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linux/drivers/block/drbd/drbd_req.c

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/*
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_conf *mdev, sector_t sector, int size);
/* Update disk stats at start of I/O request */
static void _drbd_start_io_acct(struct drbd_conf *mdev, struct drbd_request *req, struct bio *bio)
{
const int rw = bio_data_dir(bio);
int cpu;
cpu = part_stat_lock();
part_round_stats(cpu, &mdev->vdisk->part0);
part_stat_inc(cpu, &mdev->vdisk->part0, ios[rw]);
part_stat_add(cpu, &mdev->vdisk->part0, sectors[rw], bio_sectors(bio));
(void) cpu; /* The macro invocations above want the cpu argument, I do not like
the compiler warning about cpu only assigned but never used... */
part_inc_in_flight(&mdev->vdisk->part0, rw);
part_stat_unlock();
}
/* Update disk stats when completing request upwards */
static void _drbd_end_io_acct(struct drbd_conf *mdev, struct drbd_request *req)
{
int rw = bio_data_dir(req->master_bio);
unsigned long duration = jiffies - req->start_time;
int cpu;
cpu = part_stat_lock();
part_stat_add(cpu, &mdev->vdisk->part0, ticks[rw], duration);
part_round_stats(cpu, &mdev->vdisk->part0);
part_dec_in_flight(&mdev->vdisk->part0, rw);
part_stat_unlock();
}
static struct drbd_request *drbd_req_new(struct drbd_conf *mdev,
struct bio *bio_src)
{
struct drbd_request *req;
req = mempool_alloc(drbd_request_mempool, GFP_NOIO);
if (!req)
return NULL;
drbd_req_make_private_bio(req, bio_src);
req->rq_state = bio_data_dir(bio_src) == WRITE ? RQ_WRITE : 0;
req->w.mdev = mdev;
req->master_bio = bio_src;
req->epoch = 0;
drbd_clear_interval(&req->i);
req->i.sector = bio_src->bi_sector;
req->i.size = bio_src->bi_size;
req->i.local = true;
req->i.waiting = false;
INIT_LIST_HEAD(&req->tl_requests);
INIT_LIST_HEAD(&req->w.list);
return req;
}
static void drbd_req_free(struct drbd_request *req)
{
mempool_free(req, drbd_request_mempool);
}
/* rw is bio_data_dir(), only READ or WRITE */
static void _req_is_done(struct drbd_conf *mdev, struct drbd_request *req, const int rw)
{
const unsigned long s = req->rq_state;
/* remove it from the transfer log.
* well, only if it had been there in the first
* place... if it had not (local only or conflicting
* and never sent), it should still be "empty" as
* initialized in drbd_req_new(), so we can list_del() it
* here unconditionally */
list_del_init(&req->tl_requests);
/* if it was a write, we may have to set the corresponding
* bit(s) out-of-sync first. If it had a local part, we need to
* release the reference to the activity log. */
if (rw == WRITE) {
/* Set out-of-sync unless both OK flags are set
* (local only or remote failed).
* Other places where we set out-of-sync:
* READ with local io-error */
if (!(s & RQ_NET_OK) || !(s & RQ_LOCAL_OK))
drbd_set_out_of_sync(mdev, req->i.sector, req->i.size);
if ((s & RQ_NET_OK) && (s & RQ_LOCAL_OK) && (s & RQ_NET_SIS))
drbd_set_in_sync(mdev, req->i.sector, req->i.size);
/* one might be tempted to move the drbd_al_complete_io
* to the local io completion callback drbd_request_endio.
* but, if this was a mirror write, we may only
* drbd_al_complete_io after this is RQ_NET_DONE,
* otherwise the extent could be dropped from the al
* before it has actually been written on the peer.
* if we crash before our peer knows about the request,
* but after the extent has been dropped from the al,
* we would forget to resync the corresponding extent.
*/
if (s & RQ_LOCAL_MASK) {
if (get_ldev_if_state(mdev, D_FAILED)) {
if (s & RQ_IN_ACT_LOG)
drbd_al_complete_io(mdev, &req->i);
put_ldev(mdev);
} else if (__ratelimit(&drbd_ratelimit_state)) {
dev_warn(DEV, "Should have called drbd_al_complete_io(, %llu, %u), "
"but my Disk seems to have failed :(\n",
(unsigned long long) req->i.sector, req->i.size);
}
}
}
if (s & RQ_POSTPONED)
drbd_restart_write(req);
else
drbd_req_free(req);
}
static void queue_barrier(struct drbd_conf *mdev)
{
struct drbd_tl_epoch *b;
struct drbd_tconn *tconn = mdev->tconn;
/* We are within the req_lock. Once we queued the barrier for sending,
* we set the CREATE_BARRIER bit. It is cleared as soon as a new
* barrier/epoch object is added. This is the only place this bit is
* set. It indicates that the barrier for this epoch is already queued,
* and no new epoch has been created yet. */
if (test_bit(CREATE_BARRIER, &tconn->flags))
return;
b = tconn->newest_tle;
b->w.cb = w_send_barrier;
b->w.mdev = mdev;
/* inc_ap_pending done here, so we won't
* get imbalanced on connection loss.
