acquire(rrpc, rev->addr, 1);
  		if (IS_ERR_OR_NULL(rqd)) {
  			spin_unlock(&rrpc->rev_lock);
  			schedule();
  			goto try;
  		}
  
  		spin_unlock(&rrpc->rev_lock);
  
  		/* Perform read to do GC */
  		bio->bi_iter.bi_sector = rrpc_get_sector(rev->addr);

  		bio_set_op_attrs(bio,  REQ_OP_READ, 0);

  		bio->bi_private = &wait;
  		bio->bi_end_io = rrpc_end_sync_bio;
  
  		/* TODO: may fail when EXP_PG_SIZE > PAGE_SIZE */
  		bio_add_pc_page(q, bio, page, RRPC_EXPOSED_PAGE_SIZE, 0);
  
  		if (rrpc_submit_io(rrpc, bio, rqd, NVM_IOTYPE_GC)) {
  			pr_err("rrpc: gc read failed.
  ");
  			rrpc_inflight_laddr_release(rrpc, rqd);
  			goto finished;
  		}
  		wait_for_completion_io(&wait);

  		if (bio->bi_error) {
  			rrpc_inflight_laddr_release(rrpc, rqd);
  			goto finished;
  		}

  
  		bio_reset(bio);
  		reinit_completion(&wait);
  
  		bio->bi_iter.bi_sector = rrpc_get_sector(rev->addr);

  		bio_set_op_attrs(bio, REQ_OP_WRITE, 0);

  		bio->bi_private = &wait;
  		bio->bi_end_io = rrpc_end_sync_bio;
  
  		bio_add_pc_page(q, bio, page, RRPC_EXPOSED_PAGE_SIZE, 0);
  
  		/* turn the command around and write the data back to a new
  		 * address
  		 */
  		if (rrpc_submit_io(rrpc, bio, rqd, NVM_IOTYPE_GC)) {
  			pr_err("rrpc: gc write failed.
  ");
  			rrpc_inflight_laddr_release(rrpc, rqd);
  			goto finished;
  		}
  		wait_for_completion_io(&wait);
  
  		rrpc_inflight_laddr_release(rrpc, rqd);

  		if (bio->bi_error)
  			goto finished;

  
  		bio_reset(bio);
  	}
  
  finished:
  	mempool_free(page, rrpc->page_pool);
  	bio_put(bio);

  	if (!bitmap_full(rblk->invalid_pages, nr_sec_per_blk)) {

  		pr_err("nvm: failed to garbage collect block
  ");
  		return -EIO;
  	}
  
  	return 0;
  }
  
  static void rrpc_block_gc(struct work_struct *work)
  {
  	struct rrpc_block_gc *gcb = container_of(work, struct rrpc_block_gc,
  									ws_gc);
  	struct rrpc *rrpc = gcb->rrpc;
  	struct rrpc_block *rblk = gcb->rblk;

  	struct rrpc_lun *rlun = rblk->rlun;

  	struct nvm_dev *dev = rrpc->dev;

  	mempool_free(gcb, rrpc->gcb_pool);

  	pr_debug("nvm: block '%lu' being reclaimed
  ", rblk->parent->id);
  
  	if (rrpc_move_valid_pages(rrpc, rblk))

  		goto put_back;
  
  	if (nvm_erase_blk(dev, rblk->parent))
  		goto put_back;

  	rrpc_put_blk(rrpc, rblk);

  
  	return;
  
  put_back:
  	spin_lock(&rlun->lock);
  	list_add_tail(&rblk->prio, &rlun->prio_list);
  	spin_unlock(&rlun->lock);

  }
  
  /* the block with highest number of invalid pages, will be in the beginning
   * of the list
   */
  static struct rrpc_block *rblock_max_invalid(struct rrpc_block *ra,
  							struct rrpc_block *rb)
  {
  	if (ra->nr_invalid_pages == rb->nr_invalid_pages)
  		return ra;
  
  	return (ra->nr_invalid_pages < rb->nr_invalid_pages) ? rb : ra;
  }
  
  /* linearly find the block with highest number of invalid pages
   * requires lun->lock
   */
  static struct rrpc_block *block_prio_find_max(struct rrpc_lun *rlun)
  {
  	struct list_head *prio_list = &rlun->prio_list;
  	struct rrpc_block *rblock, *max;
  
  	BUG_ON(list_empty(prio_list));
  
  	max = list_first_entry(prio_list, struct rrpc_block, prio);
  	list_for_each_entry(rblock, prio_list, prio)
  		max = rblock_max_invalid(max, rblock);
  
  	return max;
  }
  
  static void rrpc_lun_gc(struct work_struct *work)
  {
  	struct rrpc_lun *rlun = container_of(work, struct rrpc_lun, ws_gc);
  	struct rrpc *rrpc = rlun->rrpc;
  	struct nvm_lun *lun = rlun->parent;
  	struct rrpc_block_gc *gcb;
  	unsigned int nr_blocks_need;
  
  	nr_blocks_need = rrpc->dev->blks_per_lun / GC_LIMIT_INVERSE;
  
  	if (nr_blocks_need < rrpc->nr_luns)
  		nr_blocks_need = rrpc->nr_luns;

  	spin_lock(&rlun->lock);

  	while (nr_blocks_need > lun->nr_free_blocks &&
  					!list_empty(&rlun->prio_list)) {
  		struct rrpc_block *rblock = block_prio_find_max(rlun);
  		struct nvm_block *block = rblock->parent;
  
  		if (!rblock->nr_invalid_pages)
  			break;

  		gcb = mempool_alloc(rrpc->gcb_pool, GFP_ATOMIC);
  		if (!gcb)
  			break;

  		list_del_init(&rblock->prio);
  
