/* drbd_req.c This file is part of DRBD by Philipp Reisner and Lars Ellenberg. Copyright (C) 2001-2008, LINBIT Information Technologies GmbH. Copyright (C) 1999-2008, Philipp Reisner . Copyright (C) 2002-2008, Lars Ellenberg . drbd is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2, or (at your option) any later version. drbd 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 drbd; see the file COPYING. If not, write to the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */ #include #include #include #include "drbd_int.h" #include "drbd_req.h" static bool drbd_may_do_local_read(struct drbd_conf *mdev, sector_t sector, int size); /* Update disk stats at start of I/O request */ static void _drbd_start_io_acct(struct drbd_conf *mdev, struct drbd_request *req, struct bio *bio) { const int rw = bio_data_dir(bio); int cpu; cpu = part_stat_lock(); part_round_stats(cpu, &mdev->vdisk->part0); part_stat_inc(cpu, &mdev->vdisk->part0, ios[rw]); part_stat_add(cpu, &mdev->vdisk->part0, sectors[rw], bio_sectors(bio)); (void) cpu; /* The macro invocations above want the cpu argument, I do not like the compiler warning about cpu only assigned but never used... */ part_inc_in_flight(&mdev->vdisk->part0, rw); part_stat_unlock(); } /* Update disk stats when completing request upwards */ static void _drbd_end_io_acct(struct drbd_conf *mdev, struct drbd_request *req) { int rw = bio_data_dir(req->master_bio); unsigned long duration = jiffies - req->start_time; int cpu; cpu = part_stat_lock(); part_stat_add(cpu, &mdev->vdisk->part0, ticks[rw], duration); part_round_stats(cpu, &mdev->vdisk->part0); part_dec_in_flight(&mdev->vdisk->part0, rw); part_stat_unlock(); } static struct drbd_request *drbd_req_new(struct drbd_conf *mdev, struct bio *bio_src) { struct drbd_request *req; req = mempool_alloc(drbd_request_mempool, GFP_NOIO); if (!req) return NULL; drbd_req_make_private_bio(req, bio_src); req->rq_state = bio_data_dir(bio_src) == WRITE ? RQ_WRITE : 0; req->w.mdev = mdev; req->master_bio = bio_src; req->epoch = 0; drbd_clear_interval(&req->i); req->i.sector = bio_src->bi_sector; req->i.size = bio_src->bi_size; req->i.local = true; req->i.waiting = false; INIT_LIST_HEAD(&req->tl_requests); INIT_LIST_HEAD(&req->w.list); /* one reference to be put by __drbd_make_request */ atomic_set(&req->completion_ref, 1); /* one kref as long as completion_ref > 0 */ kref_init(&req->kref); return req; } void drbd_req_destroy(struct kref *kref) { struct drbd_request *req = container_of(kref, struct drbd_request, kref); struct drbd_conf *mdev = req->w.mdev; const unsigned s = req->rq_state; if ((req->master_bio && !(s & RQ_POSTPONED)) || atomic_read(&req->completion_ref) || (s & RQ_LOCAL_PENDING) || ((s & RQ_NET_MASK) && !(s & RQ_NET_DONE))) { dev_err(DEV, "drbd_req_destroy: Logic BUG rq_state = 0x%x, completion_ref = %d\n", s, atomic_read(&req->completion_ref)); return; } /* remove it from the transfer log. * well, only if it had been there in the first * place... if it had not (local only or conflicting * and never sent), it should still be "empty" as * initialized in drbd_req_new(), so we can list_del() it * here unconditionally */ list_del_init(&req->tl_requests); /* if it was a write, we may have to set the corresponding * bit(s) out-of-sync first. If it had a local part, we need to * release the reference to the activity log. */ if (s & RQ_WRITE) { /* Set out-of-sync unless both OK flags are set * (local only or remote failed). * Other places where we set out-of-sync: * READ with local io-error */ if (!(s & RQ_NET_OK) || !(s & RQ_LOCAL_OK)) drbd_set_out_of_sync(mdev, req->i.sector, req->i.size); if ((s & RQ_NET_OK) && (s & RQ_LOCAL_OK) && (s & RQ_NET_SIS)) drbd_set_in_sync(mdev, req->i.sector, req->i.size); /* one might be tempted to move the drbd_al_complete_io * to the local io completion callback drbd_request_endio. * but, if this was a mirror write, we may only * drbd_al_complete_io after this is RQ_NET_DONE, * otherwise the extent could be dropped from the al * before it has actually been written on the peer. * if we crash before our peer knows about the request, * but after the extent has been dropped from the al, * we would forget to resync the corresponding extent. */ if (s & RQ_LOCAL_MASK) { if (get_ldev_if_state(mdev, D_FAILED)) { if (s & RQ_IN_ACT_LOG) drbd_al_complete_io(mdev, &req->i); put_ldev(mdev); } else if (__ratelimit(&drbd_ratelimit_state)) { dev_warn(DEV, "Should