/* 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)); (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); return req; } static void drbd_req_free(struct drbd_request *req) { mempool_free(req, drbd_request_mempool); } /* rw is bio_data_dir(), only READ or WRITE */ 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->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); } } } drbd_req_free(req); } static void queue_barrier(struct drbd_conf *mdev) { struct drbd_tl_epoch *b; struct drbd_tconn *tconn = mdev->tconn; /* 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, &tconn->flags)) return; b = tconn->newest_tle; b->w.cb = w_send_barrier; b->w.mdev = mdev; /* 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(&tconn->data.work, &b->w); set_bit(CREATE_BARRIER, &tconn->flags); } static void _about_to_complete_local_write(struct drbd_conf *mdev, struct drbd_request *req) { const unsigned long s = req->rq_state; /* Before we can signal completion to the upper layers, * we may need to close the current epoch. * We can skip this, if this request has not even been sent, because we * did not have a fully established connection yet/anymore, during * bitmap exchange, or while we are C_AHEAD due to congestion policy. */ if (mdev->state.conn >= C_CONNECTED && (s & RQ_NET_SENT) != 0 && req->epoch == mdev->tconn->newest_tle->br_number) queue_barrier(mdev); } 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. */ 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->w.mdev; int rw = req->rq_state & RQ_WRITE ? WRITE : READ; /* 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)) return; if (req->i.waiting) { /* Retry all conflicting peer requests. */ wake_up(&mdev->misc_wait); } if (s & RQ_NET_QUEUED) return; if (s & RQ_NET_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_request_endio. */ 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 (!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); /* 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); if (!(s & RQ_POSTPONED)) { m->error = ok ? 0 : (error ?: -EIO); m->bio = req->master_bio; } req->master_bio = NULL; } if (s & RQ_LOCAL_PENDING) return; if ((s & RQ_NET_MASK) == 0 || (s & RQ_NET_DONE)) { /* this is disconnected (local only) operation, * or protocol A, B, or C 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, B, or C, 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->w.mdev; if (!drbd_suspended(mdev)) _req_may_be_done(req, m); } /* 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)); req->rq_state |= RQ_NET_PENDING; 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; inc_ap_pending(mdev); break; case TO_BE_SUBMITTED: /* locally */ /* reached via __drbd_make_request */ D_ASSERT(!(req->rq_state & RQ_LOCAL_MASK)); req->rq_state |= 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; 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 ABORT_DISK_IO: req->rq_state |= RQ_LOCAL_ABORTED; if (req->rq_state & RQ_WRITE) _req_may_be_done_not_susp(req, m); else goto goto_queue_for_net_read; 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->i.sector, req->i.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); goto_queue_for_net_read: /* 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_SENT); 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 * 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() */ 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); 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->tconn->data.work, &req->w); break; case QUEUE_FOR_NET_WRITE: /* assert something? */ /* from __drbd_make_request only */ /* corresponding hlist_del is in _req_may_be_done() */ 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); /* see __drbd_make_request, * just after it grabs the req_lock */ D_ASSERT(test_bit(CREATE_BARRIER, &mdev->tconn->flags) == 0); req->epoch = mdev->tconn->newest_tle->br_number; /* increment size of current epoch */ mdev->tconn->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->tconn->data.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->newest_tle->n_writes >= p) queue_barrier(mdev); break; case QUEUE_FOR_SEND_OOS: req->rq_state |= RQ_NET_QUEUED; req->w.cb = w_send_out_of_sync; drbd_queue_work(&mdev->tconn->data.work, &req->w); break; case OOS_HANDED_TO_NETWORK: /* actually the same */ 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) atomic_add(req->i.size >> 9, &mdev->ap_in_flight); 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) { 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 (req->rq_state & RQ_NET_SENT && req->rq_state & RQ_WRITE) atomic_sub(req->i.size >> 9, &mdev->ap_in_flight); if (!