X-Git-Url: https://git.kernel.dk/?p=fio.git;a=blobdiff_plain;f=io_u.c;h=64ff73cd5555b8d4efa0303085f7944cae07544c;hp=3de04ef0eb91fe25d6561562f931ebfa7fb311f7;hb=f940128526dbe468a1951cce10c2fe5dbd23875f;hpb=6d68b99712c112fde6dedda6e6e24af3e9552d0e diff --git a/io_u.c b/io_u.c index 3de04ef0..64ff73cd 100644 --- a/io_u.c +++ b/io_u.c @@ -16,7 +16,7 @@ struct io_completion_data { int nr; /* input */ int error; /* output */ - unsigned long bytes_done[DDIR_RWDIR_CNT]; /* output */ + uint64_t bytes_done[DDIR_RWDIR_CNT]; /* output */ struct timeval time; /* output */ }; @@ -101,7 +101,7 @@ static int __get_next_rand_offset(struct thread_data *td, struct fio_file *f, r = __rand(&td->__random_state); } - dprint(FD_RANDOM, "off rand %llu\n", r); + dprint(FD_RANDOM, "off rand %llu\n", (unsigned long long) r); *b = (lastb - 1) * (r / ((uint64_t) rmax + 1.0)); } else { @@ -125,7 +125,8 @@ static int __get_next_rand_offset(struct thread_data *td, struct fio_file *f, if (random_map_free(f, *b)) goto ret; - dprint(FD_RANDOM, "get_next_rand_offset: offset %llu busy\n", *b); + dprint(FD_RANDOM, "get_next_rand_offset: offset %llu busy\n", + (unsigned long long) *b); *b = axmap_next_free(f->io_axmap, *b); if (*b == (uint64_t) -1ULL) @@ -172,18 +173,50 @@ static int get_off_from_method(struct thread_data *td, struct fio_file *f, return 1; } +/* + * Sort the reads for a verify phase in batches of verifysort_nr, if + * specified. + */ +static inline int should_sort_io(struct thread_data *td) +{ + if (!td->o.verifysort_nr || !td->o.do_verify) + return 0; + if (!td_random(td)) + return 0; + if (td->runstate != TD_VERIFYING) + return 0; + if (td->o.random_generator == FIO_RAND_GEN_TAUSWORTHE) + return 0; + + return 1; +} + +static int should_do_random(struct thread_data *td, enum fio_ddir ddir) +{ + unsigned int v; + unsigned long r; + + if (td->o.perc_rand[ddir] == 100) + return 1; + + if (td->o.use_os_rand) { + r = os_random_long(&td->seq_rand_state[ddir]); + v = 1 + (int) (100.0 * (r / (OS_RAND_MAX + 1.0))); + } else { + r = __rand(&td->__seq_rand_state[ddir]); + v = 1 + (int) (100.0 * (r / (FRAND_MAX + 1.0))); + } + + return v <= td->o.perc_rand[ddir]; +} + static int get_next_rand_offset(struct thread_data *td, struct fio_file *f, enum fio_ddir ddir, uint64_t *b) { struct rand_off *r; int i, ret = 1; - /* - * If sort not enabled, or not a pure random read workload without - * any stored write metadata, just return a random offset - */ - if (!td->o.verifysort_nr || !(ddir == DDIR_READ && td->o.do_verify && - td->o.verify != VERIFY_NONE && td_random(td))) + if (!should_sort_io(td)) return get_off_from_method(td, f, ddir, b); if (!flist_empty(&td->next_rand_list)) { @@ -223,13 +256,14 @@ static int get_next_rand_block(struct thread_data *td, struct fio_file *f, return 0; if (td->o.time_based) { - fio_file_reset(f); + fio_file_reset(td, f); if (!get_next_rand_offset(td, f, ddir, b)) return 0; } dprint(FD_IO, "%s: rand offset failed, last=%llu, size=%llu\n", - f->file_name, f->last_pos, f->real_file_size); + f->file_name, (unsigned long long) f->last_pos, + (unsigned long long) f->real_file_size); return 1; } @@ -259,7 +293,8 @@ static int get_next_seq_offset(struct thread_data *td, struct fio_file *f, } static int get_next_block(struct thread_data *td, struct io_u *io_u, - enum fio_ddir ddir, int rw_seq) + enum fio_ddir ddir, int rw_seq, + unsigned int *is_random) { struct fio_file *f = io_u->file; uint64_t b, offset; @@ -270,17 +305,31 @@ static int get_next_block(struct thread_data *td, struct io_u *io_u, b = offset = -1ULL; if (rw_seq) { - if (td_random(td)) - ret = get_next_rand_block(td, f, ddir, &b); - else + if (td_random(td)) { + if (should_do_random(td, ddir)) { + ret = get_next_rand_block(td, f, ddir, &b); + *is_random = 1; + } else { + *is_random = 0; + io_u->flags |= IO_U_F_BUSY_OK; + ret = get_next_seq_offset(td, f, ddir, &offset); + if (ret) + ret = get_next_rand_block(td, f, ddir, &b); + } + } else { + *is_random = 0; ret = get_next_seq_offset(td, f, ddir, &offset); + } } else { io_u->flags |= IO_U_F_BUSY_OK; + *is_random = 0; if (td->o.rw_seq == RW_SEQ_SEQ) { ret = get_next_seq_offset(td, f, ddir, &offset); - if (ret) + if (ret) { ret = get_next_rand_block(td, f, ddir, &b); + *is_random = 0; + } } else if (td->o.rw_seq == RW_SEQ_IDENT) { if (f->last_start != -1ULL) offset = f->last_start - f->file_offset; @@ -299,8 +348,7 @@ static int get_next_block(struct thread_data *td, struct io_u *io_u, else if (b != -1ULL) io_u->offset = b * td->o.ba[ddir]; else { - log_err("fio: bug in offset generation: offset=%llu, b=%llu\n", - offset, b); + log_err("fio: bug in offset generation: offset=%llu, b=%llu\n", (unsigned long long) offset, (unsigned long long) b); ret = 1; } } @@ -313,7 +361,8 @@ static int get_next_block(struct thread_data *td, struct io_u *io_u, * until we find a free one. For sequential io, just return the end of * the last io issued. */ -static int __get_next_offset(struct thread_data *td, struct io_u *io_u) +static int __get_next_offset(struct thread_data *td, struct io_u *io_u, + unsigned int *is_random) { struct fio_file *f = io_u->file; enum fio_ddir ddir = io_u->ddir; @@ -326,35 +375,38 @@ static int __get_next_offset(struct thread_data *td, struct io_u *io_u) td->ddir_seq_nr = td->o.ddir_seq_nr; } - if (get_next_block(td, io_u, ddir, rw_seq_hit)) + if (get_next_block(td, io_u, ddir, rw_seq_hit, is_random)) return 1; if (io_u->offset >= f->io_size) { dprint(FD_IO, "get_next_offset: offset %llu >= io_size %llu\n", - io_u->offset, f->io_size); + (unsigned long long) io_u->offset, + (unsigned long long) f->io_size); return 1; } io_u->offset += f->file_offset; if (io_u->offset >= f->real_file_size) { dprint(FD_IO, "get_next_offset: offset %llu >= size %llu\n", - io_u->offset, f->real_file_size); + (unsigned long long) io_u->offset, + (unsigned long long) f->real_file_size); return 1; } return 0; } -static int get_next_offset(struct thread_data *td, struct io_u *io_u) +static int get_next_offset(struct thread_data *td, struct io_u *io_u, + unsigned int *is_random) { if (td->flags & TD_F_PROFILE_OPS) { struct prof_io_ops *ops = &td->prof_io_ops; if (ops->fill_io_u_off) - return ops->fill_io_u_off(td, io_u); + return ops->fill_io_u_off(td, io_u, is_random); } - return __get_next_offset(td, io_u); + return __get_next_offset(td, io_u, is_random); } static inline int io_u_fits(struct thread_data *td, struct io_u *io_u, @@ -365,14 +417,20 @@ static inline int io_u_fits(struct thread_data *td, struct io_u *io_u, return io_u->offset + buflen <= f->io_size + get_start_offset(td); } -static unsigned int __get_next_buflen(struct thread_data *td, struct io_u *io_u) +static unsigned int __get_next_buflen(struct thread_data *td, struct io_u *io_u, + unsigned int is_random) { - const int ddir = io_u->ddir; + int ddir = io_u->ddir; unsigned int buflen = 0; unsigned int minbs, maxbs; unsigned long