bio-integrity.c

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/*
 * bio-integrity.c - bio data integrity extensions
 *
 * Copyright (C) 2007, 2008, 2009 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/export.h>
#include <linux/bio.h>
#include <linux/workqueue.h>
#include <linux/slab.h>

struct integrity_slab {
    struct kmem_cache *slab;
    unsigned short nr_vecs;
    char name[8];
};

#define IS(x) { .nr_vecs = x, .name = "bip-"__stringify(x) }
struct integrity_slab bip_slab[BIOVEC_NR_POOLS] __read_mostly = {
    IS(1), IS(4), IS(16), IS(64), IS(128), IS(BIO_MAX_PAGES),
};
#undef IS

static struct workqueue_struct *kintegrityd_wq;

static inline unsigned int vecs_to_idx(unsigned int nr)
{
    switch (nr) {
    case 1:
        return 0;
    case 2 ... 4:
        return 1;
    case 5 ... 16:
        return 2;
    case 17 ... 64:
        return 3;
    case 65 ... 128:
        return 4;
    case 129 ... BIO_MAX_PAGES:
        return 5;
    default:
        BUG();
    }
}

static inline int use_bip_pool(unsigned int idx)
{
    if (idx == BIOVEC_MAX_IDX)
        return 1;

    return 0;
}

struct bio_integrity_payload *bio_integrity_alloc(struct bio *bio,
                          gfp_t gfp_mask,
                          unsigned int nr_vecs)
{
    struct bio_integrity_payload *bip;
    unsigned int idx = vecs_to_idx(nr_vecs);
    struct bio_set *bs = bio->bi_pool;

    if (!bs)
        bs = fs_bio_set;

    BUG_ON(bio == NULL);
    bip = NULL;

    /* Lower order allocations come straight from slab */
    if (!use_bip_pool(idx))
        bip = kmem_cache_alloc(bip_slab[idx].slab, gfp_mask);

    /* Use mempool if lower order alloc failed or max vecs were requested */
    if (bip == NULL) {
        idx = BIOVEC_MAX_IDX;  /* so we free the payload properly later */
        bip = mempool_alloc(bs->bio_integrity_pool, gfp_mask);

        if (unlikely(bip == NULL)) {
            printk(KERN_ERR "%s: could not alloc bip\n", __func__);
            return NULL;
        }
    }

    memset(bip, 0, sizeof(*bip));

    bip->bip_slab = idx;
    bip->bip_bio = bio;
    bio->bi_integrity = bip;

    return bip;
}
EXPORT_SYMBOL(bio_integrity_alloc);

void bio_integrity_free(struct bio *bio)
{
    struct bio_integrity_payload *bip = bio->bi_integrity;
    struct bio_set *bs = bio->bi_pool;

    if (!bs)
        bs = fs_bio_set;

    BUG_ON(bip == NULL);

    /* A cloned bio doesn't own the integrity metadata */
    if (!bio_flagged(bio, BIO_CLONED) && !bio_flagged(bio, BIO_FS_INTEGRITY)
        && bip->bip_buf != NULL)
        kfree(bip->bip_buf);

    if (use_bip_pool(bip->bip_slab))
        mempool_free(bip, bs->bio_integrity_pool);
    else
        kmem_cache_free(bip_slab[bip->bip_slab].slab, bip);

    bio->bi_integrity = NULL;
}
EXPORT_SYMBOL(bio_integrity_free);

int bio_integrity_add_page(struct bio *bio, struct page *page,
               unsigned int len, unsigned int offset)
{
    struct bio_integrity_payload *bip = bio->bi_integrity;
    struct bio_vec *iv;

    if (bip->bip_vcnt >= bvec_nr_vecs(bip->bip_slab)) {
        printk(KERN_ERR "%s: bip_vec full\n", __func__);
        return 0;
    }

    iv = bip_vec_idx(bip, bip->bip_vcnt);
    BUG_ON(iv == NULL);

