/*
 * 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-map.c - pblk's lba-ppa mapping strategy
 *
 */

#include "pblk.h"

static int pblk_map_page_data(struct pblk *pblk, unsigned int sentry,
                              struct ppa_addr *ppa_list,
                              unsigned long *lun_bitmap,
                              struct pblk_sec_meta *meta_list,
                              unsigned int valid_secs)
{
        struct pblk_line *line = pblk_line_get_data(pblk);
        struct pblk_emeta *emeta;
        struct pblk_w_ctx *w_ctx;
        __le64 *lba_list;
        u64 paddr;
        int nr_secs = pblk->min_write_pgs;
        int i;

        if (pblk_line_is_full(line)) {
                struct pblk_line *prev_line = line;

                /* If we cannot allocate a new line, make sure to store metadata
                 * on current line and then fail
                 */
                line = pblk_line_replace_data(pblk);
                pblk_line_close_meta(pblk, prev_line);

                if (!line)
                        return -EINTR;
        }

        emeta = line->emeta;
        lba_list = emeta_to_lbas(pblk, emeta->buf);

        paddr = pblk_alloc_page(pblk, line, nr_secs);

        for (i = 0; i < nr_secs; i++, paddr++) {
                __le64 addr_empty = cpu_to_le64(ADDR_EMPTY);

                /* ppa to be sent to the device */
                ppa_list[i] = addr_to_gen_ppa(pblk, paddr, line->id);

                /* Write context for target bio completion on write buffer. Note
                 * that the write buffer is protected by the sync backpointer,
                 * and a single writer thread have access to each specific entry
                 * at a time. Thus, it is safe to modify the context for the
                 * entry we are setting up for submission without taking any
                 * lock or memory barrier.
                 */
                if (i < valid_secs) {
                        kref_get(&line->ref);
                        w_ctx = pblk_rb_w_ctx(&pblk->rwb, sentry + i);
                        w_ctx->ppa = ppa_list[i];
                        meta_list[i].lba = cpu_to_le64(w_ctx->lba);
                        lba_list[paddr] = cpu_to_le64(w_ctx->lba);
                        if (lba_list[paddr] != addr_empty)
                                line->nr_valid_lbas++;
                        else
                                atomic64_inc(&pblk->pad_wa);
                } else {
                        lba_list[paddr] = meta_list[i].lba = addr_empty;
                        __pblk_map_invalidate(pblk, line, paddr);
                }
        }

        pblk_down_rq(pblk, ppa_list, nr_secs, lun_bitmap);
        return 0;
}

void pblk_map_rq(struct pblk *pblk, struct nvm_rq *rqd, unsigned int sentry,
                 unsigned long *lun_bitmap, unsigned int valid_secs,
                 unsigned int off)
{
        struct pblk_sec_meta *meta_list = rqd->meta_list;
        unsigned int map_secs;
        int min = pblk->min_write_pgs;
        int i;

        for (i = off; i < rqd->nr_ppas; i += min) {
                map_secs = (i + min > valid_secs) ? (valid_secs % min) : min;
                if (pblk_map_page_data(pblk, sentry + i, &rqd->ppa_list[i],
                                        lun_bitmap, &meta_list[i], map_secs)) {
                        bio_put(rqd->bio);
                        pblk_free_rqd(pblk, rqd, PBLK_WRITE);
                        pblk_pipeline_stop(pblk);
                }
        }
}

/* only if erase_ppa is set, acquire erase semaphore */
void pblk_map_erase_rq(struct pblk *pblk, struct nvm_rq *rqd,
                       unsigned int sentry, unsigned long *lun_bitmap,
                       unsigned int valid_secs, struct ppa_addr *erase_ppa)
{
        struct nvm_tgt_dev *dev = pblk->dev;
        struct nvm_geo *geo = &dev->geo;
        struct pblk_line_meta *lm = &pblk->lm;
        struct pblk_sec_meta *meta_list = rqd->meta_list;
        struct pblk_line *e_line, *d_line;
        unsigned int map_secs;
        int min = pblk->min_write_pgs;
        int i, erase_lun;

        for (i = 0; i < rqd->nr_ppas; i += min) {
                map_secs = (i + min > valid_secs) ? (valid_secs % min) : min;
                if (pblk_map_page_data(pblk, sentry + i, &rqd->ppa_list[i],
                                        lun_bitmap, &meta_list[i], map_secs)) {
                        bio_put(rqd->bio);
                        pblk_free_rqd(pblk, rqd, PBLK_WRITE);
                        pblk_pipeline_stop(pblk);
                }

                erase_lun = pblk_ppa_to_pos(geo, rqd->ppa_list[i]);

                /* line can change after page map. We might also be writing the
                 * last line.
                 */
                e_line = pblk_line_get_erase(pblk);
                if (!e_line)
                        return pblk_map_rq(pblk, rqd, sentry, lun_bitmap,
                                                        valid_secs, i + min);

                spin_lock(&e_line->lock);
                if (!test_bit(erase_lun, e_line->erase_bitmap)) {
                        set_bit(erase_lun, e_line->erase_bitmap);
                        atomic_dec(&e_line->left_eblks);

                        *erase_ppa = rqd->ppa_list[i];
                        erase_ppa->a.blk = e_line->id;

                        spin_unlock(&e_line->lock);

                        /* Avoid evaluating e_line->left_eblks */
                        return pblk_map_rq(pblk, rqd, sentry, lun_bitmap,
                                                        valid_secs, i + min);
                }
                spin_unlock(&e_line->lock);
        }

        d_line = pblk_line_get_data(pblk);

        /* line can change after page map. We might also be writing the
         * last line.
         */
        e_line = pblk_line_get_erase(pblk);
        if (!e_line)
                return;

        /* Erase blocks that are bad in this line but might not be in next */
        if (unlikely(pblk_ppa_empty(*erase_ppa)) &&
                        bitmap_weight(d_line->blk_bitmap, lm->blk_per_line)) {
                int bit = -1;

retry:
                bit = find_next_bit(d_line->blk_bitmap,
                                                lm->blk_per_line, bit + 1);
                if (bit >= lm->blk_per_line)
                        return;

                spin_lock(&e_line->lock);
                if (test_bit(bit, e_line->erase_bitmap)) {
                        spin_unlock(&e_line->lock);
                        goto retry;
                }
                spin_unlock(&e_line->lock);

                set_bit(bit, e_line->erase_bitmap);
                atomic_dec(&e_line->left_eblks);
                *erase_ppa = pblk->luns[bit].bppa; /* set ch and lun */
                erase_ppa->a.blk = e_line->id;
        }
}