2 * Copyright (C) 2012 Red Hat, Inc.
4 * Author: Mikulas Patocka <mpatocka@redhat.com>
6 * Based on Chromium dm-verity driver (C) 2011 The Chromium OS Authors
8 * This file is released under the GPLv2.
10 * In the file "/sys/module/dm_verity/parameters/prefetch_cluster" you can set
11 * default prefetch value. Data are read in "prefetch_cluster" chunks from the
12 * hash device. Setting this greatly improves performance when data and hash
13 * are on the same disk on different partitions on devices with poor random
19 #include <linux/module.h>
20 #include <linux/device-mapper.h>
21 #include <linux/reboot.h>
22 #include <crypto/hash.h>
24 #define DM_MSG_PREFIX "verity"
26 #define DM_VERITY_ENV_LENGTH 42
27 #define DM_VERITY_ENV_VAR_NAME "DM_VERITY_ERR_BLOCK_NR"
29 #define DM_VERITY_DEFAULT_PREFETCH_SIZE 262144
31 #define DM_VERITY_MAX_LEVELS 63
32 #define DM_VERITY_MAX_CORRUPTED_ERRS 100
34 #define DM_VERITY_OPT_LOGGING "ignore_corruption"
35 #define DM_VERITY_OPT_RESTART "restart_on_corruption"
37 static unsigned dm_verity_prefetch_cluster = DM_VERITY_DEFAULT_PREFETCH_SIZE;
39 module_param_named(prefetch_cluster, dm_verity_prefetch_cluster, uint, S_IRUGO | S_IWUSR);
43 DM_VERITY_MODE_LOGGING,
44 DM_VERITY_MODE_RESTART
47 enum verity_block_type {
48 DM_VERITY_BLOCK_TYPE_DATA,
49 DM_VERITY_BLOCK_TYPE_METADATA
53 struct dm_dev *data_dev;
54 struct dm_dev *hash_dev;
56 struct dm_bufio_client *bufio;
58 struct crypto_shash *tfm;
59 u8 *root_digest; /* digest of the root block */
60 u8 *salt; /* salt: its size is salt_size */
62 sector_t data_start; /* data offset in 512-byte sectors */
63 sector_t hash_start; /* hash start in blocks */
64 sector_t data_blocks; /* the number of data blocks */
65 sector_t hash_blocks; /* the number of hash blocks */
66 unsigned char data_dev_block_bits; /* log2(data blocksize) */
67 unsigned char hash_dev_block_bits; /* log2(hash blocksize) */
68 unsigned char hash_per_block_bits; /* log2(hashes in hash block) */
69 unsigned char levels; /* the number of tree levels */
70 unsigned char version;
71 unsigned digest_size; /* digest size for the current hash algorithm */
72 unsigned shash_descsize;/* the size of temporary space for crypto */
73 int hash_failed; /* set to 1 if hash of any block failed */
74 enum verity_mode mode; /* mode for handling verification errors */
75 unsigned corrupted_errs;/* Number of errors for corrupted blocks */
77 struct workqueue_struct *verify_wq;
79 /* starting blocks for each tree level. 0 is the lowest level. */
80 sector_t hash_level_block[DM_VERITY_MAX_LEVELS];
86 /* original values of bio->bi_end_io and bio->bi_private */
87 bio_end_io_t *orig_bi_end_io;
88 void *orig_bi_private;
93 struct bvec_iter iter;
95 struct work_struct work;
98 * Three variably-size fields follow this struct:
100 * u8 hash_desc[v->shash_descsize];
101 * u8 real_digest[v->digest_size];
102 * u8 want_digest[v->digest_size];
104 * To access them use: io_hash_desc(), io_real_digest() and io_want_digest().
108 struct dm_verity_prefetch_work {
109 struct work_struct work;
115 static struct shash_desc *io_hash_desc(struct dm_verity *v, struct dm_verity_io *io)
117 return (struct shash_desc *)(io + 1);
120 static u8 *io_real_digest(struct dm_verity *v, struct dm_verity_io *io)
122 return (u8 *)(io + 1) + v->shash_descsize;
125 static u8 *io_want_digest(struct dm_verity *v, struct dm_verity_io *io)
127 return (u8 *)(io + 1) + v->shash_descsize + v->digest_size;
131 * Auxiliary structure appended to each dm-bufio buffer. If the value
132 * hash_verified is nonzero, hash of the block has been verified.
134 * The variable hash_verified is set to 0 when allocating the buffer, then
135 * it can be changed to 1 and it is never reset to 0 again.
