text: /*
   * Copyright (C) 2016 CNEX Labs
   * Initial release: Javier Gonzalez <javier@cnexlabs.com>
   *                  Matias Bjorling <matias@cnexlabs.com>
   *
   * 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.
   *
   * pblk-write.c - pblk's write path from write buffer to media
   */
  
  #include "pblk.h"
  
  static unsigned long pblk_end_w_bio(struct pblk *pblk, struct nvm_rq *rqd,
  				    struct pblk_c_ctx *c_ctx)
  {
  	struct bio *original_bio;
  	struct pblk_rb *rwb = &pblk->rwb;
  	unsigned long ret;
  	int i;
  
  	for (i = 0; i < c_ctx->nr_valid; i++) {
  		struct pblk_w_ctx *w_ctx;
  		int pos = c_ctx->sentry + i;
  		int flags;
  
  		w_ctx = pblk_rb_w_ctx(rwb, pos);
  		flags = READ_ONCE(w_ctx->flags);
  
  		if (flags & PBLK_FLUSH_ENTRY) {
  			flags &= ~PBLK_FLUSH_ENTRY;
  			/* Release flags on context. Protect from writes */
  			smp_store_release(&w_ctx->flags, flags);
  
  #ifdef CONFIG_NVM_PBLK_DEBUG
  			atomic_dec(&rwb->inflight_flush_point);
  #endif
  		}
  
  		while ((original_bio = bio_list_pop(&w_ctx->bios)))
  			bio_endio(original_bio);
  	}
  
  	if (c_ctx->nr_padded)
  		pblk_bio_free_pages(pblk, rqd->bio, c_ctx->nr_valid,
  							c_ctx->nr_padded);
  
  #ifdef CONFIG_NVM_PBLK_DEBUG
  	atomic_long_add(rqd->nr_ppas, &pblk->sync_writes);
  #endif
  
  	ret = pblk_rb_sync_advance(&pblk->rwb, c_ctx->nr_valid);
  
  	bio_put(rqd->bio);
  	pblk_free_rqd(pblk, rqd, PBLK_WRITE);
  
  	return ret;
  }
  
  static unsigned long pblk_end_queued_w_bio(struct pblk *pblk,
  					   struct nvm_rq *rqd,
  					   struct pblk_c_ctx *c_ctx)
  {
  	list_del(&c_ctx->list);
  	return pblk_end_w_bio(pblk, rqd, c_ctx);
  }
  
  static void pblk_complete_write(struct pblk *pblk, struct nvm_rq *rqd,
  				struct pblk_c_ctx *c_ctx)
  {
  	struct pblk_c_ctx *c, *r;
  	unsigned long flags;
  	unsigned long pos;
  
  #ifdef CONFIG_NVM_PBLK_DEBUG
  	atomic_long_sub(c_ctx->nr_valid, &pblk->inflight_writes);
  #endif
  
  	pblk_up_rq(pblk, rqd->ppa_list, rqd->nr_ppas, c_ctx->lun_bitmap);
  
  	pos = pblk_rb_sync_init(&pblk->rwb, &flags);
  	if (pos == c_ctx->sentry) {
  		pos = pblk_end_w_bio(pblk, rqd, c_ctx);
  
  retry:
  		list_for_each_entry_safe(c, r, &pblk->compl_list, list) {
  			rqd = nvm_rq_from_c_ctx(c);
  			if (c->sentry == pos) {
  				pos = pblk_end_queued_w_bio(pblk, rqd, c);
  				goto retry;
  			}
  		}
  	} else {
  		WARN_ON(nvm_rq_from_c_ctx(c_ctx) != rqd);
  		list_add_tail(&c_ctx->list, &pblk->compl_list);
  	}
  	pblk_rb_sync_end(&pblk->rwb, &flags);
  }
  
