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OpenCloudOS-Kernel/drivers/block/drbd/drbd_req.c

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// SPDX-License-Identifier: GPL-2.0-or-later
/*
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>.
*/
#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)
{
struct request_queue *q = device->rq_queue;
generic_start_io_acct(q, bio_op(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)
{
struct request_queue *q = device->rq_queue;
generic_end_io_acct(q, bio_op(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)
| (bio_op(bio_src) == REQ_OP_WRITE_SAME ? RQ_WSAME : 0)
| (bio_op(bio_src) == REQ_OP_WRITE_ZEROES ? RQ_ZEROES : 0)
| (bio_op(bio_src) == REQ_OP_DISCARD ? RQ_UNMAP : 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)
{
if (unlikely(m->error))
m->bio->bi_status = errno_to_blk_status(m->error);
bio_endio(m->bio);
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 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;
}
/*
* 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 (op_is_write(bio_op(req->master_bio)) &&
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.
*
* read-ahead may fail, and will not be retried.
*
* WRITE should have used all available paths already.
*/
if (!ok &&
bio_op(req->master_bio) == REQ_OP_READ &&
!(req->master_bio->bi_opf & REQ_RAHEAD) &&
!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 void 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 (!put)
return;
if (!atomic_sub_and_test(put, &req->completion_ref))
return;
drbd_req_complete(req, m);
/* local completion may still come in later,
* we need to keep the req object around. */
if (req->rq_state & RQ_LOCAL_ABORTED)
return;
if (req->rq_state & RQ_POSTPONED) {
/* don't destroy the req object just yet,
* but queue it for retry */
drbd_restart_request(req);
return;
}
kref_put(&req->kref, drbd_req_destroy);
}
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;
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 */
kref_get(&req->kref);
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 ack_receiver 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 (req->rq_state & 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);
++c_put;
}
if ((s & RQ_LOCAL_PENDING) && (clear & RQ_LOCAL_PENDING)) {
if (req->rq_state & RQ_LOCAL_ABORTED)
kref_put(&req->kref, drbd_req_destroy);
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)
kref_put(&req->kref, drbd_req_destroy);
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 we made progress, retry conflicting peer requests, if any. */
if (req->i.waiting)
wake_up(&device->misc_wait);
drbd_req_put_completion_ref(req, m, c_put);
kref_put(&req->kref, 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 read-ahead, 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_OP_DISCARD. */
mod_rq_state(req, m, RQ_LOCAL_PENDING, RQ_LOCAL_COMPLETED);
break;
case QUEUE_FOR_NET_READ:
/* READ, 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;
for (;;) {
drbd_for_each_overlap(i, &device->write_requests, sector, size) {
/* Ignore, if already completed to upper layers. */
if (i->completed)
continue;
/* Handle the first found overlap. After the schedule
* we have to restart the tree walk. */
break;
}
if (!i) /* if any */
break;
/* Indicate to wake up device->misc_wait on progress. */
prepare_to_wait(&device->misc_wait, &wait, TASK_UNINTERRUPTIBLE);
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 */
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;
}
bool drbd_should_do_remote(union drbd_dev_state s)
{
return s.pdsk == D_UP_TO_DATE ||
(s.pdsk >= D_INCONSISTENT &&
s.conn >= C_WF_BITMAP_T &&
s.conn < C_AHEAD);
/* Before proto 96 that was >= CONNECTED instead of >= C_WF_BITMAP_T.