  		BUG_ON(!block_is_full(rrpc, rblock));
  
  		pr_debug("rrpc: selected block '%lu' for GC
  ", block->id);

  		gcb->rrpc = rrpc;
  		gcb->rblk = rblock;
  		INIT_WORK(&gcb->ws_gc, rrpc_block_gc);
  
  		queue_work(rrpc->kgc_wq, &gcb->ws_gc);
  
  		nr_blocks_need--;
  	}

  	spin_unlock(&rlun->lock);

  
  	/* TODO: Hint that request queue can be started again */
  }
  
  static void rrpc_gc_queue(struct work_struct *work)
  {
  	struct rrpc_block_gc *gcb = container_of(work, struct rrpc_block_gc,
  									ws_gc);
  	struct rrpc *rrpc = gcb->rrpc;
  	struct rrpc_block *rblk = gcb->rblk;

  	struct rrpc_lun *rlun = rblk->rlun;

  
  	spin_lock(&rlun->lock);
  	list_add_tail(&rblk->prio, &rlun->prio_list);
  	spin_unlock(&rlun->lock);
  
  	mempool_free(gcb, rrpc->gcb_pool);
  	pr_debug("nvm: block '%lu' is full, allow GC (sched)
  ",
  							rblk->parent->id);
  }
  
  static const struct block_device_operations rrpc_fops = {
  	.owner		= THIS_MODULE,
  };
  
  static struct rrpc_lun *rrpc_get_lun_rr(struct rrpc *rrpc, int is_gc)
  {
  	unsigned int i;
  	struct rrpc_lun *rlun, *max_free;
  
  	if (!is_gc)
  		return get_next_lun(rrpc);
  
  	/* during GC, we don't care about RR, instead we want to make
  	 * sure that we maintain evenness between the block luns.
  	 */
  	max_free = &rrpc->luns[0];
  	/* prevent GC-ing lun from devouring pages of a lun with
  	 * little free blocks. We don't take the lock as we only need an
  	 * estimate.
  	 */
  	rrpc_for_each_lun(rrpc, rlun, i) {
  		if (rlun->parent->nr_free_blocks >
  					max_free->parent->nr_free_blocks)
  			max_free = rlun;
  	}
  
  	return max_free;
  }
  
  static struct rrpc_addr *rrpc_update_map(struct rrpc *rrpc, sector_t laddr,

  					struct rrpc_block *rblk, u64 paddr)

  {
  	struct rrpc_addr *gp;
  	struct rrpc_rev_addr *rev;

  	BUG_ON(laddr >= rrpc->nr_sects);

  
  	gp = &rrpc->trans_map[laddr];
  	spin_lock(&rrpc->rev_lock);
  	if (gp->rblk)
  		rrpc_page_invalidate(rrpc, gp);
  
  	gp->addr = paddr;
  	gp->rblk = rblk;
  
  	rev = &rrpc->rev_trans_map[gp->addr - rrpc->poffset];
  	rev->addr = laddr;
  	spin_unlock(&rrpc->rev_lock);
  
  	return gp;
  }

  static u64 rrpc_alloc_addr(struct rrpc *rrpc, struct rrpc_block *rblk)

  {

  	u64 addr = ADDR_EMPTY;

  
  	spin_lock(&rblk->lock);
  	if (block_is_full(rrpc, rblk))
  		goto out;
  
  	addr = block_to_addr(rrpc, rblk) + rblk->next_page;
  
  	rblk->next_page++;
  out:
  	spin_unlock(&rblk->lock);
  	return addr;
  }

  /* Map logical address to a physical page. The mapping implements a round robin
   * approach and allocates a page from the next lun available.

   *

   * Returns rrpc_addr with the physical address and block. Returns NULL if no
   * blocks in the next rlun are available.

   */
  static struct rrpc_addr *rrpc_map_page(struct rrpc *rrpc, sector_t laddr,
  								int is_gc)
  {
  	struct rrpc_lun *rlun;

  	struct rrpc_block *rblk, **cur_rblk;

  	struct nvm_lun *lun;

  	u64 paddr;

  	int gc_force = 0;

  
  	rlun = rrpc_get_lun_rr(rrpc, is_gc);
  	lun = rlun->parent;
  
  	if (!is_gc && lun->nr_free_blocks < rrpc->nr_luns * 4)
  		return NULL;