  /* Map remaining sectors in chunk, starting from ppa */
  static void pblk_map_remaining(struct pblk *pblk, struct ppa_addr *ppa)
  {
  	struct nvm_tgt_dev *dev = pblk->dev;
  	struct nvm_geo *geo = &dev->geo;
  	struct pblk_line *line;
  	struct ppa_addr map_ppa = *ppa;
  	u64 paddr;
  	int done = 0;
  
  	line = &pblk->lines[pblk_ppa_to_line(*ppa)];
  	spin_lock(&line->lock);
  
  	while (!done)  {
  		paddr = pblk_dev_ppa_to_line_addr(pblk, map_ppa);
  
  		if (!test_and_set_bit(paddr, line->map_bitmap))
  			line->left_msecs--;
  
  		if (!test_and_set_bit(paddr, line->invalid_bitmap))
  			le32_add_cpu(line->vsc, -1);
  
  		if (geo->version == NVM_OCSSD_SPEC_12) {
  			map_ppa.ppa++;
  			if (map_ppa.g.pg == geo->num_pg)
  				done = 1;
  		} else {
  			map_ppa.m.sec++;
  			if (map_ppa.m.sec == geo->clba)
  				done = 1;
  		}
  	}
  
  	line->w_err_gc->has_write_err = 1;
  	spin_unlock(&line->lock);
  }
  
  static void pblk_prepare_resubmit(struct pblk *pblk, unsigned int sentry,
  				  unsigned int nr_entries)
  {
  	struct pblk_rb *rb = &pblk->rwb;
  	struct pblk_rb_entry *entry;
  	struct pblk_line *line;
  	struct pblk_w_ctx *w_ctx;
  	struct ppa_addr ppa_l2p;
  	int flags;
  	unsigned int pos, i;
  
  	spin_lock(&pblk->trans_lock);
  	pos = sentry;
  	for (i = 0; i < nr_entries; i++) {
  		entry = &rb->entries[pos];
  		w_ctx = &entry->w_ctx;
  
  		/* Check if the lba has been overwritten */
  		ppa_l2p = pblk_trans_map_get(pblk, w_ctx->lba);
  		if (!pblk_ppa_comp(ppa_l2p, entry->cacheline))
  			w_ctx->lba = ADDR_EMPTY;
  
  		/* Mark up the entry as submittable again */
  		flags = READ_ONCE(w_ctx->flags);
  		flags |= PBLK_WRITTEN_DATA;
  		/* Release flags on write context. Protect from writes */
  		smp_store_release(&w_ctx->flags, flags);
  
  		/* Decrese the reference count to the line as we will
  		 * re-map these entries
  		 */
  		line = &pblk->lines[pblk_ppa_to_line(w_ctx->ppa)];
  		kref_put(&line->ref, pblk_line_put);
  
  		pos = (pos + 1) & (rb->nr_entries - 1);
  	}
  	spin_unlock(&pblk->trans_lock);
  }
  
  static void pblk_queue_resubmit(struct pblk *pblk, struct pblk_c_ctx *c_ctx)
  {
  	struct pblk_c_ctx *r_ctx;
  
  	r_ctx = kzalloc(sizeof(struct pblk_c_ctx), GFP_KERNEL);
  	if (!r_ctx)
  		return;
  
  	r_ctx->lun_bitmap = NULL;
  	r_ctx->sentry = c_ctx->sentry;
  	r_ctx->nr_valid = c_ctx->nr_valid;
  	r_ctx->nr_padded = c_ctx->nr_padded;
  
  	spin_lock(&pblk->resubmit_lock);
  	list_add_tail(&r_ctx->list, &pblk->resubmit_list);
  	spin_unlock(&pblk->resubmit_lock);
  
  #ifdef CONFIG_NVM_PBLK_DEBUG
  	atomic_long_add(c_ctx->nr_valid, &pblk->recov_writes);
  #endif
  }
  
  static void pblk_submit_rec(struct work_struct *work)
  {
  	struct pblk_rec_ctx *recovery =
  			container_of(work, struct pblk_rec_ctx, ws_rec);
  	struct pblk *pblk = recovery->pblk;
  	struct nvm_rq *rqd = recovery->rqd;
  	struct pblk_c_ctx *c_ctx = nvm_rq_to_pdu(rqd);
  	struct ppa_addr *ppa_list;
  
  	pblk_log_write_err(pblk, rqd);
  
  	if (rqd->nr_ppas == 1)
  		ppa_list = &rqd->ppa_addr;
  	else
  		ppa_list = rqd->ppa_list;
  
  	pblk_map_remaining(pblk, ppa_list);
  	pblk_queue_resubmit(pblk, c_ctx);
  
  	pblk_up_rq(pblk, rqd->ppa_list, rqd->nr_ppas, c_ctx->lun_bitmap);
  	if (c_ctx->nr_padded)
  		pblk_bio_free_pages(pblk, rqd->bio, c_ctx->nr_valid,
  							c_ctx->nr_padded);
  	bio_put(rqd->bio);
  	pblk_free_rqd(pblk, rqd, PBLK_WRITE);
  	mempool_free(recovery, &pblk->rec_pool);
  
  	atomic_dec(&pblk->inflight_io);
  }
  
  
  static void pblk_end_w_fail(struct pblk *pblk, struct nvm_rq *rqd)
  {
  	struct pblk_rec_ctx *recovery;
  
  	recovery = mempool_alloc(&pblk->rec_pool, GFP_ATOMIC);
  	if (!recovery) {
  		pblk_err(pblk, "could not allocate recovery work\n");
  		return;
  	}
  
  	recovery->pblk = pblk;
  	recovery->rqd = rqd;
  
