/*
 * 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_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_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_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_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) {
                pr_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_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);
                pr_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_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;
}

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)) {
                pr_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) {
                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);
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) {
                pr_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) {
                pr_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) {
                        pr_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) {
                        pr_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)) {
                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);
        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;
}