/*
   * 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 nvm_tgt_dev *dev = pblk->dev;
  	struct bio *original_bio;
  	unsigned long ret;
  	int i;
  
  	for (i = 0; i < c_ctx->nr_valid; i++) {
  		struct pblk_w_ctx *w_ctx;

  
  		w_ctx = pblk_rb_w_ctx(&pblk->rwb, c_ctx->sentry + i);

  		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_DEBUG

  	atomic_long_add(c_ctx->nr_valid, &pblk->sync_writes);

  #endif
  
  	ret = pblk_rb_sync_advance(&pblk->rwb, c_ctx->nr_valid);

  	nvm_dev_dma_free(dev->parent, rqd->meta_list, rqd->dma_meta_list);

  
  	bio_put(rqd->bio);
  	pblk_free_rqd(pblk, rqd, 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_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);
  }
  
  /* When a write fails, we are not sure whether the block has grown bad or a page
   * range is more susceptible to write errors. If a high number of pages fail, we
   * assume that the block is bad and we mark it accordingly. In all cases, we
   * remap and resubmit the failed entries as fast as possible; if a flush is
   * waiting on a completion, the whole stack would stall otherwise.
   */
  static void pblk_end_w_fail(struct pblk *pblk, struct nvm_rq *rqd)
  {
  	void *comp_bits = &rqd->ppa_status;
  	struct pblk_c_ctx *c_ctx = nvm_rq_to_pdu(rqd);
  	struct pblk_rec_ctx *recovery;
  	struct ppa_addr *ppa_list = rqd->ppa_list;
  	int nr_ppas = rqd->nr_ppas;
  	unsigned int c_entries;
  	int bit, ret;
  
  	if (unlikely(nr_ppas == 1))
  		ppa_list = &rqd->ppa_addr;
  
  	recovery = mempool_alloc(pblk->rec_pool, GFP_ATOMIC);
  	if (!recovery) {
  		pr_err("pblk: could not allocate recovery context
  ");
  		return;
  	}
  	INIT_LIST_HEAD(&recovery->failed);
  
  	bit = -1;
  	while ((bit = find_next_bit(comp_bits, nr_ppas, bit + 1)) < nr_ppas) {
  		struct pblk_rb_entry *entry;
  		struct ppa_addr ppa;
  
  		/* Logic error */
  		if (bit > c_ctx->nr_valid) {

  			WARN_ONCE(1, "pblk: corrupted write request
  ");

  			mempool_free(recovery, pblk->rec_pool);

  			goto out;
  		}
  
  		ppa = ppa_list[bit];
  		entry = pblk_rb_sync_scan_entry(&pblk->rwb, &ppa);
  		if (!entry) {
  			pr_err("pblk: could not scan entry on write failure
  ");

  			mempool_free(recovery, pblk->rec_pool);

  			goto out;
  		}
  
  		/* The list is filled first and emptied afterwards. No need for
  		 * protecting it with a lock
  		 */
  		list_add_tail(&entry->index, &recovery->failed);
  	}
  
  	c_entries = find_first_bit(comp_bits, nr_ppas);
  	ret = pblk_recov_setup_rq(pblk, c_ctx, recovery, comp_bits, c_entries);
  	if (ret) {
  		pr_err("pblk: could not recover from write failure
  ");

  		mempool_free(recovery, pblk->rec_pool);

  		goto out;
  	}
  
  	INIT_WORK(&recovery->ws_rec, pblk_submit_rec);

  	queue_work(pblk->close_wq, &recovery->ws_rec);

  
  out:
  	pblk_complete_write(pblk, rqd, c_ctx);
  }
  
  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_log_write_err(pblk, rqd);
  		return pblk_end_w_fail(pblk, rqd);
  	}
  #ifdef CONFIG_NVM_DEBUG
  	else

  		WARN_ONCE(rqd->bio->bi_status, "pblk: corrupted write error
  ");

  #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 nvm_tgt_dev *dev = pblk->dev;

  	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);

  		pr_err("pblk: metadata I/O failed. Line %d
  ", line->id);

