diff options
Diffstat (limited to 'drivers/block/drbd/drbd_req.c')
| -rw-r--r-- | drivers/block/drbd/drbd_req.c | 1125 |
1 files changed, 1125 insertions, 0 deletions
diff --git a/drivers/block/drbd/drbd_req.c b/drivers/block/drbd/drbd_req.c new file mode 100644 index 0000000..de81ab7 --- /dev/null +++ b/drivers/block/drbd/drbd_req.c @@ -0,0 +1,1125 @@ +/* + 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" + + +/* 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; + /* 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) { + /* 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); + /* 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); + } + } + } + + /* if it was a local io error, we want to notify our + * peer about that, and see if we need to + * detach the disk and stuff. + * to avoid allocating some special work + * struct, reuse the request. */ + + /* THINK + * why do we do this not when we detect the error, + * but delay it until it is "done", i.e. possibly + * until the next barrier ack? */ + + if (rw == WRITE && + ((s & RQ_LOCAL_MASK) && !(s & RQ_LOCAL_OK))) { + if (!(req->w.list.next == LIST_POISON1 || + list_empty(&req->w.list))) { + /* DEBUG ASSERT only; if this triggers, we + * probably corrupt the worker list here */ + dev_err(DEV, "req->w.list.next = %p\n", req->w.list.next); + dev_err(DEV, "req->w.list.prev = %p\n", req->w.list.prev); + } + req->w.cb = w_io_error; + drbd_queue_work(&mdev->data.work, &req->w); + /* drbd_req_free() is done in w_io_error */ + } else { + 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... */ +} + +/* + * 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 ... + */ +void __req_mod(struct drbd_request *req, enum drbd_req_event what, + struct bio_and_error *m) +{ + struct drbd_conf *mdev = req->mdev; + 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(req, m); + put_ldev(mdev); + break; + + case write_completed_with_error: + req->rq_state |= RQ_LOCAL_COMPLETED; + req->rq_state &= ~RQ_LOCAL_PENDING; + + dev_alert(DEV, "Local WRITE failed sec=%llus size=%u\n", + (unsigned long long)req->sector, req->size); + /* and now: check how to handle local io error. */ + __drbd_chk_io_error(mdev, FALSE); + _req_may_be_done(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(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; + + dev_alert(DEV, "Local READ failed sec=%llus size=%u\n", + (unsigned long long)req->sector, req->size); + /* _req_mod(req,to_be_send); oops, recursion... */ + D_ASSERT(!(req->rq_state & RQ_NET_MASK)); + req->rq_state |= RQ_NET_PENDING; + inc_ap_pending(mdev); + + __drbd_chk_io_error(mdev, FALSE); + put_ldev(mdev); + /* NOTE: if we have no connection, + * or know the peer has no good data either, + * then we don't actually need to "queue_for_net_read", + * but we do so anyways, since the drbd_io_error() + * and the potential state change to "Diskless" + * needs to be done from process context */ + + /* 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; + list_add_tail(&req->tl_requests, + &mdev->newest_tle->requests); + + /* increment size of current epoch */ + mdev->newest_tle->n_req++; + + /* 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_req >= 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(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(req, m); + break; + + 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); + 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(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(req, m); + /* else: done by handed_over_to_network */ + break; + + case barrier_acked: + 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); + 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(req, m); + break; + }; +} + +/* 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; + + /* 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)) { + 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 (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)) { + /* 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. + */ + if (local) { + bio_put(req->private_bio); + req->private_bio = NULL; + drbd_al_complete_io(mdev, req->sector); + put_ldev(mdev); + local = 0; + } + if (remote) + dec_ap_pending(mdev); + _drbd_end_io_acct(mdev, req); + /* THINK: do we want to fail it (-EIO), or pretend success? */ + bio_endio(req->master_bio, 0); + req->master_bio = NULL; + dec_ap_bio(mdev); + drbd_req_free(req); + remote = 0; + } + + /* 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_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); + } + bio_endio(bio, err); + drbd_req_free(req); + dec_ap_bio(mdev); + kfree(b); + + return 0; +} + +/* 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) +{ + /* Unconfigured */ + if (mdev->state.conn == C_DISCONNECTING && + mdev->state.disk == D_DISKLESS) + return 1; + + 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; + } + + /* + * Paranoia: we might have been primary, but sync target, or + * even diskless, then lost the connection. + * This should have been handled (panic? suspend?) somewhere + * else. But maybe it was not, so check again here. + * Caution: as long as we do not have a read/write lock on mdev, + * to serialize state changes, this is racy, since we may lose + * the connection *after* we test for the cstate. + */ + if (mdev->state.disk < D_UP_TO_DATE && mdev->state.pdsk < D_UP_TO_DATE) { + if (__ratelimit(&drbd_ratelimit_state)) + dev_err(DEV, "Sorry, I have no access to good data anymore.\n"); + 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_rw_flagged(bio, BIO_RW_BARRIER) && 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 two references + * atomically, otherwise we might deadlock when trying to submit the + * second one! */ + inc_ap_bio(mdev, 2); + + D_ASSERT(e_enr == s_enr + 1); + + drbd_make_request_common(mdev, &bp->bio1); + drbd_make_request_common(mdev, &bp->bio2); + 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 && mdev->ldev->dc.use_bmbv) { + backing_limit = b->merge_bvec_fn(b, bvm, bvec); + limit = min(limit, backing_limit); + } + put_ldev(mdev); + } + return limit; +} |
