diff options
Diffstat (limited to 'drivers/block/drbd/drbd_req.c')
| -rw-r--r-- | drivers/block/drbd/drbd_req.c | 1638 |
1 files changed, 1638 insertions, 0 deletions
diff --git a/drivers/block/drbd/drbd_req.c b/drivers/block/drbd/drbd_req.c new file mode 100644 index 000000000..3907202fb --- /dev/null +++ b/drivers/block/drbd/drbd_req.c @@ -0,0 +1,1638 @@ +/* + 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 <philipp.reisner@linbit.com>. + Copyright (C) 2002-2008, Lars Ellenberg <lars.ellenberg@linbit.com>. + + 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 <linux/module.h> + +#include <linux/slab.h> +#include <linux/drbd.h> +#include "drbd_int.h" +#include "drbd_req.h" + + +static bool drbd_may_do_local_read(struct drbd_device *device, sector_t sector, int size); + +/* Update disk stats at start of I/O request */ +static void _drbd_start_io_acct(struct drbd_device *device, struct drbd_request *req) +{ + generic_start_io_acct(bio_data_dir(req->master_bio), req->i.size >> 9, + &device->vdisk->part0); +} + +/* Update disk stats when completing request upwards */ +static void _drbd_end_io_acct(struct drbd_device *device, struct drbd_request *req) +{ + generic_end_io_acct(bio_data_dir(req->master_bio), + &device->vdisk->part0, req->start_jif); +} + +static struct drbd_request *drbd_req_new(struct drbd_device *device, + struct bio *bio_src) +{ + struct drbd_request *req; + + req = mempool_alloc(drbd_request_mempool, GFP_NOIO); + if (!req) + return NULL; + memset(req, 0, sizeof(*req)); + + drbd_req_make_private_bio(req, bio_src); + req->rq_state = bio_data_dir(bio_src) == WRITE ? RQ_WRITE : 0; + req->device = device; + req->master_bio = bio_src; + req->epoch = 0; + + drbd_clear_interval(&req->i); + req->i.sector = bio_src->bi_iter.bi_sector; + req->i.size = bio_src->bi_iter.bi_size; + req->i.local = true; + req->i.waiting = false; + + INIT_LIST_HEAD(&req->tl_requests); + INIT_LIST_HEAD(&req->w.list); + INIT_LIST_HEAD(&req->req_pending_master_completion); + INIT_LIST_HEAD(&req->req_pending_local); + + /* 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; +} + +static void drbd_remove_request_interval(struct rb_root *root, + struct drbd_request *req) +{ + struct drbd_device *device = req->device; + 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(&device->misc_wait); +} + +void drbd_req_destroy(struct kref *kref) +{ + struct drbd_request *req = container_of(kref, struct drbd_request, kref); + struct drbd_device *device = req->device; + 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))) { + drbd_err(device, "drbd_req_destroy: Logic BUG rq_state = 0x%x, completion_ref = %d\n", + s, atomic_read(&req->completion_ref)); + return; + } + + /* If called from mod_rq_state (expected normal case) or + * drbd_send_and_submit (the less likely normal path), this holds the + * req_lock, and req->tl_requests will typicaly be on ->transfer_log, + * though it may be still empty (never added to the transfer log). + * + * If called from do_retry(), we do NOT hold the req_lock, but we are + * still allowed to unconditionally list_del(&req->tl_requests), + * because it will be on a local on-stack list only. */ + list_del_init(&req->tl_requests); + + /* finally remove the request from the conflict detection + * respective block_id verification interval tree. */ + if (!drbd_interval_empty(&req->i)) { + struct rb_root *root; + + if (s & RQ_WRITE) + root = &device->write_requests; + else + root = &device->read_requests; + drbd_remove_request_interval(root, req); + } else if (s & (RQ_NET_MASK & ~RQ_NET_DONE) && req->i.size != 0) + drbd_err(device, "drbd_req_destroy: Logic BUG: interval empty, but: rq_state=0x%x, sect=%llu, size=%u\n", + s, (unsigned long long)req->i.sector, req->i.size); + + /* 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 */ + + /* There is a special case: + * we may notice late that IO was suspended, + * and postpone, or schedule for retry, a write, + * before it even was submitted or sent. + * In that case we do not want to touch the bitmap at all. + */ + if ((s & (RQ_POSTPONED|RQ_LOCAL_MASK|RQ_NET_MASK)) != RQ_POSTPONED) { + if (!(s & RQ_NET_OK) || !