  	/*
  	 * page allocation steps:
  	 * 1. Try to allocate new page from current rblk
  	 * 2a. If succeed, proceed to map it in and return
  	 * 2b. If fail, first try to allocate a new block from media manger,
  	 *     and then retry step 1. Retry until the normal block pool is
  	 *     exhausted.
  	 * 3. If exhausted, and garbage collector is requesting the block,
  	 *    go to the reserved block and retry step 1.
  	 *    In the case that this fails as well, or it is not GC
  	 *    requesting, report not able to retrieve a block and let the
  	 *    caller handle further processing.
  	 */

  	spin_lock(&rlun->lock);
  	cur_rblk = &rlun->cur;

  	rblk = rlun->cur;
  retry:
  	paddr = rrpc_alloc_addr(rrpc, rblk);

  	if (paddr != ADDR_EMPTY)
  		goto done;

  	if (!list_empty(&rlun->wblk_list)) {
  new_blk:
  		rblk = list_first_entry(&rlun->wblk_list, struct rrpc_block,
  									prio);
  		rrpc_set_lun_cur(rlun, rblk, cur_rblk);
  		list_del(&rblk->prio);
  		goto retry;
  	}
  	spin_unlock(&rlun->lock);
  
  	rblk = rrpc_get_blk(rrpc, rlun, gc_force);
  	if (rblk) {
  		spin_lock(&rlun->lock);
  		list_add_tail(&rblk->prio, &rlun->wblk_list);
  		/*
  		 * another thread might already have added a new block,
  		 * Therefore, make sure that one is used, instead of the
  		 * one just added.
  		 */
  		goto new_blk;
  	}
  
  	if (unlikely(is_gc) && !gc_force) {
  		/* retry from emergency gc block */
  		cur_rblk = &rlun->gc_cur;
  		rblk = rlun->gc_cur;
  		gc_force = 1;
  		spin_lock(&rlun->lock);
  		goto retry;

  	}

  	pr_err("rrpc: failed to allocate new block
  ");
  	return NULL;
  done:

  	spin_unlock(&rlun->lock);
  	return rrpc_update_map(rrpc, laddr, rblk, paddr);

  }
  
  static void rrpc_run_gc(struct rrpc *rrpc, struct rrpc_block *rblk)
  {
  	struct rrpc_block_gc *gcb;
  
  	gcb = mempool_alloc(rrpc->gcb_pool, GFP_ATOMIC);
  	if (!gcb) {
  		pr_err("rrpc: unable to queue block for gc.");
  		return;
  	}
  
  	gcb->rrpc = rrpc;
  	gcb->rblk = rblk;
  
  	INIT_WORK(&gcb->ws_gc, rrpc_gc_queue);
  	queue_work(rrpc->kgc_wq, &gcb->ws_gc);
  }
  
  static void rrpc_end_io_write(struct rrpc *rrpc, struct rrpc_rq *rrqd,
  						sector_t laddr, uint8_t npages)
  {
  	struct rrpc_addr *p;
  	struct rrpc_block *rblk;
  	struct nvm_lun *lun;
  	int cmnt_size, i;
  
  	for (i = 0; i < npages; i++) {
  		p = &rrpc->trans_map[laddr + i];
  		rblk = p->rblk;
  		lun = rblk->parent->lun;
  
  		cmnt_size = atomic_inc_return(&rblk->data_cmnt_size);

  		if (unlikely(cmnt_size == rrpc->dev->sec_per_blk))

  			rrpc_run_gc(rrpc, rblk);
  	}
  }

  static void rrpc_end_io(struct nvm_rq *rqd)

  {
  	struct rrpc *rrpc = container_of(rqd->ins, struct rrpc, instance);
  	struct rrpc_rq *rrqd = nvm_rq_to_pdu(rqd);

  	uint8_t npages = rqd->nr_ppas;

  	sector_t laddr = rrpc_get_laddr(rqd->bio) - npages;
  
  	if (bio_data_dir(rqd->bio) == WRITE)
  		rrpc_end_io_write(rrpc, rrqd, laddr, npages);

  	bio_put(rqd->bio);

  	if (rrqd->flags & NVM_IOTYPE_GC)

  		return;

  
  	rrpc_unlock_rq(rrpc, rqd);

  
  	if (npages > 1)
  		nvm_dev_dma_free(rrpc->dev, rqd->ppa_list, rqd->dma_ppa_list);

  
  	mempool_free(rqd, rrpc->rq_pool);

  }
  
  static int rrpc_read_ppalist_rq(struct rrpc *rrpc, struct bio *bio,
  			struct nvm_rq *rqd, unsigned long flags, int npages)
  {
  	struct rrpc_inflight_rq *r = rrpc_get_inflight_rq(rqd);
  	struct rrpc_addr *gp;
  	sector_t laddr = rrpc_get_laddr(bio);
  	int is_gc = flags & NVM_IOTYPE_GC;
  	int i;
  
  	if (!is_gc && rrpc_lock_rq(rrpc, bio, rqd)) {
  		nvm_dev_dma_free(rrpc->dev, rqd->ppa_list, rqd->dma_ppa_list);
  		return NVM_IO_REQUEUE;
  	}
  
  	for (i = 0; i < npages; i++) {
  		/* We assume that mapping occurs at 4KB granularity */

  		BUG_ON(!(laddr + i >= 0 && laddr + i < rrpc->nr_sects));

  		gp = &rrpc->trans_map[laddr + i];
  
  		if (gp->rblk) {
  			rqd->ppa_list[i] = rrpc_ppa_to_gaddr(rrpc->dev,
  								gp->addr);
  		} else {
  			BUG_ON(is_gc);
  			rrpc_unlock_laddr(rrpc, r);
  			nvm_dev_dma_free(rrpc->dev, rqd->ppa_list,
  							rqd->dma_ppa_list);
  			return NVM_IO_DONE;
  		}
  	}
  
  	rqd->opcode = NVM_OP_HBREAD;
  
  	return NVM_IO_OK;
  }
  
  static int rrpc_read_rq(struct rrpc *rrpc, struct bio *bio, struct nvm_rq *rqd,
  							unsigned long flags)
  {
  	struct rrpc_rq *rrqd = nvm_rq_to_pdu(rqd);
  	int is_gc = flags & NVM_IOTYPE_GC;
  	sector_t laddr = rrpc_get_laddr(bio);
  	struct rrpc_addr *gp;
  
  	if (!is_gc && rrpc_lock_rq(rrpc, bio, rqd))
  		return NVM_IO_REQUEUE;

