// SPDX-License-Identifier: GPL-2.0
/*
 * 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-read.c - pblk's read path
 */

#include "pblk.h"

/*
 * There is no guarantee that the value read from cache has not been updated and
 * resides at another location in the cache. We guarantee though that if the
 * value is read from the cache, it belongs to the mapped lba. In order to
 * guarantee and order between writes and reads are ordered, a flush must be
 * issued.
 */
static int pblk_read_from_cache(struct pblk *pblk, struct bio *bio,
                                sector_t lba, struct ppa_addr ppa)
{
#ifdef CONFIG_NVM_PBLK_DEBUG
        /* Callers must ensure that the ppa points to a cache address */
        BUG_ON(pblk_ppa_empty(ppa));
        BUG_ON(!pblk_addr_in_cache(ppa));
#endif

        return pblk_rb_copy_to_bio(&pblk->rwb, bio, lba, ppa);
}

static int pblk_read_ppalist_rq(struct pblk *pblk, struct nvm_rq *rqd,
                                 struct bio *bio, sector_t blba,
                                 bool *from_cache)
{
        void *meta_list = rqd->meta_list;
        int nr_secs, i;

retry:
        nr_secs = pblk_lookup_l2p_seq(pblk, rqd->ppa_list, blba, rqd->nr_ppas,
                                        from_cache);

        if (!*from_cache)
                goto end;

        for (i = 0; i < nr_secs; i++) {
                struct pblk_sec_meta *meta = pblk_get_meta(pblk, meta_list, i);
                sector_t lba = blba + i;

                if (pblk_ppa_empty(rqd->ppa_list[i])) {
                        __le64 addr_empty = cpu_to_le64(ADDR_EMPTY);

                        meta->lba = addr_empty;
                } else if (pblk_addr_in_cache(rqd->ppa_list[i])) {
                        /*
                         * Try to read from write buffer. The address is later
                         * checked on the write buffer to prevent retrieving
                         * overwritten data.
                         */
                        if (!pblk_read_from_cache(pblk, bio, lba,
                                                        rqd->ppa_list[i])) {
                                if (i == 0) {
                                        /*
                                         * We didn't call with bio_advance()
                                         * yet, so we can just retry.
                                         */
                                        goto retry;
                                } else {
                                        /*
                                         * We already call bio_advance()
                                         * so we cannot retry and we need
                                         * to quit that function in order
                                         * to allow caller to handle the bio
                                         * splitting in the current sector
                                         * position.
                                         */
                                        nr_secs = i;
                                        goto end;
                                }
                        }
                        meta->lba = cpu_to_le64(lba);
#ifdef CONFIG_NVM_PBLK_DEBUG
                        atomic_long_inc(&pblk->cache_reads);
#endif
                }
                bio_advance(bio, PBLK_EXPOSED_PAGE_SIZE);
        }

end:
        if (pblk_io_aligned(pblk, nr_secs))
                rqd->is_seq = 1;

#ifdef CONFIG_NVM_PBLK_DEBUG
        atomic_long_add(nr_secs, &pblk->inflight_reads);
#endif

        return nr_secs;
}


static void pblk_read_check_seq(struct pblk *pblk, struct nvm_rq *rqd,
                                sector_t blba)
{
        void *meta_list = rqd->meta_list;
        int nr_lbas = rqd->nr_ppas;
        int i;

        if (!pblk_is_oob_meta_supported(pblk))
                return;

        for (i = 0; i < nr_lbas; i++) {
                struct pblk_sec_meta *meta = pblk_get_meta(pblk, meta_list, i);
                u64 lba = le64_to_cpu(meta->lba);

                if (lba == ADDR_EMPTY)
                        continue;

                if (lba != blba + i) {
#ifdef CONFIG_NVM_PBLK_DEBUG
                        struct ppa_addr *ppa_list = nvm_rq_to_ppa_list(rqd);

                        print_ppa(pblk, &ppa_list[i], "seq", i);
#endif
                        pblk_err(pblk, "corrupted read LBA (%llu/%llu)\n",
                                                        lba, (u64)blba + i);
                        WARN_ON(1);
                }
        }
}