(s & RQ_LOCAL_OK)) + drbd_set_out_of_sync(device, req->i.sector, req->i.size); + + if ((s & RQ_NET_OK) && (s & RQ_LOCAL_OK) && (s & RQ_NET_SIS)) + drbd_set_in_sync(device, 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_IN_ACT_LOG) { + if (get_ldev_if_state(device, D_FAILED)) { + drbd_al_complete_io(device, &req->i); + put_ldev(device); + } else if (__ratelimit(&drbd_ratelimit_state)) { + drbd_warn(device, "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_connection *connection) +{ + wake_up(&connection->sender_work.q_wait); +} + +/* must hold resource->req_lock */ +void start_new_tl_epoch(struct drbd_connection *connection) +{ + /* no point closing an epoch, if it is empty, anyways. */ + if (connection->current_tle_writes == 0) + return; + + connection->current_tle_writes = 0; + atomic_inc(&connection->current_tle_nr); + wake_all_senders(connection); +} + +void complete_master_bio(struct drbd_device *device, + struct bio_and_error *m) +{ + bio_endio(m->bio, m->error); + dec_ap_bio(device); +} + + +/* 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_device *device = req->device; + 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)) { + drbd_err(device, "drbd_req_complete: Logic BUG rq_state = 0x%x\n", s); + return; + } + + if (!req->master_bio) { + drbd_err(device, "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); + + /* 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(&first_peer_device(device)->connection->current_tle_nr)) + start_new_tl_epoch(first_peer_device(device)->connection); + + /* Update disk stats */ + _drbd_end_io_acct(device, 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; + /* We leave it in the tree, to be able to verify later + * write-acks in protocol != C during resync. + * But we mark it as "complete", so it won't be counted as + * conflict in a multi-primary setup. */ + req->i.completed = true; + } + + if (req->i.waiting) + wake_up(&device->misc_wait); + + /* Either we are about to complete to upper layers, + * or we will restart this request. + * In either case, the request object will be destroyed soon, + * so better remove it from all lists. */ + list_del_init(&req->req_pending_master_completion); +} + +/* still holds resource->req_lock */ +static int drbd_req_put_completion_ref(struct drbd_request *req, struct bio_and_error *m, int put) +{ + struct drbd_device *device = req->device; + D_ASSERT(device, m || (req->rq_state & RQ_POSTPONED)); + + if (!atomic_sub_and_test(put, &req->completion_ref)) + return 0; + + 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; +} + +static void set_if_null_req_next(struct drbd_peer_device *peer_device, struct drbd_request *req) +{ + struct drbd_connection *connection = peer_device ? peer_device->connection : NULL; + if (!connection) + return; + if (connection->req_next == NULL) + connection->req_next = req; +} + +static void advance_conn_req_next(struct drbd_peer_device *peer_device, struct drbd_request *req) +{ + struct drbd_connection *connection = peer_device ? peer_device->connection : NULL; + if (!connection) + return; + if (connection->req_next != req) + return; + list_for_each_entry_continue(req, &connection->transfer_log, tl_requests) { + const unsigned s = req->rq_state; + if (s & RQ_NET_QUEUED) + break; + } + if (&req->tl_requests == &connection->transfer_log) + req = NULL; + connection->req_next = req; +} + +static void set_if_null_req_ack_pending(struct drbd_peer_device *peer_device, struct drbd_request *req) +{ + struct drbd_connection *connection = peer_device ? peer_device->connection : NULL; + if (!connection) + return; + if (connection->req_ack_pending == NULL) + connection->req_ack_pending = req; +} + +static void advance_conn_req_ack_pending(struct drbd_peer_device *peer_device, struct drbd_request *req) +{ + struct drbd_connection *connection = peer_device ? peer_device->connection : NULL; + if (!connection) + return; + if (connection->req_ack_pending != req) + return; + list_for_each_entry_continue(req, &connection->transfer_log, tl_requests) { + const unsigned s = req->rq_state; + if ((s & RQ_NET_SENT) && (s & RQ_NET_PENDING)) + break; + } + if (&req->tl_requests == &connection->transfer_log) + req = NULL; + connection->req_ack_pending = req; +} + +static void set_if_null_req_not_net_done(struct drbd_peer_device *peer_device, struct drbd_request *req) +{ + struct drbd_connection *connection = peer_device ? peer_device->connection : NULL; + if (!connection) + return; + if (connection->req_not_net_done == NULL) + connection->req_not_net_done = req; +} + +static void advance_conn_req_not_net_done(struct drbd_peer_device *peer_device, struct drbd_request *req) +{ + struct drbd_connection *connection = peer_device ? peer_device->connection : NULL; + if (!connection) + return; + if (connection->req_not_net_done != req) + return; + list_for_each_entry_continue(req, &connection->transfer_log, tl_requests) { + const unsigned s = req->rq_state; + if ((s & RQ_NET_SENT) && !