    iv->bv_page = page;
    iv->bv_len = len;
    iv->bv_offset = offset;
    bip->bip_vcnt++;

    return len;
}
EXPORT_SYMBOL(bio_integrity_add_page);

static int bdev_integrity_enabled(struct block_device *bdev, int rw)
{
    struct blk_integrity *bi = bdev_get_integrity(bdev);

    if (bi == NULL)
        return 0;

    if (rw == READ && bi->verify_fn != NULL &&
        (bi->flags & INTEGRITY_FLAG_READ))
        return 1;

    if (rw == WRITE && bi->generate_fn != NULL &&
        (bi->flags & INTEGRITY_FLAG_WRITE))
        return 1;

    return 0;
}

int bio_integrity_enabled(struct bio *bio)
{
    /* Already protected? */
    if (bio_integrity(bio))
        return 0;

    return bdev_integrity_enabled(bio->bi_bdev, bio_data_dir(bio));
}
EXPORT_SYMBOL(bio_integrity_enabled);

static inline unsigned int bio_integrity_hw_sectors(struct blk_integrity *bi,
                            unsigned int sectors)
{
    /* At this point there are only 512b or 4096b DIF/EPP devices */
    if (bi->sector_size == 4096)
        return sectors >>= 3;

    return sectors;
}

unsigned int bio_integrity_tag_size(struct bio *bio)
{
    struct blk_integrity *bi = bdev_get_integrity(bio->bi_bdev);

    BUG_ON(bio->bi_size == 0);

    return bi->tag_size * (bio->bi_size / bi->sector_size);
}
EXPORT_SYMBOL(bio_integrity_tag_size);

int bio_integrity_tag(struct bio *bio, void *tag_buf, unsigned int len, int set)
{
    struct bio_integrity_payload *bip = bio->bi_integrity;
    struct blk_integrity *bi = bdev_get_integrity(bio->bi_bdev);
    unsigned int nr_sectors;

    BUG_ON(bip->bip_buf == NULL);

    if (bi->tag_size == 0)
        return -1;

    nr_sectors = bio_integrity_hw_sectors(bi,
                    DIV_ROUND_UP(len, bi->tag_size));

    if (nr_sectors * bi->tuple_size > bip->bip_size) {
        printk(KERN_ERR "%s: tag too big for bio: %u > %u\n",
               __func__, nr_sectors * bi->tuple_size, bip->bip_size);
        return -1;
    }

    if (set)
        bi->set_tag_fn(bip->bip_buf, tag_buf, nr_sectors);
    else
        bi->get_tag_fn(bip->bip_buf, tag_buf, nr_sectors);

    return 0;
}

int bio_integrity_set_tag(struct bio *bio, void *tag_buf, unsigned int len)
{
    BUG_ON(bio_data_dir(bio) != WRITE);

    return bio_integrity_tag(bio, tag_buf, len, 1);
}
EXPORT_SYMBOL(bio_integrity_set_tag);

int bio_integrity_get_tag(struct bio *bio, void *tag_buf, unsigned int len)
{
    BUG_ON(bio_data_dir(bio) != READ);

    return bio_integrity_tag(bio, tag_buf, len, 0);
}
EXPORT_SYMBOL(bio_integrity_get_tag);

static void bio_integrity_generate(struct bio *bio)
{
    struct blk_integrity *bi = bdev_get_integrity(bio->bi_bdev);
    struct blk_integrity_exchg bix;
    struct bio_vec *bv;
    sector_t sector = bio->bi_sector;
    unsigned int i, sectors, total;
    void *prot_buf = bio->bi_integrity->bip_buf;

    total = 0;
    bix.disk_name = bio->bi_bdev->bd_disk->disk_name;
    bix.sector_size = bi->sector_size;

    bio_for_each_segment(bv, bio, i) {
        void *kaddr = kmap_atomic(bv->bv_page);
        bix.data_buf = kaddr + bv->bv_offset;
        bix.data_size = bv->bv_len;
        bix.prot_buf = prot_buf;
        bix.sector = sector;