  	}
  #ifdef CONFIG_NVM_DEBUG
  	else
  		WARN_ONCE(rqd->bio->bi_status, "pblk: corrupted write error
  ");
  #endif
  
  	sync = atomic_add_return(rqd->nr_ppas, &emeta->sync);
  	if (sync == emeta->nr_entries)

  		pblk_line_run_ws(pblk, line, NULL, pblk_line_close_ws,
  								pblk->close_wq);

  
  	bio_put(rqd->bio);

  	nvm_dev_dma_free(dev->parent, rqd->meta_list, rqd->dma_meta_list);

  	pblk_free_rqd(pblk, rqd, READ);

  
  	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, 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 pblk_c_ctx *c_ctx, struct ppa_addr *erase_ppa)

  {
  	struct pblk_line_meta *lm = &pblk->lm;

  	struct pblk_line *e_line = pblk_line_get_erase(pblk);

  	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 = 0;
  
  	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;

  }
  
  int pblk_setup_w_rec_rq(struct pblk *pblk, struct nvm_rq *rqd,
  			struct pblk_c_ctx *c_ctx)
  {
  	struct pblk_line_meta *lm = &pblk->lm;
  	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, rqd->nr_ppas, pblk_end_io_write);

  	if (ret)
  		return ret;
  
  	pblk_map_rq(pblk, rqd, c_ctx->sentry, lun_bitmap, c_ctx->nr_valid, 0);
  
  	rqd->ppa_status = (u64)0;
  	rqd->flags = pblk_set_progr_mode(pblk, WRITE);
  
  	return ret;
  }
  
  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_DEBUG
  	if ((!secs_to_sync && secs_to_flush)
  			|| (secs_to_sync < 0)
  			|| (secs_to_sync > secs_avail && !secs_to_flush)) {
  		pr_err("pblk: bad sector calculation (a:%d,s:%d,f:%d)
  ",
  				secs_avail, secs_to_sync, secs_to_flush);
  	}
  #endif
  
  	return secs_to_sync;
  }

  static inline int pblk_valid_meta_ppa(struct pblk *pblk,
  				      struct pblk_line *meta_line,
  				      struct ppa_addr *ppa_list, int nr_ppas)
  {
  	struct nvm_tgt_dev *dev = pblk->dev;
  	struct nvm_geo *geo = &dev->geo;
  	struct pblk_line *data_line;
  	struct ppa_addr ppa, ppa_opt;
  	u64 paddr;
  	int i;
  
  	data_line = &pblk->lines[pblk_dev_ppa_to_line(ppa_list[0])];
  	paddr = pblk_lookup_page(pblk, meta_line);
  	ppa = addr_to_gen_ppa(pblk, paddr, 0);
  
  	if (test_bit(pblk_ppa_to_pos(geo, ppa), data_line->blk_bitmap))
  		return 1;
  
  	/* 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 a LUN deadlock. In this case, modify
  	 * the distance to not be optimal, but allow metadata I/Os to succeed.
  	 */
  	ppa_opt = addr_to_gen_ppa(pblk, paddr + data_line->meta_distance, 0);
  	if (unlikely(ppa_opt.ppa == ppa.ppa)) {
  		data_line->meta_distance--;
  		return 0;
  	}
  
  	for (i = 0; i < nr_ppas; i += pblk->min_write_pgs)
  		if (ppa_list[i].g.ch == ppa_opt.g.ch &&
  					ppa_list[i].g.lun == ppa_opt.g.lun)
  			return 1;
  
  	if (test_bit(pblk_ppa_to_pos(geo, ppa_opt), data_line->blk_bitmap)) {
  		for (i = 0; i < nr_ppas; i += pblk->min_write_pgs)
  			if (ppa_list[i].g.ch == ppa.g.ch &&
  						ppa_list[i].g.lun == ppa.g.lun)
  				return 0;
  
  		return 1;
  	}
  
  	return 0;
  }
  
  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, READ);
  	if (IS_ERR(rqd)) {
  		pr_err("pblk: cannot allocate write req.
  ");
  		return PTR_ERR(rqd);
  	}
  	m_ctx = nvm_rq_to_pdu(rqd);
  	m_ctx->private = meta_line;
  
  	rq_len = rq_ppas * geo->sec_size;
  	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)) {
  		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);
  		WARN(!bitmap_full(meta_line->map_bitmap, lm->sec_per_line),
  				"pblk: corrupt meta line %d
  ", meta_line->id);
  		spin_unlock(&l_mg->close_lock);
  	}

