/*
 * blk-integrity.c - Block layer data integrity extensions
 *
 * Copyright (C) 2007, 2008 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/blkdev.h>
#include <linux/backing-dev.h>
#include <linux/mempool.h>
#include <linux/bio.h>
#include <linux/scatterlist.h>
#include <linux/export.h>
#include <linux/slab.h>

#include "blk.h"

/**
 * blk_rq_count_integrity_sg - Count number of integrity scatterlist elements
 * @q:          request queue
 * @bio:        bio with integrity metadata attached
 *
 * Description: Returns the number of elements required in a
 * scatterlist corresponding to the integrity metadata in a bio.
 */
int blk_rq_count_integrity_sg(struct request_queue *q, struct bio *bio)
{
        struct bio_vec iv, ivprv = { NULL };
        unsigned int segments = 0;
        unsigned int seg_size = 0;
        struct bvec_iter iter;
        int prev = 0;

        bio_for_each_integrity_vec(iv, bio, iter) {

                if (prev) {
                        if (!BIOVEC_PHYS_MERGEABLE(&ivprv, &iv))
                                goto new_segment;

                        if (!BIOVEC_SEG_BOUNDARY(q, &ivprv, &iv))
                                goto new_segment;

                        if (seg_size + iv.bv_len > queue_max_segment_size(q))
                                goto new_segment;

                        seg_size += iv.bv_len;
                } else {
new_segment:
                        segments++;
                        seg_size = iv.bv_len;
                }

                prev = 1;
                ivprv = iv;
        }

        return segments;
}
EXPORT_SYMBOL(blk_rq_count_integrity_sg);

/**
 * blk_rq_map_integrity_sg - Map integrity metadata into a scatterlist
 * @q:          request queue
 * @bio:        bio with integrity metadata attached
 * @sglist:     target scatterlist
 *
 * Description: Map the integrity vectors in request into a
 * scatterlist.  The scatterlist must be big enough to hold all
 * elements.  I.e. sized using blk_rq_count_integrity_sg().
 */
int blk_rq_map_integrity_sg(struct request_queue *q, struct bio *bio,
                            struct scatterlist *sglist)
{
        struct bio_vec iv, ivprv = { NULL };
        struct scatterlist *sg = NULL;
        unsigned int segments = 0;
        struct bvec_iter iter;
        int prev = 0;

        bio_for_each_integrity_vec(iv, bio, iter) {

                if (prev) {
                        if (!BIOVEC_PHYS_MERGEABLE(&ivprv, &iv))
                                goto new_segment;

                        if (!BIOVEC_SEG_BOUNDARY(q, &ivprv, &iv))
                                goto new_segment;

                        if (sg->length + iv.bv_len > queue_max_segment_size(q))
                                goto new_segment;

                        sg->length += iv.bv_len;
                } else {
new_segment:
                        if (!sg)
                                sg = sglist;
                        else {
                                sg_unmark_end(sg);
                                sg = sg_next(sg);
                        }

                        sg_set_page(sg, iv.bv_page, iv.bv_len, iv.bv_offset);
                        segments++;
                }

                prev = 1;
                ivprv = iv;
        }

        if (sg)
                sg_mark_end(sg);

        return segments;
}
EXPORT_SYMBOL(blk_rq_map_integrity_sg);

/**
 * blk_integrity_compare - Compare integrity profile of two disks
 * @gd1:        Disk to compare
 * @gd2:        Disk to compare
 *
 * Description: Meta-devices like DM and MD need to verify that all
 * sub-devices use the same integrity format before advertising to
 * upper layers that they can send/receive integrity metadata.  This
 * function can be used to check whether two gendisk devices have
 * compatible integrity formats.
 */
int blk_integrity_compare(struct gendisk *gd1, struct gendisk *gd2)
{
        struct blk_integrity *b1 = &gd1->queue->integrity;
        struct blk_integrity *b2 = &gd2->queue->integrity;

        if (!b1->profile && !b2->profile)
                return 0;

        if (!b1->profile || !b2->profile)
                return -1;

        if (b1->interval_exp != b2->interval_exp) {
                pr_err("%s: %s/%s protection interval %u != %u\n",
                       __func__, gd1->disk_name, gd2->disk_name,
                       1 << b1->interval_exp, 1 << b2->interval_exp);
                return -1;
        }

        if (b1->tuple_size != b2->tuple_size) {
                pr_err("%s: %s/%s tuple sz %u != %u\n", __func__,
                       gd1->disk_name, gd2->disk_name,
                       b1->tuple_size, b2->tuple_size);
                return -1;
        }

        if (b1->tag_size && b2->tag_size && (b1->tag_size != b2->tag_size)) {
                pr_err("%s: %s/%s tag sz %u != %u\n", __func__,
                       gd1->disk_name, gd2->disk_name,
                       b1->tag_size, b2->tag_size);
                return -1;
        }