r, rand_max; - assert(ddir_rw(ddir)); + assert(ddir_rw(io_u->ddir)); + + if (td->o.bs_is_seq_rand) + ddir = is_random ? DDIR_WRITE: DDIR_READ; + else + ddir = io_u->ddir; minbs = td->o.min_bs[ddir]; maxbs = td->o.max_bs[ddir]; @@ -417,6 +475,10 @@ static unsigned int __get_next_buflen(struct thread_data *td, struct io_u *io_u) } } + if (td->o.do_verify && td->o.verify != VERIFY_NONE) + buflen = (buflen + td->o.verify_interval - 1) & + ~(td->o.verify_interval - 1); + if (!td->o.bs_unaligned && is_power_of_2(minbs)) buflen = (buflen + minbs - 1) & ~(minbs - 1); @@ -425,16 +487,17 @@ static unsigned int __get_next_buflen(struct thread_data *td, struct io_u *io_u) return buflen; } -static unsigned int get_next_buflen(struct thread_data *td, struct io_u *io_u) +static unsigned int get_next_buflen(struct thread_data *td, struct io_u *io_u, + unsigned int is_random) { if (td->flags & TD_F_PROFILE_OPS) { struct prof_io_ops *ops = &td->prof_io_ops; if (ops->fill_io_u_size) - return ops->fill_io_u_size(td, io_u); + return ops->fill_io_u_size(td, io_u, is_random); } - return __get_next_buflen(td, io_u); + return __get_next_buflen(td, io_u, is_random); } static void set_rwmix_bytes(struct thread_data *td) @@ -469,6 +532,24 @@ static inline enum fio_ddir get_rand_ddir(struct thread_data *td) return DDIR_WRITE; } +void io_u_quiesce(struct thread_data *td) +{ + /* + * We are going to sleep, ensure that we flush anything pending as + * not to skew our latency numbers. + * + * Changed to only monitor 'in flight' requests here instead of the + * td->cur_depth, b/c td->cur_depth does not accurately represent + * io's that have been actually submitted to an async engine, + * and cur_depth is meaningless for sync engines. + */ + while (td->io_u_in_flight) { + int fio_unused ret; + + ret = io_u_queued_complete(td, 1, NULL); + } +} + static enum fio_ddir rate_ddir(struct thread_data *td, enum fio_ddir ddir) { enum fio_ddir odir = ddir ^ 1; @@ -484,7 +565,7 @@ static enum fio_ddir rate_ddir(struct thread_data *td, enum fio_ddir ddir) * We have too much pending sleep in this direction. See if we * should switch. */ - if (td_rw(td)) { + if (td_rw(td) && td->o.rwmix[odir]) { /* * Other direction does not have too much pending, switch */ @@ -505,20 +586,7 @@ static enum fio_ddir rate_ddir(struct thread_data *td, enum fio_ddir ddir) } else usec = td->rate_pending_usleep[ddir]; - /* - * We are going to sleep, ensure that we flush anything pending as - * not to skew our latency numbers. - * - * Changed to only monitor 'in flight' requests here instead of the - * td->cur_depth, b/c td->cur_depth does not accurately represent - * io's that have been actually submitted to an async engine, - * and cur_depth is meaningless for sync engines. - */ - if (td->io_u_in_flight) { - int fio_unused ret; - - ret = io_u_queued_complete(td, td->io_u_in_flight, NULL); - } + io_u_quiesce(td); fio_gettime(&t, NULL); usec_sleep(td, usec); @@ -532,6 +600,7 @@ static enum fio_ddir rate_ddir(struct thread_data *td, enum fio_ddir ddir) if (ddir_trim(ddir)) return ddir; + return ddir; } @@ -599,7 +668,7 @@ static enum fio_ddir get_rw_ddir(struct thread_data *td) static void set_rw_ddir(struct thread_data *td, struct io_u *io_u) { - io_u->ddir = get_rw_ddir(td); + io_u->ddir = io_u->acct_ddir = get_rw_ddir(td); if (io_u->ddir == DDIR_WRITE && (td->io_ops->flags & FIO_BARRIER) && td->o.barrier_blocks && @@ -628,8 +697,7 @@ void put_io_u(struct thread_data *td, struct io_u *io_u) if (io_u->flags & IO_U_F_IN_CUR_DEPTH) td->cur_depth--; - flist_del_init(&io_u->list); - flist_add(&io_u->list, &td->io_u_freelist); + io_u_qpush(&td->io_u_freelist, io_u); td_io_u_unlock(td); td_io_u_free_notify(td); } @@ -643,26 +711,29 @@ void clear_io_u(struct thread_data *td, struct io_u *io_u) void requeue_io_u(struct thread_data *td, struct io_u **io_u) { struct io_u *__io_u = *io_u; + enum fio_ddir ddir = acct_ddir(__io_u); dprint(FD_IO, "requeue %p\n", __io_u); td_io_u_lock(td); __io_u->flags |= IO_U_F_FREE; - if ((__io_u->flags & IO_U_F_FLIGHT) && ddir_rw(__io_u->ddir)) - td->io_issues[__io_u->ddir]--; + if ((__io_u->flags & IO_U_F_FLIGHT) && ddir_rw(ddir)) + td->io_issues[ddir]--; __io_u->flags &= ~IO_U_F_FLIGHT; if (__io_u->flags & IO_U_F_IN_CUR_DEPTH) td->cur_depth--; - flist_del(&__io_u->list); - flist_add_tail(&__io_u->list, &td->io_u_requeues); + + io_u_rpush(&td->io_u_requeues, __io_u); td_io_u_unlock(td); *io_u = NULL; } static int fill_io_u(struct thread_data *td, struct io_u *io_u) { + unsigned int is_random; + if (td->io_ops->flags & FIO_NOIO) goto out; @@ -688,12 +759,12 @@ static int fill_io_u(struct thread_data *td, struct io_u *io_u) * No log, let the seq/rand engine retrieve the next buflen and * position. */ - if (get_next_offset(td, io_u)) { + if (get_next_offset(td, io_u, &is_random)) { dprint(FD_IO, "io_u %p, failed getting offset\n", io_u); return 1; } - io_u->buflen = get_next_buflen(td, io_u); + io_u->buflen = get_next_buflen(td, io_u, is_random); if (!io_u->buflen) { dprint(FD_IO, "io_u %p, failed getting buflen\n", io_u); return 1; @@ -701,8 +772,9 @@ static int fill_io_u(struct thread_data *td, struct io_u *io_u) if (io_u->offset + io_u->buflen > io_u->file->real_file_size) { dprint(FD_IO, "io_u %p, offset too large\n", io_u); - dprint(FD_IO, " off=%llu/%lu > %llu\n", io_u->offset, - io_u->buflen, io_u->file->real_file_size); + dprint(FD_IO, " off=%llu/%lu > %llu\n", + (unsigned long long) io_u->offset, io_u->buflen, + (unsigned long long) io_u->file->real_file_size); return 1; } @@ -712,13 +784,9 @@ static int fill_io_u(struct thread_data *td, struct io_u *io_u) if (td_random(td) && file_randommap(td, io_u->file)) mark_random_map(td, io_u); - /* - * If using a write iolog, store this entry. - */ out: dprint_io_u(io_u, "fill_io_u"); td->zone_bytes += io_u->buflen; - log_io_u(td, io_u); return 0; } @@ -1058,18 +1126,148 @@ static int set_io_u_file(struct thread_data *td, struct io_u *io_u) return 0; } +static void lat_fatal(struct thread_data *td, struct io_completion_data *icd, + unsigned long tusec, unsigned long max_usec) +{ + if (!td->error) + log_err("fio: latency of %lu usec exceeds specified max (%lu usec)\n", tusec, max_usec); + td_verror(td, ETIMEDOUT, "max latency exceeded"); + icd->error = ETIMEDOUT; +} + +static void lat_new_cycle(struct thread_data *td) +{ + fio_gettime(&td->latency_ts, NULL); + td->latency_ios = ddir_rw_sum(td->io_blocks); + td->latency_failed = 0; +} + +/* + * We had an IO outside the latency target. Reduce the queue depth. If we + * are at QD=1, then it's time to give up. + */ +static int __lat_target_failed(struct thread_data *td) +{ + if (td->latency_qd == 1) + return 1; + + td->latency_qd_high = td->latency_qd; + td->latency_qd = (td->latency_qd + td->latency_qd_low) / 2; + + dprint(FD_RATE, "Ramped down: %d %d %d\n", td->latency_qd_low, td->latency_qd, td->latency_qd_high); + + /* + * When we ramp QD down, quiesce existing IO to prevent + * a storm of ramp downs