137 * There is no lock around this value, a race condition can at worst cause
138 * that multiple processes verify the hash of the same buffer simultaneously
139 * and write 1 to hash_verified simultaneously.
140 * This condition is harmless, so we don't need locking.
147 * Initialize struct buffer_aux for a freshly created buffer.
149 static void dm_bufio_alloc_callback(struct dm_buffer *buf)
151 struct buffer_aux *aux = dm_bufio_get_aux_data(buf);
153 aux->hash_verified = 0;
157 * Translate input sector number to the sector number on the target device.
159 static sector_t verity_map_sector(struct dm_verity *v, sector_t bi_sector)
161 return v->data_start + dm_target_offset(v->ti, bi_sector);
165 * Return hash position of a specified block at a specified tree level
166 * (0 is the lowest level).
167 * The lowest "hash_per_block_bits"-bits of the result denote hash position
168 * inside a hash block. The remaining bits denote location of the hash block.
170 static sector_t verity_position_at_level(struct dm_verity *v, sector_t block,
173 return block >> (level * v->hash_per_block_bits);
176 static void verity_hash_at_level(struct dm_verity *v, sector_t block, int level,
177 sector_t *hash_block, unsigned *offset)
179 sector_t position = verity_position_at_level(v, block, level);
182 *hash_block = v->hash_level_block[level] + (position >> v->hash_per_block_bits);
187 idx = position & ((1 << v->hash_per_block_bits) - 1);
189 *offset = idx * v->digest_size;
191 *offset = idx << (v->hash_dev_block_bits - v->hash_per_block_bits);
195 * Handle verification errors.
197 static int verity_handle_err(struct dm_verity *v, enum verity_block_type type,
198 unsigned long long block)
200 char verity_env[DM_VERITY_ENV_LENGTH];
201 char *envp[] = { verity_env, NULL };
202 const char *type_str = "";
203 struct mapped_device *md = dm_table_get_md(v->ti->table);
205 /* Corruption should be visible in device status in all modes */
208 if (v->corrupted_errs >= DM_VERITY_MAX_CORRUPTED_ERRS)
214 case DM_VERITY_BLOCK_TYPE_DATA:
217 case DM_VERITY_BLOCK_TYPE_METADATA:
218 type_str = "metadata";
224 DMERR("%s: %s block %llu is corrupted", v->data_dev->name, type_str,
227 if (v->corrupted_errs == DM_VERITY_MAX_CORRUPTED_ERRS)
228 DMERR("%s: reached maximum errors", v->data_dev->name);
230 snprintf(verity_env, DM_VERITY_ENV_LENGTH, "%s=%d,%llu",
231 DM_VERITY_ENV_VAR_NAME, type, block);
233 kobject_uevent_env(&disk_to_dev(dm_disk(md))->kobj, KOBJ_CHANGE, envp);
236 if (v->mode == DM_VERITY_MODE_LOGGING)
239 if (v->mode == DM_VERITY_MODE_RESTART)
240 kernel_restart("dm-verity device corrupted");
246 * Verify hash of a metadata block pertaining to the specified data block
247 * ("block" argument) at a specified level ("level" argument).
249 * On successful return, io_want_digest(v, io) contains the hash value for
250 * a lower tree level or for the data block (if we're at the lowest leve).
252 * If "skip_unverified" is true, unverified buffer is skipped and 1 is returned.
253 * If "skip_unverified" is false, unverified buffer is hashed and verified
254 * against current value of io_want_digest(v, io).
256 static int verity_verify_level(struct dm_verity_io *io, sector_t block,
257 int level, bool skip_unverified)
259 struct dm_verity *v = io->v;
260 struct dm_buffer *buf;
261 struct buffer_aux *aux;
267 verity_hash_at_level(v, block, level, &hash_block, &offset);
269 data = dm_bufio_read(v->bufio, hash_block, &buf);
270 if (unlikely(IS_ERR(data)))
271 return PTR_ERR(data);
273 aux = dm_bufio_get_aux_data(buf);
275 if (!aux->hash_verified) {
276 struct shash_desc *desc;
279 if (skip_unverified) {
284 desc = io_hash_desc(v, io);
286 desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP;
287 r = crypto_shash_init(desc);
289 DMERR("crypto_shash_init failed: %d", r);
293 if (likely(v->version >= 1)) {
294 r = crypto_shash_update(desc, v->salt, v->salt_size);
296 DMERR("crypto_shash_update failed: %d", r);
301 r = crypto_shash_update(desc, data, 1 << v->hash_dev_block_bits);
303 DMERR("crypto_shash_update failed: %d", r);
308 r = crypto_shash_update(desc, v->salt, v->salt_size);
310 DMERR("crypto_shash_update failed: %d", r);
315 result = io_real_digest(v, io);
316 r = crypto_shash_final(desc, result);
318 DMERR("crypto_shash_final failed: %d", r);
321 if (unlikely(memcmp(result, io_want_digest(v, io), v->digest_size))) {
322 if (verity_handle_err(v, DM_VERITY_BLOCK_TYPE_METADATA,
328 aux->hash_verified = 1;
333 memcpy(io_want_digest(v, io), data, v->digest_size);
335 dm_bufio_release(buf);
339 dm_bufio_release(buf);
345 * Verify one "dm_verity_io" structure.