/*
 * There can be holes in the lba list.
 */
static void pblk_read_check_rand(struct pblk *pblk, struct nvm_rq *rqd,
                                 u64 *lba_list, int nr_lbas)
{
        void *meta_lba_list = rqd->meta_list;
        int i, j;

        if (!pblk_is_oob_meta_supported(pblk))
                return;

        for (i = 0, j = 0; i < nr_lbas; i++) {
                struct pblk_sec_meta *meta = pblk_get_meta(pblk,
                                                           meta_lba_list, j);
                u64 lba = lba_list[i];
                u64 meta_lba;

                if (lba == ADDR_EMPTY)
                        continue;

                meta_lba = le64_to_cpu(meta->lba);

                if (lba != meta_lba) {
#ifdef CONFIG_NVM_PBLK_DEBUG
                        struct ppa_addr *ppa_list = nvm_rq_to_ppa_list(rqd);

                        print_ppa(pblk, &ppa_list[j], "rnd", j);
#endif
                        pblk_err(pblk, "corrupted read LBA (%llu/%llu)\n",
                                                        meta_lba, lba);
                        WARN_ON(1);
                }

                j++;
        }

        WARN_ONCE(j != rqd->nr_ppas, "pblk: corrupted random request\n");
}

static void pblk_end_user_read(struct bio *bio, int error)
{
        if (error && error != NVM_RSP_WARN_HIGHECC)
                bio_io_error(bio);
        else
                bio_endio(bio);
}

static void __pblk_end_io_read(struct pblk *pblk, struct nvm_rq *rqd,
                               bool put_line)
{
        struct pblk_g_ctx *r_ctx = nvm_rq_to_pdu(rqd);
        struct bio *int_bio = rqd->bio;
        unsigned long start_time = r_ctx->start_time;

        bio_end_io_acct(int_bio, start_time);

        if (rqd->error)
                pblk_log_read_err(pblk, rqd);

        pblk_read_check_seq(pblk, rqd, r_ctx->lba);
        bio_put(int_bio);

        if (put_line)
                pblk_rq_to_line_put(pblk, rqd);

#ifdef CONFIG_NVM_PBLK_DEBUG
        atomic_long_add(rqd->nr_ppas, &pblk->sync_reads);
        atomic_long_sub(rqd->nr_ppas, &pblk->inflight_reads);
#endif

        pblk_free_rqd(pblk, rqd, PBLK_READ);
        atomic_dec(&pblk->inflight_io);
}

static void pblk_end_io_read(struct nvm_rq *rqd)
{
        struct pblk *pblk = rqd->private;
        struct pblk_g_ctx *r_ctx = nvm_rq_to_pdu(rqd);
        struct bio *bio = (struct bio *)r_ctx->private;

        pblk_end_user_read(bio, rqd->error);
        __pblk_end_io_read(pblk, rqd, true);
}

static void pblk_read_rq(struct pblk *pblk, struct nvm_rq *rqd, struct bio *bio,
                         sector_t lba, bool *from_cache)
{
        struct pblk_sec_meta *meta = pblk_get_meta(pblk, rqd->meta_list, 0);
        struct ppa_addr ppa;

        pblk_lookup_l2p_seq(pblk, &ppa, lba, 1, from_cache);

#ifdef CONFIG_NVM_PBLK_DEBUG
        atomic_long_inc(&pblk->inflight_reads);
#endif

retry:
        if (pblk_ppa_empty(ppa)) {
                __le64 addr_empty = cpu_to_le64(ADDR_EMPTY);

                meta->lba = addr_empty;
                return;
        }

        /* Try to read from write buffer. The address is later checked on the
         * write buffer to prevent retrieving overwritten data.
         */
        if (pblk_addr_in_cache(ppa)) {
                if (!pblk_read_from_cache(pblk, bio, lba, ppa)) {
                        pblk_lookup_l2p_seq(pblk, &ppa, lba, 1, from_cache);
                        goto retry;
                }

                meta->lba = cpu_to_le64(lba);

