/* 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" /* 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_stat_inc(cpu, &mdev->vdisk->part0, ios[rw]); part_stat_add(cpu, &mdev->vdisk->part0, sectors[rw], bio_sectors(bio)); 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 void _req_is_done(struct drbd_conf *mdev, struct drbd_request *req, const int rw) { const unsigned long s = req->rq_state; /* 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(&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 (rw == 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->sector, req->size); if ((s & RQ_NET_OK) && (s & RQ_LOCAL_OK) && (s & RQ_NET_SIS)) drbd_set_in_sync(mdev, req->sector, req->size); /* one might be tempted to move the drbd_al_complete_io * to the local io completion callback drbd_endio_pri. * 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)) { drbd_al_complete_io(mdev, req->sector); put_ldev(mdev); } else if (__ratelimit(&drbd_ratelimit_state)) { dev_warn(DEV, "Should have called drbd_al_complete_io(, %llu), " "but my Disk seems to have failed :(\n", (unsigned long long) req->sector); } } } drbd_req_free(req); } static void queue_barrier(struct drbd_conf *mdev) { struct drbd_tl_epoch *b; /* We are within the req_lock. Once we queued the barrier for sending, * we set the CREATE_BARRIER bit. It is cleared as soon as a new * barrier/epoch object is added. This is the only place this bit is * set. It indicates that the barrier for this epoch is already queued, * and no new epoch has been created yet. */ if (test_bit(CREATE_BARRIER, &mdev->flags)) return; b = mdev->newest_tle; b->w.cb = w_send_barrier; /* inc_ap_pending done here, so we won't * get imbalanced on connection loss. * dec_ap_pending will be done in got_BarrierAck * or (on connection loss) in tl_clear. */ inc_ap_pending(mdev); drbd_queue_work(&mdev->data.work, &b->w); set_bit(CREATE_BARRIER, &mdev->flags); } static void _about_to_complete_local_write(struct drbd_conf *mdev, struct drbd_request *req) { const unsigned long s = req->rq_state; struct drbd_request *i; struct drbd_epoch_entry *e; struct hlist_node *n; struct hlist_head *slot; /* before we can signal completion to the upper layers, * we may need to close the current epoch */ if (mdev->state.conn >= C_CONNECTED && req->epoch == mdev->newest_tle->br_number) queue_barrier(mdev); /* we need to do the conflict detection stuff, * if we have the ee_hash (two_primaries) and * this has been on the network */ if ((s & RQ_NET_DONE) && mdev->ee_hash != NULL) { const sector_t sector = req->sector; const int size = req->size; /* ASSERT: * there must be no conflicting requests, since * they must have been failed on the spot */ #define OVERLAPS overlaps(sector, size, i->sector, i->size) slot = tl_hash_slot(mdev, sector); hlist_for_each_entry(i, n, slot, colision) { if (OVERLAPS) { dev_alert(DEV, "LOGIC BUG: completed: %p %llus +%u; " "other: %p %llus +%u\n", req, (unsigned long long)sector, size, i, (unsigned long long)i->sector, i->size); } } /* maybe "wake" those conflicting epoch entries * that wait for this request to finish. * * currently, there can be only _one_ such ee * (well, or some more, which would be pending * P_DISCARD_ACK not yet sent by the asender...), * since we block the receiver thread upon the * first conflict detection, which will wait on * misc_wait. maybe we want to assert that? * * anyways, if we found one, * we just have to do a wake_up. */ #undef OVERLAPS #define OVERLAPS overlaps(sector, size, e->sector, e->size) slot = ee_hash_slot(mdev, req->sector); hlist_for_each_entry(e, n, slot, colision) { if (OVERLAPS) { wake_up(&mdev->misc_wait); break; } } } #undef OVERLAPS } void complete_master_bio(struct drbd_conf *mdev, struct bio_and_error *m) { bio_endio(m->bio, m->error); dec_ap_bio(mdev); } /* 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. */ void _req_may_be_done(struct drbd_request *req, struct bio_and_error *m) { const unsigned long s = req->rq_state; struct drbd_conf *mdev = req->mdev; /* only WRITES may end up here without a master bio (on barrier ack) */ int rw = req->master_bio ? bio_data_dir(req->master_bio) : WRITE; /* 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_NET_QUEUED) return; if (s & RQ_NET_PENDING) return; if (s & RQ_LOCAL_PENDING) return; if (req->master_bio) { /* this is data_received (remote read) * or protocol C P_WRITE_ACK * or protocol B P_RECV_ACK * or protocol A "handed_over_to_network" (SendAck) * or canceled or failed, * or killed from the transfer log due to connection loss. */ /* * 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_endio_pri. */ int ok = (s & RQ_LOCAL_OK) || (s & RQ_NET_OK); int error = PTR_ERR(req->private_bio); /* remove the request from the conflict detection * respective block_id verification hash */ if (!hlist_unhashed(&req->colision)) hlist_del(&req->colision); else D_ASSERT((s & RQ_NET_MASK) == 0); /* for writes we need to do some extra housekeeping */ if (rw == WRITE) _about_to_complete_local_write(mdev, req); /* Update disk stats */ _drbd_end_io_acct(mdev, req); m->error = ok ? 0 : (error ?: -EIO); m->bio = req->master_bio; req->master_bio = NULL; } if ((s & RQ_NET_MASK) == 0 || (s & RQ_NET_DONE)) { /* this is disconnected (local only) operation, * or protocol C P_WRITE_ACK, * or protocol A or B P_BARRIER_ACK, * or killed from the transfer log due to connection loss. */ _req_is_done(mdev, req, rw); } /* else: network part and not DONE yet. that is * protocol A or B, barrier ack still pending... */ } static void _req_may_be_done_not_susp(struct drbd_request *req, struct bio_and_error *m) { struct drbd_conf *mdev = req->mdev; if (!mdev->state.susp) _req_may_be_done(req, m); } /* * checks whether there was an overlapping request * or ee already registered. * * if so, return 1, in which case this request is completed on the spot, * without ever being submitted or send. * * return 0 if it is ok to submit this request. * * NOTE: * paranoia: assume something above us is broken, and issues different write * requests for the same block simultaneously... * * To ensure these won't be reordered differently on both nodes, resulting in * diverging data sets, we discard the later one(s). Not that this is supposed * to happen, but this is the rationale why we also have to check for * conflicting requests with local origin, and why we have to do so regardless * of whether we allowed multiple primaries. * * BTW, in case we only have one primary, the ee_hash is empty anyways, and the * second hlist_for_each_entry becomes a noop. This is even simpler than to * grab a reference on the net_conf, and check for the two_primaries flag... */ static int _req_conflicts(struct drbd_request *req) { struct drbd_conf *mdev = req->mdev; const sector_t sector = req->sector; const int size = req->size; struct drbd_request *i; struct drbd_epoch_entry *e; struct hlist_node *n; struct hlist_head *slot; D_ASSERT(hlist_unhashed(&req->colision)); if (!get_net_conf(mdev)) return 0; /* BUG_ON */ ERR_IF (mdev->tl_hash_s == 0) goto out_no_conflict; BUG_ON(mdev->tl_hash == NULL); #define OVERLAPS overlaps(i->sector, i->size, sector, size) slot = tl_hash_slot(mdev, sector); hlist_for_each_entry(i, n, slot, colision) { if (OVERLAPS) { dev_alert(DEV, "%s[%u] Concurrent local write detected! " "[DISCARD L] new: %llus +%u; " "pending: %llus +%u\n", current->comm, current->pid, (unsigned long long)sector, size, (unsigned long long)i->sector, i->size); goto out_conflict; } } if (mdev->ee_hash_s) { /* now, check for overlapping requests with remote origin */ BUG_ON(mdev->ee_hash == NULL); #undef OVERLAPS #define OVERLAPS overlaps(e->sector, e->size, sector, size) slot = ee_hash_slot(mdev, sector); hlist_for_each_entry(e, n, slot, colision) { if (OVERLAPS) { dev_alert(DEV, "%s[%u] Concurrent remote write