* dec_ap_pending will be done in got_BarrierAck
* or (on connection loss) in tl_clear. */
inc_ap_pending(mdev);
drbd_queue_work(&tconn->data.work, &b->w);
set_bit(CREATE_BARRIER, &tconn->flags);
}
static void _about_to_complete_local_write(struct drbd_conf *mdev,
struct drbd_request *req)
{
const unsigned long s = req->rq_state;
/* Before we can signal completion to the upper layers,
* we may need to close the current epoch.
* We can skip this, if this request has not even been sent, because we
* did not have a fully established connection yet/anymore, during
* bitmap exchange, or while we are C_AHEAD due to congestion policy.
*/
if (mdev->state.conn >= C_CONNECTED &&
(s & RQ_NET_SENT) != 0 &&
req->epoch == mdev->tconn->newest_tle->br_number)
queue_barrier(mdev);
}
void complete_master_bio(struct drbd_conf *mdev,
struct bio_and_error *m)
{
bio_endio(m->bio, m->error);
dec_ap_bio(mdev);
}
static void drbd_remove_request_interval(struct rb_root *root,
struct drbd_request *req)
{
struct drbd_conf *mdev = req->w.mdev;
struct drbd_interval *i = &req->i;
drbd_remove_interval(root, i);
/* Wake up any processes waiting for this request to complete. */
if (i->waiting)
wake_up(&mdev->misc_wait);
}
static void maybe_wakeup_conflicting_requests(struct drbd_request *req)
{
const unsigned long s = req->rq_state;
if (s & RQ_LOCAL_PENDING && !(s & RQ_LOCAL_ABORTED))
return;
if (req->i.waiting)
/* Retry all conflicting peer requests. */
wake_up(&req->w.mdev->misc_wait);
}
static
void req_may_be_done(struct drbd_request *req)
{
const unsigned long s = req->rq_state;
struct drbd_conf *mdev = req->w.mdev;
int rw = req->rq_state & RQ_WRITE ? WRITE : READ;
/* req->master_bio still present means: Not yet completed.
*
* Unless this is RQ_POSTPONED, which will cause _req_is_done() to
* queue it on the retry workqueue instead of destroying it.
*/
if (req->master_bio && !(s & RQ_POSTPONED))
return;
/* Local still pending, even though master_bio is already completed?
* may happen for RQ_LOCAL_ABORTED requests. */
if (s & RQ_LOCAL_PENDING)
return;
if ((s & RQ_NET_MASK) == 0 || (s & RQ_NET_DONE)) {
/* this is disconnected (local only) operation,
* or protocol A, B, or C P_BARRIER_ACK,
* or killed from the transfer log due to connection loss. */
_req_is_done(mdev, req, rw);
}
/* else: network part and not DONE yet. that is
* protocol A, B, or C, barrier ack still pending... */
}
/* 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 req_may_be_completed(struct drbd_request *req, struct bio_and_error *m)
{
const unsigned long s = req->rq_state;
struct drbd_conf *mdev = req->w.mdev;
/* we must not complete the master bio, while it is
* still being processed by _drbd_send_zc_bio (drbd_send_dblock)
* not yet acknowledged by the peer
* not yet completed by the local io subsystem
* these flags may get cleared in any order by
* the worker,
* the receiver,
* the bio_endio completion callbacks.
*/
if (s & RQ_LOCAL_PENDING && !(s & RQ_LOCAL_ABORTED))
return;
if (s & RQ_NET_QUEUED)
return;
if (s & RQ_NET_PENDING)
return;
if (req->master_bio) {
int rw = bio_rw(req->master_bio);
/* this is DATA_RECEIVED (remote read)
* or protocol C P_WRITE_ACK
* or protocol B P_RECV_ACK
* or protocol A "HANDED_OVER_TO_NETWORK" (SendAck)
* or canceled or failed,
* or killed from the transfer log due to connection loss.
*/
/*
* figure out whether to report success or failure.
*
* report success when at least one of the operations succeeded.
* or, to put the other way,
* only report failure, when both operations failed.
*
* what to do about the failures is handled elsewhere.
* what we need to do here is just: complete the master_bio.
*
* local completion error, if any, has been stored as ERR_PTR
* in private_bio within drbd_request_endio.
