blk-integrity.c

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/*
 * blk-integrity.c - Block layer data integrity extensions
 *
 * Copyright (C) 2007, 2008 Oracle Corporation
 * Written by: Martin K. Petersen <[email protected]>
 *
 * 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/mempool.h>
#include <linux/bio.h>
#include <linux/scatterlist.h>
#include <linux/export.h>
#include <linux/slab.h>

#include "blk.h"

static struct kmem_cache *integrity_cachep;

static const char *bi_unsupported_name = "unsupported";

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;
    unsigned int i = 0;

    bio_for_each_integrity_vec(iv, bio, i) {

        if (ivprv) {
            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;
        }

        ivprv = iv;
    }

    return segments;
}
EXPORT_SYMBOL(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;
    unsigned int i = 0;

    bio_for_each_integrity_vec(iv, bio, i) {

        if (ivprv) {
            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->page_link &= ~0x02;
                sg = sg_next(sg);
            }

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

        ivprv = iv;
    }

    if (sg)
        sg_mark_end(sg);

    return segments;
}
EXPORT_SYMBOL(blk_rq_map_integrity_sg);

int blk_integrity_compare(struct gendisk *gd1, struct gendisk *gd2)
{
    struct blk_integrity *b1 = gd1->integrity;
    struct blk_integrity *b2 = gd2->integrity;

    if (!b1 && !b2)
        return 0;

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

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

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

    return 0;
}
EXPORT_SYMBOL(blk_integrity_compare);

int blk_integrity_merge_rq(struct request_queue *q, struct request *req,
               struct request *next)
{
    if (blk_integrity_rq(req) != blk_integrity_rq(next))
        return -1;

    if (req->nr_integrity_segments + next->nr_integrity_segments >
        q->limits.max_integrity_segments)
        return -1;

    return 0;
}
EXPORT_SYMBOL(blk_integrity_merge_rq);

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

    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 -1;

    req->nr_integrity_segments += nr_integrity_segs;

    return 0;
}
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 blk_integrity *bi =
        container_of(kobj, struct blk_integrity, kobj);
    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 blk_integrity *bi =
        container_of(kobj, struct blk_integrity, kobj);
    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 != NULL && bi->name != NULL)
        return sprintf(page, "%s\n", bi->name);
    else
        return sprintf(page, "none\n");
}

static ssize_t integrity_tag_size_show(struct blk_integrity *bi, char *page)
{
    if (bi != NULL)
        return sprintf(page, "%u\n", bi->tag_size);
    else
        return sprintf(page, "0\n");
}

static ssize_t integrity_read_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 |= INTEGRITY_FLAG_READ;
    else
        bi->flags &= ~INTEGRITY_FLAG_READ;

    return count;
}

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

static ssize_t integrity_write_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 |= INTEGRITY_FLAG_WRITE;
    else
        bi->flags &= ~INTEGRITY_FLAG_WRITE;

    return count;
}

static ssize_t integrity_write_show(struct blk_integrity *bi, char *page)
{
    return sprintf(page, "%d\n", (bi->flags & INTEGRITY_FLAG_WRITE) != 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_read_entry = {
    .attr = { .name = "read_verify", .mode = S_IRUGO | S_IWUSR },
    .show = integrity_read_show,
    .store = integrity_read_store,
};

static struct integrity_sysfs_entry integrity_write_entry = {
    .attr = { .name = "write_generate", .mode = S_IRUGO | S_IWUSR },
    .show = integrity_write_show,
    .store = integrity_write_store,
};

static struct attribute *integrity_attrs[] = {
    &integrity_format_entry.attr,
    &integrity_tag_size_entry.attr,
    &integrity_read_entry.attr,
    &integrity_write_entry.attr,
    NULL,
};

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

static int __init blk_dev_integrity_init(void)
{
    integrity_cachep = kmem_cache_create("blkdev_integrity",
                         sizeof(struct blk_integrity),
                         0, SLAB_PANIC, NULL);
    return 0;
}
subsys_initcall(blk_dev_integrity_init);

static void blk_integrity_release(struct kobject *kobj)
{
    struct blk_integrity *bi =
        container_of(kobj, struct blk_integrity, kobj);

    kmem_cache_free(integrity_cachep, bi);
}

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

bool blk_integrity_is_initialized(struct gendisk *disk)
{
    struct blk_integrity *bi = blk_get_integrity(disk);

    return (bi && bi->name && strcmp(bi->name, bi_unsupported_name) != 0);
}
EXPORT_SYMBOL(blk_integrity_is_initialized);

int blk_integrity_register(struct gendisk *disk, struct blk_integrity *template)
{
    struct blk_integrity *bi;

    BUG_ON(disk == NULL);

    if (disk->integrity == NULL) {
        bi = kmem_cache_alloc(integrity_cachep,
                      GFP_KERNEL | __GFP_ZERO);
        if (!bi)
            return -1;

        if (kobject_init_and_add(&bi->kobj, &integrity_ktype,
                     &disk_to_dev(disk)->kobj,
                     "%s", "integrity")) {
            kmem_cache_free(integrity_cachep, bi);
            return -1;
        }

        kobject_uevent(&bi->kobj, KOBJ_ADD);

        bi->flags |= INTEGRITY_FLAG_READ | INTEGRITY_FLAG_WRITE;
        bi->sector_size = queue_logical_block_size(disk->queue);
        disk->integrity = bi;
    } else
        bi = disk->integrity;

    /* Use the provided profile as template */
    if (template != NULL) {
        bi->name = template->name;
        bi->generate_fn = template->generate_fn;
        bi->verify_fn = template->verify_fn;
        bi->tuple_size = template->tuple_size;
        bi->set_tag_fn = template->set_tag_fn;
        bi->get_tag_fn = template->get_tag_fn;
        bi->tag_size = template->tag_size;
    } else
        bi->name = bi_unsupported_name;

    return 0;
}
EXPORT_SYMBOL(blk_integrity_register);

void blk_integrity_unregister(struct gendisk *disk)
{
    struct blk_integrity *bi;

    if (!disk || !disk->integrity)
        return;

    bi = disk->integrity;

    kobject_uevent(&bi->kobj, KOBJ_REMOVE);
    kobject_del(&bi->kobj);
    kobject_put(&bi->kobj);
    disk->integrity = NULL;
}
EXPORT_SYMBOL(blk_integrity_unregister);