        bi->generate_fn(&bix);

        sectors = bv->bv_len / bi->sector_size;
        sector += sectors;
        prot_buf += sectors * bi->tuple_size;
        total += sectors * bi->tuple_size;
        BUG_ON(total > bio->bi_integrity->bip_size);

        kunmap_atomic(kaddr);
    }
}

static inline unsigned short blk_integrity_tuple_size(struct blk_integrity *bi)
{
    if (bi)
        return bi->tuple_size;

    return 0;
}

int bio_integrity_prep(struct bio *bio)
{
    struct bio_integrity_payload *bip;
    struct blk_integrity *bi;
    struct request_queue *q;
    void *buf;
    unsigned long start, end;
    unsigned int len, nr_pages;
    unsigned int bytes, offset, i;
    unsigned int sectors;

    bi = bdev_get_integrity(bio->bi_bdev);
    q = bdev_get_queue(bio->bi_bdev);
    BUG_ON(bi == NULL);
    BUG_ON(bio_integrity(bio));

    sectors = bio_integrity_hw_sectors(bi, bio_sectors(bio));

    /* Allocate kernel buffer for protection data */
    len = sectors * blk_integrity_tuple_size(bi);
    buf = kmalloc(len, GFP_NOIO | q->bounce_gfp);
    if (unlikely(buf == NULL)) {
        printk(KERN_ERR "could not allocate integrity buffer\n");
        return -ENOMEM;
    }

    end = (((unsigned long) buf) + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
    start = ((unsigned long) buf) >> PAGE_SHIFT;
    nr_pages = end - start;

    /* Allocate bio integrity payload and integrity vectors */
    bip = bio_integrity_alloc(bio, GFP_NOIO, nr_pages);
    if (unlikely(bip == NULL)) {
        printk(KERN_ERR "could not allocate data integrity bioset\n");
        kfree(buf);
        return -EIO;
    }

    bip->bip_buf = buf;
    bip->bip_size = len;
    bip->bip_sector = bio->bi_sector;

    /* Map it */
    offset = offset_in_page(buf);
    for (i = 0 ; i < nr_pages ; i++) {
        int ret;
        bytes = PAGE_SIZE - offset;

        if (len <= 0)
            break;

        if (bytes > len)
            bytes = len;

        ret = bio_integrity_add_page(bio, virt_to_page(buf),
                         bytes, offset);

        if (ret == 0)
            return 0;

        if (ret < bytes)
            break;

        buf += bytes;
        len -= bytes;
        offset = 0;
    }

    /* Install custom I/O completion handler if read verify is enabled */
    if (bio_data_dir(bio) == READ) {
        bip->bip_end_io = bio->bi_end_io;
        bio->bi_end_io = bio_integrity_endio;
    }

    /* Auto-generate integrity metadata if this is a write */
    if (bio_data_dir(bio) == WRITE)
        bio_integrity_generate(bio);

    return 0;
}
EXPORT_SYMBOL(bio_integrity_prep);

static int bio_integrity_verify(struct bio *bio)
{
    struct blk_integrity *bi = bdev_get_integrity(bio->bi_bdev);
    struct blk_integrity_exchg bix;
    struct bio_vec *bv;
    sector_t sector = bio->bi_integrity->bip_sector;
    unsigned int i, sectors, total, ret;
    void *prot_buf = bio->bi_integrity->bip_buf;

    ret = total = 0;
    bix.disk_name = bio->bi_bdev->bd_disk->disk_name;
    bix.sector_size = bi->sector_size;

    bio_for_each_segment(bv, bio, i) {
        void *kaddr = kmap_atomic(bv->bv_page);
        bix.data_buf = kaddr + bv->bv_offset;
        bix.data_size = bv->bv_len;
        bix.prot_buf = prot_buf;
        bix.sector = sector;

