/* * IO verification helpers */ #include #include #include #include #include #include "fio.h" #include "verify.h" #include "smalloc.h" #include "crc/md5.h" #include "crc/crc64.h" #include "crc/crc32.h" #include "crc/crc32c.h" #include "crc/crc16.h" #include "crc/crc7.h" #include "crc/sha256.h" #include "crc/sha512.h" #include "crc/sha1.h" static void fill_random_bytes(struct thread_data *td, void *p, unsigned int len) { unsigned int todo; int r; while (len) { r = os_random_long(&td->verify_state); /* * lrand48_r seems to be broken and only fill the bottom * 32-bits, even on 64-bit archs with 64-bit longs */ todo = sizeof(r); if (todo > len) todo = len; memcpy(p, &r, todo); len -= todo; p += todo; } } static void fill_pattern(struct thread_data *td, void *p, unsigned int len) { switch (td->o.verify_pattern_bytes) { case 0: dprint(FD_VERIFY, "fill random bytes len=%u\n", len); fill_random_bytes(td, p, len); break; case 1: dprint(FD_VERIFY, "fill verify pattern b=0 len=%u\n", len); memset(p, td->o.verify_pattern[0], len); break; default: { unsigned int i = 0, size = 0; unsigned char *b = p; dprint(FD_VERIFY, "fill verify pattern b=%d len=%u\n", td->o.verify_pattern_bytes, len); while (i < len) { size = td->o.verify_pattern_bytes; if (size > (len - i)) size = len - i; memcpy(b+i, td->o.verify_pattern, size); i += size; } break; } } } static void memswp(void *buf1, void *buf2, unsigned int len) { char swap[200]; assert(len <= sizeof(swap)); memcpy(&swap, buf1, len); memcpy(buf1, buf2, len); memcpy(buf2, &swap, len); } static void hexdump(void *buffer, int len) { unsigned char *p = buffer; int i; for (i = 0; i < len; i++) log_err("%02x", p[i]); log_err("\n"); } /* * Prepare for seperation of verify_header and checksum header */ static inline unsigned int __hdr_size(int verify_type) { unsigned int len = len; switch (verify_type) { case VERIFY_NONE: case VERIFY_NULL: len = 0; break; case VERIFY_MD5: len = sizeof(struct vhdr_md5); break; case VERIFY_CRC64: len = sizeof(struct vhdr_crc64); break; case VERIFY_CRC32C: case VERIFY_CRC32: case VERIFY_CRC32C_INTEL: len = sizeof(struct vhdr_crc32); break; case VERIFY_CRC16: len = sizeof(struct vhdr_crc16); break; case VERIFY_CRC7: len = sizeof(struct vhdr_crc7); break; case VERIFY_SHA256: len = sizeof(struct vhdr_sha256); break; case VERIFY_SHA512: len = sizeof(struct vhdr_sha512); break; case VERIFY_META: len = sizeof(struct vhdr_meta); break; case VERIFY_SHA1: len = sizeof(struct vhdr_sha1); break; default: log_err("fio: unknown verify header!\n"); assert(0); } return len + sizeof(struct verify_header); } static inline unsigned int hdr_size(struct verify_header *hdr) { return __hdr_size(hdr->verify_type); } static void *hdr_priv(struct verify_header *hdr) { void *priv = hdr; return priv + sizeof(struct verify_header); } /* * Verify container, pass info to verify handlers and allow them to * pass info back in case of error */ struct vcont { /* * Input */ struct io_u *io_u; unsigned int hdr_num; /* * Output, only valid in case of error */ const char *name; void *good_crc; void *bad_crc; unsigned int crc_len; }; static void log_verify_failure(struct verify_header *hdr, struct vcont *vc) { unsigned long long offset; offset = vc->io_u->offset; offset += vc->hdr_num * hdr->len; log_err("%.8s: verify