347 static int verity_verify_io(struct dm_verity_io *io)
349 struct dm_verity *v = io->v;
350 struct bio *bio = dm_bio_from_per_bio_data(io,
351 v->ti->per_bio_data_size);
355 for (b = 0; b < io->n_blocks; b++) {
356 struct shash_desc *desc;
361 if (likely(v->levels)) {
363 * First, we try to get the requested hash for
364 * the current block. If the hash block itself is
365 * verified, zero is returned. If it isn't, this
366 * function returns 0 and we fall back to whole
367 * chain verification.
369 int r = verity_verify_level(io, io->block + b, 0, true);
371 goto test_block_hash;
376 memcpy(io_want_digest(v, io), v->root_digest, v->digest_size);
378 for (i = v->levels - 1; i >= 0; i--) {
379 int r = verity_verify_level(io, io->block + b, i, false);
385 desc = io_hash_desc(v, io);
387 desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP;
388 r = crypto_shash_init(desc);
390 DMERR("crypto_shash_init failed: %d", r);
394 if (likely(v->version >= 1)) {
395 r = crypto_shash_update(desc, v->salt, v->salt_size);
397 DMERR("crypto_shash_update failed: %d", r);
401 todo = 1 << v->data_dev_block_bits;
405 struct bio_vec bv = bio_iter_iovec(bio, io->iter);
407 page = kmap_atomic(bv.bv_page);
409 if (likely(len >= todo))
411 r = crypto_shash_update(desc, page + bv.bv_offset, len);
415 DMERR("crypto_shash_update failed: %d", r);
419 bio_advance_iter(bio, &io->iter, len);
424 r = crypto_shash_update(desc, v->salt, v->salt_size);
426 DMERR("crypto_shash_update failed: %d", r);
431 result = io_real_digest(v, io);
432 r = crypto_shash_final(desc, result);
434 DMERR("crypto_shash_final failed: %d", r);
437 if (unlikely(memcmp(result, io_want_digest(v, io), v->digest_size))) {
438 if (verity_handle_err(v, DM_VERITY_BLOCK_TYPE_DATA,
448 * End one "io" structure with a given error.
450 static void verity_finish_io(struct dm_verity_io *io, int error)
452 struct dm_verity *v = io->v;
453 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_bio_data_size);
455 bio->bi_end_io = io->orig_bi_end_io;
456 bio->bi_private = io->orig_bi_private;
458 bio_endio(bio, error);
461 static void verity_work(struct work_struct *w)
463 struct dm_verity_io *io = container_of(w, struct dm_verity_io, work);
465 verity_finish_io(io, verity_verify_io(io));
468 static void verity_end_io(struct bio *bio, int error)
470 struct dm_verity_io *io = bio->bi_private;
473 verity_finish_io(io, error);
477 INIT_WORK(&io->work, verity_work);
478 queue_work(io->v->verify_wq, &io->work);
482 * Prefetch buffers for the specified io.