  	BUG_ON(!(laddr >= 0 && laddr < rrpc->nr_sects));

  	gp = &rrpc->trans_map[laddr];
  
  	if (gp->rblk) {
  		rqd->ppa_addr = rrpc_ppa_to_gaddr(rrpc->dev, gp->addr);
  	} else {
  		BUG_ON(is_gc);
  		rrpc_unlock_rq(rrpc, rqd);
  		return NVM_IO_DONE;
  	}
  
  	rqd->opcode = NVM_OP_HBREAD;
  	rrqd->addr = gp;
  
  	return NVM_IO_OK;
  }
  
  static int rrpc_write_ppalist_rq(struct rrpc *rrpc, struct bio *bio,
  			struct nvm_rq *rqd, unsigned long flags, int npages)
  {
  	struct rrpc_inflight_rq *r = rrpc_get_inflight_rq(rqd);
  	struct rrpc_addr *p;
  	sector_t laddr = rrpc_get_laddr(bio);
  	int is_gc = flags & NVM_IOTYPE_GC;
  	int i;
  
  	if (!is_gc && rrpc_lock_rq(rrpc, bio, rqd)) {
  		nvm_dev_dma_free(rrpc->dev, rqd->ppa_list, rqd->dma_ppa_list);
  		return NVM_IO_REQUEUE;
  	}
  
  	for (i = 0; i < npages; i++) {
  		/* We assume that mapping occurs at 4KB granularity */
  		p = rrpc_map_page(rrpc, laddr + i, is_gc);
  		if (!p) {
  			BUG_ON(is_gc);
  			rrpc_unlock_laddr(rrpc, r);
  			nvm_dev_dma_free(rrpc->dev, rqd->ppa_list,
  							rqd->dma_ppa_list);
  			rrpc_gc_kick(rrpc);
  			return NVM_IO_REQUEUE;
  		}
  
  		rqd->ppa_list[i] = rrpc_ppa_to_gaddr(rrpc->dev,
  								p->addr);
  	}
  
  	rqd->opcode = NVM_OP_HBWRITE;
  
  	return NVM_IO_OK;
  }
  
  static int rrpc_write_rq(struct rrpc *rrpc, struct bio *bio,
  				struct nvm_rq *rqd, unsigned long flags)
  {
  	struct rrpc_rq *rrqd = nvm_rq_to_pdu(rqd);
  	struct rrpc_addr *p;
  	int is_gc = flags & NVM_IOTYPE_GC;
  	sector_t laddr = rrpc_get_laddr(bio);
  
  	if (!is_gc && rrpc_lock_rq(rrpc, bio, rqd))
  		return NVM_IO_REQUEUE;
  
  	p = rrpc_map_page(rrpc, laddr, is_gc);
  	if (!p) {
  		BUG_ON(is_gc);
  		rrpc_unlock_rq(rrpc, rqd);
  		rrpc_gc_kick(rrpc);
  		return NVM_IO_REQUEUE;
  	}
  
  	rqd->ppa_addr = rrpc_ppa_to_gaddr(rrpc->dev, p->addr);
  	rqd->opcode = NVM_OP_HBWRITE;
  	rrqd->addr = p;
  
  	return NVM_IO_OK;
  }
  
  static int rrpc_setup_rq(struct rrpc *rrpc, struct bio *bio,
  			struct nvm_rq *rqd, unsigned long flags, uint8_t npages)
  {
  	if (npages > 1) {
  		rqd->ppa_list = nvm_dev_dma_alloc(rrpc->dev, GFP_KERNEL,
  							&rqd->dma_ppa_list);
  		if (!rqd->ppa_list) {
  			pr_err("rrpc: not able to allocate ppa list
  ");
  			return NVM_IO_ERR;
  		}

  		if (bio_op(bio) == REQ_OP_WRITE)

  			return rrpc_write_ppalist_rq(rrpc, bio, rqd, flags,
  									npages);
  
  		return rrpc_read_ppalist_rq(rrpc, bio, rqd, flags, npages);
  	}

  	if (bio_op(bio) == REQ_OP_WRITE)

  		return rrpc_write_rq(rrpc, bio, rqd, flags);
  
  	return rrpc_read_rq(rrpc, bio, rqd, flags);
  }
  
  static int rrpc_submit_io(struct rrpc *rrpc, struct bio *bio,
  				struct nvm_rq *rqd, unsigned long flags)
  {
  	int err;
  	struct rrpc_rq *rrq = nvm_rq_to_pdu(rqd);
  	uint8_t nr_pages = rrpc_get_pages(bio);
  	int bio_size = bio_sectors(bio) << 9;
  
  	if (bio_size < rrpc->dev->sec_size)
  		return NVM_IO_ERR;
  	else if (bio_size > rrpc->dev->max_rq_size)
  		return NVM_IO_ERR;
  