failed at file %s offset %llu, length %u\n", vc->name, vc->io_u->file->file_name, offset, hdr->len); if (vc->good_crc && vc->bad_crc) { log_err(" Expected CRC: "); hexdump(vc->good_crc, vc->crc_len); log_err(" Received CRC: "); hexdump(vc->bad_crc, vc->crc_len); } } /* * Return data area 'header_num' */ static inline void *io_u_verify_off(struct verify_header *hdr, struct vcont *vc) { return vc->io_u->buf + vc->hdr_num * hdr->len + hdr_size(hdr); } static int verify_io_u_meta(struct verify_header *hdr, struct thread_data *td, struct vcont *vc) { struct vhdr_meta *vh = hdr_priv(hdr); struct io_u *io_u = vc->io_u; dprint(FD_VERIFY, "meta verify io_u %p, len %u\n", io_u, hdr->len); if (vh->offset == io_u->offset + vc->hdr_num * td->o.verify_interval) return 0; vc->name = "meta"; log_verify_failure(hdr, vc); return EILSEQ; } static int verify_io_u_sha512(struct verify_header *hdr, struct vcont *vc) { void *p = io_u_verify_off(hdr, vc); struct vhdr_sha512 *vh = hdr_priv(hdr); uint8_t sha512[128]; struct sha512_ctx sha512_ctx = { .buf = sha512, }; dprint(FD_VERIFY, "sha512 verify io_u %p, len %u\n", vc->io_u, hdr->len); sha512_init(&sha512_ctx); sha512_update(&sha512_ctx, p, hdr->len - hdr_size(hdr)); if (!memcmp(vh->sha512, sha512_ctx.buf, sizeof(sha512))) return 0; vc->name = "sha512"; vc->good_crc = vh->sha512; vc->bad_crc = sha512_ctx.buf; vc->crc_len = sizeof(vh->sha512); log_verify_failure(hdr, vc); return EILSEQ; } static int verify_io_u_sha256(struct verify_header *hdr, struct vcont *vc) { void *p = io_u_verify_off(hdr, vc); struct vhdr_sha256 *vh = hdr_priv(hdr); uint8_t sha256[64]; struct sha256_ctx sha256_ctx = { .buf = sha256, }; dprint(FD_VERIFY, "sha256 verify io_u %p, len %u\n", vc->io_u, hdr->len); sha256_init(&sha256_ctx); sha256_update(&sha256_ctx, p, hdr->len - hdr_size(hdr)); if (!memcmp(vh->sha256, sha256_ctx.buf, sizeof(sha256))) return 0; vc->name = "sha256"; vc->good_crc = vh->sha256; vc->bad_crc = sha256_ctx.buf; vc->crc_len = sizeof(vh->sha256); log_verify_failure(hdr, vc); return EILSEQ; } static int verify_io_u_sha1(struct verify_header *hdr, struct vcont *vc) { void *p = io_u_verify_off(hdr, vc); struct vhdr_sha1 *vh = hdr_priv(hdr); uint32_t sha1[5]; struct sha1_ctx sha1_ctx = { .H = sha1, }; dprint(FD_VERIFY, "sha1 verify io_u %p, len %u\n", vc->io_u, hdr->len); sha1_init(&sha1_ctx); sha1_update(&sha1_ctx, p, hdr->len - hdr_size(hdr)); if (!memcmp(vh->sha1, sha1_ctx.H, sizeof(sha1))) return 0; vc->name = "sha1"; vc->good_crc = vh->sha1; vc->bad_crc = sha1_ctx.H; vc->crc_len = sizeof(vh->sha1); log_verify_failure(hdr, vc); return EILSEQ; } static int verify_io_u_crc7(struct verify_header *hdr, struct vcont *vc) { void *p = io_u_verify_off(hdr, vc); struct vhdr_crc7 *vh = hdr_priv(hdr); unsigned char c; dprint(FD_VERIFY, "crc7 verify io_u %p, len %u\n", vc->io_u, hdr->len); c = crc7(p, hdr->len - hdr_size(hdr)); if (c == vh->crc7) return 0; vc->name = "crc7"; vc->good_crc = &vh->crc7; vc->bad_crc = &c; vc->crc_len = 1; log_verify_failure(hdr, vc); return EILSEQ; } static int verify_io_u_crc16(struct verify_header *hdr, struct vcont *vc) { void *p = io_u_verify_off(hdr, vc); struct vhdr_crc16 *vh = hdr_priv(hdr); unsigned short c; dprint(FD_VERIFY, "crc16 verify io_u %p, len %u\n", vc->io_u, hdr->len); c = crc16(p, hdr->len - hdr_size(hdr)); if (c == vh->crc16) return 0; vc->name = "crc16"; vc->good_crc = &vh->crc16; vc->bad_crc = &c; vc->crc_len = 2; log_verify_failure(hdr, vc); return EILSEQ; } static int verify_io_u_crc64(struct verify_header *hdr, struct vcont *vc) { void *p = io_u_verify_off(hdr, vc); struct vhdr_crc64 *vh = hdr_priv(hdr); unsigned long long c; dprint(FD_VERIFY, "crc64 verify io_u %p, len %u\n", vc->io_u, hdr->len); c = crc64(p, hdr->len - hdr_size(hdr)); if (c == vh->crc64) return 0; vc->name = "crc64"; vc->good_crc = &vh->crc64; vc->bad_crc = &c; vc->crc_len = 8; log_verify_failure(hdr, vc); return EILSEQ; } static int verify_io_u_crc32(struct verify_header *hdr, struct vcont *vc) { void *p = io_u_verify_off(hdr, vc); struct vhdr_crc32 *vh = hdr_priv(hdr); uint32_t c; dprint(FD_VERIFY, "crc32 verify io_u %p, len %u\n", vc->io_u, hdr->len); c = crc32(p, hdr->len - hdr_size(hdr)); if (c == vh->crc32) return 0; vc->name = "crc32"; vc->good_crc = &vh->crc32; vc->bad_crc = &c; vc->crc_len = 4; log_verify_failure(hdr, vc); return EILSEQ; } static int verify_io_u_crc32c(struct verify_header *hdr, struct vcont *vc) { void *p = io_u_verify_off(hdr, vc); struct vhdr_crc32 *vh = hdr_priv(hdr); uint32_t c; dprint(FD_VERIFY, "crc32c verify io_u %p, len %u\n", vc->io_u, hdr->len); if (hdr->verify_type == VERIFY_CRC32C_INTEL) c = crc32c_intel(p, hdr->len - hdr_size(hdr)); else c = crc32c(p, hdr->len - hdr_size(hdr)); if (c == vh->crc32) return 0; vc->name = "crc32c"; vc->good_crc = &vh->crc32; vc->bad_crc = &c; vc->crc_len = 4; log_verify_failure(hdr, vc); return EILSEQ; } static int verify_io_u_md5(struct verify_header *hdr, struct vcont *vc) { void *p = io_u_verify_off(hdr, vc); struct vhdr_md5 *vh = hdr_priv(hdr); uint32_t hash[MD5_HASH_WORDS]; struct md5_ctx md5_ctx = { .hash = hash, }; dprint(FD_VERIFY, "md5 verify io_u %p, len %u\n", vc->io_u, hdr->len); md5_init(&md5_ctx); md5_update(&md5_ctx, p, hdr->len - hdr_size(hdr)); if (!memcmp(vh->md5_digest, md5_ctx.hash, sizeof(hash))) return 0; vc->name = "md5"; vc->good_crc = vh->md5_digest; vc->bad_crc = md5_ctx.hash; vc->crc_len = sizeof(hash); log_verify_failure(hdr, vc); return EILSEQ; } static unsigned int hweight8(unsigned int w) { unsigned int res = w - ((w >> 1) & 0x55); res = (res & 0x33) + ((res >> 2) & 0x33); return (res + (res >> 4)) & 0x0F; } int verify_io_u_pattern(char *pattern, unsigned long pattern_size, char *buf, unsigned int len, unsigned int mod) { unsigned int i; for (i = 0; i < len; i++) { if (buf[i] != pattern[mod]) { unsigned int bits; bits = hweight8(buf[i] ^ pattern[mod]); log_err("fio: got pattern %x, wanted %x. Bad bits %d\n", buf[i], pattern[mod], bits); log_err("fio: bad pattern block offset %u\n", i); return EILSEQ; } mod++; if (mod == pattern_size) mod = 0; } return 0; } /* * Push IO verification to a separate thread */ int verify_io_u_async(struct thread_data *td, struct io_u *io_u) { if (io_u->file) put_file_log(td, io_u->file); io_u->file = NULL; pthread_mutex_lock(&td->io_u_lock); if (io_u->flags & IO_U_F_IN_CUR_DEPTH) { td->cur_depth--; io_u->flags &= ~IO_U_F_IN_CUR_DEPTH; } flist_del(&io_u->list); flist_add_tail(&io_u->list, &td->verify_list); io_u->flags |= IO_U_F_FREE_DEF; pthread_mutex_unlock(&td->io_u_lock); pthread_cond_signal(&td->verify_cond); return 