  	INIT_WORK(&recovery->ws_rec, pblk_submit_rec);
  	queue_work(pblk->close_wq, &recovery->ws_rec);
  }
  
  static void pblk_end_io_write(struct nvm_rq *rqd)
  {
  	struct pblk *pblk = rqd->private;
  	struct pblk_c_ctx *c_ctx = nvm_rq_to_pdu(rqd);
  
  	if (rqd->error) {
  		pblk_end_w_fail(pblk, rqd);
  		return;
  	}
  #ifdef CONFIG_NVM_PBLK_DEBUG
  	else
  		WARN_ONCE(rqd->bio->bi_status, "pblk: corrupted write error\n");
  #endif
  
  	pblk_complete_write(pblk, rqd, c_ctx);
  	atomic_dec(&pblk->inflight_io);
  }
  
  static void pblk_end_io_write_meta(struct nvm_rq *rqd)
  {
  	struct pblk *pblk = rqd->private;
  	struct pblk_g_ctx *m_ctx = nvm_rq_to_pdu(rqd);
  	struct pblk_line *line = m_ctx->private;
  	struct pblk_emeta *emeta = line->emeta;
  	int sync;
  
  	pblk_up_page(pblk, rqd->ppa_list, rqd->nr_ppas);
  
  	if (rqd->error) {
  		pblk_log_write_err(pblk, rqd);
  		pblk_err(pblk, "metadata I/O failed. Line %d\n", line->id);
  		line->w_err_gc->has_write_err = 1;
  	}
  
  	sync = atomic_add_return(rqd->nr_ppas, &emeta->sync);
  	if (sync == emeta->nr_entries)
  		pblk_gen_run_ws(pblk, line, NULL, pblk_line_close_ws,
  						GFP_ATOMIC, pblk->close_wq);
  
  	pblk_free_rqd(pblk, rqd, PBLK_WRITE_INT);
  
  	atomic_dec(&pblk->inflight_io);
  }
  
  static int pblk_alloc_w_rq(struct pblk *pblk, struct nvm_rq *rqd,
  			   unsigned int nr_secs,
  			   nvm_end_io_fn(*end_io))
  {
  	struct nvm_tgt_dev *dev = pblk->dev;
  
  	/* Setup write request */
  	rqd->opcode = NVM_OP_PWRITE;
  	rqd->nr_ppas = nr_secs;
  	rqd->flags = pblk_set_progr_mode(pblk, PBLK_WRITE);
  	rqd->private = pblk;
  	rqd->end_io = end_io;
  
  	rqd->meta_list = nvm_dev_dma_alloc(dev->parent, GFP_KERNEL,
  							&rqd->dma_meta_list);
  	if (!rqd->meta_list)
  		return -ENOMEM;
  
  	rqd->ppa_list = rqd->meta_list + pblk_dma_meta_size;
  	rqd->dma_ppa_list = rqd->dma_meta_list + pblk_dma_meta_size;
  
  	return 0;
  }
  
  static int pblk_setup_w_rq(struct pblk *pblk, struct nvm_rq *rqd,
  			   struct ppa_addr *erase_ppa)
  {
  	struct pblk_line_meta *lm = &pblk->lm;
  	struct pblk_line *e_line = pblk_line_get_erase(pblk);
  	struct pblk_c_ctx *c_ctx = nvm_rq_to_pdu(rqd);
  	unsigned int valid = c_ctx->nr_valid;
  	unsigned int padded = c_ctx->nr_padded;
  	unsigned int nr_secs = valid + padded;
  	unsigned long *lun_bitmap;
  	int ret;
  
  	lun_bitmap = kzalloc(lm->lun_bitmap_len, GFP_KERNEL);
  	if (!lun_bitmap)
  		return -ENOMEM;
  	c_ctx->lun_bitmap = lun_bitmap;
  