detected!" " [DISCARD L] new: %llus +%u; " "pending: %llus +%u\n", current->comm, current->pid, (unsigned long long)sector, size, (unsigned long long)e->sector, e->size); goto out_conflict; } } } #undef OVERLAPS out_no_conflict: /* this is like it should be, and what we expected. * our users do behave after all... */ put_net_conf(mdev); return 0; out_conflict: put_net_conf(mdev); return 1; } /* 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->mdev; int rv = 0; 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_send: /* via network */ /* reached via drbd_make_request_common * and from w_read_retry_remote */ D_ASSERT(!(req->rq_state & RQ_NET_MASK)); req->rq_state |= RQ_NET_PENDING; inc_ap_pending(mdev); break; case to_be_submitted: /* locally */ /* reached via drbd_make_request_common */ D_ASSERT(!(req->rq_state & RQ_LOCAL_MASK)); req->rq_state |= RQ_LOCAL_PENDING; break; case completed_ok: if (bio_data_dir(req->master_bio) == WRITE) mdev->writ_cnt += req->size>>9; else mdev->read_cnt += req->size>>9; req->rq_state |= (RQ_LOCAL_COMPLETED|RQ_LOCAL_OK); req->rq_state &= ~RQ_LOCAL_PENDING; _req_may_be_done_not_susp(req, m); put_ldev(mdev); break; case write_completed_with_error: req->rq_state |= RQ_LOCAL_COMPLETED; req->rq_state &= ~RQ_LOCAL_PENDING; __drbd_chk_io_error(mdev, FALSE); _req_may_be_done_not_susp(req, m); put_ldev(mdev); break; case read_ahead_completed_with_error: /* it is legal to fail READA */ req->rq_state |= RQ_LOCAL_COMPLETED; req->rq_state &= ~RQ_LOCAL_PENDING; _req_may_be_done_not_susp(req, m); put_ldev(mdev); break; case read_completed_with_error: drbd_set_out_of_sync(mdev, req->sector, req->size); req->rq_state |= RQ_LOCAL_COMPLETED; req->rq_state &= ~RQ_LOCAL_PENDING; D_ASSERT(!(req->rq_state & RQ_NET_MASK)); __drbd_chk_io_error(mdev, FALSE); put_ldev(mdev); /* no point in retrying if there is no good remote data, * or we have no connection. */ if (mdev->state.pdsk != D_UP_TO_DATE) { _req_may_be_done_not_susp(req, m); break; } /* _req_mod(req,to_be_send); oops, recursion... */ req->rq_state |= RQ_NET_PENDING; inc_ap_pending(mdev); /* fall through: _req_mod(req,queue_for_net_read); */ 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_common * or from bio_endio during read io-error recovery */ /* so we can verify the handle in the answer packet * corresponding hlist_del is in _req_may_be_done() */ hlist_add_head(&req->colision, ar_hash_slot(mdev, req->sector)); set_bit(UNPLUG_REMOTE, &mdev->flags); D_ASSERT(req->rq_state & RQ_NET_PENDING); req->rq_state |= RQ_NET_QUEUED; req->w.cb = (req->rq_state & RQ_LOCAL_MASK) ? w_read_retry_remote : w_send_read_req; drbd_queue_work(&mdev->data.work, &req->w); break; case queue_for_net_write: /* assert something? */ /* from drbd_make_request_common only */ hlist_add_head(&req->colision, tl_hash_slot(mdev, req->sector)); /* corresponding hlist_del is in _req_may_be_done() */ /* 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_common, 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); /* see drbd_make_request_common, * just after it grabs the req_lock */ D_ASSERT(test_bit(CREATE_BARRIER, &mdev->flags) == 0); req->epoch = mdev->newest_tle->br_number; /* increment size of current epoch */ mdev->newest_tle->n_writes++; /* queue work item to send data */ D_ASSERT(req->rq_state & RQ_NET_PENDING); req->rq_state |= RQ_NET_QUEUED; req->w.cb = w_send_dblock; drbd_queue_work(&mdev->data.work, &req->w); /* close the epoch, in case it outgrew the limit */ if (mdev->newest_tle->n_writes >= mdev->net_conf->max_epoch_size) queue_barrier(mdev); break; case send_canceled: /* treat it the same */ 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 */ req->rq_state &= ~RQ_NET_QUEUED; /* if we did it right, tl_clear should be scheduled only after * this, so this should not be necessary! */ _req_may_be_done_not_susp(req, m); break; case handed_over_to_network: /* assert something? */ if (bio_data_dir(req->master_bio) == WRITE && mdev->net_conf->wire_protocol == DRBD_PROT_A) { /* this is what is dangerous about protocol A: * pretend it was successfully written on the peer. */ if (req->rq_state & RQ_NET_PENDING) { dec_ap_pending(mdev); req->rq_state &= ~RQ_NET_PENDING; req->rq_state |= 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 */ } req->rq_state &= ~RQ_NET_QUEUED; req->rq_state |= RQ_NET_SENT; /* because _drbd_send_zc_bio could sleep, and may want to * dereference the bio even after the "write_acked_by_peer" and * "completed_ok" events came in, once we return from * _drbd_send_zc_bio (drbd_send_dblock), we have to check * whether it is done already, and end it. */ _req_may_be_done_not_susp(req, m); break; case read_retry_remote_canceled: req->rq_state &= ~RQ_NET_QUEUED; /* fall through, in case we raced with drbd_disconnect */ case connection_lost_while_pending: /* transfer log cleanup after connection loss */ /* assert something? */ if (req->rq_state & RQ_NET_PENDING) dec_ap_pending(mdev); req->rq_state &= ~(RQ_NET_OK|RQ_NET_PENDING); req->rq_state |= RQ_NET_DONE; /* if it is still queued, we may not complete it here. * it will be canceled soon. */ if (!(req->rq_state & RQ_NET_QUEUED)) _req_may_be_done(req, m); /* Allowed while state.susp */ break; case write_acked_by_peer_and_sis: req->rq_state |= RQ_NET_SIS; case conflict_discarded_by_peer: /* 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 (what == conflict_discarded_by_peer) dev_alert(DEV, "Got DiscardAck packet %llus +%u!" " DRBD is not a random data generator!\n", (unsigned long long)req->sector, req->size); req->rq_state |= RQ_NET_DONE; /* fall through */ case write_acked_by_peer: /* protocol C; successfully written on peer. * Nothing 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. * * A barrier request is expected to have forced all prior * requests onto stable storage, so completion of a barrier * request could set NET_DONE right here, and not wait for the * P_BARRIER_ACK, but that is an unnecessary optimization. */ /* this makes it effectively the same as for: */ case recv_acked_by_peer: /* protocol B; pretends to be successfully written on peer. * see also notes above in handed_over_to_network about * protocol != C */ req->rq_state |= RQ_NET_OK; D_ASSERT(req->rq_state & RQ_NET_PENDING); dec_ap_pending(mdev); req->rq_state &= ~RQ_NET_PENDING; _req_may_be_done_not_susp(req, m); break; case neg_acked: /* assert something? */ if (req->rq_state & RQ_NET_PENDING) dec_ap_pending(mdev); req->rq_state &= ~(RQ_NET_OK|RQ_NET_PENDING); req->rq_state |= RQ_NET_DONE; _req_may_be_done_not_susp(req, m); /* else: done by handed_over_to_network */ break; case fail_frozen_disk_io: if (!(req->rq_state & RQ_LOCAL_COMPLETED)) break; _req_may_be_done(req, m); /* Allowed while state.susp */ break; case restart_frozen_disk_io: if (!(req->rq_state & RQ_LOCAL_COMPLETED)) break; req->rq_state &= ~RQ_LOCAL_COMPLETED; rv = MR_READ; if (bio_data_dir(req->master_bio) == WRITE) rv = MR_WRITE; get_ldev(mdev); req->w.cb = w_restart_disk_io; drbd_queue_work(&mdev->data.work, &req->w); break; case resend: /* 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 was missing. Trowing them out of the TL here by pretending we got a BARRIER_ACK We ensure that the peer was not rebooted */ if (!(req->rq_state & RQ_NET_OK)) { if (req->w.cb) { drbd_queue_work(&mdev->data.work, &req->w); rv = req->rq_state & RQ_WRITE ? MR_WRITE : MR_READ; } break; } /* else, fall through to barrier_acked */ case barrier_acked: if (!