have called drbd_al_complete_io(, %llu, %u), " "but my Disk seems to have failed :(\n", (unsigned long long) req->i.sector, req->i.size); } } } mempool_free(req, drbd_request_mempool); } static void wake_all_senders(struct drbd_tconn *tconn) { wake_up(&tconn->sender_work.q_wait); } /* must hold resource->req_lock */ static void start_new_tl_epoch(struct drbd_tconn *tconn) { tconn->current_tle_writes = 0; atomic_inc(&tconn->current_tle_nr); wake_all_senders(tconn); } void complete_master_bio(struct drbd_conf *mdev, struct bio_and_error *m) { bio_endio(m->bio, m->error); dec_ap_bio(mdev); } static void drbd_remove_request_interval(struct rb_root *root, struct drbd_request *req) { struct drbd_conf *mdev = req->w.mdev; struct drbd_interval *i = &req->i; drbd_remove_interval(root, i); /* Wake up any processes waiting for this request to complete. */ if (i->waiting) wake_up(&mdev->misc_wait); } /* Helper for __req_mod(). * Set m->bio to the master bio, if it is fit to be completed, * or leave it alone (it is initialized to NULL in __req_mod), * if it has already been completed, or cannot be completed yet. * If m->bio is set, the error status to be returned is placed in m->error. */ static void drbd_req_complete(struct drbd_request *req, struct bio_and_error *m) { const unsigned s = req->rq_state; struct drbd_conf *mdev = req->w.mdev; int rw; int error, ok; /* we must not complete the master bio, while it is * still being processed by _drbd_send_zc_bio (drbd_send_dblock) * not yet acknowledged by the peer * not yet completed by the local io subsystem * these flags may get cleared in any order by * the worker, * the receiver, * the bio_endio completion callbacks. */ if ((s & RQ_LOCAL_PENDING && !(s & RQ_LOCAL_ABORTED)) || (s & RQ_NET_QUEUED) || (s & RQ_NET_PENDING) || (s & RQ_COMPLETION_SUSP)) { dev_err(DEV, "drbd_req_complete: Logic BUG rq_state = 0x%x\n", s); return; } if (!req->master_bio) { dev_err(DEV, "drbd_req_complete: Logic BUG, master_bio == NULL!\n"); return; } rw = bio_rw(req->master_bio); /* * figure out whether to report success or failure. * * report success when at least one of the operations succeeded. * or, to put the other way, * only report failure, when both operations failed. * * what to do about the failures is handled elsewhere. * what we need to do here is just: complete the master_bio. * * local completion error, if any, has been stored as ERR_PTR * in private_bio within drbd_request_endio. */ ok = (s & RQ_LOCAL_OK) || (s & RQ_NET_OK); error = PTR_ERR(req->private_bio); /* remove the request from the conflict detection * respective block_id verification hash */ if (!drbd_interval_empty(&req->i)) { struct rb_root *root; if (rw == WRITE) root = &mdev->write_requests; else root = &mdev->read_requests; drbd_remove_request_interval(root, req); } else if (!(s & RQ_POSTPONED)) D_ASSERT((s & (RQ_NET_MASK & ~RQ_NET_DONE)) == 0); /* Before we can signal completion to the upper layers, * we may need to close the current transfer log epoch. * We are within the request lock, so we can simply compare * the request epoch number with the current transfer log * epoch number. If they match, increase the current_tle_nr, * and reset the transfer log epoch write_cnt. */ if (rw == WRITE && req->epoch == atomic_read(&mdev->tconn->current_tle_nr)) start_new_tl_epoch(mdev->tconn); /* Update disk stats */ _drbd_end_io_acct(mdev, req); /* If READ failed, * have it be pushed back to the retry work queue, * so it will re-enter __drbd_make_request(), * and be re-assigned to a suitable local or remote path, * or failed if we do not have access to good data anymore. * * Unless it was failed early by __drbd_make_request(), * because no path was available, in which case * it was not even added to the transfer_log. * * READA may fail, and will not be retried. * * WRITE should have used all available paths already. */ if (!ok && rw == READ && !list_empty(&req->tl_requests)) req->rq_state |= RQ_POSTPONED; if (!(req->rq_state & RQ_POSTPONED)) { m->error = ok ? 0 : (error ?: -EIO); m->bio = req->master_bio; req->master_bio = NULL; } } static int drbd_req_put_completion_ref(struct drbd_request *req, struct bio_and_error *m, int put) { struct drbd_conf *mdev = req->w.mdev; D_ASSERT(m || (req->rq_state & RQ_POSTPONED)); if (!atomic_sub_and_test(put, &req->completion_ref)) return 0; if (drbd_suspended(mdev)) { /* We do not allow completion while suspended. Re-get a * reference, so whatever happens when this is resumed * may put and complete. */ D_ASSERT(!