        if (b1->profile != b2->profile) {
                pr_err("%s: %s/%s type %s != %s\n", __func__,
                       gd1->disk_name, gd2->disk_name,
                       b1->profile->name, b2->profile->name);
                return -1;
        }

        return 0;
}
EXPORT_SYMBOL(blk_integrity_compare);

bool blk_integrity_merge_rq(struct request_queue *q, struct request *req,
                            struct request *next)
{
        if (blk_integrity_rq(req) == 0 && blk_integrity_rq(next) == 0)
                return true;

        if (blk_integrity_rq(req) == 0 || blk_integrity_rq(next) == 0)
                return false;

        if (bio_integrity(req->bio)->bip_flags !=
            bio_integrity(next->bio)->bip_flags)
                return false;

        if (req->nr_integrity_segments + next->nr_integrity_segments >
            q->limits.max_integrity_segments)
                return false;

        if (integrity_req_gap_back_merge(req, next->bio))
                return false;

        return true;
}
EXPORT_SYMBOL(blk_integrity_merge_rq);

bool blk_integrity_merge_bio(struct request_queue *q, struct request *req,
                             struct bio *bio)
{
        int nr_integrity_segs;
        struct bio *next = bio->bi_next;

        if (blk_integrity_rq(req) == 0 && bio_integrity(bio) == NULL)
                return true;

        if (blk_integrity_rq(req) == 0 || bio_integrity(bio) == NULL)
                return false;

        if (bio_integrity(req->bio)->bip_flags != bio_integrity(bio)->bip_flags)
                return false;

        bio->bi_next = NULL;
        nr_integrity_segs = blk_rq_count_integrity_sg(q, bio);
        bio->bi_next = next;

        if (req->nr_integrity_segments + nr_integrity_segs >
            q->limits.max_integrity_segments)
                return false;

        req->nr_integrity_segments += nr_integrity_segs;

        return true;
}
EXPORT_SYMBOL(blk_integrity_merge_bio);

struct integrity_sysfs_entry {
        struct attribute attr;
        ssize_t (*show)(struct blk_integrity *, char *);
        ssize_t (*store)(struct blk_integrity *, const char *, size_t);
};

static ssize_t integrity_attr_show(struct kobject *kobj, struct attribute *attr,
                                   char *page)
{
        struct gendisk *disk = container_of(kobj, struct gendisk, integrity_kobj);
        struct blk_integrity *bi = &disk->queue->integrity;
        struct integrity_sysfs_entry *entry =
                container_of(attr, struct integrity_sysfs_entry, attr);

        return entry->show(bi, page);
}

static ssize_t integrity_attr_store(struct kobject *kobj,
                                    struct attribute *attr, const char *page,
                                    size_t count)
{
        struct gendisk *disk = container_of(kobj, struct gendisk, integrity_kobj);
        struct blk_integrity *bi = &disk->queue->integrity;
        struct integrity_sysfs_entry *entry =
                container_of(attr, struct integrity_sysfs_entry, attr);
        ssize_t ret = 0;

        if (entry->store)
                ret = entry->store(bi, page, count);

        return ret;
}

static ssize_t integrity_format_show(struct blk_integrity *bi, char *page)
{
        if (bi->profile && bi->profile->name)
                return sprintf(page, "%s\n", bi->profile->name);
        else
                return sprintf(page, "none\n");
}

static ssize_t integrity_tag_size_show(struct blk_integrity *bi, char *page)
{
        return sprintf(page, "%u\n", bi->tag_size);
}

static ssize_t integrity_interval_show(struct blk_integrity *bi, char *page)
{
        return sprintf(page, "%u\n",
                       bi->interval_exp ? 1 << bi->interval_exp : 0);
}

static ssize_t integrity_verify_store(struct blk_integrity *bi,
                                      const char *page, size_t count)
{
        char *p = (char *) page;
        unsigned long val = simple_strtoul(p, &p, 10);

        if (val)
                bi->flags |= BLK_INTEGRITY_VERIFY;
        else
                bi->flags &= ~BLK_INTEGRITY_VERIFY;

        return count;
}

static ssize_t integrity_verify_show(struct blk_integrity *bi, char *page)
{
        return sprintf(page, "%d\n", (bi->flags & BLK_INTEGRITY_VERIFY) != 0);
}

static ssize_t integrity_generate_store(struct blk_integrity *bi,
                                        const char *page, size_t count)
{
        char *p = (char *) page;
        unsigned long val = simple_strtoul(p, &p, 10);

        if (val)
                bi->flags |= BLK_INTEGRITY_GENERATE;
        else
                bi->flags &= ~BLK_INTEGRITY_GENERATE;

        return count;
}

static ssize_t integrity_generate_show(struct blk_integrity *bi, char *page)
{
        return sprintf(page, "%d\n", (bi->flags & BLK_INTEGRITY_GENERATE) != 0);
}