(s & RQ_NET_DONE)) + break; + } + if (&req->tl_requests == &connection->transfer_log) + req = NULL; + connection->req_not_net_done = req; +} + +/* 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_device *device = req->device; + struct drbd_peer_device *peer_device = first_peer_device(device); + unsigned s = req->rq_state; + int c_put = 0; + int k_put = 0; + + if (drbd_suspended(device) && !((s | clear) & RQ_COMPLETION_SUSP)) + set |= RQ_COMPLETION_SUSP; + + /* 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(device); + atomic_inc(&req->completion_ref); + } + + if (!(s & RQ_NET_QUEUED) && (set & RQ_NET_QUEUED)) { + atomic_inc(&req->completion_ref); + set_if_null_req_next(peer_device, req); + } + + 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)) { + /* potentially already completed in the asender thread */ + if (!(s & RQ_NET_DONE)) { + atomic_add(req->i.size >> 9, &device->ap_in_flight); + set_if_null_req_not_net_done(peer_device, req); + } + if (s & RQ_NET_PENDING) + set_if_null_req_ack_pending(peer_device, req); + } + + if (!(s & RQ_COMPLETION_SUSP) && (set & RQ_COMPLETION_SUSP)) + atomic_inc(&req->completion_ref); + + /* 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(device, 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; + list_del_init(&req->req_pending_local); + } + + if ((s & RQ_NET_PENDING) && (clear & RQ_NET_PENDING)) { + dec_ap_pending(device); + ++c_put; + req->acked_jif = jiffies; + advance_conn_req_ack_pending(peer_device, req); + } + + if ((s & RQ_NET_QUEUED) && (clear & RQ_NET_QUEUED)) { + ++c_put; + advance_conn_req_next(peer_device, req); + } + + if (!(s & RQ_NET_DONE) && (set & RQ_NET_DONE)) { + if (s & RQ_NET_SENT) + atomic_sub(req->i.size >> 9, &device->ap_in_flight); + if (s & RQ_EXP_BARR_ACK) + ++k_put; + req->net_done_jif = jiffies; + + /* in ahead/behind mode, or just in case, + * before we finally destroy this request, + * the caching pointers must not reference it anymore */ + advance_conn_req_next(peer_device, req); + advance_conn_req_ack_pending(peer_device, req); + advance_conn_req_not_net_done(peer_device, req); + } + + /* 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) + drbd_err(device, + "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(&device->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); +} + +static void drbd_report_io_error(struct drbd_device *device, struct drbd_request *req) +{ + char b[BDEVNAME_SIZE]; + + if (!__ratelimit(&drbd_ratelimit_state)) + return; + + drbd_warn(device, "local %s IO error sector %llu+%u on %s\n", + (req->rq_state & RQ_WRITE) ? "WRITE" : "READ", + (unsigned long long)req->i.sector, + req->i.size >> 9, + bdevname(device->ldev->backing_bdev, b)); +} + +/* Helper for HANDED_OVER_TO_NETWORK. + * Is this a protocol A write (neither WRITE_ACK nor RECEIVE_ACK expected)? + * Is it also still "PENDING"? + * --> If so, clear PENDING and set NET_OK below. + * If it is a protocol A write, but not RQ_PENDING anymore, neg-ack was faster + * (and we must not set RQ_NET_OK) */ +static inline bool is_pending_write_protocol_A(struct drbd_request *req) +{ + return (req->rq_state & + (RQ_WRITE|RQ_NET_PENDING|RQ_EXP_WRITE_ACK|RQ_EXP_RECEIVE_ACK)) + == (RQ_WRITE|RQ_NET_PENDING); +} + +/* 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_device *const device = req->device; + struct drbd_peer_device *const peer_device = first_peer_device(device); + struct drbd_connection *const connection = peer_device ? peer_device->connection : NULL; + struct net_conf *nc; + int p, rv = 0; + + if (m) + m->bio = NULL; + + switch (what) { + default: + drbd_err(device, "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(device, !(req->rq_state & RQ_NET_MASK)); + rcu_read_lock(); + nc = rcu_dereference(connection->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(device, !