summaryrefslogtreecommitdiffstats
path: root/kernel/drivers/block/drbd/drbd_req.c
diff options
context:
space:
mode:
Diffstat (limited to 'kernel/drivers/block/drbd/drbd_req.c')
-rw-r--r--kernel/drivers/block/drbd/drbd_req.c1638
1 files changed, 1638 insertions, 0 deletions
diff --git a/kernel/drivers/block/drbd/drbd_req.c b/kernel/drivers/block/drbd/drbd_req.c
new file mode 100644
index 000000000..3907202fb
--- /dev/null
+++ b/kernel/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);
+}