(req->rq_state & RQ_COMPLETION_SUSP)); req->rq_state |= RQ_COMPLETION_SUSP; atomic_inc(&req->completion_ref); return 0; } /* else */ drbd_req_complete(req, m); if (req->rq_state & RQ_POSTPONED) { /* don't destroy the req object just yet, * but queue it for retry */ drbd_restart_request(req); return 0; } return 1; } /* I'd like this to be the only place that manipulates * req->completion_ref and req->kref. */ static void mod_rq_state(struct drbd_request *req, struct bio_and_error *m, int clear, int set) { struct drbd_conf *mdev = req->w.mdev; unsigned s = req->rq_state; int c_put = 0; int k_put = 0; /* apply */ req->rq_state &= ~clear; req->rq_state |= set; /* no change? */ if (req->rq_state == s) return; /* intent: get references */ if (!(s & RQ_LOCAL_PENDING) && (set & RQ_LOCAL_PENDING)) atomic_inc(&req->completion_ref); if (!(s & RQ_NET_PENDING) && (set & RQ_NET_PENDING)) { inc_ap_pending(mdev); atomic_inc(&req->completion_ref); } if (!(s & RQ_NET_QUEUED) && (set & RQ_NET_QUEUED)) atomic_inc(&req->completion_ref); if (!(s & RQ_EXP_BARR_ACK) && (set & RQ_EXP_BARR_ACK)) kref_get(&req->kref); /* wait for the DONE */ if (!(s & RQ_NET_SENT) && (set & RQ_NET_SENT)) atomic_add(req->i.size >> 9, &mdev->ap_in_flight); /* progress: put references */ if ((s & RQ_COMPLETION_SUSP) && (clear & RQ_COMPLETION_SUSP)) ++c_put; if (!(s & RQ_LOCAL_ABORTED) && (set & RQ_LOCAL_ABORTED)) { D_ASSERT(req->rq_state & RQ_LOCAL_PENDING); /* local completion may still come in later, * we need to keep the req object around. */ kref_get(&req->kref); ++c_put; } if ((s & RQ_LOCAL_PENDING) && (clear & RQ_LOCAL_PENDING)) { if (req->rq_state & RQ_LOCAL_ABORTED) ++k_put; else ++c_put; } if ((s & RQ_NET_PENDING) && (clear & RQ_NET_PENDING)) { dec_ap_pending(mdev); ++c_put; } if ((s & RQ_NET_QUEUED) && (clear & RQ_NET_QUEUED)) ++c_put; if ((s & RQ_EXP_BARR_ACK) && !(s & RQ_NET_DONE) && (set & RQ_NET_DONE)) { if (req->rq_state & RQ_NET_SENT) atomic_sub(req->i.size >> 9, &mdev->ap_in_flight); ++k_put; } /* potentially complete and destroy */ if (k_put || c_put) { /* Completion does it's own kref_put. If we are going to * kref_sub below, we need req to be still around then. */ int at_least = k_put + !!c_put; int refcount = atomic_read(&req->kref.refcount); if (refcount < at_least) dev_err(DEV, "mod_rq_state: Logic BUG: %x -> %x: refcount = %d, should be >= %d\n", s, req->rq_state, refcount, at_least); } /* If we made progress, retry conflicting peer requests, if any. */ if (req->i.waiting) wake_up(&mdev->misc_wait); if (c_put) k_put += drbd_req_put_completion_ref(req, m, c_put); if (k_put) kref_sub(&req->kref, k_put, drbd_req_destroy); } /* obviously this could be coded as many single functions * instead of one huge switch, * or by putting the code directly in the respective locations * (as it has been before). * * but having it this way * enforces that it is all in this one place, where it is easier to audit, * it makes it obvious that whatever "event" "happens" to a request should * happen "atomically" within the req_lock, * and it enforces that we have to think in a very structured manner * about the "events" that may happen to a request during its life time ... */ int __req_mod(struct drbd_request *req, enum drbd_req_event what, struct bio_and_error *m) { struct drbd_conf *mdev = req->w.mdev; struct net_conf *nc; int p, rv = 0; if (m) m->bio = NULL; switch (what) { default: dev_err(DEV, "LOGIC BUG in %s:%u\n", __FILE__ , __LINE__); break; /* does not happen... * initialization done in drbd_req_new case CREATED: break; */ case TO_BE_SENT: /* via network */ /* reached via __drbd_make_request * and from w_read_retry_remote */ D_ASSERT(!(req->rq_state & RQ_NET_MASK)); rcu_read_lock(); nc = rcu_dereference(mdev->tconn->net_conf); p = nc->wire_protocol; rcu_read_unlock(); req->rq_state |= p == DRBD_PROT_C ? RQ_EXP_WRITE_ACK : p == DRBD_PROT_B ? RQ_EXP_RECEIVE_ACK : 0; mod_rq_state(req, m, 0, RQ_NET_PENDING); break; case TO_BE_SUBMITTED: /* locally */ /* reached via __drbd_make_request */ D_ASSERT(!