#ifdef CONFIG_NVM_PBLK_DEBUG
                atomic_long_inc(&pblk->cache_reads);
#endif
        } else {
                rqd->ppa_addr = ppa;
        }
}

void pblk_submit_read(struct pblk *pblk, struct bio *bio)
{
        sector_t blba = pblk_get_lba(bio);
        unsigned int nr_secs = pblk_get_secs(bio);
        bool from_cache;
        struct pblk_g_ctx *r_ctx;
        struct nvm_rq *rqd;
        struct bio *int_bio, *split_bio;
        unsigned long start_time;

        start_time = bio_start_io_acct(bio);

        rqd = pblk_alloc_rqd(pblk, PBLK_READ);

        rqd->opcode = NVM_OP_PREAD;
        rqd->nr_ppas = nr_secs;
        rqd->private = pblk;
        rqd->end_io = pblk_end_io_read;

        r_ctx = nvm_rq_to_pdu(rqd);
        r_ctx->start_time = start_time;
        r_ctx->lba = blba;

        if (pblk_alloc_rqd_meta(pblk, rqd)) {
                bio_io_error(bio);
                pblk_free_rqd(pblk, rqd, PBLK_READ);
                return;
        }

        /* Clone read bio to deal internally with:
         * -read errors when reading from drive
         * -bio_advance() calls during cache reads
         */
        int_bio = bio_clone_fast(bio, GFP_KERNEL, &pblk_bio_set);

        if (nr_secs > 1)
                nr_secs = pblk_read_ppalist_rq(pblk, rqd, int_bio, blba,
                                                &from_cache);
        else
                pblk_read_rq(pblk, rqd, int_bio, blba, &from_cache);

split_retry:
        r_ctx->private = bio; /* original bio */
        rqd->bio = int_bio; /* internal bio */

        if (from_cache && nr_secs == rqd->nr_ppas) {
                /* All data was read from cache, we can complete the IO. */
                pblk_end_user_read(bio, 0);
                atomic_inc(&pblk->inflight_io);
                __pblk_end_io_read(pblk, rqd, false);
        } else if (nr_secs != rqd->nr_ppas) {
                /* The read bio request could be partially filled by the write
                 * buffer, but there are some holes that need to be read from
                 * the drive. In order to handle this, we will use block layer
                 * mechanism to split this request in to smaller ones and make
                 * a chain of it.
                 */
                split_bio = bio_split(bio, nr_secs * NR_PHY_IN_LOG, GFP_KERNEL,
                                        &pblk_bio_set);
                bio_chain(split_bio, bio);
                submit_bio_noacct(bio);

                /* New bio contains first N sectors of the previous one, so
                 * we can continue to use existing rqd, but we need to shrink
                 * the number of PPAs in it. New bio is also guaranteed that
                 * it contains only either data from cache or from drive, newer
                 * mix of them.
                 */
                bio = split_bio;
                rqd->nr_ppas = nr_secs;
                if (rqd->nr_ppas == 1)
                        rqd->ppa_addr = rqd->ppa_list[0];

                /* Recreate int_bio - existing might have some needed internal
                 * fields modified already.
                 */
                bio_put(int_bio);
                int_bio = bio_clone_fast(bio, GFP_KERNEL, &pblk_bio_set);
                goto split_retry;
        } else if (pblk_submit_io(pblk, rqd, NULL)) {
                /* Submitting IO to drive failed, let's report an error */
                rqd->error = -ENODEV;
                pblk_end_io_read(rqd);
        }
}

static int read_ppalist_rq_gc(struct pblk *pblk, struct nvm_rq *rqd,
                              struct pblk_line *line, u64 *lba_list,
                              u64 *paddr_list_gc, unsigned int nr_secs)
{
        struct ppa_addr ppa_list_l2p[NVM_MAX_VLBA];
        struct ppa_addr ppa_gc;
        int valid_secs = 0;
        int i;

        pblk_lookup_l2p_rand(pblk, ppa_list_l2p, lba_list, nr_secs);