due to pending higher depth. + */ + io_u_quiesce(td); + lat_new_cycle(td); + return 0; +} + +static int lat_target_failed(struct thread_data *td) +{ + if (td->o.latency_percentile.u.f == 100.0) + return __lat_target_failed(td); + + td->latency_failed++; + return 0; +} + +void lat_target_init(struct thread_data *td) +{ + if (td->o.latency_target) { + dprint(FD_RATE, "Latency target=%llu\n", td->o.latency_target); + fio_gettime(&td->latency_ts, NULL); + td->latency_qd = 1; + td->latency_qd_high = td->o.iodepth; + td->latency_qd_low = 1; + td->latency_ios = ddir_rw_sum(td->io_blocks); + } else + td->latency_qd = td->o.iodepth; +} + +static void lat_target_success(struct thread_data *td) +{ + const unsigned int qd = td->latency_qd; + + td->latency_qd_low = td->latency_qd; + + /* + * If we haven't failed yet, we double up to a failing value instead + * of bisecting from highest possible queue depth. If we have set + * a limit other than td->o.iodepth, bisect between that. + */ + if (td->latency_qd_high != td->o.iodepth) + td->latency_qd = (td->latency_qd + td->latency_qd_high) / 2; + else + td->latency_qd *= 2; + + if (td->latency_qd > td->o.iodepth) + td->latency_qd = td->o.iodepth; + + dprint(FD_RATE, "Ramped up: %d %d %d\n", td->latency_qd_low, td->latency_qd, td->latency_qd_high); + /* + * Same as last one, we are done + */ + if (td->latency_qd == qd) + td->done = 1; + + lat_new_cycle(td); +} + +/* + * Check if we can bump the queue depth + */ +void lat_target_check(struct thread_data *td) +{ + uint64_t usec_window; + uint64_t ios; + double success_ios; + + usec_window = utime_since_now(&td->latency_ts); + if (usec_window < td->o.latency_window) + return; + + ios = ddir_rw_sum(td->io_blocks) - td->latency_ios; + success_ios = (double) (ios - td->latency_failed) / (double) ios; + success_ios *= 100.0; + + dprint(FD_RATE, "Success rate: %.2f%% (target %.2f%%)\n", success_ios, td->o.latency_percentile.u.f); + + if (success_ios >= td->o.latency_percentile.u.f) + lat_target_success(td); + else + __lat_target_failed(td); +} + +/* + * If latency target is enabled, we might be ramping up or down and not + * using the full queue depth available. + */ +int queue_full(struct thread_data *td) +{ + const int qempty = io_u_qempty(&td->io_u_freelist); + + if (qempty) + return 1; + if (!td->o.latency_target) + return 0; + + return td->cur_depth >= td->latency_qd; +} struct io_u *__get_io_u(struct thread_data *td) { - struct io_u *io_u = NULL; + struct io_u *io_u; td_io_u_lock(td); again: - if (!flist_empty(&td->io_u_requeues)) - io_u = flist_entry(td->io_u_requeues.next, struct io_u, list); + if (!io_u_rempty(&td->io_u_requeues)) + io_u = io_u_rpop(&td->io_u_requeues); else if (!queue_full(td)) { - io_u = flist_entry(td->io_u_freelist.next, struct io_u, list); + io_u = io_u_qpop(&td->io_u_freelist); io_u->buflen = 0; io_u->resid = 0; @@ -1084,10 +1282,10 @@ again: io_u->flags &= ~IO_U_F_VER_LIST; io_u->error = 0; - flist_del(&io_u->list); - flist_add_tail(&io_u->list, &td->io_u_busylist); + io_u->acct_ddir = -1; td->cur_depth++; io_u->flags |= IO_U_F_IN_CUR_DEPTH; + io_u->ipo = NULL; } else if (td->o.verify_async) { /* * We ran out, wait for async verify threads to finish and @@ -1321,11 +1519,18 @@ static void account_io_completion(struct thread_data *td, struct io_u *io_u, tusec = utime_since(&io_u->start_time, &icd->time); add_lat_sample(td, idx, tusec, bytes); - if (td->o.max_latency && tusec > td->o.max_latency) { - if (!td->error) - log_err("fio: latency of %lu usec exceeds specified max (%u usec)\n", tusec, td->o.max_latency); - td_verror(td, ETIMEDOUT, "max latency exceeded"); - icd->error = ETIMEDOUT; + if (td->flags & TD_F_PROFILE_OPS) { + struct prof_io_ops *ops = &td->prof_io_ops; + + if (ops->io_u_lat) + icd->error = ops->io_u_lat(td, tusec); + } + + if (td->o.max_latency && tusec > td->o.max_latency) + lat_fatal(td, icd, tusec, td->o.max_latency); + if (td->o.latency_target && tusec > td->o.latency_target) { + if (lat_target_failed(td)) + lat_fatal(td, icd, tusec, td->o.latency_target); } } @@ -1337,7 +1542,10 @@ static void account_io_completion(struct thread_data *td, struct io_u *io_u, if (!td->o.disable_bw) add_bw_sample(td, idx, bytes, &icd->time); - add_iops_sample(td, idx, &icd->time); + add_iops_sample(td, idx, bytes, &icd->time); + + if (td->o.number_ios && !--td->o.number_ios) + td->done = 1; } static long long usec_for_io(struct thread_data *td, enum fio_ddir ddir) @@ -1361,6 +1569,15 @@ static void io_completed(struct thread_data *td, struct io_u *io_u, td_io_u_lock(td); assert(io_u->flags & IO_U_F_FLIGHT); io_u->flags &= ~(IO_U_F_FLIGHT | IO_U_F_BUSY_OK); + + /* + * Mark IO ok to verify + */ + if (io_u->ipo) { + io_u->ipo->flags &= ~IP_F_IN_FLIGHT; + write_barrier(); + } + td_io_u_unlock(td); if (ddir_sync(io_u->ddir)) { @@ -1416,11 +1633,6 @@ static void io_completed(struct thread_data *td, struct io_u *io_u, utime_since_now(&td->start)); } - if (td_write(td) && idx == DDIR_WRITE && - td->o.do_verify && - td->o.verify != VERIFY_NONE) - log_io_piece(td, io_u); - icd->bytes_done[idx] += bytes; if (io_u->end_io) { @@ -1481,7 +1693,7 @@ static void ios_completed(struct thread_data *td, * Complete a single io_u for the sync engines. */ int io_u_sync_complete(struct thread_data *td, struct io_u *io_u, - unsigned long *bytes) + uint64_t *bytes) { struct io_completion_data icd; @@ -1510,7 +1722,7 @@ int io_u_sync_complete(struct thread_data *td, struct io_u *io_u, * Called to complete min_events number of io for the async engines. */ int io_u_queued_complete(struct thread_data *td, int min_evts, - unsigned long *bytes) + uint64_t *bytes) { struct io_completion_data icd; struct timespec *tvp = NULL; @@ -1559,25 +1771,35 @@ void io_u_queued(struct thread_data *td, struct io_u *io_u) } } -/* - * "randomly" fill the buffer contents - */ -void io_u_fill_buffer(struct thread_data *td, struct io_u *io_u, - unsigned int min_write, unsigned int max_bs) +void fill_io_buffer(struct thread_data *td, void *buf, unsigned int min_write, + unsigned int max_bs) { - io_u->buf_filled_len = 0; - - if (!td->o.zero_buffers) { + if (td->o.buffer_pattern_bytes) + fill_buffer_pattern(td, buf, max_bs); + else if (!td->o.zero_buffers) { unsigned int perc = td->o.compress_percentage; if (perc) { unsigned int seg = min_write; seg = min(min_write, td->o.compress_chunk); - fill_random_buf_percentage(&td->buf_state, io_u->buf, + if (!seg) + seg = min_write; + + fill_random_buf_percentage(&td->buf_state, buf, perc, seg, max_bs); } else - fill_random_buf(&td->buf_state, io_u->buf, max_bs); + fill_random_buf(&td->buf_state, buf, max_bs); } else - memset(io_u->buf, 0, max_bs); + memset(buf, 0, max_bs); +} + +/* + * "randomly" fill the buffer contents + */ +void io_u_fill_buffer(struct thread_data *td, struct io_u *io_u, + unsigned int min_write, unsigned int max_bs) +{ + io_u->buf_filled_len = 0; + fill_io_buffer(td, io_u->buf, min_write, max_bs); }