        ret = bi->verify_fn(&bix);

        if (ret) {
            kunmap_atomic(kaddr);
            return ret;
        }

        sectors = bv->bv_len / bi->sector_size;
        sector += sectors;
        prot_buf += sectors * bi->tuple_size;
        total += sectors * bi->tuple_size;
        BUG_ON(total > bio->bi_integrity->bip_size);

        kunmap_atomic(kaddr);
    }

    return ret;
}

static void bio_integrity_verify_fn(struct work_struct *work)
{
    struct bio_integrity_payload *bip =
        container_of(work, struct bio_integrity_payload, bip_work);
    struct bio *bio = bip->bip_bio;
    int error;

    error = bio_integrity_verify(bio);

    /* Restore original bio completion handler */
    bio->bi_end_io = bip->bip_end_io;
    bio_endio(bio, error);
}

void bio_integrity_endio(struct bio *bio, int error)
{
    struct bio_integrity_payload *bip = bio->bi_integrity;

    BUG_ON(bip->bip_bio != bio);

    /* In case of an I/O error there is no point in verifying the
     * integrity metadata.  Restore original bio end_io handler
     * and run it.
     */
    if (error) {
        bio->bi_end_io = bip->bip_end_io;
        bio_endio(bio, error);

        return;
    }

    INIT_WORK(&bip->bip_work, bio_integrity_verify_fn);
    queue_work(kintegrityd_wq, &bip->bip_work);
}
EXPORT_SYMBOL(bio_integrity_endio);

void bio_integrity_mark_head(struct bio_integrity_payload *bip,
                 unsigned int skip)
{
    struct bio_vec *iv;
    unsigned int i;

    bip_for_each_vec(iv, bip, i) {
        if (skip == 0) {
            bip->bip_idx = i;
            return;
        } else if (skip >= iv->bv_len) {
            skip -= iv->bv_len;
        } else { /* skip < iv->bv_len) */
            iv->bv_offset += skip;
            iv->bv_len -= skip;
            bip->bip_idx = i;
            return;
        }
    }
}

void bio_integrity_mark_tail(struct bio_integrity_payload *bip,
                 unsigned int len)
{
    struct bio_vec *iv;
    unsigned int i;

    bip_for_each_vec(iv, bip, i) {
        if (len == 0) {
            bip->bip_vcnt = i;
            return;
        } else if (len >= iv->bv_len) {
            len -= iv->bv_len;
        } else { /* len < iv->bv_len) */
            iv->bv_len = len;
            len = 0;
        }
    }
}

void bio_integrity_advance(struct bio *bio, unsigned int bytes_done)
{
    struct bio_integrity_payload *bip = bio->bi_integrity;
    struct blk_integrity *bi = bdev_get_integrity(bio->bi_bdev);
    unsigned int nr_sectors;

    BUG_ON(bip == NULL);
    BUG_ON(bi == NULL);

    nr_sectors = bio_integrity_hw_sectors(bi, bytes_done >> 9);
    bio_integrity_mark_head(bip, nr_sectors * bi->tuple_size);
}
EXPORT_SYMBOL(bio_integrity_advance);

void bio_integrity_trim(struct bio *bio, unsigned int offset,
            unsigned int sectors)
{
    struct bio_integrity_payload *bip = bio->bi_integrity;
    struct blk_integrity *bi = bdev_get_integrity(bio->bi_bdev);
    unsigned int nr_sectors;