(req->rq_state & RQ_LOCAL_MASK)); mod_rq_state(req, m, 0, RQ_LOCAL_PENDING); break; case COMPLETED_OK: if (req->rq_state & RQ_WRITE) mdev->writ_cnt += req->i.size >> 9; else mdev->read_cnt += req->i.size >> 9; mod_rq_state(req, m, RQ_LOCAL_PENDING, RQ_LOCAL_COMPLETED|RQ_LOCAL_OK); break; case ABORT_DISK_IO: mod_rq_state(req, m, 0, RQ_LOCAL_ABORTED); break; case READ_COMPLETED_WITH_ERROR: drbd_set_out_of_sync(mdev, req->i.sector, req->i.size); /* fall through. */ case WRITE_COMPLETED_WITH_ERROR: __drbd_chk_io_error(mdev, DRBD_IO_ERROR); /* fall through. */ case READ_AHEAD_COMPLETED_WITH_ERROR: /* it is legal to fail READA, no __drbd_chk_io_error in that case. */ mod_rq_state(req, m, RQ_LOCAL_PENDING, RQ_LOCAL_COMPLETED); break; case QUEUE_FOR_NET_READ: /* READ or READA, and * no local disk, * or target area marked as invalid, * or just got an io-error. */ /* from __drbd_make_request * or from bio_endio during read io-error recovery */ /* So we can verify the handle in the answer packet. * Corresponding drbd_remove_request_interval is in * drbd_req_complete() */ D_ASSERT(drbd_interval_empty(&req->i)); drbd_insert_interval(&mdev->read_requests, &req->i); set_bit(UNPLUG_REMOTE, &mdev->flags); D_ASSERT(req->rq_state & RQ_NET_PENDING); D_ASSERT((req->rq_state & RQ_LOCAL_MASK) == 0); mod_rq_state(req, m, 0, RQ_NET_QUEUED); req->w.cb = w_send_read_req; drbd_queue_work(&mdev->tconn->sender_work, &req->w); break; case QUEUE_FOR_NET_WRITE: /* assert something? */ /* from __drbd_make_request only */ /* Corresponding drbd_remove_request_interval is in * drbd_req_complete() */ D_ASSERT(drbd_interval_empty(&req->i)); drbd_insert_interval(&mdev->write_requests, &req->i); /* NOTE * In case the req ended up on the transfer log before being * queued on the worker, it could lead to this request being * missed during cleanup after connection loss. * So we have to do both operations here, * within the same lock that protects the transfer log. * * _req_add_to_epoch(req); this has to be after the * _maybe_start_new_epoch(req); which happened in * __drbd_make_request, because we now may set the bit * again ourselves to close the current epoch. * * Add req to the (now) current epoch (barrier). */ /* otherwise we may lose an unplug, which may cause some remote * io-scheduler timeout to expire, increasing maximum latency, * hurting performance. */ set_bit(UNPLUG_REMOTE, &mdev->flags); /* queue work item to send data */ D_ASSERT(req->rq_state & RQ_NET_PENDING); mod_rq_state(req, m, 0, RQ_NET_QUEUED|RQ_EXP_BARR_ACK); req->w.cb = w_send_dblock; drbd_queue_work(&mdev->tconn->sender_work, &req->w); /* close the epoch, in case it outgrew the limit */ rcu_read_lock(); nc = rcu_dereference(mdev->tconn->net_conf); p = nc->max_epoch_size; rcu_read_unlock(); if (mdev->tconn->current_tle_writes >= p) start_new_tl_epoch(mdev->tconn); break; case QUEUE_FOR_SEND_OOS: mod_rq_state(req, m, 0, RQ_NET_QUEUED); req->w.cb = w_send_out_of_sync; drbd_queue_work(&mdev->tconn->sender_work, &req->w); break; case READ_RETRY_REMOTE_CANCELED: case SEND_CANCELED: case SEND_FAILED: /* real cleanup will be done from tl_clear. just update flags * so it is no longer marked as on the worker queue */ mod_rq_state(req, m, RQ_NET_QUEUED, 0); break; case HANDED_OVER_TO_NETWORK: /* assert something? */ if (bio_data_dir(req->master_bio) == WRITE && !(req->rq_state & (RQ_EXP_RECEIVE_ACK | RQ_EXP_WRITE_ACK))) { /* this is what is dangerous about protocol A: * pretend it was successfully written on the peer. */ if (req->rq_state & RQ_NET_PENDING) mod_rq_state(req, m, RQ_NET_PENDING, RQ_NET_OK); /* else: neg-ack was faster... */ /* it is still not yet RQ_NET_DONE until the * corresponding epoch barrier got acked as well, * so we know what to dirty on connection loss */ } mod_rq_state(req, m, RQ_NET_QUEUED, RQ_NET_SENT); break; case OOS_HANDED_TO_NETWORK: /* Was not set PENDING, no longer QUEUED, so is now DONE * as far as this connection is concerned. */ mod_rq_state(req, m, RQ_NET_QUEUED, RQ_NET_DONE); break; case CONNECTION_LOST_WHILE_PENDING: /* transfer log cleanup after connection loss */ mod_rq_state(req, m, RQ_NET_OK|RQ_NET_PENDING|RQ_COMPLETION_SUSP, RQ_NET_DONE); break; case DISCARD_WRITE: /* for discarded conflicting writes of multiple primaries, * there is no need to keep anything in the tl, potential * node crashes are covered by the activity log. * * If this request had been marked as RQ_POSTPONED before, * it will actually not be discarded, but "restarted", * resubmitted from the retry worker context. */ D_ASSERT(req->rq_state & RQ_NET_PENDING); D_ASSERT(req->rq_state & RQ_EXP_WRITE_ACK); mod_rq_state(req, m, RQ_NET_PENDING, RQ_NET_DONE|RQ_NET_OK); break; case WRITE_ACKED_BY_PEER_AND_SIS: req->rq_state |= RQ_NET_SIS; case