  	err = rrpc_setup_rq(rrpc, bio, rqd, flags, nr_pages);
  	if (err)
  		return err;
  
  	bio_get(bio);
  	rqd->bio = bio;
  	rqd->ins = &rrpc->instance;

  	rqd->nr_ppas = nr_pages;

  	rrq->flags = flags;
  
  	err = nvm_submit_io(rrpc->dev, rqd);
  	if (err) {
  		pr_err("rrpc: I/O submission failed: %d
  ", err);

  		bio_put(bio);

  		if (!(flags & NVM_IOTYPE_GC)) {
  			rrpc_unlock_rq(rrpc, rqd);

  			if (rqd->nr_ppas > 1)

  				nvm_dev_dma_free(rrpc->dev,
  			rqd->ppa_list, rqd->dma_ppa_list);
  		}

  		return NVM_IO_ERR;
  	}
  
  	return NVM_IO_OK;
  }

  static blk_qc_t rrpc_make_rq(struct request_queue *q, struct bio *bio)

  {
  	struct rrpc *rrpc = q->queuedata;
  	struct nvm_rq *rqd;
  	int err;

  	if (bio_op(bio) == REQ_OP_DISCARD) {

  		rrpc_discard(rrpc, bio);

  		return BLK_QC_T_NONE;

  	}
  
  	rqd = mempool_alloc(rrpc->rq_pool, GFP_KERNEL);
  	if (!rqd) {
  		pr_err_ratelimited("rrpc: not able to queue bio.");
  		bio_io_error(bio);

  		return BLK_QC_T_NONE;

  	}
  	memset(rqd, 0, sizeof(struct nvm_rq));
  
  	err = rrpc_submit_io(rrpc, bio, rqd, NVM_IOTYPE_NONE);
  	switch (err) {
  	case NVM_IO_OK:

  		return BLK_QC_T_NONE;

  	case NVM_IO_ERR:
  		bio_io_error(bio);
  		break;
  	case NVM_IO_DONE:
  		bio_endio(bio);
  		break;
  	case NVM_IO_REQUEUE:
  		spin_lock(&rrpc->bio_lock);
  		bio_list_add(&rrpc->requeue_bios, bio);
  		spin_unlock(&rrpc->bio_lock);
  		queue_work(rrpc->kgc_wq, &rrpc->ws_requeue);
  		break;
  	}
  
  	mempool_free(rqd, rrpc->rq_pool);

  	return BLK_QC_T_NONE;

  }
  
  static void rrpc_requeue(struct work_struct *work)
  {
  	struct rrpc *rrpc = container_of(work, struct rrpc, ws_requeue);
  	struct bio_list bios;
  	struct bio *bio;
  
  	bio_list_init(&bios);
  
  	spin_lock(&rrpc->bio_lock);
  	bio_list_merge(&bios, &rrpc->requeue_bios);
  	bio_list_init(&rrpc->requeue_bios);
  	spin_unlock(&rrpc->bio_lock);
  
  	while ((bio = bio_list_pop(&bios)))
  		rrpc_make_rq(rrpc->disk->queue, bio);
  }
  
  static void rrpc_gc_free(struct rrpc *rrpc)
  {

  	if (rrpc->krqd_wq)
  		destroy_workqueue(rrpc->krqd_wq);
  
  	if (rrpc->kgc_wq)
  		destroy_workqueue(rrpc->kgc_wq);

  }
  
  static int rrpc_gc_init(struct rrpc *rrpc)
  {
  	rrpc->krqd_wq = alloc_workqueue("rrpc-lun", WQ_MEM_RECLAIM|WQ_UNBOUND,
  								rrpc->nr_luns);
  	if (!rrpc->krqd_wq)
  		return -ENOMEM;
  
  	rrpc->kgc_wq = alloc_workqueue("rrpc-bg", WQ_MEM_RECLAIM, 1);
  	if (!rrpc->kgc_wq)
  		return -ENOMEM;
  
  	setup_timer(&rrpc->gc_timer, rrpc_gc_timer, (unsigned long)rrpc);
  
  	return 0;
  }
  
  static void rrpc_map_free(struct rrpc *rrpc)
  {
  	vfree(rrpc->rev_trans_map);
  	vfree(rrpc->trans_map);
  }
  
  static int rrpc_l2p_update(u64 slba, u32 nlb, __le64 *entries, void *private)
  {
  	struct rrpc *rrpc = (struct rrpc *)private;
  	struct nvm_dev *dev = rrpc->dev;
  	struct rrpc_addr *addr = rrpc->trans_map + slba;
  	struct rrpc_rev_addr *raddr = rrpc->rev_trans_map;

  	u64 elba = slba + nlb;
  	u64 i;

  	if (unlikely(elba > dev->total_secs)) {

  		pr_err("nvm: L2P data from device is out of bounds!
  ");
  		return -EINVAL;
  	}
  
  	for (i = 0; i < nlb; i++) {
  		u64 pba = le64_to_cpu(entries[i]);

  		unsigned int mod;