0; } int verify_io_u(struct thread_data *td, struct io_u *io_u) { struct verify_header *hdr; unsigned int hdr_size, hdr_inc, hdr_num = 0; void *p; int ret; if (td->o.verify == VERIFY_NULL || io_u->ddir != DDIR_READ) return 0; hdr_inc = io_u->buflen; if (td->o.verify_interval) hdr_inc = td->o.verify_interval; ret = 0; for (p = io_u->buf; p < io_u->buf + io_u->buflen; p += hdr_inc, hdr_num++) { struct vcont vc = { .io_u = io_u, .hdr_num = hdr_num, }; if (ret && td->o.verify_fatal) break; hdr_size = __hdr_size(td->o.verify); if (td->o.verify_offset) memswp(p, p + td->o.verify_offset, hdr_size); hdr = p; if (hdr->fio_magic != FIO_HDR_MAGIC) { log_err("verify: bad magic header %x, wanted %x at file %s offset %llu, length %u\n", hdr->fio_magic, FIO_HDR_MAGIC, io_u->file->file_name, io_u->offset + hdr_num * hdr->len, hdr->len); return EILSEQ; } if (td->o.verify_pattern_bytes) { dprint(FD_VERIFY, "pattern verify io_u %p, len %u\n", io_u, hdr->len); ret = verify_io_u_pattern(td->o.verify_pattern, td->o.verify_pattern_bytes, p + hdr_size, hdr_inc - hdr_size, hdr_size % td->o.verify_pattern_bytes); if (ret) { log_err("pattern: verify failed at file %s offset %llu, length %u\n", io_u->file->file_name, io_u->offset + hdr_num * hdr->len, hdr->len); } /* * Also verify the meta data, if applicable */ if (hdr->verify_type == VERIFY_META) ret |= verify_io_u_meta(hdr, td, &vc); continue; } switch (hdr->verify_type) { case VERIFY_MD5: ret = verify_io_u_md5(hdr, &vc); break; case VERIFY_CRC64: ret = verify_io_u_crc64(hdr, &vc); break; case VERIFY_CRC32C: case VERIFY_CRC32C_INTEL: ret = verify_io_u_crc32c(hdr, &vc); break; case VERIFY_CRC32: ret = verify_io_u_crc32(hdr, &vc); break; case VERIFY_CRC16: ret = verify_io_u_crc16(hdr, &vc); break; case VERIFY_CRC7: ret = verify_io_u_crc7(hdr, &vc); break; case VERIFY_SHA256: ret = verify_io_u_sha256(hdr, &vc); break; case VERIFY_SHA512: ret = verify_io_u_sha512(hdr, &vc); break; case VERIFY_META: ret = verify_io_u_meta(hdr, td, &vc); break; case VERIFY_SHA1: ret = verify_io_u_sha1(hdr, &vc); break; default: log_err("Bad verify type %u\n", hdr->verify_type); ret = EINVAL; } } if (ret && td->o.verify_fatal) td->terminate = 1; return ret; } static void fill_meta(struct verify_header *hdr, struct thread_data *td, struct io_u *io_u, unsigned int header_num) { struct vhdr_meta *vh = hdr_priv(hdr); vh->thread = td->thread_number; vh->time_sec = io_u->start_time.tv_sec; vh->time_usec = io_u->start_time.tv_usec; vh->numberio = td->io_issues[DDIR_WRITE]; vh->offset = io_u->offset + header_num * td->o.verify_interval; } static void fill_sha512(struct verify_header *hdr, void *p, unsigned int len) { struct vhdr_sha512 *vh = hdr_priv(hdr); struct sha512_ctx sha512_ctx = { .buf = vh->sha512, }; sha512_init(&sha512_ctx); sha512_update(&sha512_ctx, p, len); } static void fill_sha256(struct verify_header *hdr, void *p, unsigned int len) { struct vhdr_sha256 *vh = hdr_priv(hdr); struct sha256_ctx sha256_ctx = { .buf = vh->sha256, }; sha256_init(&sha256_ctx); sha256_update(&sha256_ctx, p, len); } static void fill_sha1(struct verify_header *hdr, void *p, unsigned int len) { struct vhdr_sha1 *vh = hdr_priv(hdr); struct sha1_ctx sha1_ctx = { .H = vh->sha1, }; sha1_init(&sha1_ctx); sha1_update(&sha1_ctx, p, len); } static