  	pblk_down_page(pblk, rqd->ppa_list, rqd->nr_ppas);

  	ret = pblk_submit_io(pblk, rqd);
  	if (ret) {
  		pr_err("pblk: emeta I/O submission failed: %d
  ", 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);

  
  	nvm_dev_dma_free(dev->parent, rqd->meta_list, rqd->dma_meta_list);

  fail_free_bio:

  	if (likely(l_mg->emeta_alloc_type == PBLK_VMALLOC_META))
  		bio_put(bio);

  fail_free_rqd:
  	pblk_free_rqd(pblk, rqd, READ);
  	return ret;
  }
  
  static int pblk_sched_meta_io(struct pblk *pblk, struct ppa_addr *prev_list,
  			       int prev_n)
  {
  	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 0;
  	}
  	meta_line = list_first_entry(&l_mg->emeta_list, struct pblk_line, list);
  	if (bitmap_full(meta_line->map_bitmap, lm->sec_per_line))
  		goto retry;
  	spin_unlock(&l_mg->close_lock);
  
  	if (!pblk_valid_meta_ppa(pblk, meta_line, prev_list, prev_n))
  		return 0;
  
  	return pblk_submit_meta_io(pblk, meta_line);
  }

  static int pblk_submit_io_set(struct pblk *pblk, struct nvm_rq *rqd)
  {
  	struct pblk_c_ctx *c_ctx = nvm_rq_to_pdu(rqd);
  	struct ppa_addr erase_ppa;
  	int err;
  
  	ppa_set_empty(&erase_ppa);
  
  	/* Assign lbas to ppas and populate request structure */
  	err = pblk_setup_w_rq(pblk, rqd, c_ctx, &erase_ppa);
  	if (err) {
  		pr_err("pblk: could not setup write request: %d
  ", err);
  		return NVM_IO_ERR;
  	}

  	if (likely(ppa_empty(erase_ppa))) {
  		/* Submit metadata write for previous data line */
  		err = pblk_sched_meta_io(pblk, rqd->ppa_list, rqd->nr_ppas);
  		if (err) {
  			pr_err("pblk: metadata I/O submission failed: %d", err);
  			return NVM_IO_ERR;
  		}
  
  		/* Submit data write for current data line */
  		err = pblk_submit_io(pblk, rqd);
  		if (err) {
  			pr_err("pblk: data I/O submission failed: %d
  ", err);
  			return NVM_IO_ERR;
  		}
  	} else {
  		/* Submit data write for current data line */
  		err = pblk_submit_io(pblk, rqd);
  		if (err) {
  			pr_err("pblk: data I/O submission failed: %d
  ", err);
  			return NVM_IO_ERR;
  		}

  		/* Submit available 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));
  		}

  	}
  
  	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;

  
  	/* 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_sync_point_count(&pblk->rwb);
  	if (!secs_to_flush && secs_avail < pblk->min_write_pgs)
  		return 1;
  
  	rqd = pblk_alloc_rqd(pblk, WRITE);
  	if (IS_ERR(rqd)) {
  		pr_err("pblk: cannot allocate write req.
  ");
  		return 1;
  	}

  
  	bio = bio_alloc(GFP_KERNEL, pblk->max_write_pgs);
  	if (!bio) {
  		pr_err("pblk: cannot allocate write 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;
  
  	secs_to_sync = pblk_calc_secs_to_sync(pblk, secs_avail, secs_to_flush);
  	if (secs_to_sync > pblk->max_write_pgs) {
  		pr_err("pblk: bad buffer sync calculation
  ");
  		goto fail_put_bio;
  	}
  
  	secs_to_com = (secs_to_sync > secs_avail) ? secs_avail : secs_to_sync;
  	pos = pblk_rb_read_commit(&pblk->rwb, secs_to_com);

  	if (pblk_rb_read_to_bio(&pblk->rwb, rqd, bio, pos, secs_to_sync,
  								secs_avail)) {

  		pr_err("pblk: corrupted write bio
  ");
  		goto fail_put_bio;
  	}

  	if (pblk_submit_io_set(pblk, rqd))

  		goto fail_free_bio;

  
  #ifdef CONFIG_NVM_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);
  fail_free_rqd:
  	pblk_free_rqd(pblk, rqd, 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;
  }