  	ret = pblk_alloc_w_rq(pblk, rqd, nr_secs, pblk_end_io_write);
  	if (ret) {
  		kfree(lun_bitmap);
  		return ret;
  	}
  
  	if (likely(!e_line || !atomic_read(&e_line->left_eblks)))
  		pblk_map_rq(pblk, rqd, c_ctx->sentry, lun_bitmap, valid, 0);
  	else
  		pblk_map_erase_rq(pblk, rqd, c_ctx->sentry, lun_bitmap,
  							valid, erase_ppa);
  
  	return 0;
  }
  
  static int pblk_calc_secs_to_sync(struct pblk *pblk, unsigned int secs_avail,
  				  unsigned int secs_to_flush)
  {
  	int secs_to_sync;
  
  	secs_to_sync = pblk_calc_secs(pblk, secs_avail, secs_to_flush);
  
  #ifdef CONFIG_NVM_PBLK_DEBUG
  	if ((!secs_to_sync && secs_to_flush)
  			|| (secs_to_sync < 0)
  			|| (secs_to_sync > secs_avail && !secs_to_flush)) {
  		pblk_err(pblk, "bad sector calculation (a:%d,s:%d,f:%d)\n",
  				secs_avail, secs_to_sync, secs_to_flush);
  	}
  #endif
  
  	return secs_to_sync;
  }
  
  int pblk_submit_meta_io(struct pblk *pblk, struct pblk_line *meta_line)
  {
  	struct nvm_tgt_dev *dev = pblk->dev;
  	struct nvm_geo *geo = &dev->geo;
  	struct pblk_line_mgmt *l_mg = &pblk->l_mg;
  	struct pblk_line_meta *lm = &pblk->lm;
  	struct pblk_emeta *emeta = meta_line->emeta;
  	struct pblk_g_ctx *m_ctx;
  	struct bio *bio;
  	struct nvm_rq *rqd;
  	void *data;
  	u64 paddr;
  	int rq_ppas = pblk->min_write_pgs;
  	int id = meta_line->id;
  	int rq_len;
  	int i, j;
  	int ret;
  
  	rqd = pblk_alloc_rqd(pblk, PBLK_WRITE_INT);
  
  	m_ctx = nvm_rq_to_pdu(rqd);
  	m_ctx->private = meta_line;
  
  	rq_len = rq_ppas * geo->csecs;
  	data = ((void *)emeta->buf) + emeta->mem;
  
  	bio = pblk_bio_map_addr(pblk, data, rq_ppas, rq_len,
  					l_mg->emeta_alloc_type, GFP_KERNEL);
  	if (IS_ERR(bio)) {
  		pblk_err(pblk, "failed to map emeta io");
  		ret = PTR_ERR(bio);
  		goto fail_free_rqd;
  	}
  	bio->bi_iter.bi_sector = 0; /* internal bio */
  	bio_set_op_attrs(bio, REQ_OP_WRITE, 0);
  	rqd->bio = bio;
  
  	ret = pblk_alloc_w_rq(pblk, rqd, rq_ppas, pblk_end_io_write_meta);
  	if (ret)
  		goto fail_free_bio;
  
  	for (i = 0; i < rqd->nr_ppas; ) {
  		spin_lock(&meta_line->lock);
  		paddr = __pblk_alloc_page(pblk, meta_line, rq_ppas);
  		spin_unlock(&meta_line->lock);
  		for (j = 0; j < rq_ppas; j++, i++, paddr++)
  			rqd->ppa_list[i] = addr_to_gen_ppa(pblk, paddr, id);
  	}
  
  	emeta->mem += rq_len;
  	if (emeta->mem >= lm->emeta_len[0]) {
  		spin_lock(&l_mg->close_lock);
  		list_del(&meta_line->list);
  		spin_unlock(&l_mg->close_lock);
  	}
  
  	pblk_down_page(pblk, rqd->ppa_list, rqd->nr_ppas);
  
  	ret = pblk_submit_io(pblk, rqd);
  	if (ret) {
  		pblk_err(pblk, "emeta I/O submission failed: %d\n", ret);
  		goto fail_rollback;
  	}
  
  	return NVM_IO_OK;
  