483 * The root buffer is not prefetched, it is assumed that it will be cached
486 static void verity_prefetch_io(struct work_struct *work)
488 struct dm_verity_prefetch_work *pw =
489 container_of(work, struct dm_verity_prefetch_work, work);
490 struct dm_verity *v = pw->v;
493 for (i = v->levels - 2; i >= 0; i--) {
494 sector_t hash_block_start;
495 sector_t hash_block_end;
496 verity_hash_at_level(v, pw->block, i, &hash_block_start, NULL);
497 verity_hash_at_level(v, pw->block + pw->n_blocks - 1, i, &hash_block_end, NULL);
499 unsigned cluster = ACCESS_ONCE(dm_verity_prefetch_cluster);
501 cluster >>= v->data_dev_block_bits;
502 if (unlikely(!cluster))
503 goto no_prefetch_cluster;
505 if (unlikely(cluster & (cluster - 1)))
506 cluster = 1 << __fls(cluster);
508 hash_block_start &= ~(sector_t)(cluster - 1);
509 hash_block_end |= cluster - 1;
510 if (unlikely(hash_block_end >= v->hash_blocks))
511 hash_block_end = v->hash_blocks - 1;
514 dm_bufio_prefetch(v->bufio, hash_block_start,
515 hash_block_end - hash_block_start + 1);
521 static void verity_submit_prefetch(struct dm_verity *v, struct dm_verity_io *io)
523 struct dm_verity_prefetch_work *pw;
525 pw = kmalloc(sizeof(struct dm_verity_prefetch_work),
526 GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN);
531 INIT_WORK(&pw->work, verity_prefetch_io);
533 pw->block = io->block;
534 pw->n_blocks = io->n_blocks;
535 queue_work(v->verify_wq, &pw->work);
539 * Bio map function. It allocates dm_verity_io structure and bio vector and
540 * fills them. Then it issues prefetches and the I/O.
542 static int verity_map(struct dm_target *ti, struct bio *bio)
544 struct dm_verity *v = ti->private;
545 struct dm_verity_io *io;
547 bio->bi_bdev = v->data_dev->bdev;
548 bio->bi_iter.bi_sector = verity_map_sector(v, bio->bi_iter.bi_sector);
550 if (((unsigned)bio->bi_iter.bi_sector | bio_sectors(bio)) &
551 ((1 << (v->data_dev_block_bits - SECTOR_SHIFT)) - 1)) {
552 DMERR_LIMIT("unaligned io");
556 if (bio_end_sector(bio) >>
557 (v->data_dev_block_bits - SECTOR_SHIFT) > v->data_blocks) {
558 DMERR_LIMIT("io out of range");
562 if (bio_data_dir(bio) == WRITE)
565 io = dm_per_bio_data(bio, ti->per_bio_data_size);
567 io->orig_bi_end_io = bio->bi_end_io;
568 io->orig_bi_private = bio->bi_private;
569 io->block = bio->bi_iter.bi_sector >> (v->data_dev_block_bits - SECTOR_SHIFT);
570 io->n_blocks = bio->bi_iter.bi_size >> v->data_dev_block_bits;
572 bio->bi_end_io = verity_end_io;
573 bio->bi_private = io;
574 io->iter = bio->bi_iter;
576 verity_submit_prefetch(v, io);
578 generic_make_request(bio);
580 return DM_MAPIO_SUBMITTED;
584 * Status: V (valid) or C (corruption found)
586 static void verity_status(struct dm_target *ti, status_type_t type,
587 unsigned status_flags, char *result, unsigned maxlen)
589 struct dm_verity *v = ti->private;
594 case STATUSTYPE_INFO:
595 DMEMIT("%c", v->hash_failed ? 'C' : 'V');
597 case STATUSTYPE_TABLE:
598 DMEMIT("%u %s %s %u %u %llu %llu %s ",
602 1 << v->data_dev_block_bits,
603 1 << v->hash_dev_block_bits,
604 (unsigned long long)v->data_blocks,
605 (unsigned long long)v->hash_start,
608 for (x = 0; x < v->digest_size; x++)
609 DMEMIT("%02x", v->root_digest[x]);
614 for (x = 0; x < v->salt_size; x++)
615 DMEMIT("%02x", v->salt[x]);
616 if (v->mode != DM_VERITY_MODE_EIO) {
619 case DM_VERITY_MODE_LOGGING:
620 DMEMIT(DM_VERITY_OPT_LOGGING);
622 case DM_VERITY_MODE_RESTART:
623 DMEMIT(DM_VERITY_OPT_RESTART);
633 static int verity_ioctl(struct dm_target *ti, unsigned cmd,
636 struct dm_verity *v = ti->private;
640 ti->len != i_size_read(v->data_dev->bdev->bd_inode) >> SECTOR_SHIFT)