WRITE_ACKED_BY_PEER: D_ASSERT(req->rq_state & RQ_EXP_WRITE_ACK); /* protocol C; successfully written on peer. * Nothing more to do here. * We want to keep the tl in place for all protocols, to cater * for volatile write-back caches on lower level devices. */ goto ack_common; case RECV_ACKED_BY_PEER: D_ASSERT(req->rq_state & RQ_EXP_RECEIVE_ACK); /* protocol B; pretends to be successfully written on peer. * see also notes above in HANDED_OVER_TO_NETWORK about * protocol != C */ ack_common: D_ASSERT(req->rq_state & RQ_NET_PENDING); mod_rq_state(req, m, RQ_NET_PENDING, RQ_NET_OK); break; case POSTPONE_WRITE: D_ASSERT(req->rq_state & RQ_EXP_WRITE_ACK); /* If this node has already detected the write conflict, the * worker will be waiting on misc_wait. Wake it up once this * request has completed locally. */ D_ASSERT(req->rq_state & RQ_NET_PENDING); req->rq_state |= RQ_POSTPONED; if (req->i.waiting) wake_up(&mdev->misc_wait); /* Do not clear RQ_NET_PENDING. This request will make further * progress via restart_conflicting_writes() or * fail_postponed_requests(). Hopefully. */ break; case NEG_ACKED: mod_rq_state(req, m, RQ_NET_OK|RQ_NET_PENDING, RQ_NET_DONE); break; case FAIL_FROZEN_DISK_IO: if (!(req->rq_state & RQ_LOCAL_COMPLETED)) break; mod_rq_state(req, m, RQ_COMPLETION_SUSP, 0); break; case RESTART_FROZEN_DISK_IO: if (!(req->rq_state & RQ_LOCAL_COMPLETED)) break; mod_rq_state(req, m, RQ_COMPLETION_SUSP|RQ_LOCAL_COMPLETED, RQ_LOCAL_PENDING); rv = MR_READ; if (bio_data_dir(req->master_bio) == WRITE) rv = MR_WRITE; get_ldev(mdev); /* always succeeds in this call path */ req->w.cb = w_restart_disk_io; drbd_queue_work(&mdev->tconn->sender_work, &req->w); break; case RESEND: /* Simply complete (local only) READs. */ if (!(req->rq_state & RQ_WRITE) && !req->w.cb) { mod_rq_state(req, m, RQ_COMPLETION_SUSP, 0); break; } /* If RQ_NET_OK is already set, we got a P_WRITE_ACK or P_RECV_ACK before the connection loss (B&C only); only P_BARRIER_ACK (or the local completion?) was missing when we suspended. Throwing them out of the TL here by pretending we got a BARRIER_ACK. During connection handshake, we ensure that the peer was not rebooted. */ if (!(req->rq_state & RQ_NET_OK)) { /* FIXME could this possibly be a req->w.cb == w_send_out_of_sync? * in that case we must not set RQ_NET_PENDING. */ mod_rq_state(req, m, RQ_COMPLETION_SUSP, RQ_NET_QUEUED|RQ_NET_PENDING); if (req->w.cb) { drbd_queue_work(&mdev->tconn->sender_work, &req->w); rv = req->rq_state & RQ_WRITE ? MR_WRITE : MR_READ; } /* else: FIXME can this happen? */ break; } /* else, fall through to BARRIER_ACKED */ case BARRIER_ACKED: /* barrier ack for READ requests does not make sense */ if (!(req->rq_state & RQ_WRITE)) break; if (req->rq_state & RQ_NET_PENDING) { /* barrier came in before all requests were acked. * this is bad, because if the connection is lost now, * we won't be able to clean them up... */ dev_err(DEV, "FIXME (BARRIER_ACKED but pending)\n"); } /* Allowed to complete requests, even while suspended. * As this is called for all requests within a matching epoch, * we need to filter, and only set RQ_NET_DONE for those that * have actually been on the wire. */ mod_rq_state(req, m, RQ_COMPLETION_SUSP, (req->rq_state & RQ_NET_MASK) ? RQ_NET_DONE : 0); break; case DATA_RECEIVED: D_ASSERT(req->rq_state & RQ_NET_PENDING); mod_rq_state(req, m, RQ_NET_PENDING, RQ_NET_OK|RQ_NET_DONE); break; }; return rv; } /* we may do a local read if: * - we are consistent (of course), * - or we are generally inconsistent, * BUT we are still/already IN SYNC for this area. * since size may be bigger than BM_BLOCK_SIZE, * we may need to check several bits. */ static bool drbd_may_do_local_read(struct drbd_conf *mdev, sector_t sector, int size) { unsigned long sbnr, ebnr; sector_t esector, nr_sectors; if (mdev->state.disk == D_UP_TO_DATE) return true; if (mdev->state.disk != D_INCONSISTENT) return false; esector = sector + (size >> 9) - 1; nr_sectors = drbd_get_capacity(mdev->this_bdev); D_ASSERT(sector < nr_sectors); D_ASSERT(esector < nr_sectors); sbnr = BM_SECT_TO_BIT(sector); ebnr = BM_SECT_TO_BIT(esector); return drbd_bm_count_bits(mdev, sbnr, ebnr) == 0; } static bool remote_due_to_read_balancing(struct drbd_conf *mdev, sector_t sector, enum drbd_read_balancing rbm) { struct backing_dev_info *bdi; int stripe_shift; switch (rbm) { case RB_CONGESTED_REMOTE: bdi = &mdev->ldev->backing_bdev->bd_disk->queue->backing_dev_info; return