(req->rq_state & RQ_WRITE) && mdev->state.disk == D_UP_TO_DATE && !IS_ERR_OR_NULL(req->private_bio)) goto goto_read_retry_local; /* 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 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. */ req->rq_state |= RQ_NET_DONE; /* fall through */ case WRITE_ACKED_BY_PEER: D_ASSERT(req->rq_state & RQ_EXP_WRITE_ACK); /* 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. */ goto ack_common; /* this makes it effectively the same as for: */ 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: req->rq_state |= RQ_NET_OK; D_ASSERT(req->rq_state & RQ_NET_PENDING); dec_ap_pending(mdev); atomic_sub(req->i.size >> 9, &mdev->ap_in_flight); req->rq_state &= ~RQ_NET_PENDING; _req_may_be_done_not_susp(req, m); 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; _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); atomic_sub(req->i.size >> 9, &mdev->ap_in_flight); } req->rq_state &= ~(RQ_NET_OK|RQ_NET_PENDING); req->rq_state |= RQ_NET_DONE; if (!(req->rq_state & RQ_WRITE) && mdev->state.disk == D_UP_TO_DATE && !IS_ERR_OR_NULL(req->private_bio)) goto goto_read_retry_local; _req_may_be_done_not_susp(req, m); /* else: done by HANDED_OVER_TO_NETWORK */ break; goto_read_retry_local: req->rq_state |= RQ_LOCAL_PENDING; req->private_bio->bi_bdev = mdev->ldev->backing_bdev; generic_make_request(req->private_bio); 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->tconn->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->tconn->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 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"); list_move(&req->tl_requests, &mdev->tconn->out_of_sequence_requests); } if ((req->rq_state & RQ_NET_MASK) != 0) { req->rq_state |= RQ_NET_DONE; if (!(req->rq_state & (RQ_EXP_RECEIVE_ACK | RQ_EXP_WRITE_ACK))) atomic_sub(req->i.size>>9, &mdev->ap_in_flight); } _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); if (!IS_ERR_OR_NULL(req->private_bio)) { bio_put(req->private_bio); req->private_bio = NULL; put_ldev(mdev); } _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 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) { enum drbd_read_balancing rbm; struct backing_dev_info *bdi; if (mdev->state.pdsk < D_UP_TO_DATE) return false; rcu_read_lock(); rbm = rcu_dereference(mdev->ldev->disk_conf)->read_balancing; rcu_read_unlock(); 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_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. */ static int complete_conflicting_writes(struct drbd_conf *mdev, sector_t sector, int size) { for(;;) { struct drbd_interval *i; int err; i = drbd_find_overlap(&mdev->write_requests, sector, size); if (!i) return 0; err = drbd_wait_misc(mdev, i); if (err) return err; } } int __drbd_make_request(struct drbd_conf *mdev, struct bio *bio, unsigned long start_time) { 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; struct net_conf *nc; int local, remote, send_oos = 0; int err; 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; } req->start_time = start_time; 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); } else if (remote_due_to_read_balancing(mdev)) { /* Keep the private bio in case we need it for a local retry */ local = 0; } } 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 && !test_bit(AL_SUSPENDED, &mdev->flags)) { req->rq_state |= RQ_IN_ACT_LOG; drbd_al_begin_io(mdev, &req->i); } remote = remote && drbd_should_do_remote(mdev->state); send_oos = rw == WRITE && drbd_should_send_out_of_sync(mdev->state); D_ASSERT(!(remote && send_oos)); if (!