641 r = scsi_verify_blk_ioctl(NULL, cmd);
643 return r ? : __blkdev_driver_ioctl(v->data_dev->bdev, v->data_dev->mode,
647 static int verity_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
648 struct bio_vec *biovec, int max_size)
650 struct dm_verity *v = ti->private;
651 struct request_queue *q = bdev_get_queue(v->data_dev->bdev);
653 if (!q->merge_bvec_fn)
656 bvm->bi_bdev = v->data_dev->bdev;
657 bvm->bi_sector = verity_map_sector(v, bvm->bi_sector);
659 return min(max_size, q->merge_bvec_fn(q, bvm, biovec));
662 static int verity_iterate_devices(struct dm_target *ti,
663 iterate_devices_callout_fn fn, void *data)
665 struct dm_verity *v = ti->private;
667 return fn(ti, v->data_dev, v->data_start, ti->len, data);
670 static void verity_io_hints(struct dm_target *ti, struct queue_limits *limits)
672 struct dm_verity *v = ti->private;
674 if (limits->logical_block_size < 1 << v->data_dev_block_bits)
675 limits->logical_block_size = 1 << v->data_dev_block_bits;
677 if (limits->physical_block_size < 1 << v->data_dev_block_bits)
678 limits->physical_block_size = 1 << v->data_dev_block_bits;
680 blk_limits_io_min(limits, limits->logical_block_size);
683 static void verity_dtr(struct dm_target *ti)
685 struct dm_verity *v = ti->private;
688 destroy_workqueue(v->verify_wq);
691 dm_bufio_client_destroy(v->bufio);
694 kfree(v->root_digest);
697 crypto_free_shash(v->tfm);
702 dm_put_device(ti, v->hash_dev);
705 dm_put_device(ti, v->data_dev);
712 * <version> The current format is version 1.
713 * Vsn 0 is compatible with original Chromium OS releases.
718 * <the number of data blocks>
722 * <salt> Hex string or "-" if no salt.
724 static int verity_ctr(struct dm_target *ti, unsigned argc, char **argv)
727 struct dm_arg_set as;
728 const char *opt_string;
729 unsigned int num, opt_params;
730 unsigned long long num_ll;
733 sector_t hash_position;
736 static struct dm_arg _args[] = {
737 {0, 1, "Invalid number of feature args"},
740 v = kzalloc(sizeof(struct dm_verity), GFP_KERNEL);
742 ti->error = "Cannot allocate verity structure";
748 if ((dm_table_get_mode(ti->table) & ~FMODE_READ)) {
749 ti->error = "Device must be readonly";
755 ti->error = "Not enough arguments";
760 if (sscanf(argv[0], "%u%c", &num, &dummy) != 1 ||
762 ti->error = "Invalid version";
768 r = dm_get_device(ti, argv[1], FMODE_READ, &v->data_dev);
770 ti->error = "Data device lookup failed";
774 r = dm_get_device(ti, argv[2], FMODE_READ, &v->hash_dev);
776 ti->error = "Data device lookup failed";
780 if (sscanf(argv[3], "%u%c", &num, &dummy) != 1 ||
781 !num || (num & (num - 1)) ||
782 num < bdev_logical_block_size(v->data_dev->bdev) ||
784 ti->error = "Invalid data device block size";
788 v->data_dev_block_bits = __ffs(num);
790 if (sscanf(argv[4], "%u%c", &num, &dummy) != 1 ||
791 !num || (num & (num - 1)) ||
792 num < bdev_logical_block_size(v->hash_dev->bdev) ||
794 ti->error = "Invalid hash device block size";
798 v->hash_dev_block_bits = __ffs(num);
800 if (sscanf(argv[5], "%llu%c", &num_ll, &dummy) != 1 ||
801 (sector_t)(num_ll << (v->data_dev_block_bits - SECTOR_SHIFT))
802 >> (v->data_dev_block_bits - SECTOR_SHIFT) != num_ll) {
803 ti->error = "Invalid data blocks";
807 v->data_blocks = num_ll;
809 if (ti->len > (v->data_blocks << (v->data_dev_block_bits - SECTOR_SHIFT))) {
810 ti->error = "Data device is too small";
815 if (sscanf(argv[6], "%llu%c", &num_ll, &dummy) != 1 ||
816 (sector_t)(num_ll << (v->hash_dev_block_bits - SECTOR_SHIFT))
817 >> (v->hash_dev_block_bits - SECTOR_SHIFT) != num_ll) {
818 ti->error = "Invalid hash start";
822 v->hash_start = num_ll;
824 v->alg_name = kstrdup(argv[7], GFP_KERNEL);