(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) + device->writ_cnt += req->i.size >> 9; + else + device->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 WRITE_COMPLETED_WITH_ERROR: + drbd_report_io_error(device, req); + __drbd_chk_io_error(device, DRBD_WRITE_ERROR); + mod_rq_state(req, m, RQ_LOCAL_PENDING, RQ_LOCAL_COMPLETED); + break; + + case READ_COMPLETED_WITH_ERROR: + drbd_set_out_of_sync(device, req->i.sector, req->i.size); + drbd_report_io_error(device, req); + __drbd_chk_io_error(device, DRBD_READ_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 DISCARD_COMPLETED_NOTSUPP: + case DISCARD_COMPLETED_WITH_ERROR: + /* I'd rather not detach from local disk just because it + * failed a REQ_DISCARD. */ + 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(device, drbd_interval_empty(&req->i)); + drbd_insert_interval(&device->read_requests, &req->i); + + set_bit(UNPLUG_REMOTE, &device->flags); + + D_ASSERT(device, req->rq_state & RQ_NET_PENDING); + D_ASSERT(device, (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(&connection->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(device, drbd_interval_empty(&req->i)); + drbd_insert_interval(&device->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, &device->flags); + + /* queue work item to send data */ + D_ASSERT(device, 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(&connection->sender_work, + &req->w); + + /* close the epoch, in case it outgrew the limit */ + rcu_read_lock(); + nc = rcu_dereference(connection->net_conf); + p = nc->max_epoch_size; + rcu_read_unlock(); + if (connection->current_tle_writes >= p) + start_new_tl_epoch(connection); + + 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(&connection->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 (is_pending_write_protocol_A(req)) + /* this is what is dangerous about protocol A: + * pretend it was successfully written on the peer. */ + mod_rq_state(req, m, RQ_NET_QUEUED|RQ_NET_PENDING, + RQ_NET_SENT|RQ_NET_OK); + else + mod_rq_state(req, m, RQ_NET_QUEUED, RQ_NET_SENT); + /* 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. */ + 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 CONFLICT_RESOLVED: + /* for superseded 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 completed, but "restarted", + * resubmitted from the retry worker context. */ + D_ASSERT(device, req->rq_state & RQ_NET_PENDING); + D_ASSERT(device, 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: + /* Normal operation protocol C: successfully written on peer. + * During resync, even in protocol != C, + * we requested an explicit write ack anyways. + * Which means we cannot even assert anything here. + * 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(device, 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: + mod_rq_state(req, m, RQ_NET_PENDING, RQ_NET_OK); + break; + + case POSTPONE_WRITE: + D_ASSERT(device, 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(device, req->rq_state & RQ_NET_PENDING); + req->rq_state |= RQ_POSTPONED; + if (req->i.waiting) + wake_up(&device->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, 0); + 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(device); /* always succeeds in this call path */ + req->w.cb = w_restart_disk_io; + drbd_queue_work(&connection->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->dw.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) { + /* w.cb expected to be w_send_dblock, or w_send_read_req */ + drbd_queue_work(&connection->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... */ + drbd_err(device, "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(device, req->rq_state & RQ_NET_PENDING); + mod_rq_state(req, m, RQ_NET_PENDING, RQ_NET_OK|RQ_NET_DONE); + break; + + case QUEUE_AS_DRBD_BARRIER: + start_new_tl_epoch(connection); + mod_rq_state(req, m, 0, 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_device *device, sector_t sector, int size) +{ + unsigned long sbnr, ebnr; + sector_t esector, nr_sectors; + + if (device->state.disk == D_UP_TO_DATE) + return true; + if (device->state.disk != D_INCONSISTENT) + return false; + esector = sector + (size >> 9) - 1; + nr_sectors = drbd_get_capacity(device->this_bdev); + D_ASSERT(device, sector < nr_sectors); + D_ASSERT(device, esector < nr_sectors); + + sbnr = BM_SECT_TO_BIT(sector); + ebnr = BM_SECT_TO_BIT(esector); + + return drbd_bm_count_bits(device, sbnr, ebnr) == 0; +} + +static bool remote_due_to_read_balancing(struct drbd_device *device, sector_t sector, + enum drbd_read_balancing rbm) +{ + struct backing_dev_info *bdi; + int stripe_shift; + + switch (rbm) { + case RB_CONGESTED_REMOTE: + bdi = &device->ldev->backing_bdev->bd_disk->queue->backing_dev_info; + return bdi_read_congested(bdi); + case RB_LEAST_PENDING: + return atomic_read(&device->local_cnt) > + atomic_read(&device->ap_pending_cnt) + atomic_read(&device->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, &device->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_device *device = req->device; + struct drbd_interval *i; + sector_t sector = req->i.sector; + int size = req->i.size; + + i = drbd_find_overlap(&device->write_requests, sector, size); + if (!i) + return; + + for (;;) { + prepare_to_wait(&device->misc_wait, &wait, TASK_UNINTERRUPTIBLE); + i = drbd_find_overlap(&device->write_requests, sector, size); + if (!i) + break; + /* Indicate to wake up device->misc_wait on progress. */ + i->waiting = true; + spin_unlock_irq(&device->resource->req_lock); + schedule(); + spin_lock_irq(&device->resource->req_lock); + } + finish_wait(&device->misc_wait, &wait); +} + +/* called within req_lock and rcu_read_lock() */ +static void maybe_pull_ahead(struct drbd_device *device) +{ + struct drbd_connection *connection = first_peer_device(device)->connection; + struct net_conf *nc; + bool congested = false; + enum drbd_on_congestion on_congestion; + + rcu_read_lock(); + nc = rcu_dereference(connection->net_conf); + on_congestion = nc ? nc->on_congestion : OC_BLOCK; + rcu_read_unlock(); + if (on_congestion == OC_BLOCK || + connection->agreed_pro_version < 96) + return; + + if (on_congestion == OC_PULL_AHEAD && device->state.conn == C_AHEAD) + return; /* nothing to do ... */ + + /* 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 device->act_log is there. + */ + if (!get_ldev_if_state(device, D_UP_TO_DATE)) + return; + + if (nc->cong_fill && + atomic_read(&device->ap_in_flight) >= nc->cong_fill) { + drbd_info(device, "Congestion-fill threshold reached\n"); + congested = true; + } + + if (device->act_log->used >= nc->cong_extents) { + drbd_info(device, "Congestion-extents threshold reached\n"); + congested = true; + } + + if (congested) { + /* start a new epoch for non-mirrored writes */ + start_new_tl_epoch(first_peer_device(device)->connection); + + if (on_congestion == OC_PULL_AHEAD) + _drbd_set_state(_NS(device, conn, C_AHEAD), 0, NULL); + else /*nc->on_congestion == OC_DISCONNECT */ + _drbd_set_state(_NS(device, conn, C_DISCONNECTING), 0, NULL); + } + put_ldev(device); +} + +/* 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_device *device = req->device; + enum drbd_read_balancing rbm; + + if (req->private_bio) { + if (!drbd_may_do_local_read(device, + req->i.sector, req->i.size)) { + bio_put(req->private_bio); + req->private_bio = NULL; + put_ldev(device); + } + } + + if (device->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(device->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(device, req->i.sector, rbm)) { + if (req->private_bio) { + bio_put(req->private_bio); + req->private_bio = NULL; + put_ldev(device); + } + 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_device *device = req->device; + int remote, send_oos; + + remote = drbd_should_do_remote(device->state); + send_oos = drbd_should_send_out_of_sync(device->state); + + /* 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(device, req->master_bio->bi_rw & REQ_FLUSH); + if (remote) + _req_mod(req, QUEUE_AS_DRBD_BARRIER); + return remote; + } + + if (!remote && !send_oos) + return 0; + + D_ASSERT(device, !(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(device, 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_device *device = req->device; + struct bio *bio = req->private_bio; + const int rw = bio_rw(bio); + + bio->bi_bdev = device->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(device)) { + req->pre_submit_jif = jiffies; + if (drbd_insert_fault(device, + 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(device); + } else + bio_endio(bio, -EIO); +} + +static void drbd_queue_write(struct drbd_device *device, struct drbd_request *req) +{ + spin_lock_irq(&device->resource->req_lock); + list_add_tail(&req->tl_requests, &device->submit.writes); + list_add_tail(&req->req_pending_master_completion, + &device->pending_master_completion[1 /* WRITE */]); + spin_unlock_irq(&device->resource->req_lock); + queue_work(device->submit.wq, &device->submit.worker); + /* do_submit() may sleep internally