(req->rq_state & RQ_WRITE)) break; if (req->rq_state & RQ_NET_PENDING) { /* barrier came in before all requests have been 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"); list_move(&req->tl_requests, &mdev->out_of_sequence_requests); } D_ASSERT(req->rq_state & RQ_NET_SENT); req->rq_state |= RQ_NET_DONE; _req_may_be_done(req, m); /* Allowed while state.susp */ break; case data_received: D_ASSERT(req->rq_state & RQ_NET_PENDING); dec_ap_pending(mdev); req->rq_state &= ~RQ_NET_PENDING; req->rq_state |= (RQ_NET_OK|RQ_NET_DONE); _req_may_be_done_not_susp(req, m); 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 int 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 1; if (mdev->state.disk >= D_OUTDATED) return 0; if (mdev->state.disk < D_INCONSISTENT) return 0; /* state.disk == D_INCONSISTENT We will have a look at the BitMap */ nr_sectors = drbd_get_capacity(mdev->this_bdev); esector = sector + (size >> 9) - 1; D_ASSERT(sector < nr_sectors); D_ASSERT(esector < nr_sectors); sbnr = BM_SECT_TO_BIT(sector); ebnr = BM_SECT_TO_BIT(esector); return 0 == drbd_bm_count_bits(mdev, sbnr, ebnr); } static int drbd_make_request_common(struct drbd_conf *mdev, struct bio *bio) { const int rw = bio_rw(bio); const int size = bio->bi_size; const sector_t sector = bio->bi_sector; struct drbd_tl_epoch *b = NULL; struct drbd_request *req; int local, remote; int err = -EIO; int ret = 0; /* 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 0; } local = get_ldev(mdev); if (!local) { bio_put(req->private_bio); /* or we get a bio leak */ req->private_bio = NULL; } if (rw == WRITE) { remote = 1; } else { /* READ || READA */ if (local) { if (!drbd_may_do_local_read(mdev, sector, size)) { /* we could kick the syncer to * sync this extent asap, wait for * it, then continue locally. * Or just issue the request remotely. */ local = 0; bio_put(req->private_bio); req->private_bio = NULL; put_ldev(mdev); } } remote = !local && mdev->state.pdsk >= D_UP_TO_DATE; } /* If we have a disk, but a READA request is mapped to remote, * we are R_PRIMARY, D_INCONSISTENT, SyncTarget. * Just fail that READA request right here. * * THINK: maybe fail all READA when not local? * or make this configurable... * if network is slow, READA won't do any good. */ if (rw == READA && mdev->state.disk >= D_INCONSISTENT && !local) { err = -EWOULDBLOCK; goto fail_and_free_req; } /* 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. */ if (rw == WRITE && local) drbd_al_begin_io(mdev, sector); remote = remote && (mdev->state.pdsk == D_UP_TO_DATE || (mdev->state.pdsk == D_INCONSISTENT && mdev->state.conn >= C_CONNECTED)); if (!(local || remote) && !mdev->state.susp) { dev_err(DEV, "IO ERROR: neither local nor remote disk\n"); goto fail_free_complete; } /* For WRITE request, we have to make sure that we have an * unused_spare_tle, in case we need to start a new epoch. * I try to be smart and avoid to pre-allocate always "just in case", * but there is a race between testing the bit and pointer outside the * spinlock, and grabbing the spinlock. * if we lost that race, we retry. */ if (rw == WRITE && remote && mdev->unused_spare_tle == NULL && test_bit(CREATE_BARRIER, &mdev->flags)) { allocate_barrier: b = kmalloc(sizeof(struct drbd_tl_epoch), GFP_NOIO); if (!b) { dev_err(DEV, "Failed to alloc barrier.\n"); err = -ENOMEM; goto fail_free_complete; } } /* GOOD, everything prepared, grab the spin_lock */ spin_lock_irq(&mdev->req_lock); if (mdev->state.susp) { /* If we got suspended, use the retry mechanism of generic_make_request() to restart processing of this bio. In the next call to drbd_make_request_26 we sleep in inc_ap_bio() */ ret = 1; spin_unlock_irq(&mdev->req_lock); goto fail_free_complete; } if (remote) { remote = (mdev->state.pdsk == D_UP_TO_DATE || (mdev->state.pdsk == D_INCONSISTENT && mdev->state.conn >= C_CONNECTED)); if (!remote) dev_warn(DEV, "lost connection while grabbing the req_lock!\n"); if (!