static ssize_t integrity_device_show(struct blk_integrity *bi, char *page)
{
        return sprintf(page, "%u\n",
                       (bi->flags & BLK_INTEGRITY_DEVICE_CAPABLE) != 0);
}

static struct integrity_sysfs_entry integrity_format_entry = {
        .attr = { .name = "format", .mode = S_IRUGO },
        .show = integrity_format_show,
};

static struct integrity_sysfs_entry integrity_tag_size_entry = {
        .attr = { .name = "tag_size", .mode = S_IRUGO },
        .show = integrity_tag_size_show,
};

static struct integrity_sysfs_entry integrity_interval_entry = {
        .attr = { .name = "protection_interval_bytes", .mode = S_IRUGO },
        .show = integrity_interval_show,
};

static struct integrity_sysfs_entry integrity_verify_entry = {
        .attr = { .name = "read_verify", .mode = S_IRUGO | S_IWUSR },
        .show = integrity_verify_show,
        .store = integrity_verify_store,
};

static struct integrity_sysfs_entry integrity_generate_entry = {
        .attr = { .name = "write_generate", .mode = S_IRUGO | S_IWUSR },
        .show = integrity_generate_show,
        .store = integrity_generate_store,
};

static struct integrity_sysfs_entry integrity_device_entry = {
        .attr = { .name = "device_is_integrity_capable", .mode = S_IRUGO },
        .show = integrity_device_show,
};

static struct attribute *integrity_attrs[] = {
        &integrity_format_entry.attr,
        &integrity_tag_size_entry.attr,
        &integrity_interval_entry.attr,
        &integrity_verify_entry.attr,
        &integrity_generate_entry.attr,
        &integrity_device_entry.attr,
        NULL,
};

static const struct sysfs_ops integrity_ops = {
        .show   = &integrity_attr_show,
        .store  = &integrity_attr_store,
};

static struct kobj_type integrity_ktype = {
        .default_attrs  = integrity_attrs,
        .sysfs_ops      = &integrity_ops,
};

static int blk_integrity_nop_fn(struct blk_integrity_iter *iter)
{
        return 0;
}

static struct blk_integrity_profile nop_profile = {
        .name = "nop",
        .generate_fn = blk_integrity_nop_fn,
        .verify_fn = blk_integrity_nop_fn,
};

/**
 * blk_integrity_register - Register a gendisk as being integrity-capable
 * @disk:       struct gendisk pointer to make integrity-aware
 * @template:   block integrity profile to register
 *
 * Description: When a device needs to advertise itself as being able to
 * send/receive integrity metadata it must use this function to register
 * the capability with the block layer. The template is a blk_integrity
 * struct with values appropriate for the underlying hardware. See
 * Documentation/block/data-integrity.txt.
 */
void blk_integrity_register(struct gendisk *disk, struct blk_integrity *template)
{
        struct blk_integrity *bi = &disk->queue->integrity;

        bi->flags = BLK_INTEGRITY_VERIFY | BLK_INTEGRITY_GENERATE |
                template->flags;
        bi->interval_exp = ilog2(queue_logical_block_size(disk->queue));
        bi->profile = template->profile ? template->profile : &nop_profile;
        bi->tuple_size = template->tuple_size;
        bi->tag_size = template->tag_size;

        blk_integrity_revalidate(disk);
}
EXPORT_SYMBOL(blk_integrity_register);

/**
 * blk_integrity_unregister - Unregister block integrity profile
 * @disk:       disk whose integrity profile to unregister
 *
 * Description: This function unregisters the integrity capability from
 * a block device.
 */
void blk_integrity_unregister(struct gendisk *disk)
{
        blk_integrity_revalidate(disk);
        memset(&disk->queue->integrity, 0, sizeof(struct blk_integrity));
}
EXPORT_SYMBOL(blk_integrity_unregister);

void blk_integrity_revalidate(struct gendisk *disk)
{
        struct blk_integrity *bi = &disk->queue->integrity;

        if (!(disk->flags & GENHD_FL_UP))
                return;

        if (bi->profile)
                disk->queue->backing_dev_info.capabilities |=
                        BDI_CAP_STABLE_WRITES;
        else
                disk->queue->backing_dev_info.capabilities &=
                        ~BDI_CAP_STABLE_WRITES;
}

void blk_integrity_add(struct gendisk *disk)
{
        if (kobject_init_and_add(&disk->integrity_kobj, &integrity_ktype,
                                 &disk_to_dev(disk)->kobj, "%s", "integrity"))
                return;

        kobject_uevent(&disk->integrity_kobj, KOBJ_ADD);
}

void blk_integrity_del(struct gendisk *disk)
{
        kobject_uevent(&disk->integrity_kobj, KOBJ_REMOVE);
        kobject_del(&disk->integrity_kobj);
        kobject_put(&disk->integrity_kobj);
}