826 ti->error = "Cannot allocate algorithm name";
831 v->tfm = crypto_alloc_shash(v->alg_name, 0, 0);
832 if (IS_ERR(v->tfm)) {
833 ti->error = "Cannot initialize hash function";
838 v->digest_size = crypto_shash_digestsize(v->tfm);
839 if ((1 << v->hash_dev_block_bits) < v->digest_size * 2) {
840 ti->error = "Digest size too big";
845 sizeof(struct shash_desc) + crypto_shash_descsize(v->tfm);
847 v->root_digest = kmalloc(v->digest_size, GFP_KERNEL);
848 if (!v->root_digest) {
849 ti->error = "Cannot allocate root digest";
853 if (strlen(argv[8]) != v->digest_size * 2 ||
854 hex2bin(v->root_digest, argv[8], v->digest_size)) {
855 ti->error = "Invalid root digest";
860 if (strcmp(argv[9], "-")) {
861 v->salt_size = strlen(argv[9]) / 2;
862 v->salt = kmalloc(v->salt_size, GFP_KERNEL);
864 ti->error = "Cannot allocate salt";
868 if (strlen(argv[9]) != v->salt_size * 2 ||
869 hex2bin(v->salt, argv[9], v->salt_size)) {
870 ti->error = "Invalid salt";
879 /* Optional parameters */
884 r = dm_read_arg_group(_args, &as, &opt_params, &ti->error);
890 opt_string = dm_shift_arg(&as);
892 ti->error = "Not enough feature arguments";
897 if (!strcasecmp(opt_string, DM_VERITY_OPT_LOGGING))
898 v->mode = DM_VERITY_MODE_LOGGING;
899 else if (!strcasecmp(opt_string, DM_VERITY_OPT_RESTART))
900 v->mode = DM_VERITY_MODE_RESTART;
902 ti->error = "Invalid feature arguments";
909 v->hash_per_block_bits =
910 __fls((1 << v->hash_dev_block_bits) / v->digest_size);
914 while (v->hash_per_block_bits * v->levels < 64 &&
915 (unsigned long long)(v->data_blocks - 1) >>
916 (v->hash_per_block_bits * v->levels))
919 if (v->levels > DM_VERITY_MAX_LEVELS) {
920 ti->error = "Too many tree levels";
925 hash_position = v->hash_start;
926 for (i = v->levels - 1; i >= 0; i--) {
928 v->hash_level_block[i] = hash_position;
929 s = (v->data_blocks + ((sector_t)1 << ((i + 1) * v->hash_per_block_bits)) - 1)
930 >> ((i + 1) * v->hash_per_block_bits);
931 if (hash_position + s < hash_position) {
932 ti->error = "Hash device offset overflow";
938 v->hash_blocks = hash_position;
940 v->bufio = dm_bufio_client_create(v->hash_dev->bdev,
941 1 << v->hash_dev_block_bits, 1, sizeof(struct buffer_aux),
942 dm_bufio_alloc_callback, NULL);
943 if (IS_ERR(v->bufio)) {
944 ti->error = "Cannot initialize dm-bufio";
945 r = PTR_ERR(v->bufio);
950 if (dm_bufio_get_device_size(v->bufio) < v->hash_blocks) {
951 ti->error = "Hash device is too small";
956 ti->per_bio_data_size = roundup(sizeof(struct dm_verity_io) + v->shash_descsize + v->digest_size * 2, __alignof__(struct dm_verity_io));
958 /* WQ_UNBOUND greatly improves performance when running on ramdisk */
959 v->verify_wq = alloc_workqueue("kverityd", WQ_CPU_INTENSIVE | WQ_MEM_RECLAIM | WQ_UNBOUND, num_online_cpus());
961 ti->error = "Cannot allocate workqueue";
974 static struct target_type verity_target = {
976 .version = {1, 2, 0},
977 .module = THIS_MODULE,
981 .status = verity_status,
982 .ioctl = verity_ioctl,
983 .merge = verity_merge,
984 .iterate_devices = verity_iterate_devices,
985 .io_hints = verity_io_hints,
988 static int __init dm_verity_init(void)
992 r = dm_register_target(&verity_target);
994 DMERR("register failed %d", r);
999 static void __exit dm_verity_exit(void)
1001 dm_unregister_target(&verity_target);
1004 module_init(dm_verity_init);
1005 module_exit(dm_verity_exit);
1007 MODULE_AUTHOR("Mikulas Patocka <mpatocka@redhat.com>");
1008 MODULE_AUTHOR("Mandeep Baines <msb@chromium.org>");
1009 MODULE_AUTHOR("Will Drewry <wad@chromium.org>");
1010 MODULE_DESCRIPTION(DM_NAME " target for transparent disk integrity checking");
1011 MODULE_LICENSE("GPL");