(local || remote) && !drbd_suspended(mdev)) { if (__ratelimit(&drbd_ratelimit_state)) dev_err(DEV, "IO ERROR: neither local nor remote disk\n"); err = -EIO; 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 || send_oos) && mdev->tconn->unused_spare_tle == NULL && test_bit(CREATE_BARRIER, &mdev->tconn->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->tconn->req_lock); if (rw == WRITE) { err = complete_conflicting_writes(mdev, sector, size); if (err) { if (err != -ERESTARTSYS) _conn_request_state(mdev->tconn, NS(conn, C_TIMEOUT), CS_HARD); spin_unlock_irq(&mdev->tconn->req_lock); err = -EIO; goto fail_free_complete; } } if (drbd_suspended(mdev)) { /* 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 we sleep in inc_ap_bio() */ ret = 1; spin_unlock_irq(&mdev->tconn->req_lock); goto fail_free_complete; } if (remote || send_oos) { remote = drbd_should_do_remote(mdev->state); send_oos = rw == WRITE && drbd_should_send_out_of_sync(mdev->state); D_ASSERT(!(remote && send_oos)); if (!(remote || send_oos)) 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->tconn->req_lock); err = -EIO; goto fail_free_complete; } } if (b && mdev->tconn->unused_spare_tle == NULL) { mdev->tconn->unused_spare_tle = b; b = NULL; } if (rw == WRITE && (remote || send_oos) && mdev->tconn->unused_spare_tle == NULL && test_bit(CREATE_BARRIER, &mdev->tconn->flags)) { /* someone closed the current epoch * while we were grabbing the spinlock */ spin_unlock_irq(&mdev->tconn->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 || send_oos) && mdev->tconn->unused_spare_tle && test_and_clear_bit(CREATE_BARRIER, &mdev->tconn->flags)) { _tl_add_barrier(mdev->tconn, mdev->tconn->unused_spare_tle); mdev->tconn->unused_spare_tle = NULL; } else { D_ASSERT(!(remote && rw == WRITE && test_bit(CREATE_BARRIER, &mdev->tconn->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_SENT); if (local) _req_mod(req, TO_BE_SUBMITTED); list_add_tail(&req->tl_requests, &mdev->tconn->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); } if (send_oos && drbd_set_out_of_sync(mdev, sector, size)) _req_mod(req, QUEUE_FOR_SEND_OOS); rcu_read_lock(); nc = rcu_dereference(mdev->tconn->net_conf); if (remote && nc->on_congestion != OC_BLOCK && mdev->tconn->agreed_pro_version >= 96) { int congested = 0; if (nc->cong_fill && atomic_read(&mdev->ap_in_flight) >= nc->cong_fill) { dev_info(DEV, "Congestion-fill threshold reached\n"); congested = 1; } if (mdev->act_log->used >= nc->cong_extents) { dev_info(DEV, "Congestion-extents threshold reached\n"); congested = 1; } if (congested) { queue_barrier(mdev); /* last barrier, after mirrored writes */ if (nc->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); } } rcu_read_unlock(); spin_unlock_irq(&mdev->tconn->req_lock); kfree(b); /* if someone else has beaten us to it... */ if (local) { req->private_bio->bi_bdev = mdev->ldev->backing_bdev; /* State may have changed since we grabbed our reference on the * mdev->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(req->private_bio, -EIO); else generic_make_request(req->private_bio); put_ldev(mdev); } else bio_endio(req->private_bio, -EIO); } return 0; fail_free_complete: if (req->rq_state & RQ_IN_ACT_LOG) drbd_al_complete_io(mdev, &req->i); fail_and_free_req: if (!IS_ERR_OR_NULL(req->private_bio)) { 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; } 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(bio->bi_size > 0); D_ASSERT(IS_ALIGNED(bio->bi_size, 512)); inc_ap_bio(mdev); return __drbd_make_request(mdev, bio, start_time); } /* 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; } 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 list_head *le; struct net_conf *nc; unsigned long ent = 0, dt = 0, et, nt; /* effective timeout = ko_count * timeout */ rcu_read_lock(); nc = rcu_dereference(tconn->net_conf); ent = nc ? nc->timeout * HZ/10 * nc->ko_count : 0; if (get_ldev(mdev)) { 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 || (mdev->state.conn < C_WF_REPORT_PARAMS && mdev->state.disk <= D_FAILED)) return; /* Recurring timer stopped */ spin_lock_irq(&tconn->req_lock); le = &tconn->oldest_tle->requests; if (list_empty(le)) { spin_unlock_irq(&tconn->req_lock); mod_timer(&mdev->request_timer, jiffies + et); return; } le = le->prev; req = list_entry(le, struct drbd_request, tl_requests); if (ent && req->rq_state & RQ_NET_PENDING) { if (time_is_before_eq_jiffies(req->start_time + 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) { if (time_is_before_eq_jiffies(req->start_time + dt)) { dev_warn(DEV, "Local backing device failed to meet the disk-timeout\n"); __drbd_chk_io_error(mdev, 1); } } nt = (time_is_before_eq_jiffies(req->start_time + et) ? jiffies : req->start_time) + et; spin_unlock_irq(&tconn->req_lock); mod_timer(&mdev->request_timer, nt); }