/*
 * t10_pi.c - Functions for generating and verifying T10 Protection
 *            Information.
 *
 * Copyright (C) 2007, 2008, 2014 Oracle Corporation
 * Written by: Martin K. Petersen <martin.petersen@oracle.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.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; see the file COPYING.  If not, write to
 * the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139,
 * USA.
 *
 */

#include <linux/t10-pi.h>
#include <linux/blkdev.h>
#include <linux/crc-t10dif.h>
#include <linux/module.h>
#include <net/checksum.h>

typedef __be16 (csum_fn) (void *, unsigned int);

static __be16 t10_pi_crc_fn(void *data, unsigned int len)
{
        return cpu_to_be16(crc_t10dif(data, len));
}

static __be16 t10_pi_ip_fn(void *data, unsigned int len)
{
        return (__force __be16)ip_compute_csum(data, len);
}

/*
 * Type 1 and Type 2 protection use the same format: 16 bit guard tag,
 * 16 bit app tag, 32 bit reference tag. Type 3 does not define the ref
 * tag.
 */
static blk_status_t t10_pi_generate(struct blk_integrity_iter *iter,
                csum_fn *fn, enum t10_dif_type type)
{
        unsigned int i;

        for (i = 0 ; i < iter->data_size ; i += iter->interval) {
                struct t10_pi_tuple *pi = iter->prot_buf;

                pi->guard_tag = fn(iter->data_buf, iter->interval);
                pi->app_tag = 0;

                if (type == T10_PI_TYPE1_PROTECTION)
                        pi->ref_tag = cpu_to_be32(lower_32_bits(iter->seed));
                else
                        pi->ref_tag = 0;

                iter->data_buf += iter->interval;
                iter->prot_buf += sizeof(struct t10_pi_tuple);
                iter->seed++;
        }

        return BLK_STS_OK;
}

static blk_status_t t10_pi_verify(struct blk_integrity_iter *iter,
                csum_fn *fn, enum t10_dif_type type)
{
        unsigned int i;

        BUG_ON(type == T10_PI_TYPE0_PROTECTION);

        for (i = 0 ; i < iter->data_size ; i += iter->interval) {
                struct t10_pi_tuple *pi = iter->prot_buf;
                __be16 csum;

                if (type == T10_PI_TYPE1_PROTECTION ||
                    type == T10_PI_TYPE2_PROTECTION) {
                        if (pi->app_tag == T10_PI_APP_ESCAPE)
                                goto next;

                        if (be32_to_cpu(pi->ref_tag) !=
                            lower_32_bits(iter->seed)) {
                                pr_err("%s: ref tag error at location %llu " \
                                       "(rcvd %u)\n", iter->disk_name,
                                       (unsigned long long)
                                       iter->seed, be32_to_cpu(pi->ref_tag));
                                return BLK_STS_PROTECTION;
                        }
                } else if (type == T10_PI_TYPE3_PROTECTION) {
                        if (pi->app_tag == T10_PI_APP_ESCAPE &&
                            pi->ref_tag == T10_PI_REF_ESCAPE)
                                goto next;
                }

                csum = fn(iter->data_buf, iter->interval);

                if (pi->guard_tag != csum) {
                        pr_err("%s: guard tag error at sector %llu " \
                               "(rcvd %04x, want %04x)\n", iter->disk_name,
                               (unsigned long long)iter->seed,
                               be16_to_cpu(pi->guard_tag), be16_to_cpu(csum));
                        return BLK_STS_PROTECTION;
                }

next:
                iter->data_buf += iter->interval;
                iter->prot_buf += sizeof(struct t10_pi_tuple);
                iter->seed++;
        }

        return BLK_STS_OK;
}

static blk_status_t t10_pi_type1_generate_crc(struct blk_integrity_iter *iter)
{
        return t10_pi_generate(iter, t10_pi_crc_fn, T10_PI_TYPE1_PROTECTION);
}

static blk_status_t t10_pi_type1_generate_ip(struct blk_integrity_iter *iter)
{
        return t10_pi_generate(iter, t10_pi_ip_fn, T10_PI_TYPE1_PROTECTION);
}

static blk_status_t t10_pi_type1_verify_crc(struct blk_integrity_iter *iter)
{
        return t10_pi_verify(iter, t10_pi_crc_fn, T10_PI_TYPE1_PROTECTION);
}

static blk_status_t t10_pi_type1_verify_ip(struct blk_integrity_iter *iter)
{
        return t10_pi_verify(iter, t10_pi_ip_fn, T10_PI_TYPE1_PROTECTION);
}

/**
 * t10_pi_type1_prepare - prepare PI prior submitting request to device
 * @rq:              request with PI that should be prepared
 *
 * For Type 1/Type 2, the virtual start sector is the one that was
 * originally submitted by the block layer for the ref_tag usage. Due to
 * partitioning, MD/DM cloning, etc. the actual physical start sector is
 * likely to be different. Remap protection information to match the
 * physical LBA.
 */
static void t10_pi_type1_prepare(struct request *rq)
{
        const int tuple_sz = rq->q->integrity.tuple_size;
        u32 ref_tag = t10_pi_ref_tag(rq);
        struct bio *bio;

        __rq_for_each_bio(bio, rq) {
                struct bio_integrity_payload *bip = bio_integrity(bio);
                u32 virt = bip_get_seed(bip) & 0xffffffff;
                struct bio_vec iv;
                struct bvec_iter iter;

                /* Already remapped? */
                if (bip->bip_flags & BIP_MAPPED_INTEGRITY)
                        break;

                bip_for_each_vec(iv, bip, iter) {
                        void *p, *pmap;
                        unsigned int j;