void fill_crc7(struct verify_header *hdr, void *p, unsigned int len) { struct vhdr_crc7 *vh = hdr_priv(hdr); vh->crc7 = crc7(p, len); } static void fill_crc16(struct verify_header *hdr, void *p, unsigned int len) { struct vhdr_crc16 *vh = hdr_priv(hdr); vh->crc16 = crc16(p, len); } static void fill_crc32(struct verify_header *hdr, void *p, unsigned int len) { struct vhdr_crc32 *vh = hdr_priv(hdr); vh->crc32 = crc32(p, len); } static void fill_crc32c(struct verify_header *hdr, void *p, unsigned int len) { struct vhdr_crc32 *vh = hdr_priv(hdr); if (hdr->verify_type == VERIFY_CRC32C_INTEL) vh->crc32 = crc32c_intel(p, len); else vh->crc32 = crc32c(p, len); } static void fill_crc64(struct verify_header *hdr, void *p, unsigned int len) { struct vhdr_crc64 *vh = hdr_priv(hdr); vh->crc64 = crc64(p, len); } static void fill_md5(struct verify_header *hdr, void *p, unsigned int len) { struct vhdr_md5 *vh = hdr_priv(hdr); struct md5_ctx md5_ctx = { .hash = (uint32_t *) vh->md5_digest, }; md5_init(&md5_ctx); md5_update(&md5_ctx, p, len); } /* * fill body of io_u->buf with random data and add a header with the * crc32 or md5 sum of that data. */ void populate_verify_io_u(struct thread_data *td, struct io_u *io_u) { struct verify_header *hdr; void *p = io_u->buf, *data; unsigned int hdr_inc, data_len, header_num = 0; if (td->o.verify == VERIFY_NULL) return; fill_pattern(td, p, io_u->buflen); hdr_inc = io_u->buflen; if (td->o.verify_interval) hdr_inc = td->o.verify_interval; for (; p < io_u->buf + io_u->buflen; p += hdr_inc) { hdr = p; hdr->fio_magic = FIO_HDR_MAGIC; hdr->verify_type = td->o.verify; hdr->len = hdr_inc; data_len = hdr_inc - hdr_size(hdr); data = p + hdr_size(hdr); switch (td->o.verify) { case VERIFY_MD5: dprint(FD_VERIFY, "fill md5 io_u %p, len %u\n", io_u, hdr->len); fill_md5(hdr, data, data_len); break; case VERIFY_CRC64: dprint(FD_VERIFY, "fill crc64 io_u %p, len %u\n", io_u, hdr->len); fill_crc64(hdr, data, data_len); break; case VERIFY_CRC32C: case VERIFY_CRC32C_INTEL: dprint(FD_VERIFY, "fill crc32c io_u %p, len %u\n", io_u, hdr->len); fill_crc32c(hdr, data, data_len); break; case VERIFY_CRC32: dprint(FD_VERIFY, "fill crc32 io_u %p, len %u\n", io_u, hdr->len); fill_crc32(hdr, data, data_len); break; case VERIFY_CRC16: dprint(FD_VERIFY, "fill crc16 io_u %p, len %u\n", io_u, hdr->len); fill_crc16(hdr, data, data_len); break; case VERIFY_CRC7: dprint(FD_VERIFY, "fill crc7 io_u %p, len %u\n", io_u, hdr->len); fill_crc7(hdr, data, data_len); break; case VERIFY_SHA256: dprint(FD_VERIFY, "fill sha256 io_u %p, len %u\n", io_u, hdr->len); fill_sha256(hdr, data, data_len); break; case VERIFY_SHA512: dprint(FD_VERIFY, "fill sha512 io_u %p, len %u\n", io_u, hdr->len); fill_sha512(hdr, data, data_len); break; case VERIFY_META: dprint(FD_VERIFY, "fill meta io_u %p, len %u\n", io_u, hdr->len); fill_meta(hdr, td, io_u, header_num); break; case VERIFY_SHA1: dprint(FD_VERIFY, "fill sha1 io_u %p, len %u\n", io_u, hdr->len); fill_sha1(hdr, data, data_len); break; default: log_err("fio: bad verify type: %d\n", td->o.verify); assert(0); } if (td->o.verify_offset) memswp(p, p + td->o.verify_offset, hdr_size(hdr)); header_num++; } } int get_next_verify(struct thread_data *td, struct io_u *io_u) { struct io_piece *ipo = NULL; /* * this io_u is from a requeue, we already filled the offsets */ if (io_u->file) return 0; if (!RB_EMPTY_ROOT(&td->io_hist_tree)) { struct rb_node *n = rb_first(&td->io_hist_tree); ipo = rb_entry(n, struct io_piece, rb_node); rb_erase(n, &td->io_hist_tree); td->io_hist_len--; } else if (!flist_empty(&td->io_hist_list)) { ipo = flist_entry(td->io_hist_list.next, struct io_piece, list); td->io_hist_len--; flist_del(&ipo->list); } if (ipo) { io_u->offset = ipo->offset; io_u->buflen = ipo->len; io_u->file = ipo->file; if (!fio_file_open(io_u->file)) { int r = td_io_open_file(td, io_u->file); if (r) { dprint(FD_VERIFY, "failed file %s open\n", io_u->file->file_name); return 1; } } get_file(ipo->file); assert(fio_file_open(io_u->file)); io_u->ddir = DDIR_READ; io_u->xfer_buf = io_u->buf; io_u->xfer_buflen = io_u->buflen; free(ipo); dprint(FD_VERIFY, "get_next_verify: ret io_u %p\n", io_u); return 0; } dprint(FD_VERIFY, "get_next_verify: empty\n"); return 1; } static void *verify_async_thread(void *data) { struct thread_data *td = data; struct io_u *io_u; int ret = 0; if (td->o.verify_cpumask_set && fio_setaffinity(td->pid, td->o.verify_cpumask)) { log_err("fio: failed setting verify thread affinity\n"); goto done; } do { FLIST_HEAD(list); read_barrier(); if (td->verify_thread_exit) break; pthread_mutex_lock(&td->io_u_lock); while (flist_empty(&td->verify_list) && !td->verify_thread_exit) { ret = pthread_cond_wait(&td->verify_cond, &td->io_u_lock); if (ret) { pthread_mutex_unlock(&td->io_u_lock); break; } } flist_splice_init(&td->verify_list, &list); pthread_mutex_unlock(&td->io_u_lock); if (flist_empty(&list)) continue; while (!flist_empty(&list)) { io_u = flist_entry(list.next, struct io_u, list); flist_del_init(&io_u->list); ret = verify_io_u(td, io_u); put_io_u(td, io_u); if (!ret) continue; if (td->o.continue_on_error && td_non_fatal_error(ret)) { update_error_count(td, ret); td_clear_error(td); ret = 0; } } } while (!ret); if (ret) { td_verror(td, ret, "async_verify"); if (td->o.verify_fatal) td->terminate = 1; } done: pthread_mutex_lock(&td->io_u_lock); td->nr_verify_threads--; pthread_mutex_unlock(&td->io_u_lock); pthread_cond_signal(&td->free_cond); return NULL; } int verify_async_init(struct thread_data *td) { int i, ret; td->verify_thread_exit = 0; td->verify_threads = malloc(sizeof(pthread_t) * td->o.verify_async); for (i = 0; i < td->o.verify_async; i++) { ret = pthread_create(&td->verify_threads[i], NULL, verify_async_thread, td); if (ret) { log_err("fio: async verify creation failed: %s\n", strerror(ret)); break; } ret = pthread_detach(td->verify_threads[i]); if (ret) { log_err("fio: async verify thread detach failed: %s\n", strerror(ret)); break; } td->nr_verify_threads++; } if (i != td->o.verify_async) { log_err("fio: only %d verify threads started, exiting\n", i); td->verify_thread_exit = 1; write_barrier(); pthread_cond_broadcast(&td->verify_cond); return 1; } return 0; } void verify_async_exit(struct thread_data *td) { td->verify_thread_exit = 1; write_barrier(); pthread_cond_broadcast(&td->verify_cond); pthread_mutex_lock(&td->io_u_lock); while (td->nr_verify_threads) pthread_cond_wait(&td->free_cond, &td->io_u_lock); pthread_mutex_unlock(&td->io_u_lock); free(td->verify_threads); td->verify_threads = NULL; }