That is equivalent since before 96 IO was frozen in the C_WF_BITMAP*
states. */
}
static bool drbd_should_send_out_of_sync(union drbd_dev_state s)
{
return s.conn == C_AHEAD || s.conn == C_WF_BITMAP_S;
/* pdsk = D_INCONSISTENT as a consequence. Protocol 96 check not necessary
since we enter state C_AHEAD only if proto >= 96 */
}
/* 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_opf & REQ_PREFLUSH);
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_process_discard_or_zeroes_req(struct drbd_request *req, int flags)
{
int err = drbd_issue_discard_or_zero_out(req->device,
req->i.sector, req->i.size >> 9, flags);
if (err)
req->private_bio->bi_status = BLK_STS_IOERR;
bio_endio(req->private_bio);
}
static void
drbd_submit_req_private_bio(struct drbd_request *req)
{
struct drbd_device *device = req->device;
struct bio *bio = req->private_bio;
unsigned int type;
if (bio_op(bio) != REQ_OP_READ)
type = DRBD_FAULT_DT_WR;
else if (bio->bi_opf & REQ_RAHEAD)
type = DRBD_FAULT_DT_RA;
else
type = DRBD_FAULT_DT_RD;
bio_set_dev(bio, 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)) {
if (drbd_insert_fault(device, type))
bio_io_error(bio);
else if (bio_op(bio) == REQ_OP_WRITE_ZEROES)
drbd_process_discard_or_zeroes_req(req, EE_ZEROOUT |
((bio->bi_opf & REQ_NOUNMAP) ? 0 : EE_TRIM));
else if (bio_op(bio) == REQ_OP_DISCARD)
drbd_process_discard_or_zeroes_req(req, EE_TRIM);
else
generic_make_request(bio);
put_ldev(device);
} else
bio_io_error(bio);
}
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->bi_status = BLK_STS_RESOURCE;
bio_endio(bio);
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);
/* process discards always from our submitter thread */
if (bio_op(bio) == REQ_OP_WRITE_ZEROES ||
bio_op(bio) == REQ_OP_DISCARD)
goto queue_for_submitter_thread;
if (rw == WRITE && req->private_bio && req->i.size
&& !test_bit(AL_SUSPENDED, &device->flags)) {
if (!drbd_al_begin_io_fastpath(device, &req->i))
goto queue_for_submitter_thread;
req->rq_state |= RQ_IN_ACT_LOG;
req->in_actlog_jif = jiffies;
}
return req;
queue_for_submitter_thread:
atomic_inc(&device->ap_actlog_cnt);
drbd_queue_write(device, req);
return NULL;
}
/* Require at least one path to current data.
* We don't want to allow writes on C_STANDALONE D_INCONSISTENT:
* We would not allow to read what was written,
* we would not have bumped the data generation uuids,
* we would cause data divergence for all the wrong reasons.
*
* If we don't see at least one D_UP_TO_DATE, we will fail this request,
* which either returns EIO, or, if OND_SUSPEND_IO is set, suspends IO,
* and queues for retry later.
*/
static bool may_do_writes(struct drbd_device *device)
{
const union drbd_dev_state s = device->state;
return s.disk == D_UP_TO_DATE || s.pdsk == D_UP_TO_DATE;
}
struct drbd_plug_cb {
struct blk_plug_cb cb;
struct drbd_request *most_recent_req;
/* do we need more? */
};
static void drbd_unplug(struct blk_plug_cb *cb, bool from_schedule)
{
struct drbd_plug_cb *plug = container_of(cb, struct drbd_plug_cb, cb);
struct drbd_resource *resource = plug->cb.data;
struct drbd_request *req = plug->most_recent_req;
kfree(cb);
if (!req)
return;
spin_lock_irq(&resource->req_lock);
/* In case the sender did not process it yet, raise the flag to
* have it followed with P_UNPLUG_REMOTE just after. */
req->rq_state |= RQ_UNPLUG;
/* but also queue a generic unplug */
drbd_queue_unplug(req->device);
kref_put(&req->kref, drbd_req_destroy);
spin_unlock_irq(&resource->req_lock);
}
static struct drbd_plug_cb* drbd_check_plugged(struct drbd_resource *resource)
{
/* A lot of text to say
* return (struct drbd_plug_cb*)blk_check_plugged(); */
struct drbd_plug_cb *plug;
struct blk_plug_cb *cb = blk_check_plugged(drbd_unplug, resource, sizeof(*plug));
if (cb)
plug = container_of(cb, struct drbd_plug_cb, cb);
else
plug = NULL;
return plug;
}
static void drbd_update_plug(struct drbd_plug_cb *plug, struct drbd_request *req)
{
struct drbd_request *tmp = plug->most_recent_req;
/* Will be sent to some peer.
