path: root/fs/bio-integrity.c

/*
 * bio-integrity.c - bio data integrity extensions
 *
 * Copyright (C) 2007, 2008, 2009 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/mempool.h>
#include <linux/bio.h>
#include <linux/workqueue.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_NR_POOLS)
		return 1;

	return 0;
}

/**
 * bio_integrity_alloc_bioset - Allocate integrity payload and attach it to bio
 * @bio:	bio to attach integrity metadata to
 * @gfp_mask:	Memory allocation mask
 * @nr_vecs:	Number of integrity metadata scatter-gather elements
 * @bs:		bio_set to allocate from
 *
 * Description: This function prepares a bio for attaching integrity
 * metadata.  nr_vecs specifies the maximum number of pages containing
 * integrity metadata that can be attached.
 */
struct bio_integrity_payload *bio_integrity_alloc_bioset(struct bio *bio,
							 gfp_t gfp_mask,
							 unsigned int nr_vecs,
							 struct bio_set *bs)
{
	struct bio_integrity_payload *bip;
	unsigned int idx = vecs_to_idx(nr_vecs);

	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) {
		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_bioset);

/**
 * bio_integrity_alloc - Allocate integrity payload and attach it to bio
 * @bio:	bio to attach integrity metadata to
 * @gfp_mask:	Memory allocation mask
 * @nr_vecs:	Number of integrity metadata scatter-gather elements
 *
 * Description: This function prepares a bio for attaching integrity
 * metadata.  nr_vecs specifies the maximum number of pages containing
 * integrity metadata that can be attached.
 */
struct bio_integrity_payload *bio_integrity_alloc(struct bio *bio,
						  gfp_t gfp_mask,
						  unsigned int nr_vecs)
{
	return bio_integrity_alloc_bioset(bio, gfp_mask, nr_vecs, fs_bio_set);
}
EXPORT_SYMBOL(bio_integrity_alloc);

/**
 * bio_integrity_free - Free bio integrity payload
 * @bio:	bio containing bip to be freed
 * @bs:		bio_set this bio was allocated from
 *
 * Description: Used to free the integrity portion of a bio. Usually
 * called from bio_free().
 */
void bio_integrity_free(struct bio *bio, struct bio_set *bs)
{
	struct bio_integrity_payload *bip = bio->bi_integrity;

	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);

/**
 * bio_integrity_add_page - Attach integrity metadata
 * @bio:	bio to update
 * @page:	page containing integrity metadata
 * @len:	number of bytes of integrity metadata in page
 * @offset:	start offset within page
 *
 * Description: Attach a page containing integrity metadata to bio.
 */
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;
}

/**
 * bio_integrity_enabled - Check whether integrity can be passed
 * @bio:	bio to check
 *
 * Description: Determines whether bio_integrity_prep() can be called
 * on this bio or not.	bio data direction and target device must be
 * set prior to calling.  The functions honors the write_generate and
 * read_verify flags in sysfs.
 */
int bio_integrity_enabled(struct bio *bio)
{
	/* Already protected? */
	if (bio_integrity(bio))
		return 0;

	return bdev_integrity_enabled(bio->bi_bd