bdi_read_congested(bdi); case RB_LEAST_PENDING: return atomic_read(&mdev->local_cnt) > atomic_read(&mdev->ap_pending_cnt) + atomic_read(&mdev->rs_pending_cnt); case RB_32K_STRIPING: /* stripe_shift = 15 */ case RB_64K_STRIPING: case RB_128K_STRIPING: case RB_256K_STRIPING: case RB_512K_STRIPING: case RB_1M_STRIPING: /* stripe_shift = 20 */ stripe_shift = (rbm - RB_32K_STRIPING + 15); return (sector >> (stripe_shift - 9)) & 1; case RB_ROUND_ROBIN: return test_and_change_bit(READ_BALANCE_RR, &mdev->flags); case RB_PREFER_REMOTE: return true; case RB_PREFER_LOCAL: default: return false; } } /* * complete_conflicting_writes - wait for any conflicting write requests * * The write_requests tree contains all active write requests which we * currently know about. Wait for any requests to complete which conflict with * the new one. * * Only way out: remove the conflicting intervals from the tree. */ static void complete_conflicting_writes(struct drbd_request *req) { DEFINE_WAIT(wait); struct drbd_conf *mdev = req->w.mdev; struct drbd_interval *i; sector_t sector = req->i.sector; int size = req->i.size; i = drbd_find_overlap(&mdev->write_requests, sector, size); if (!i) return; for (;;) { prepare_to_wait(&mdev->misc_wait, &wait, TASK_UNINTERRUPTIBLE); i = drbd_find_overlap(&mdev->write_requests, sector, size); if (!i) break; /* Indicate to wake up device->misc_wait on progress. */ i->waiting = true; spin_unlock_irq(&mdev->tconn->req_lock); schedule(); spin_lock_irq(&mdev->tconn->req_lock); } finish_wait(&mdev->misc_wait, &wait); } /* called within req_lock and rcu_read_lock() */ static void maybe_pull_ahead(struct drbd_conf *mdev) { struct drbd_tconn *tconn = mdev->tconn; struct net_conf *nc; bool congested = false; enum drbd_on_congestion on_congestion; nc = rcu_dereference(tconn->net_conf); on_congestion = nc ? nc->on_congestion : OC_BLOCK; if (on_congestion == OC_BLOCK || tconn->agreed_pro_version < 96) return; /* If I don't even have good local storage, we can not reasonably try * to pull ahead of the peer. We also need the local reference to make * sure mdev->act_log is there. */ if (!get_ldev_if_state(mdev, D_UP_TO_DATE)) return; if (nc->cong_fill && atomic_read(&mdev->ap_in_flight) >= nc->cong_fill) { dev_info(DEV, "Congestion-fill threshold reached\n"); congested = true; } if (mdev->act_log->used >= nc->cong_extents) { dev_info(DEV, "Congestion-extents threshold reached\n"); congested = true; } if (congested) { if (mdev->tconn->current_tle_writes) /* start a new epoch for non-mirrored writes */ start_new_tl_epoch(mdev->tconn); if (on_congestion == OC_PULL_AHEAD) _drbd_set_state(_NS(mdev, conn, C_AHEAD), 0, NULL); else /*nc->on_congestion == OC_DISCONNECT */ _drbd_set_state(_NS(mdev, conn, C_DISCONNECTING), 0, NULL); } put_ldev(mdev); } /* If this returns false, and req->private_bio is still set, * this should be submitted locally. * * If it returns false, but req->private_bio is not set, * we do not have access to good data :( * * Otherwise, this destroys req->private_bio, if any, * and returns true. */ static bool do_remote_read(struct drbd_request *req) { struct drbd_conf *mdev = req->w.mdev; enum drbd_read_balancing rbm; if (req->private_bio) { if (!drbd_may_do_local_read(mdev, req->i.sector, req->i.size)) { bio_put(req->private_bio); req->private_bio = NULL; put_ldev(mdev); } } if (mdev->state.pdsk != D_UP_TO_DATE) return false; if (req->private_bio == NULL) return true; /* TODO: improve read balancing decisions, take into account drbd * protocol, pending requests etc. */ rcu_read_lock(); rbm = rcu_dereference(mdev->ldev->disk_conf)->read_balancing; rcu_read_unlock(); if (rbm == RB_PREFER_LOCAL && req->private_bio) return false; /* submit locally */ if (remote_due_to_read_balancing(mdev, req->i.sector, rbm)) { if (req->private_bio) { bio_put(req->private_bio); req->private_bio = NULL; put_ldev(mdev); } return true; } return false; } /* returns number of connections (== 1, for drbd 8.4) * expected to actually write this data, * which does NOT include those that we are L_AHEAD for. */ static int drbd_process_write_request(struct drbd_request *req) { struct drbd_conf *mdev = req->w.mdev; int remote, send_oos; rcu_read_lock(); remote = drbd_should_do_remote(mdev->state); if (remote) { maybe_pull_ahead(mdev); remote = drbd_should_do_remote(mdev->state); } send_oos = drbd_should_send_out_of_sync(mdev->state); rcu_read_unlock(); /* Need to replicate writes. Unless it is an empty flush, * which is better mapped to a DRBD P_BARRIER packet, * also for drbd wire protocol compatibility reasons. * If this was a flush, just start a new epoch. * Unless the current epoch was empty anyways, or we are not currently * replicating, in which case there is no point. */ if (unlikely(req->i.size == 0)) { /* The only size==0 bios we expect are empty flushes. */ D_ASSERT(req->master_bio->bi_rw & REQ_FLUSH); if (remote && mdev->tconn->current_tle_writes) start_new_tl_epoch(mdev->tconn); return 0; } if (!remote && !send_oos) return 0; D_ASSERT(!