(local || remote)) { dev_err(DEV, "IO ERROR: neither local nor remote disk\n"); spin_unlock_irq(&mdev->req_lock); goto fail_free_complete; } } if (b && mdev->unused_spare_tle == NULL) { mdev->unused_spare_tle = b; b = NULL; } if (rw == WRITE && remote && mdev->unused_spare_tle == NULL && test_bit(CREATE_BARRIER, &mdev->flags)) { /* someone closed the current epoch * while we were grabbing the spinlock */ spin_unlock_irq(&mdev->req_lock); goto allocate_barrier; } /* Update disk stats */ _drbd_start_io_acct(mdev, req, bio); /* _maybe_start_new_epoch(mdev); * If we need to generate a write barrier packet, we have to add the * new epoch (barrier) object, and queue the barrier packet for sending, * and queue the req's data after it _within the same lock_, otherwise * we have race conditions were the reorder domains could be mixed up. * * Even read requests may start a new epoch and queue the corresponding * barrier packet. To get the write ordering right, we only have to * make sure that, if this is a write request and it triggered a * barrier packet, this request is queued within the same spinlock. */ if (remote && mdev->unused_spare_tle && test_and_clear_bit(CREATE_BARRIER, &mdev->flags)) { _tl_add_barrier(mdev, mdev->unused_spare_tle); mdev->unused_spare_tle = NULL; } else { D_ASSERT(!(remote && rw == WRITE && test_bit(CREATE_BARRIER, &mdev->flags))); } /* NOTE * Actually, 'local' may be wrong here already, since we may have failed * to write to the meta data, and may become wrong anytime because of * local io-error for some other request, which would lead to us * "detaching" the local disk. * * 'remote' may become wrong any time because the network could fail. * * This is a harmless race condition, though, since it is handled * correctly at the appropriate places; so it just defers the failure * of the respective operation. */ /* mark them early for readability. * this just sets some state flags. */ if (remote) _req_mod(req, to_be_send); if (local) _req_mod(req, to_be_submitted); /* check this request on the collision detection hash tables. * if we have a conflict, just complete it here. * THINK do we want to check reads, too? (I don't think so...) */ if (rw == WRITE && _req_conflicts(req)) goto fail_conflicting; list_add_tail(&req->tl_requests, &mdev->newest_tle->requests); /* NOTE remote first: to get the concurrent write detection right, * we must register the request before start of local IO. */ if (remote) { /* either WRITE and C_CONNECTED, * or READ, and no local disk, * or READ, but not in sync. */ _req_mod(req, (rw == WRITE) ? queue_for_net_write : queue_for_net_read); } spin_unlock_irq(&mdev->req_lock); kfree(b); /* if someone else has beaten us to it... */ if (local) { req->private_bio->bi_bdev = mdev->ldev->backing_bdev; if (FAULT_ACTIVE(mdev, rw == WRITE ? DRBD_FAULT_DT_WR : rw == READ ? DRBD_FAULT_DT_RD : DRBD_FAULT_DT_RA)) bio_endio(req->private_bio, -EIO); else generic_make_request(req->private_bio); } /* we need to plug ALWAYS since we possibly need to kick lo_dev. * we plug after submit, so we won't miss an unplug event */ drbd_plug_device(mdev); return 0; fail_conflicting: /* this is a conflicting request. * even though it may have been only _partially_ * overlapping with one of the currently pending requests, * without even submitting or sending it, we will * pretend that it was successfully served right now. */ _drbd_end_io_acct(mdev, req); spin_unlock_irq(&mdev->req_lock); if (remote) dec_ap_pending(mdev); /* THINK: do we want to fail it (-EIO), or pretend success? * this pretends success. */ err = 0; fail_free_complete: if (rw == WRITE && local) drbd_al_complete_io(mdev, sector); fail_and_free_req: if (local) { bio_put(req->private_bio); req->private_bio = NULL; put_ldev(mdev); } if (!ret) bio_endio(bio, err); drbd_req_free(req); dec_ap_bio(mdev); kfree(b); return ret; } /* helper function for drbd_make_request * if we can determine just by the mdev (state) that this request will fail, * return 1 * otherwise return 0 */ static int drbd_fail_request_early(struct drbd_conf *mdev, int is_write) { if (mdev->state.role != R_PRIMARY && (!allow_oos || is_write)) { if (__ratelimit(&drbd_ratelimit_state)) { dev_err(DEV, "Process %s[%u] tried to %s; " "since we are not in Primary