  		/* LNVM treats address-spaces as silos, LBA and PBA are
  		 * equally large and zero-indexed.
  		 */

  		if (unlikely(pba >= dev->total_secs && pba != U64_MAX)) {

  			pr_err("nvm: L2P data entry is out of bounds!
  ");
  			return -EINVAL;
  		}
  
  		/* Address zero is a special one. The first page on a disk is
  		 * protected. As it often holds internal device boot
  		 * information.
  		 */
  		if (!pba)
  			continue;

  		div_u64_rem(pba, rrpc->nr_sects, &mod);

  		addr[i].addr = pba;

  		raddr[mod].addr = slba + i;

  	}
  
  	return 0;
  }
  
  static int rrpc_map_init(struct rrpc *rrpc)
  {
  	struct nvm_dev *dev = rrpc->dev;
  	sector_t i;
  	int ret;

  	rrpc->trans_map = vzalloc(sizeof(struct rrpc_addr) * rrpc->nr_sects);

  	if (!rrpc->trans_map)
  		return -ENOMEM;
  
  	rrpc->rev_trans_map = vmalloc(sizeof(struct rrpc_rev_addr)

  							* rrpc->nr_sects);

  	if (!rrpc->rev_trans_map)
  		return -ENOMEM;

  	for (i = 0; i < rrpc->nr_sects; i++) {

  		struct rrpc_addr *p = &rrpc->trans_map[i];
  		struct rrpc_rev_addr *r = &rrpc->rev_trans_map[i];
  
  		p->addr = ADDR_EMPTY;
  		r->addr = ADDR_EMPTY;
  	}
  
  	if (!dev->ops->get_l2p_tbl)
  		return 0;
  
  	/* Bring up the mapping table from device */

  	ret = dev->ops->get_l2p_tbl(dev, rrpc->soffset, rrpc->nr_sects,
  					rrpc_l2p_update, rrpc);

  	if (ret) {
  		pr_err("nvm: rrpc: could not read L2P table.
  ");
  		return -EINVAL;
  	}
  
  	return 0;
  }

  /* Minimum pages needed within a lun */
  #define PAGE_POOL_SIZE 16
  #define ADDR_POOL_SIZE 64
  
  static int rrpc_core_init(struct rrpc *rrpc)
  {
  	down_write(&rrpc_lock);
  	if (!rrpc_gcb_cache) {
  		rrpc_gcb_cache = kmem_cache_create("rrpc_gcb",
  				sizeof(struct rrpc_block_gc), 0, 0, NULL);
  		if (!rrpc_gcb_cache) {
  			up_write(&rrpc_lock);
  			return -ENOMEM;
  		}
  
  		rrpc_rq_cache = kmem_cache_create("rrpc_rq",
  				sizeof(struct nvm_rq) + sizeof(struct rrpc_rq),
  				0, 0, NULL);
  		if (!rrpc_rq_cache) {
  			kmem_cache_destroy(rrpc_gcb_cache);
  			up_write(&rrpc_lock);
  			return -ENOMEM;
  		}
  	}
  	up_write(&rrpc_lock);
  
  	rrpc->page_pool = mempool_create_page_pool(PAGE_POOL_SIZE, 0);
  	if (!rrpc->page_pool)
  		return -ENOMEM;
  
  	rrpc->gcb_pool = mempool_create_slab_pool(rrpc->dev->nr_luns,
  								rrpc_gcb_cache);
  	if (!rrpc->gcb_pool)
  		return -ENOMEM;
  
  	rrpc->rq_pool = mempool_create_slab_pool(64, rrpc_rq_cache);
  	if (!rrpc->rq_pool)
  		return -ENOMEM;
  
  	spin_lock_init(&rrpc->inflights.lock);
  	INIT_LIST_HEAD(&rrpc->inflights.reqs);
  
  	return 0;
  }
  
  static void rrpc_core_free(struct rrpc *rrpc)
  {
  	mempool_destroy(rrpc->page_pool);
  	mempool_destroy(rrpc->gcb_pool);
  	mempool_destroy(rrpc->rq_pool);
  }
  
  static void rrpc_luns_free(struct rrpc *rrpc)
  {

  	struct nvm_dev *dev = rrpc->dev;
  	struct nvm_lun *lun;
  	struct rrpc_lun *rlun;
  	int i;
  
  	if (!rrpc->luns)
  		return;
  
  	for (i = 0; i < rrpc->nr_luns; i++) {
  		rlun = &rrpc->luns[i];
  		lun = rlun->parent;
  		if (!lun)
  			break;
  		dev->mt->release_lun(dev, lun->id);
  		vfree(rlun->blocks);
  	}

  	kfree(rrpc->luns);
  }
  
  static int rrpc_luns_init(struct rrpc *rrpc, int lun_begin, int lun_end)
  {
  	struct nvm_dev *dev = rrpc->dev;
  	struct rrpc_lun *rlun;

  	int i, j, ret = -EINVAL;

  	if (dev->sec_per_blk > MAX_INVALID_PAGES_STORAGE * BITS_PER_LONG) {

  		pr_err("rrpc: number of pages per block too high.");
  		return -EINVAL;
  	}

  	spin_lock_init(&rrpc->rev_lock);
  
  	rrpc->luns = kcalloc(rrpc->nr_luns, sizeof(struct rrpc_lun),
  								GFP_KERNEL);
  	if (!rrpc->luns)
  		return -ENOMEM;
  