on al_wait, too */ + wake_up(&device->al_wait); +} + +/* returns the new drbd_request pointer, if the caller is expected to + * drbd_send_and_submit() it (to save latency), or NULL if we queued the + * request on the submitter thread. + * Returns ERR_PTR(-ENOMEM) if we cannot allocate a drbd_request. + */ +static struct drbd_request * +drbd_request_prepare(struct drbd_device *device, struct bio *bio, unsigned long start_jif) +{ + const int rw = bio_data_dir(bio); + struct drbd_request *req; + + /* allocate outside of all locks; */ + req = drbd_req_new(device, bio); + if (!req) { + dec_ap_bio(device); + /* only pass the error to the upper layers. + * if user cannot handle io errors, that's not our business. */ + drbd_err(device, "could not kmalloc() req\n"); + bio_endio(bio, -ENOMEM); + return ERR_PTR(-ENOMEM); + } + req->start_jif = start_jif; + + if (!get_ldev(device)) { + bio_put(req->private_bio); + req->private_bio = NULL; + } + + /* Update disk stats */ + _drbd_start_io_acct(device, req); + + if (rw == WRITE && req->private_bio && req->i.size + && !test_bit(AL_SUSPENDED, &device->flags)) { + if (!drbd_al_begin_io_fastpath(device, &req->i)) { + atomic_inc(&device->ap_actlog_cnt); + drbd_queue_write(device, req); + return NULL; + } + req->rq_state |= RQ_IN_ACT_LOG; + req->in_actlog_jif = jiffies; + } + + return req; +} + +static void drbd_send_and_submit(struct drbd_device *device, struct drbd_request *req) +{ + struct drbd_resource *resource = device->resource; + const int rw = bio_rw(req->master_bio); + struct bio_and_error m = { NULL, }; + bool no_remote = false; + bool submit_private_bio = false; + + spin_lock_irq(&resource->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! */ + + /* check for congestion, and potentially stop sending + * full data updates, but start sending "dirty bits" only. */ + maybe_pull_ahead(device); + } + + + if (drbd_suspended(device)) { + /* push back and retry: */ + req->rq_state |= RQ_POSTPONED; + if (req->private_bio) { + bio_put(req->private_bio); + req->private_bio = NULL; + put_ldev(device); + } + goto out; + } + + /* 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(&first_peer_device(device)->connection->current_tle_nr); + + /* no point in adding empty flushes to the transfer log, + * they are mapped to drbd barriers already. */ + if (likely(req->i.size!=0)) { + if (rw == WRITE) + first_peer_device(device)->connection->current_tle_writes++; + + list_add_tail(&req->tl_requests, &first_peer_device(device)->connection->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 it took the fast path in drbd_request_prepare, add it here. + * The slow path has added it already. */ + if (list_empty(&req->req_pending_master_completion)) + list_add_tail(&req->req_pending_master_completion, + &device->pending_master_completion[rw == WRITE]); + if (req->private_bio) { + /* needs to be marked within the same spinlock */ + list_add_tail(&req->req_pending_local, + &device->pending_completion[rw == WRITE]); + _req_mod(req, TO_BE_SUBMITTED); + /* but we need to give up the spinlock to submit */ + submit_private_bio = true; + } else if (no_remote) { +nodata: + if (__ratelimit(&drbd_ratelimit_state)) + drbd_err(device, "IO ERROR: neither local nor remote data, sector %llu+%u\n", + (unsigned long long)req->i.sector, req->i.size >> 9); + /* 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(&resource->req_lock); + + /* Even though above is a kref_put(), this is safe. + * As long as we still need to submit our private bio, + * we hold a completion ref, and the request cannot disappear. + * If however this request did not even have a private bio to submit + * (e.g. remote read), req may already be invalid now. + * That's why we cannot check on req->private_bio. */ + if (submit_private_bio) + drbd_submit_req_private_bio(req); + if (m.bio) + complete_master_bio(device, &m); +} + +void __drbd_make_request(struct drbd_device *device, struct bio *bio, unsigned long start_jif) +{ + struct drbd_request *req = drbd_request_prepare(device, bio, start_jif); + if (IS_ERR_OR_NULL(req)) + return; + drbd_send_and_submit(device, req); +} + +static void submit_fast_path(struct drbd_device *device, struct list_head *incoming) +{ + struct drbd_request *req, *tmp; + list_for_each_entry_safe(req, tmp, incoming, tl_requests) { + const int rw = bio_data_dir(req->master_bio); + + if (rw == WRITE /* rw != WRITE should not even end up here! */ + && req->private_bio && req->i.size + && !test_bit(AL_SUSPENDED, &device->flags)) { + if (!drbd_al_begin_io_fastpath(device, &req->i)) + continue; + + req->rq_state |= RQ_IN_ACT_LOG; + req->in_actlog_jif = jiffies; + atomic_dec(&device->ap_actlog_cnt); + } + + list_del_init(&req->tl_requests); + drbd_send_and_submit(device, req); + } +} + +static bool prepare_al_transaction_nonblock(struct drbd_device *device, + struct list_head *incoming, + struct list_head *pending, + struct list_head *later) +{ + struct drbd_request *req, *tmp; + int wake = 0; + int err; + + spin_lock_irq(&device->al_lock); + list_for_each_entry_safe(req, tmp, incoming, tl_requests) { + err = drbd_al_begin_io_nonblock(device, &req->i); + if (err == -ENOBUFS) + break; + if (err == -EBUSY) + wake = 1; + if (err) + list_move_tail(&req->tl_requests, later); + else + list_move_tail(&req->tl_requests, pending); + } + spin_unlock_irq(&device->al_lock); + if (wake) + wake_up(&device->al_wait); + return !list_empty(pending); +} + +void send_and_submit_pending(struct drbd_device *device, struct list_head *pending) +{ + struct drbd_request *req, *tmp; + + list_for_each_entry_safe(req, tmp, pending, tl_requests) { + req->rq_state |= RQ_IN_ACT_LOG; + req->in_actlog_jif = jiffies; + atomic_dec(&device->ap_actlog_cnt); + list_del_init(&req->tl_requests); + drbd_send_and_submit(device, req); + } +} + +void do_submit(struct work_struct *ws) +{ + struct drbd_device *device = container_of(ws, struct drbd_device, submit.worker); + LIST_HEAD(incoming); /* from drbd_make_request() */ + LIST_HEAD(pending); /* to be submitted after next AL-transaction commit */ + LIST_HEAD(busy); /* blocked by resync requests */ + + /* grab new incoming requests */ + spin_lock_irq(&device->resource->req_lock); + list_splice_tail_init(&device->submit.writes, &incoming); + spin_unlock_irq(&device->resource->req_lock); + + for (;;) { + DEFINE_WAIT(wait); + + /* move used-to-be-busy back to front of incoming */ + list_splice_init(&busy, &incoming); + submit_fast_path(device, &incoming); + if (list_empty(&incoming)) + break; + + for (;;) { + prepare_to_wait(&device->al_wait, &wait, TASK_UNINTERRUPTIBLE); + + list_splice_init(&busy, &incoming); + prepare_al_transaction_nonblock(device, &incoming, &pending, &busy); + if (!list_empty(&pending)) + break; + + schedule(); + + /* If all currently "hot" activity log extents are kept busy by + * incoming requests, we still must not totally starve new + * requests to "cold" extents. + * Something left on &incoming means there had not been + * enough update slots available, and the activity log + * has been marked as "starving". + * + * Try again now, without looking for new requests, + * effectively blocking all new requests until we made + * at least _some_ progress with what we currently have. + */ + if (!list_empty(&incoming)) + continue; + + /* Nothing moved to pending, but nothing left + * on incoming: all moved to busy! + * Grab new and iterate. */ + spin_lock_irq(&device->resource->req_lock); + list_splice_tail_init(&device->submit.writes, &incoming); + spin_unlock_irq(&device->resource->req_lock); + } + finish_wait(&device->al_wait, &wait); + + /* If the transaction was full, before all incoming requests + * had been processed, skip ahead to commit, and iterate + * without splicing in more incoming requests from upper layers. + * + * Else, if all incoming have been processed, + * they have become either "pending" (to be submitted after + * next transaction commit) or "busy" (blocked by resync). + * + * Maybe more was queued, while we prepared the transaction? + * Try to stuff those into this transaction as well. + * Be strictly non-blocking here, + * we already have something to commit. + * + * Commit if we don't make any more progres. + */ + + while (list_empty(&incoming)) { + LIST_HEAD(more_pending); + LIST_HEAD(more_incoming); + bool made_progress; + + /* It is ok to look outside the lock, + * it's only an optimization anyways */ + if (list_empty(&device->submit.writes)) + break; + + spin_lock_irq(&device->resource->req_lock); + list_splice_tail_init(&device->submit.writes, &more_incoming); + spin_unlock_irq(&device->resource->req_lock); + + if (list_empty(&more_incoming)) + break; + + made_progress = prepare_al_transaction_nonblock(device, &more_incoming, &more_pending, &busy); + + list_splice_tail_init(&more_pending, &pending); + list_splice_tail_init(&more_incoming, &incoming); + if (!made_progress) + break; + } + + drbd_al_begin_io_commit(device); + send_and_submit_pending(device, &pending); + } +} + +void drbd_make_request(struct request_queue *q, struct bio *bio) +{ + struct drbd_device *device = (struct drbd_device *) q->queuedata; + unsigned long start_jif; + + start_jif = jiffies; + + /* + * what we "blindly" assume: + */ + D_ASSERT(device, IS_ALIGNED(bio->bi_iter.bi_size, 512)); + + inc_ap_bio(device); + __drbd_make_request(device, bio, start_jif); +} + +/* 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_device *device = (struct drbd_device *) q->queuedata; + unsigned int bio_size = bvm->bi_size; + int limit = DRBD_MAX_BIO_SIZE; + int backing_limit; + + if (bio_size && get_ldev(device)) { + unsigned int max_hw_sectors = queue_max_hw_sectors(q); + struct request_queue * const b = + device->ldev->backing_bdev->bd_disk->queue; + if (b->merge_bvec_fn) { + bvm->bi_bdev = device->ldev->backing_bdev; + backing_limit = b->merge_bvec_fn(b, bvm, bvec); + limit = min(limit, backing_limit); + } + put_ldev(device); + if ((limit >> 9) > max_hw_sectors) + limit = max_hw_sectors << 9; + } + return limit; +} + +void request_timer_fn(unsigned long data) +{ + struct drbd_device *device = (struct drbd_device *) data; + struct drbd_connection *connection = first_peer_device(device)->connection; + struct drbd_request *req_read, *req_write, *req_peer; /* oldest request */ + struct net_conf *nc; + unsigned long oldest_submit_jif; + unsigned long ent = 0, dt = 0, et, nt; /* effective timeout = ko_count * timeout */ + unsigned long now; + + rcu_read_lock(); + nc = rcu_dereference(connection->net_conf); + if (nc && device->state.conn >= C_WF_REPORT_PARAMS) + ent = nc->timeout * HZ/10 * nc->ko_count; + + if (get_ldev(device)) { /* implicit state.disk >= D_INCONSISTENT */ + dt = rcu_dereference(device->ldev->disk_conf)->disk_timeout * HZ / 10; + put_ldev(device); + } + rcu_read_unlock(); + + et = min_not_zero(dt, ent); + + if (!et) + return; /* Recurring timer stopped */ + + now = jiffies; + nt = now + et; + + spin_lock_irq(&device->resource->req_lock); + req_read = list_first_entry_or_null(&device->pending_completion[0], struct drbd_request, req_pending_local); + req_write = list_first_entry_or_null(&device->pending_completion[1], struct drbd_request, req_pending_local); + req_peer = connection->req_not_net_done; + /* maybe the oldest request waiting for the peer is in fact still + * blocking in tcp sendmsg */ + if (!req_peer && connection->req_next && connection->req_next->pre_send_jif) + req_peer = connection->req_next; + + /* evaluate the oldest peer request only in one timer! */ + if (req_peer && req_peer->device != device) + req_peer = NULL; + + /* do we have something to evaluate? */ + if (req_peer == NULL && req_write == NULL && req_read == NULL) + goto out; + + oldest_submit_jif = + (req_write && req_read) + ? ( time_before(req_write->pre_submit_jif, req_read->pre_submit_jif) + ? req_write->pre_submit_jif : req_read->pre_submit_jif ) + : req_write ? req_write->pre_submit_jif + : req_read ? req_read->pre_submit_jif : now; + + /* 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_peer && + time_after(now, req_peer->pre_send_jif + ent) && + !time_in_range(now, connection->last_reconnect_jif, connection->last_reconnect_jif + ent)) { + drbd_warn(device, "Remote failed to finish a request within ko-count * timeout\n"); + _conn_request_state(connection, NS(conn, C_TIMEOUT), CS_VERBOSE | CS_HARD); + } + if (dt && oldest_submit_jif != now && + time_after(now, oldest_submit_jif + dt) && + !time_in_range(now, device->last_reattach_jif, device->last_reattach_jif + dt)) { + drbd_warn(device, "Local backing device failed to meet the disk-timeout\n"); + __drbd_chk_io_error(device, DRBD_FORCE_DETACH); + } + + /* Reschedule timer for the nearest not already expired timeout. + * Fallback to now + min(effective network timeout, disk timeout). */ + ent = (ent && req_peer && time_before(now, req_peer->pre_send_jif + ent)) + ? req_peer->pre_send_jif + ent : now + et; + dt = (dt && oldest_submit_jif != now && time_before(now, oldest_submit_jif + dt)) + ? oldest_submit_jif + dt : now + et; + nt = time_before(ent, dt) ? ent : dt; +out: + spin_unlock_irq(&device->resource->req_lock); + mod_timer(&device->request_timer, nt); +} |