  fail_rollback:
  	pblk_up_page(pblk, rqd->ppa_list, rqd->nr_ppas);
  	spin_lock(&l_mg->close_lock);
  	pblk_dealloc_page(pblk, meta_line, rq_ppas);
  	list_add(&meta_line->list, &meta_line->list);
  	spin_unlock(&l_mg->close_lock);
  fail_free_bio:
  	bio_put(bio);
  fail_free_rqd:
  	pblk_free_rqd(pblk, rqd, PBLK_WRITE_INT);
  	return ret;
  }
  
  static inline bool pblk_valid_meta_ppa(struct pblk *pblk,
  				       struct pblk_line *meta_line,
  				       struct nvm_rq *data_rqd)
  {
  	struct nvm_tgt_dev *dev = pblk->dev;
  	struct nvm_geo *geo = &dev->geo;
  	struct pblk_c_ctx *data_c_ctx = nvm_rq_to_pdu(data_rqd);
  	struct pblk_line *data_line = pblk_line_get_data(pblk);
  	struct ppa_addr ppa, ppa_opt;
  	u64 paddr;
  	int pos_opt;
  
  	/* Schedule a metadata I/O that is half the distance from the data I/O
  	 * with regards to the number of LUNs forming the pblk instance. This
  	 * balances LUN conflicts across every I/O.
  	 *
  	 * When the LUN configuration changes (e.g., due to GC), this distance
  	 * can align, which would result on metadata and data I/Os colliding. In
  	 * this case, modify the distance to not be optimal, but move the
  	 * optimal in the right direction.
  	 */
  	paddr = pblk_lookup_page(pblk, meta_line);
  	ppa = addr_to_gen_ppa(pblk, paddr, 0);
  	ppa_opt = addr_to_gen_ppa(pblk, paddr + data_line->meta_distance, 0);
  	pos_opt = pblk_ppa_to_pos(geo, ppa_opt);
  
  	if (test_bit(pos_opt, data_c_ctx->lun_bitmap) ||
  				test_bit(pos_opt, data_line->blk_bitmap))
  		return true;
  
  	if (unlikely(pblk_ppa_comp(ppa_opt, ppa)))
  		data_line->meta_distance--;
  
  	return false;
  }
  
  static struct pblk_line *pblk_should_submit_meta_io(struct pblk *pblk,
  						    struct nvm_rq *data_rqd)
  {
  	struct pblk_line_meta *lm = &pblk->lm;
  	struct pblk_line_mgmt *l_mg = &pblk->l_mg;
  	struct pblk_line *meta_line;
  
  	spin_lock(&l_mg->close_lock);
  retry:
  	if (list_empty(&l_mg->emeta_list)) {
  		spin_unlock(&l_mg->close_lock);
  		return NULL;
  	}
  	meta_line = list_first_entry(&l_mg->emeta_list, struct pblk_line, list);
  	if (meta_line->emeta->mem >= lm->emeta_len[0])
  		goto retry;
  	spin_unlock(&l_mg->close_lock);
  
  	if (!pblk_valid_meta_ppa(pblk, meta_line, data_rqd))
  		return NULL;
  
  	return meta_line;
  }
  
  static int pblk_submit_io_set(struct pblk *pblk, struct nvm_rq *rqd)
  {
  	struct ppa_addr erase_ppa;
  	struct pblk_line *meta_line;
  	int err;
  
  	pblk_ppa_set_empty(&erase_ppa);
  
  	/* Assign lbas to ppas and populate request structure */
  	err = pblk_setup_w_rq(pblk, rqd, &erase_ppa);
  	if (err) {
  		pblk_err(pblk, "could not setup write request: %d\n", err);
  		return NVM_IO_ERR;
  	}
  
  	meta_line = pblk_should_submit_meta_io(pblk, rqd);
  
  	/* Submit data write for current data line */
  	err = pblk_submit_io(pblk, rqd);
  	if (err) {
  		pblk_err(pblk, "data I/O submission failed: %d\n", err);
  		return NVM_IO_ERR;
  	}
  
  	if (!pblk_ppa_empty(erase_ppa)) {
  		/* Submit erase for next data line */
  		if (pblk_blk_erase_async(pblk, erase_ppa)) {
  			struct pblk_line *e_line = pblk_line_get_erase(pblk);
  			struct nvm_tgt_dev *dev = pblk->dev;
  			struct nvm_geo *geo = &dev->geo;
  			int bit;
  
  			atomic_inc(&e_line->left_eblks);
  			bit = pblk_ppa_to_pos(geo, erase_ppa);
  			WARN_ON(!test_and_clear_bit(bit, e_line->erase_bitmap));
  		}
  	}
  