  	/* 1:1 mapping */
  	for (i = 0; i < rrpc->nr_luns; i++) {

  		int lunid = lun_begin + i;
  		struct nvm_lun *lun;

  		if (dev->mt->reserve_lun(dev, lunid)) {
  			pr_err("rrpc: lun %u is already allocated
  ", lunid);
  			goto err;
  		}

  		lun = dev->mt->get_lun(dev, lunid);
  		if (!lun)
  			goto err;

  		rlun = &rrpc->luns[i];
  		rlun->parent = lun;

  		rlun->blocks = vzalloc(sizeof(struct rrpc_block) *
  						rrpc->dev->blks_per_lun);

  		if (!rlun->blocks) {
  			ret = -ENOMEM;

  			goto err;

  		}

  
  		for (j = 0; j < rrpc->dev->blks_per_lun; j++) {
  			struct rrpc_block *rblk = &rlun->blocks[j];
  			struct nvm_block *blk = &lun->blocks[j];
  
  			rblk->parent = blk;

  			rblk->rlun = rlun;

  			INIT_LIST_HEAD(&rblk->prio);
  			spin_lock_init(&rblk->lock);
  		}

  
  		rlun->rrpc = rrpc;
  		INIT_LIST_HEAD(&rlun->prio_list);

  		INIT_LIST_HEAD(&rlun->wblk_list);

  
  		INIT_WORK(&rlun->ws_gc, rrpc_lun_gc);
  		spin_lock_init(&rlun->lock);

  	}
  
  	return 0;
  err:

  	return ret;

  }

  /* returns 0 on success and stores the beginning address in *begin */
  static int rrpc_area_init(struct rrpc *rrpc, sector_t *begin)
  {
  	struct nvm_dev *dev = rrpc->dev;
  	struct nvmm_type *mt = dev->mt;
  	sector_t size = rrpc->nr_sects * dev->sec_size;

  	int ret;

  
  	size >>= 9;

  	ret = mt->get_area(dev, begin, size);
  	if (!ret)
  		*begin >>= (ilog2(dev->sec_size) - 9);
  
  	return ret;

  }
  
  static void rrpc_area_free(struct rrpc *rrpc)
  {
  	struct nvm_dev *dev = rrpc->dev;
  	struct nvmm_type *mt = dev->mt;

  	sector_t begin = rrpc->soffset << (ilog2(dev->sec_size) - 9);

  	mt->put_area(dev, begin);

  }

  static void rrpc_free(struct rrpc *rrpc)
  {
  	rrpc_gc_free(rrpc);
  	rrpc_map_free(rrpc);
  	rrpc_core_free(rrpc);
  	rrpc_luns_free(rrpc);

  	rrpc_area_free(rrpc);

  
  	kfree(rrpc);
  }
  
  static void rrpc_exit(void *private)
  {
  	struct rrpc *rrpc = private;
  
  	del_timer(&rrpc->gc_timer);
  
  	flush_workqueue(rrpc->krqd_wq);
  	flush_workqueue(rrpc->kgc_wq);
  
  	rrpc_free(rrpc);
  }
  
  static sector_t rrpc_capacity(void *private)
  {
  	struct rrpc *rrpc = private;
  	struct nvm_dev *dev = rrpc->dev;
  	sector_t reserved, provisioned;
  
  	/* cur, gc, and two emergency blocks for each lun */

  	reserved = rrpc->nr_luns * dev->sec_per_blk * 4;

  	provisioned = rrpc->nr_sects - reserved;

  	if (reserved > rrpc->nr_sects) {

  		pr_err("rrpc: not enough space available to expose storage.
  ");
  		return 0;
  	}
  
  	sector_div(provisioned, 10);
  	return provisioned * 9 * NR_PHY_IN_LOG;
  }
  
  /*
   * Looks up the logical address from reverse trans map and check if its valid by
   * comparing the logical to physical address with the physical address.
   * Returns 0 on free, otherwise 1 if in use
   */
  static void rrpc_block_map_update(struct rrpc *rrpc, struct rrpc_block *rblk)
  {
  	struct nvm_dev *dev = rrpc->dev;
  	int offset;
  	struct rrpc_addr *laddr;

  	u64 bpaddr, paddr, pladdr;

  	bpaddr = block_to_rel_addr(rrpc, rblk);
  	for (offset = 0; offset < dev->sec_per_blk; offset++) {
  		paddr = bpaddr + offset;

  
  		pladdr = rrpc->rev_trans_map[paddr].addr;
  		if (pladdr == ADDR_EMPTY)
  			continue;
  
  		laddr = &rrpc->trans_map[pladdr];
  
  		if (paddr == laddr->addr) {
  			laddr->rblk = rblk;
  		} else {
  			set_bit(offset, rblk->invalid_pages);
  			rblk->nr_invalid_pages++;
  		}
  	}
  }
  
  static int rrpc_blocks_init(struct rrpc *rrpc)
  {
  	struct rrpc_lun *rlun;
  	struct rrpc_block *rblk;
  	int lun_iter, blk_iter;
  
  	for (lun_iter = 0; lun_iter < rrpc->nr_luns; lun_iter++) {
  		rlun = &rrpc->luns[lun_iter];
  
  		for (blk_iter = 0; blk_iter < rrpc->dev->blks_per_lun;
  								blk_iter++) {
  			rblk = &rlun->blocks[blk_iter];
  			rrpc_block_map_update(rrpc, rblk);
  		}
  	}
  
  	return 0;
  }
  
  static int rrpc_luns_configure(struct rrpc *rrpc)
  {
  	struct rrpc_lun *rlun;
  	struct rrpc_block *rblk;
  	int i;
  
  	for (i = 0; i < rrpc->nr_luns; i++) {
  		rlun = &rrpc->luns[i];
  
  		rblk = rrpc_get_blk(rrpc, rlun, 0);
  		if (!rblk)

  			goto err;

  		rrpc_set_lun_cur(rlun, rblk, &rlun->cur);