        for (i = 0; i < nr_secs; i++) {
                if (lba_list[i] == ADDR_EMPTY)
                        continue;

                ppa_gc = addr_to_gen_ppa(pblk, paddr_list_gc[i], line->id);
                if (!pblk_ppa_comp(ppa_list_l2p[i], ppa_gc)) {
                        paddr_list_gc[i] = lba_list[i] = ADDR_EMPTY;
                        continue;
                }

                rqd->ppa_list[valid_secs++] = ppa_list_l2p[i];
        }

#ifdef CONFIG_NVM_PBLK_DEBUG
        atomic_long_add(valid_secs, &pblk->inflight_reads);
#endif

        return valid_secs;
}

static int read_rq_gc(struct pblk *pblk, struct nvm_rq *rqd,
                      struct pblk_line *line, sector_t lba,
                      u64 paddr_gc)
{
        struct ppa_addr ppa_l2p, ppa_gc;
        int valid_secs = 0;

        if (lba == ADDR_EMPTY)
                goto out;

        /* logic error: lba out-of-bounds */
        if (lba >= pblk->capacity) {
                WARN(1, "pblk: read lba out of bounds\n");
                goto out;
        }

        spin_lock(&pblk->trans_lock);
        ppa_l2p = pblk_trans_map_get(pblk, lba);
        spin_unlock(&pblk->trans_lock);

        ppa_gc = addr_to_gen_ppa(pblk, paddr_gc, line->id);
        if (!pblk_ppa_comp(ppa_l2p, ppa_gc))
                goto out;

        rqd->ppa_addr = ppa_l2p;
        valid_secs = 1;

#ifdef CONFIG_NVM_PBLK_DEBUG
        atomic_long_inc(&pblk->inflight_reads);
#endif

out:
        return valid_secs;
}

int pblk_submit_read_gc(struct pblk *pblk, struct pblk_gc_rq *gc_rq)
{
        struct nvm_rq rqd;
        int ret = NVM_IO_OK;

        memset(&rqd, 0, sizeof(struct nvm_rq));

        ret = pblk_alloc_rqd_meta(pblk, &rqd);
        if (ret)
                return ret;

        if (gc_rq->nr_secs > 1) {
                gc_rq->secs_to_gc = read_ppalist_rq_gc(pblk, &rqd, gc_rq->line,
                                                        gc_rq->lba_list,
                                                        gc_rq->paddr_list,
                                                        gc_rq->nr_secs);
                if (gc_rq->secs_to_gc == 1)
                        rqd.ppa_addr = rqd.ppa_list[0];
        } else {
                gc_rq->secs_to_gc = read_rq_gc(pblk, &rqd, gc_rq->line,
                                                        gc_rq->lba_list[0],
                                                        gc_rq->paddr_list[0]);
        }

        if (!(gc_rq->secs_to_gc))
                goto out;

        rqd.opcode = NVM_OP_PREAD;
        rqd.nr_ppas = gc_rq->secs_to_gc;

        if (pblk_submit_io_sync(pblk, &rqd, gc_rq->data)) {
                ret = -EIO;
                goto err_free_dma;
        }

        pblk_read_check_rand(pblk, &rqd, gc_rq->lba_list, gc_rq->nr_secs);

        atomic_dec(&pblk->inflight_io);

        if (rqd.error) {
                atomic_long_inc(&pblk->read_failed_gc);
#ifdef CONFIG_NVM_PBLK_DEBUG
                pblk_print_failed_rqd(pblk, &rqd, rqd.error);
#endif
        }

#ifdef CONFIG_NVM_PBLK_DEBUG
        atomic_long_add(gc_rq->secs_to_gc, &pblk->sync_reads);
        atomic_long_add(gc_rq->secs_to_gc, &pblk->recov_gc_reads);
        atomic_long_sub(gc_rq->secs_to_gc, &pblk->inflight_reads);
#endif

out:
        pblk_free_rqd_meta(pblk, &rqd);
        return ret;

err_free_dma:
        pblk_free_rqd_meta(pblk, &rqd);
        return ret;
}