(remote && send_oos)); if (remote) { _req_mod(req, TO_BE_SENT); _req_mod(req, QUEUE_FOR_NET_WRITE); } else if (drbd_set_out_of_sync(mdev, req->i.sector, req->i.size)) _req_mod(req, QUEUE_FOR_SEND_OOS); return remote; } static void drbd_submit_req_private_bio(struct drbd_request *req) { struct drbd_conf *mdev = req->w.mdev; struct bio *bio = req->private_bio; const int rw = bio_rw(bio); bio->bi_bdev = mdev->ldev->backing_bdev; /* State may have changed since we grabbed our reference on the * ->ldev member. Double check, and short-circuit to endio. * In case the last activity log transaction failed to get on * stable storage, and this is a WRITE, we may not even submit * this bio. */ if (get_ldev(mdev)) { if (drbd_insert_fault(mdev, rw == WRITE ? DRBD_FAULT_DT_WR : rw == READ ? DRBD_FAULT_DT_RD : DRBD_FAULT_DT_RA)) bio_endio(bio, -EIO); else generic_make_request(bio); put_ldev(mdev); } else bio_endio(bio, -EIO); } void __drbd_make_request(struct drbd_conf *mdev, struct bio *bio, unsigned long start_time) { const int rw = bio_rw(bio); struct bio_and_error m = { NULL, }; struct drbd_request *req; bool no_remote = false; /* allocate outside of all locks; */ req = drbd_req_new(mdev, bio); if (!req) { dec_ap_bio(mdev); /* only pass the error to the upper layers. * if user cannot handle io errors, that's not our business. */ dev_err(DEV, "could not kmalloc() req\n"); bio_endio(bio, -ENOMEM); return; } req->start_time = start_time; if (!get_ldev(mdev)) { bio_put(req->private_bio); req->private_bio = NULL; } /* For WRITES going to the local disk, grab a reference on the target * extent. This waits for any resync activity in the corresponding * resync extent to finish, and, if necessary, pulls in the target * extent into the activity log, which involves further disk io because * of transactional on-disk meta data updates. * Empty flushes don't need to go into the activity log, they can only * flush data for pending writes which are already in there. */ if (rw == WRITE && req->private_bio && req->i.size && !test_bit(AL_SUSPENDED, &mdev->flags)) { req->rq_state |= RQ_IN_ACT_LOG; drbd_al_begin_io(mdev, &req->i); } spin_lock_irq(&mdev->tconn->req_lock); if (rw == WRITE) { /* This may temporarily give up the req_lock, * but will re-aquire it before it returns here. * Needs to be before the check on drbd_suspended() */ complete_conflicting_writes(req); } /* no more giving up req_lock from now on! */ if (drbd_suspended(mdev)) { /* push back and retry: */ req->rq_state |= RQ_POSTPONED; if (req->private_bio) { bio_put(req->private_bio); req->private_bio = NULL; } goto out; } /* Update disk stats */ _drbd_start_io_acct(mdev, req, bio); /* We fail READ/READA early, if we can not serve it. * We must do this before req is registered on any lists. * Otherwise, drbd_req_complete() will queue failed READ for retry. */ if (rw != WRITE) { if (!do_remote_read(req) && !req->private_bio) goto nodata; } /* which transfer log epoch does this belong to? */ req->epoch = atomic_read(&mdev->tconn->current_tle_nr); if (rw == WRITE) mdev->tconn->current_tle_writes++; /* no point in adding empty flushes to the transfer log, * they are mapped to drbd barriers already. */ if (likely(req->i.size!