    BUG_ON(bip == NULL);
    BUG_ON(bi == NULL);
    BUG_ON(!bio_flagged(bio, BIO_CLONED));

    nr_sectors = bio_integrity_hw_sectors(bi, sectors);
    bip->bip_sector = bip->bip_sector + offset;
    bio_integrity_mark_head(bip, offset * bi->tuple_size);
    bio_integrity_mark_tail(bip, sectors * bi->tuple_size);
}
EXPORT_SYMBOL(bio_integrity_trim);

void bio_integrity_split(struct bio *bio, struct bio_pair *bp, int sectors)
{
    struct blk_integrity *bi;
    struct bio_integrity_payload *bip = bio->bi_integrity;
    unsigned int nr_sectors;

    if (bio_integrity(bio) == 0)
        return;

    bi = bdev_get_integrity(bio->bi_bdev);
    BUG_ON(bi == NULL);
    BUG_ON(bip->bip_vcnt != 1);

    nr_sectors = bio_integrity_hw_sectors(bi, sectors);

    bp->bio1.bi_integrity = &bp->bip1;
    bp->bio2.bi_integrity = &bp->bip2;

    bp->iv1 = bip->bip_vec[0];
    bp->iv2 = bip->bip_vec[0];

    bp->bip1.bip_vec[0] = bp->iv1;
    bp->bip2.bip_vec[0] = bp->iv2;

    bp->iv1.bv_len = sectors * bi->tuple_size;
    bp->iv2.bv_offset += sectors * bi->tuple_size;
    bp->iv2.bv_len -= sectors * bi->tuple_size;

    bp->bip1.bip_sector = bio->bi_integrity->bip_sector;
    bp->bip2.bip_sector = bio->bi_integrity->bip_sector + nr_sectors;

    bp->bip1.bip_vcnt = bp->bip2.bip_vcnt = 1;
    bp->bip1.bip_idx = bp->bip2.bip_idx = 0;
}
EXPORT_SYMBOL(bio_integrity_split);

int bio_integrity_clone(struct bio *bio, struct bio *bio_src,
            gfp_t gfp_mask)
{
    struct bio_integrity_payload *bip_src = bio_src->bi_integrity;
    struct bio_integrity_payload *bip;

    BUG_ON(bip_src == NULL);

    bip = bio_integrity_alloc(bio, gfp_mask, bip_src->bip_vcnt);

    if (bip == NULL)
        return -EIO;

    memcpy(bip->bip_vec, bip_src->bip_vec,
           bip_src->bip_vcnt * sizeof(struct bio_vec));

    bip->bip_sector = bip_src->bip_sector;
    bip->bip_vcnt = bip_src->bip_vcnt;
    bip->bip_idx = bip_src->bip_idx;

    return 0;
}
EXPORT_SYMBOL(bio_integrity_clone);

int bioset_integrity_create(struct bio_set *bs, int pool_size)
{
    unsigned int max_slab = vecs_to_idx(BIO_MAX_PAGES);

    if (bs->bio_integrity_pool)
        return 0;

    bs->bio_integrity_pool =
        mempool_create_slab_pool(pool_size, bip_slab[max_slab].slab);

    if (!bs->bio_integrity_pool)
        return -1;

    return 0;
}
EXPORT_SYMBOL(bioset_integrity_create);

void bioset_integrity_free(struct bio_set *bs)
{
    if (bs->bio_integrity_pool)
        mempool_destroy(bs->bio_integrity_pool);
}
EXPORT_SYMBOL(bioset_integrity_free);

void __init bio_integrity_init(void)
{
    unsigned int i;

    /*
     * kintegrityd won't block much but may burn a lot of CPU cycles.
     * Make it highpri CPU intensive wq with max concurrency of 1.
     */
    kintegrityd_wq = alloc_workqueue("kintegrityd", WQ_MEM_RECLAIM |
                     WQ_HIGHPRI | WQ_CPU_INTENSIVE, 1);
    if (!kintegrityd_wq)
        panic("Failed to create kintegrityd\n");

    for (i = 0 ; i < BIOVEC_NR_POOLS ; i++) {
        unsigned int size;

        size = sizeof(struct bio_integrity_payload)
            + bip_slab[i].nr_vecs * sizeof(struct bio_vec);

        bip_slab[i].slab =
            kmem_cache_create(bip_slab[i].name, size, 0,
                      SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
    }
}