  
  		/* Emergency gc block */
  		rblk = rrpc_get_blk(rrpc, rlun, 1);
  		if (!rblk)

  			goto err;

  		rrpc_set_lun_cur(rlun, rblk, &rlun->gc_cur);

  	}
  
  	return 0;

  err:
  	rrpc_put_blks(rrpc);
  	return -EINVAL;

  }
  
  static struct nvm_tgt_type tt_rrpc;
  
  static void *rrpc_init(struct nvm_dev *dev, struct gendisk *tdisk,
  						int lun_begin, int lun_end)
  {
  	struct request_queue *bqueue = dev->q;
  	struct request_queue *tqueue = tdisk->queue;
  	struct rrpc *rrpc;

  	sector_t soffset;

  	int ret;
  
  	if (!(dev->identity.dom & NVM_RSP_L2P)) {
  		pr_err("nvm: rrpc: device does not support l2p (%x)
  ",
  							dev->identity.dom);
  		return ERR_PTR(-EINVAL);
  	}
  
  	rrpc = kzalloc(sizeof(struct rrpc), GFP_KERNEL);
  	if (!rrpc)
  		return ERR_PTR(-ENOMEM);
  
  	rrpc->instance.tt = &tt_rrpc;
  	rrpc->dev = dev;
  	rrpc->disk = tdisk;
  
  	bio_list_init(&rrpc->requeue_bios);
  	spin_lock_init(&rrpc->bio_lock);
  	INIT_WORK(&rrpc->ws_requeue, rrpc_requeue);
  
  	rrpc->nr_luns = lun_end - lun_begin + 1;

  	rrpc->total_blocks = (unsigned long)dev->blks_per_lun * rrpc->nr_luns;
  	rrpc->nr_sects = (unsigned long long)dev->sec_per_lun * rrpc->nr_luns;

  
  	/* simple round-robin strategy */
  	atomic_set(&rrpc->next_lun, -1);

  	ret = rrpc_area_init(rrpc, &soffset);
  	if (ret < 0) {
  		pr_err("nvm: rrpc: could not initialize area
  ");
  		return ERR_PTR(ret);
  	}
  	rrpc->soffset = soffset;

  	ret = rrpc_luns_init(rrpc, lun_begin, lun_end);
  	if (ret) {
  		pr_err("nvm: rrpc: could not initialize luns
  ");
  		goto err;
  	}
  
  	rrpc->poffset = dev->sec_per_lun * lun_begin;
  	rrpc->lun_offset = lun_begin;
  
  	ret = rrpc_core_init(rrpc);
  	if (ret) {
  		pr_err("nvm: rrpc: could not initialize core
  ");
  		goto err;
  	}
  
  	ret = rrpc_map_init(rrpc);
  	if (ret) {
  		pr_err("nvm: rrpc: could not initialize maps
  ");
  		goto err;
  	}
  
  	ret = rrpc_blocks_init(rrpc);
  	if (ret) {
  		pr_err("nvm: rrpc: could not initialize state for blocks
  ");
  		goto err;
  	}
  
  	ret = rrpc_luns_configure(rrpc);
  	if (ret) {
  		pr_err("nvm: rrpc: not enough blocks available in LUNs.
  ");
  		goto err;
  	}
  
  	ret = rrpc_gc_init(rrpc);
  	if (ret) {
  		pr_err("nvm: rrpc: could not initialize gc
  ");
  		goto err;
  	}
  
  	/* inherit the size from the underlying device */
  	blk_queue_logical_block_size(tqueue, queue_physical_block_size(bqueue));
  	blk_queue_max_hw_sectors(tqueue, queue_max_hw_sectors(bqueue));
  
  	pr_info("nvm: rrpc initialized with %u luns and %llu pages.
  ",

  			rrpc->nr_luns, (unsigned long long)rrpc->nr_sects);

  
  	mod_timer(&rrpc->gc_timer, jiffies + msecs_to_jiffies(10));
  
  	return rrpc;
  err:
  	rrpc_free(rrpc);
  	return ERR_PTR(ret);
  }
  
  /* round robin, page-based FTL, and cost-based GC */
  static struct nvm_tgt_type tt_rrpc = {
  	.name		= "rrpc",
  	.version	= {1, 0, 0},
  
  	.make_rq	= rrpc_make_rq,
  	.capacity	= rrpc_capacity,
  	.end_io		= rrpc_end_io,
  
  	.init		= rrpc_init,
  	.exit		= rrpc_exit,
  };
  
  static int __init rrpc_module_init(void)
  {

  	return nvm_register_tgt_type(&tt_rrpc);

  }
  
  static void rrpc_module_exit(void)
  {

  	nvm_unregister_tgt_type(&tt_rrpc);

  }
  
  module_init(rrpc_module_init);
  module_exit(rrpc_module_exit);
  MODULE_LICENSE("GPL v2");
  MODULE_DESCRIPTION("Block-Device Target for Open-Channel SSDs");