* Remember to tag it with UNPLUG_REMOTE on unplug */
kref_get(&req->kref);
plug->most_recent_req = req;
if (tmp)
kref_put(&tmp->kref, drbd_req_destroy);
}
static void drbd_send_and_submit(struct drbd_device *device, struct drbd_request *req)
{
struct drbd_resource *resource = device->resource;
const int rw = bio_data_dir(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 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 (req->private_bio && !may_do_writes(device)) {
bio_put(req->private_bio);
req->private_bio = NULL;
put_ldev(device);
goto nodata;
}
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 (no_remote == false) {
struct drbd_plug_cb *plug = drbd_check_plugged(resource);
if (plug)
drbd_update_plug(plug, req);
}
/* 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 */
req->pre_submit_jif = jiffies;
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:
drbd_req_put_completion_ref(req, &m, 1);
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 blk_plug plug;
struct drbd_request *req, *tmp;
blk_start_plug(&plug);
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);
}
blk_finish_plug(&plug);
}
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;
int wake = 0;
int err;
spin_lock_irq(&device->al_lock);
while ((req = list_first_entry_or_null(incoming, struct drbd_request, 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);
}
static void send_and_submit_pending(struct drbd_device *device, struct list_head *pending)
{
struct blk_plug plug;
struct drbd_request *req;
blk_start_plug(&plug);
while ((req = list_first_entry_or_null(pending, struct drbd_request, 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);
}
blk_finish_plug(&plug);
}
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);
}
}
blk_qc_t drbd_make_request(struct request_queue *q, struct bio *bio)
{
struct drbd_device *device = (struct drbd_device *) q->queuedata;
unsigned long start_jif;
blk_queue_split(q, &bio);
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);
return BLK_QC_T_NONE;
}
static bool net_timeout_reached(struct drbd_request *net_req,
struct drbd_connection *connection,
unsigned long now, unsigned long ent,
unsigned int ko_count, unsigned int timeout)
{
struct drbd_device *device = net_req->device;
if (!time_after(now, net_req->pre_send_jif + ent))
return false;
if (time_in_range(now, connection->last_reconnect_jif, connection->last_reconnect_jif + ent))
return false;
if (net_req->rq_state & RQ_NET_PENDING) {
drbd_warn(device, "Remote failed to finish a request within %ums > ko-count (%u) * timeout (%u * 0.1s)\n",
jiffies_to_msecs(now - net_req->pre_send_jif), ko_count, timeout);
return true;
}
/* We received an ACK already (or are using protocol A),
* but are waiting for the epoch closing barrier ack.
* Check if we sent the barrier already. We should not blame the peer
* for being unresponsive, if we did not even ask it yet. */
if (net_req->epoch == connection->send.current_epoch_nr) {
drbd_warn(device,
"We did not send a P_BARRIER for %ums > ko-count (%u) * timeout (%u * 0.1s); drbd kernel thread blocked?\n",
jiffies_to_msecs(now - net_req->pre_send_jif), ko_count, timeout);
return false;
}
/* Worst case: we may have been blocked for whatever reason, then
* suddenly are able to send a lot of requests (and epoch separating
* barriers) in quick succession.
* The timestamp of the net_req may be much too old and not correspond
* to the sending time of the relevant unack'ed barrier packet, so
* would trigger a spurious timeout. The latest barrier packet may
* have a too recent timestamp to trigger the timeout, potentially miss
* a timeout. Right now we don't have a place to conveniently store
* these timestamps.
* But in this particular situation, the application requests are still
* completed to upper layers, DRBD should still "feel" responsive.
* No need yet to kill this connection, it may still recover.
* If not, eventually we will have queued enough into the network for
* us to block. From that point of view, the timestamp of the last sent
* barrier packet is relevant enough.
*/
if (time_after(now, connection->send.last_sent_barrier_jif + ent)) {
drbd_warn(device, "Remote failed to answer a P_BARRIER (sent at %lu jif; now=%lu jif) within %ums > ko-count (%u) * timeout (%u * 0.1s)\n",
connection->send.last_sent_barrier_jif, now,
jiffies_to_msecs(now - connection->send.last_sent_barrier_jif), ko_count, timeout);
return true;
}
return false;
}
/* A request is considered timed out, if
* - we have some effective timeout from the configuration,
* with some 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.
*/
void request_timer_fn(struct timer_list *t)
{
struct drbd_device *device = from_timer(device, t, request_timer);
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;
unsigned int ko_count = 0, timeout = 0;
rcu_read_lock();
nc = rcu_dereference(connection->net_conf);
if (nc && device->state.conn >= C_WF_REPORT_PARAMS) {
ko_count = nc->ko_count;
timeout = nc->timeout;
}
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();
ent = timeout * HZ/10 * ko_count;
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);
/* maybe the oldest request waiting for the peer is in fact still
* blocking in tcp sendmsg. That's ok, though, that's handled via the
* socket send timeout, requesting a ping, and bumping ko-count in
* we_should_drop_the_connection().
*/
/* check the oldest request we did successfully sent,
* but which is still waiting for an ACK. */
req_peer = connection->req_ack_pending;
/* if we don't have such request (e.g. protocoll A)
* check the oldest requests which is still waiting on its epoch
* closing barrier ack. */
if (!req_peer)
req_peer = connection->req_not_net_done;
/* 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;
if (ent && req_peer && net_timeout_reached(req_peer, connection, now, ent, ko_count, timeout))
_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);
}
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