/*
 * 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);
        }

#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\n");
                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\n");
                        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\n");
                        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\n");
                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\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 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\n", line->id);
        }
#ifdef CONFIG_NVM_DEBUG
        else
                WARN_ONCE(rqd->bio->bi_status, "pblk: corrupted write error\n");
#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)\n",
                                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.\n");
                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\n", 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\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);

        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\n", 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\n", 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\n", 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, rqd->nr_ppas, 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.\n");
                return 1;
        }

        bio = bio_alloc(GFP_KERNEL, pblk->max_write_pgs);
        if (!bio) {
                pr_err("pblk: cannot allocate write bio\n");
                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\n");
                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\n");
                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;
}