=0)) list_add_tail(&req->tl_requests, &mdev->tconn->transfer_log); if (rw == WRITE) { if (!drbd_process_write_request(req)) no_remote = true; } else { /* We either have a private_bio, or we can read from remote. * Otherwise we had done the goto nodata above. */ if (req->private_bio == NULL) { _req_mod(req, TO_BE_SENT); _req_mod(req, QUEUE_FOR_NET_READ); } else no_remote = true; } if (req->private_bio) { /* needs to be marked within the same spinlock */ _req_mod(req, TO_BE_SUBMITTED); /* but we need to give up the spinlock to submit */ spin_unlock_irq(&mdev->tconn->req_lock); drbd_submit_req_private_bio(req); spin_lock_irq(&mdev->tconn->req_lock); } else if (no_remote) { nodata: if (__ratelimit(&drbd_ratelimit_state)) dev_err(DEV, "IO ERROR: neither local nor remote disk\n"); /* A write may have been queued for send_oos, however. * So we can not simply free it, we must go through drbd_req_put_completion_ref() */ } out: if (drbd_req_put_completion_ref(req, &m, 1)) kref_put(&req->kref, drbd_req_destroy); spin_unlock_irq(&mdev->tconn->req_lock); if (m.bio) complete_master_bio(mdev, &m); return; } int drbd_make_request(struct request_queue *q, struct bio *bio) { struct drbd_conf *mdev = (struct drbd_conf *) q->queuedata; unsigned long start_time; start_time = jiffies; /* * what we "blindly" assume: */ D_ASSERT(IS_ALIGNED(bio->bi_size, 512)); inc_ap_bio(mdev); __drbd_make_request(mdev, bio, start_time); return 0; } /* This is called by bio_add_page(). * * q->max_hw_sectors and other global limits are already enforced there. * * We need to call down to our lower level device, * in case it has special restrictions. * * We also may need to enforce configured max-bio-bvecs limits. * * As long as the BIO is empty we have to allow at least one bvec, * regardless of size and offset, so no need to ask lower levels. */ int drbd_merge_bvec(struct request_queue *q, struct bvec_merge_data *bvm, struct bio_vec *bvec) { struct drbd_conf *mdev = (struct drbd_conf *) q->queuedata; unsigned int bio_size = bvm->bi_size; int limit = DRBD_MAX_BIO_SIZE; int backing_limit; if (bio_size && get_ldev(mdev)) { struct request_queue * const b = mdev->ldev->backing_bdev->bd_disk->queue; if (b->merge_bvec_fn) { backing_limit = b->merge_bvec_fn(b, bvm, bvec); limit = min(limit, backing_limit); } put_ldev(mdev); } return limit; } struct drbd_request *find_oldest_request(struct drbd_tconn *tconn) { /* Walk the transfer log, * and find the oldest not yet completed request */ struct drbd_request *r; list_for_each_entry(r, &tconn->transfer_log, tl_requests) { if (atomic_read(&r->completion_ref)) return r; } return NULL; } void request_timer_fn(unsigned long data) { struct drbd_conf *mdev = (struct drbd_conf *) data; struct drbd_tconn *tconn = mdev->tconn; struct drbd_request *req; /* oldest request */ struct net_conf *nc; unsigned long ent = 0, dt = 0, et, nt; /* effective timeout = ko_count * timeout */ unsigned long now; rcu_read_lock(); nc = rcu_dereference(tconn->net_conf); if (nc && mdev->state.conn >= C_WF_REPORT_PARAMS) ent = nc->timeout * HZ/10 * nc->ko_count; if (get_ldev(mdev)) { /* implicit state.disk >= D_INCONSISTENT */ dt = rcu_dereference(mdev->ldev->disk_conf)->disk_timeout * HZ / 10; put_ldev(mdev); } rcu_read_unlock(); et = min_not_zero(dt, ent); if (!et) return; /* Recurring timer stopped */ now = jiffies; spin_lock_irq(&tconn->req_lock); req = find_oldest_request(tconn); if (!req) { spin_unlock_irq(&tconn->req_lock); mod_timer(&mdev->request_timer, now + et); return; } /* The request is considered timed out, if * - we have some effective timeout from the configuration, * with above state restrictions applied, * - the oldest request is waiting for a response from the network * resp. the local disk, * - the oldest request is in fact older than the effective timeout, * - the connection was established (resp. disk was attached) * for longer than the timeout already. * Note that for 32bit jiffies and very stable connections/disks, * we may have a wrap around, which is catched by * !time_in_range(now, last_..._jif, last_..._jif + timeout). * * Side effect: once per 32bit wrap-around interval, which means every * ~198 days with 250 HZ, we have a window where the timeout would need * to expire twice (worst case) to become effective. Good enough. */ if (ent && req->rq_state & RQ_NET_PENDING && time_after(now, req->start_time + ent) && !time_in_range(now, tconn->last_reconnect_jif, tconn->last_reconnect_jif + ent)) { dev_warn(DEV, "Remote failed to finish a request within ko-count * timeout\n"); _drbd_set_state(_NS(mdev, conn, C_TIMEOUT), CS_VERBOSE | CS_HARD, NULL); } if (dt && req->rq_state & RQ_LOCAL_PENDING && req->w.mdev == mdev && time_after(now, req->start_time + dt) && !time_in_range(now, mdev->last_reattach_jif, mdev->last_reattach_jif + dt)) { dev_warn(DEV, "Local backing device failed to meet the disk-timeout\n"); __drbd_chk_io_error(mdev, DRBD_FORCE_DETACH); } nt = (time_after(now, req->start_time + et) ? now : req->start_time) + et; spin_unlock_irq(&tconn->req_lock); mod_timer(&mdev->request_timer, nt); }