                        pmap = kmap_atomic(iv.bv_page);
                        p = pmap + iv.bv_offset;
                        for (j = 0; j < iv.bv_len; j += tuple_sz) {
                                struct t10_pi_tuple *pi = p;

                                if (be32_to_cpu(pi->ref_tag) == virt)
                                        pi->ref_tag = cpu_to_be32(ref_tag);
                                virt++;
                                ref_tag++;
                                p += tuple_sz;
                        }

                        kunmap_atomic(pmap);
                }

                bip->bip_flags |= BIP_MAPPED_INTEGRITY;
        }
}

/**
 * t10_pi_type1_complete - prepare PI prior returning request to the blk layer
 * @rq:              request with PI that should be prepared
 * @nr_bytes:        total bytes to prepare
 *
 * For Type 1/Type 2, the virtual start sector is the one that was
 * originally submitted by the block layer for the ref_tag usage. Due to
 * partitioning, MD/DM cloning, etc. the actual physical start sector is
 * likely to be different. Since the physical start sector was submitted
 * to the device, we should remap it back to virtual values expected by the
 * block layer.
 */
static void t10_pi_type1_complete(struct request *rq, unsigned int nr_bytes)
{
        unsigned intervals = nr_bytes >> rq->q->integrity.interval_exp;
        const int tuple_sz = rq->q->integrity.tuple_size;
        u32 ref_tag = t10_pi_ref_tag(rq);
        struct bio *bio;

        __rq_for_each_bio(bio, rq) {
                struct bio_integrity_payload *bip = bio_integrity(bio);
                u32 virt = bip_get_seed(bip) & 0xffffffff;
                struct bio_vec iv;
                struct bvec_iter iter;

                bip_for_each_vec(iv, bip, iter) {
                        void *p, *pmap;
                        unsigned int j;

                        pmap = kmap_atomic(iv.bv_page);
                        p = pmap + iv.bv_offset;
                        for (j = 0; j < iv.bv_len && intervals; j += tuple_sz) {
                                struct t10_pi_tuple *pi = p;

                                if (be32_to_cpu(pi->ref_tag) == ref_tag)
                                        pi->ref_tag = cpu_to_be32(virt);
                                virt++;
                                ref_tag++;
                                intervals--;
                                p += tuple_sz;
                        }

                        kunmap_atomic(pmap);
                }
        }
}

static blk_status_t t10_pi_type3_generate_crc(struct blk_integrity_iter *iter)
{
        return t10_pi_generate(iter, t10_pi_crc_fn, T10_PI_TYPE3_PROTECTION);
}

static blk_status_t t10_pi_type3_generate_ip(struct blk_integrity_iter *iter)
{
        return t10_pi_generate(iter, t10_pi_ip_fn, T10_PI_TYPE3_PROTECTION);
}

static blk_status_t t10_pi_type3_verify_crc(struct blk_integrity_iter *iter)
{
        return t10_pi_verify(iter, t10_pi_crc_fn, T10_PI_TYPE3_PROTECTION);
}

static blk_status_t t10_pi_type3_verify_ip(struct blk_integrity_iter *iter)
{
        return t10_pi_verify(iter, t10_pi_ip_fn, T10_PI_TYPE3_PROTECTION);
}

/* Type 3 does not have a reference tag so no remapping is required. */
static void t10_pi_type3_prepare(struct request *rq)
{
}

/* Type 3 does not have a reference tag so no remapping is required. */
static void t10_pi_type3_complete(struct request *rq, unsigned int nr_bytes)
{
}

static const struct blk_integrity_profile_ext_ops t10_pi_type1_ops = {
        .prepare_fn             = t10_pi_type1_prepare,
        .complete_fn            = t10_pi_type1_complete,
};

const struct blk_integrity_profile t10_pi_type1_crc = {
        .name                   = "T10-DIF-TYPE1-CRC",
        .generate_fn            = t10_pi_type1_generate_crc,
        .verify_fn              = t10_pi_type1_verify_crc,
        .ext_ops                = &t10_pi_type1_ops,
};
EXPORT_SYMBOL(t10_pi_type1_crc);

const struct blk_integrity_profile t10_pi_type1_ip = {
        .name                   = "T10-DIF-TYPE1-IP",
        .generate_fn            = t10_pi_type1_generate_ip,
        .verify_fn              = t10_pi_type1_verify_ip,
        .ext_ops                = &t10_pi_type1_ops,
};
EXPORT_SYMBOL(t10_pi_type1_ip);

static const struct blk_integrity_profile_ext_ops t10_pi_type3_ops = {
        .prepare_fn             = t10_pi_type3_prepare,
        .complete_fn            = t10_pi_type3_complete,
};

const struct blk_integrity_profile t10_pi_type3_crc = {
        .name                   = "T10-DIF-TYPE3-CRC",
        .generate_fn            = t10_pi_type3_generate_crc,
        .verify_fn              = t10_pi_type3_verify_crc,
        .ext_ops                = &t10_pi_type3_ops,
};
EXPORT_SYMBOL(t10_pi_type3_crc);

const struct blk_integrity_profile t10_pi_type3_ip = {
        .name                   = "T10-DIF-TYPE3-IP",
        .generate_fn            = t10_pi_type3_generate_ip,
        .verify_fn              = t10_pi_type3_verify_ip,
        .ext_ops                = &t10_pi_type3_ops,
};
EXPORT_SYMBOL(t10_pi_type3_ip);

MODULE_LICENSE("GPL");