// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright 2022 Red Hat, Inc.
*/
#include <linux/bio.h>
#include <linux/blk-crypto.h>
#include <linux/blk-integrity.h>
#include "dm-core.h"
static inline bool dm_bvec_iter_rewind(const struct bio_vec *bv,
struct bvec_iter *iter,
unsigned int bytes)
{
int idx;
iter->bi_size += bytes;
if (bytes <= iter->bi_bvec_done) {
iter->bi_bvec_done -= bytes;
return true;
}
bytes -= iter->bi_bvec_done;
idx = iter->bi_idx - 1;
while (idx >= 0 && bytes && bytes > bv[idx].bv_len) {
bytes -= bv[idx].bv_len;
idx--;
}
if (WARN_ONCE(idx < 0 && bytes,
"Attempted to rewind iter beyond bvec's boundaries\n")) {
iter->bi_size -= bytes;
iter->bi_bvec_done = 0;
iter->bi_idx = 0;
return false;
}
iter->bi_idx = idx;
iter->bi_bvec_done = bv[idx].bv_len - bytes;
return true;
}
#if defined(CONFIG_BLK_DEV_INTEGRITY)
/**
* dm_bio_integrity_rewind - Rewind integrity vector
* @bio: bio whose integrity vector to update
* @bytes_done: number of data bytes to rewind
*
* Description: This function calculates how many integrity bytes the
* number of completed data bytes correspond to and rewind the
* integrity vector accordingly.
*/
static void dm_bio_integrity_rewind(struct bio *bio, unsigned int bytes_done)
{
struct bio_integrity_payload *bip = bio_integrity(bio);
struct blk_integrity *bi = blk_get_integrity(bio->bi_bdev->bd_disk);
unsigned int bytes = bio_integrity_bytes(bi, bytes_done >> 9);
bip->bip_iter.bi_sector -= bio_integrity_intervals(bi, bytes_done >> 9);
dm_bvec_iter_rewind(bip->bip_vec, &bip->bip_iter, bytes);
}
#else /* CONFIG_BLK_DEV_INTEGRITY */
static inline void dm_bio_integrity_rewind(struct bio *bio,
unsigned int bytes_done)
{
}
#endif
#if defined(CONFIG_BLK_INLINE_ENCRYPTION)
/* Decrements @dun by @dec, treating @dun as a multi-limb integer. */
static void dm_bio_crypt_dun_decrement(u64 dun[BLK_CRYPTO_DUN_ARRAY_SIZE],
unsigned int dec)
{
int i;
for (i = 0; dec && i < BLK_CRYPTO_DUN_ARRAY_SIZE; i++) {
u64 prev = dun[i];
dun[i] -= dec;
if (dun[i] > prev)
dec = 1;
else
dec = 0;
}
}
static void dm_bio_crypt_rewind(struct bio *bio, unsigned int bytes)
{
struct bio_crypt_ctx *bc = bio->bi_crypt_context;
dm_bio_crypt_dun_decrement(bc->bc_dun,
bytes >> bc->bc_key->data_unit_size_bits);
}
#else /* CONFIG_BLK_INLINE_ENCRYPTION */
static inline void dm_bio_crypt_rewind(struct bio *bio, unsigned int bytes)
{
}
#endif
static inline void dm_bio_rewind_iter(const struct bio *bio,
struct bvec_iter *iter, unsigned int bytes)
{
iter->bi_sector -= bytes >> 9;
/* No advance means no rewind */
if (bio_no_advance_iter(bio))
iter->bi_size += bytes;
else
dm_bvec_iter_rewind(bio->bi_io_vec, iter, bytes);
}
/**
* dm_bio_rewind - update ->bi_iter of @bio by rewinding @bytes.
* @bio: bio to rewind
* @bytes: how many bytes to rewind
*
* WARNING:
* Caller must ensure that @bio has a fixed end sector, to allow
* rewinding from end of bio and restoring its original position.
* Caller is also responsibile for restoring bio's size.
*/
static void dm_bio_rewind(struct bio *bio, unsigned int bytes)
{
if (bio_integrity(bio))
dm_bio_integrity_rewind(bio, bytes);
if (bio_has_crypt_ctx(bio))
dm_bio_crypt_rewind(bio, bytes);
dm_bio_rewind_iter(bio, &bio->bi_iter, bytes);
}
void dm_io_rewind(struct dm_io *io, struct bio_set *bs)
{
struct bio *orig = io->orig_bio;
struct bio *new_orig = bio_alloc_clone(orig->bi_bdev, orig,
GFP_NOIO, bs);
/*
* dm_bio_rewind can restore to previous position since the
* end sector is fixed for original bio, but we still need
* to restore bio's size manually (using io->sectors).
*/
dm_bio_rewind(new_orig, ((io->sector_offset << 9) -
orig->bi_iter.bi_size));
bio_trim(new_orig, 0, io->sectors);
bio_chain(new_orig, orig);
/*
* __bi_remaining was increased (by dm_split_and_process_bio),
* so must drop the one added in bio_chain.
*/
atomic_dec(&orig->__bi_remaining);
io->orig_bio = new_orig;
}
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