  	if (meta_line) {
  		/* Submit metadata write for previous data line */
  		err = pblk_submit_meta_io(pblk, meta_line);
  		if (err) {
  			pblk_err(pblk, "metadata I/O submission failed: %d",
  					err);
  			return NVM_IO_ERR;
  		}
  	}
  
  	return NVM_IO_OK;
  }
  
  static void pblk_free_write_rqd(struct pblk *pblk, struct nvm_rq *rqd)
  {
  	struct pblk_c_ctx *c_ctx = nvm_rq_to_pdu(rqd);
  	struct bio *bio = rqd->bio;
  
  	if (c_ctx->nr_padded)
  		pblk_bio_free_pages(pblk, bio, c_ctx->nr_valid,
  							c_ctx->nr_padded);
  }
  
  static int pblk_submit_write(struct pblk *pblk)
  {
  	struct bio *bio;
  	struct nvm_rq *rqd;
  	unsigned int secs_avail, secs_to_sync, secs_to_com;
  	unsigned int secs_to_flush;
  	unsigned long pos;
  	unsigned int resubmit;
  
  	spin_lock(&pblk->resubmit_lock);
  	resubmit = !list_empty(&pblk->resubmit_list);
  	spin_unlock(&pblk->resubmit_lock);
  
  	/* Resubmit failed writes first */
  	if (resubmit) {
  		struct pblk_c_ctx *r_ctx;
  
  		spin_lock(&pblk->resubmit_lock);
  		r_ctx = list_first_entry(&pblk->resubmit_list,
  					struct pblk_c_ctx, list);
  		list_del(&r_ctx->list);
  		spin_unlock(&pblk->resubmit_lock);
  
  		secs_avail = r_ctx->nr_valid;
  		pos = r_ctx->sentry;
  
  		pblk_prepare_resubmit(pblk, pos, secs_avail);
  		secs_to_sync = pblk_calc_secs_to_sync(pblk, secs_avail,
  				secs_avail);
  
  		kfree(r_ctx);
  	} else {
  		/* If there are no sectors in the cache,
  		 * flushes (bios without data) will be cleared on
  		 * the cache threads
  		 */
  		secs_avail = pblk_rb_read_count(&pblk->rwb);
  		if (!secs_avail)
  			return 1;
  
  		secs_to_flush = pblk_rb_flush_point_count(&pblk->rwb);
  		if (!secs_to_flush && secs_avail < pblk->min_write_pgs)
  			return 1;
  
  		secs_to_sync = pblk_calc_secs_to_sync(pblk, secs_avail,
  					secs_to_flush);
  		if (secs_to_sync > pblk->max_write_pgs) {
  			pblk_err(pblk, "bad buffer sync calculation\n");
  			return 1;
  		}
  
  		secs_to_com = (secs_to_sync > secs_avail) ?
  			secs_avail : secs_to_sync;
  		pos = pblk_rb_read_commit(&pblk->rwb, secs_to_com);
  	}
  
  	bio = bio_alloc(GFP_KERNEL, secs_to_sync);
  
  	bio->bi_iter.bi_sector = 0; /* internal bio */
  	bio_set_op_attrs(bio, REQ_OP_WRITE, 0);
  
  	rqd = pblk_alloc_rqd(pblk, PBLK_WRITE);
  	rqd->bio = bio;
  
  	if (pblk_rb_read_to_bio(&pblk->rwb, rqd, pos, secs_to_sync,
  								secs_avail)) {
  		pblk_err(pblk, "corrupted write bio\n");
  		goto fail_put_bio;
  	}
  
  	if (pblk_submit_io_set(pblk, rqd))
  		goto fail_free_bio;
  
  #ifdef CONFIG_NVM_PBLK_DEBUG
  	atomic_long_add(secs_to_sync, &pblk->sub_writes);
  #endif
  
  	return 0;
  
  fail_free_bio:
  	pblk_free_write_rqd(pblk, rqd);
  fail_put_bio:
  	bio_put(bio);
  	pblk_free_rqd(pblk, rqd, PBLK_WRITE);
  
  	return 1;
  }
  
  int pblk_write_ts(void *data)
  {
  	struct pblk *pblk = data;
  
  	while (!kthread_should_stop()) {
  		if (!pblk_submit_write(pblk))
  			continue;
  		set_current_state(TASK_INTERRUPTIBLE);
  		io_schedule();
  	}
  
  	return 0;
  }
  