state, " "we cannot allow this\n", current->comm, current->pid, is_write ? "WRITE" : "READ"); } return 1; } return 0; } int drbd_make_request_26(struct request_queue *q, struct bio *bio) { unsigned int s_enr, e_enr; struct drbd_conf *mdev = (struct drbd_conf *) q->queuedata; if (drbd_fail_request_early(mdev, bio_data_dir(bio) & WRITE)) { bio_endio(bio, -EPERM); return 0; } /* Reject barrier requests if we know the underlying device does * not support them. * XXX: Need to get this info from peer as well some how so we * XXX: reject if EITHER side/data/metadata area does not support them. * * because of those XXX, this is not yet enabled, * i.e. in drbd_init_set_defaults we set the NO_BARRIER_SUPP bit. */ if (unlikely(bio->bi_rw & REQ_HARDBARRIER) && test_bit(NO_BARRIER_SUPP, &mdev->flags)) { /* dev_warn(DEV, "Rejecting barrier request as underlying device does not support\n"); */ bio_endio(bio, -EOPNOTSUPP); return 0; } /* * what we "blindly" assume: */ D_ASSERT(bio->bi_size > 0); D_ASSERT((bio->bi_size & 0x1ff) == 0); D_ASSERT(bio->bi_idx == 0); /* to make some things easier, force alignment of requests within the * granularity of our hash tables */ s_enr = bio->bi_sector >> HT_SHIFT; e_enr = (bio->bi_sector+(bio->bi_size>>9)-1) >> HT_SHIFT; if (likely(s_enr == e_enr)) { inc_ap_bio(mdev, 1); return drbd_make_request_common(mdev, bio); } /* can this bio be split generically? * Maybe add our own split-arbitrary-bios function. */ if (bio->bi_vcnt != 1 || bio->bi_idx != 0 || bio->bi_size > DRBD_MAX_SEGMENT_SIZE) { /* rather error out here than BUG in bio_split */ dev_err(DEV, "bio would need to, but cannot, be split: " "(vcnt=%u,idx=%u,size=%u,sector=%llu)\n", bio->bi_vcnt, bio->bi_idx, bio->bi_size, (unsigned long long)bio->bi_sector); bio_endio(bio, -EINVAL); } else { /* This bio crosses some boundary, so we have to split it. */ struct bio_pair *bp; /* works for the "do not cross hash slot boundaries" case * e.g. sector 262269, size 4096 * s_enr = 262269 >> 6 = 4097 * e_enr = (262269+8-1) >> 6 = 4098 * HT_SHIFT = 6 * sps = 64, mask = 63 * first_sectors = 64 - (262269 & 63) = 3 */ const sector_t sect = bio->bi_sector; const int sps = 1 << HT_SHIFT; /* sectors per slot */ const int mask = sps - 1; const sector_t first_sectors = sps - (sect & mask); bp = bio_split(bio, #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,28) bio_split_pool, #endif first_sectors); /* we need to get a "reference count" (ap_bio_cnt) * to avoid races with the disconnect/reconnect/suspend code. * In case we need to split the bio here, we need to get three references * atomically, otherwise we might deadlock when trying to submit the * second one! */ inc_ap_bio(mdev, 3); D_ASSERT(e_enr == s_enr + 1); while (drbd_make_request_common(mdev, &bp->bio1)) inc_ap_bio(mdev, 1); while (drbd_make_request_common(mdev, &bp->bio2)) inc_ap_bio(mdev, 1); dec_ap_bio(mdev); bio_pair_release(bp); } return 0; } /* This is called by bio_add_page(). With this function we reduce * the number of BIOs that span over multiple DRBD_MAX_SEGMENT_SIZEs * units (was AL_EXTENTs). * * we do the calculation within the lower 32bit of the byte offsets, * since we don't care for actual offset, but only check whether it * would cross "activity log extent" boundaries. * * As long as the BIO is empty we have to allow at least one bvec, * regardless of size and offset. so the resulting bio may still * cross extent boundaries. those are dealt with (bio_split) in * drbd_make_request_26. */ 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_offset = (unsigned int)bvm->bi_sector << 9; /* 32 bit */ unsigned int bio_size = bvm->bi_size; int limit, backing_limit; limit = DRBD_MAX_SEGMENT_SIZE - ((bio_offset & (DRBD_MAX_SEGMENT_SIZE-1)) + bio_size); if (limit < 0) limit = 0; if (bio_size == 0) { if (limit <= bvec->bv_len) limit = bvec->bv_len; } else if (limit && 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; }