*/
int ok = (s & RQ_LOCAL_OK) || (s & RQ_NET_OK);
int error = PTR_ERR(req->private_bio);
/* remove the request from the conflict detection
* respective block_id verification hash */
if (!drbd_interval_empty(&req->i)) {
struct rb_root *root;
if (rw == WRITE)
root = &mdev->write_requests;
else
root = &mdev->read_requests;
drbd_remove_request_interval(root, req);
} else if (!(s & RQ_POSTPONED))
D_ASSERT((s & (RQ_NET_MASK & ~RQ_NET_DONE)) == 0);
/* for writes we need to do some extra housekeeping */
if (rw == WRITE)
_about_to_complete_local_write(mdev, req);
/* Update disk stats */
_drbd_end_io_acct(mdev, req);
/* if 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.
* READA may fail.
* WRITE should have used all available paths already.
*/
if (!ok && rw == READ)
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;
} else {
/* Assert that this will be _req_is_done()
* with this very invokation. */
/* FIXME:
* what about (RQ_LOCAL_PENDING | RQ_LOCAL_ABORTED)?
*/
D_ASSERT(!(s & RQ_LOCAL_PENDING));
D_ASSERT(s & RQ_NET_DONE);
}
}
req_may_be_done(req);
}
static void req_may_be_completed_not_susp(struct drbd_request *req, struct bio_and_error *m)
{
struct drbd_conf *mdev = req->w.mdev;
if (!drbd_suspended(mdev))
req_may_be_completed(req, m);
}
/* obviously this could be coded as many single functions
* instead of one huge switch,
* or by putting the code directly in the respective locations
* (as it has been before).
*
* but having it this way
* enforces that it is all in this one place, where it is easier to audit,
* it makes it obvious that whatever "event" "happens" to a request should
* happen "atomically" within the req_lock,
* and it enforces that we have to think in a very structured manner
* about the "events" that may happen to a request during its life time ...
*/
int __req_mod(struct drbd_request *req, enum drbd_req_event what,
struct bio_and_error *m)
{
struct drbd_conf *mdev = req->w.mdev;
struct net_conf *nc;
int p, rv = 0;
if (m)
m->bio = NULL;
switch (what) {
default:
dev_err(DEV, "LOGIC BUG in %s:%u\n", __FILE__ , __LINE__);
break;
/* does not happen...
* initialization done in drbd_req_new
case CREATED:
break;
*/
case TO_BE_SENT: /* via network */
/* reached via __drbd_make_request
* and from w_read_retry_remote */
D_ASSERT(!(req->rq_state & RQ_NET_MASK));
req->rq_state |= RQ_NET_PENDING;
rcu_read_lock();
nc = rcu_dereference(mdev->tconn->net_conf);
p = nc->wire_protocol;
rcu_read_unlock();
req->rq_state |=
p == DRBD_PROT_C ? RQ_EXP_WRITE_ACK :
p == DRBD_PROT_B ? RQ_EXP_RECEIVE_ACK : 0;
inc_ap_pending(mdev);
break;
case TO_BE_SUBMITTED: /* locally */
/* reached via __drbd_make_request */
D_ASSERT(!(req->rq_state & RQ_LOCAL_MASK));
req->rq_state |= RQ_LOCAL_PENDING;
break;
case COMPLETED_OK:
if (req->rq_state & RQ_WRITE)
mdev->writ_cnt += req->i.size >> 9;
else
mdev->read_cnt += req->i.size >> 9;
req->rq_state |= (RQ_LOCAL_COMPLETED|RQ_LOCAL_OK);
req->rq_state &= ~RQ_LOCAL_PENDING;
maybe_wakeup_conflicting_requests(req);
req_may_be_completed_not_susp(req, m);
break;
case ABORT_DISK_IO:
req->rq_state |= RQ_LOCAL_ABORTED;
req_may_be_completed_not_susp(req, m);
break;
case WRITE_COMPLETED_WITH_ERROR:
req->rq_state |= RQ_LOCAL_COMPLETED;
req->rq_state &= ~RQ_LOCAL_PENDING;
__drbd_chk_io_error(mdev, false);
maybe_wakeup_conflicting_requests(req);
req_may_be_completed_not_susp(req, m);
break;
case READ_AHEAD_COMPLETED_WITH_ERROR:
/* it is legal to fail READA */
req->rq_state |= RQ_LOCAL_COMPLETED;
req->rq_state &= ~RQ_LOCAL_PENDING;
req_may_be_completed_not_susp(req, m);
break;
case READ_COMPLETED_WITH_ERROR:
drbd_set_out_of_sync(mdev, req->i.sector, req->i.size);
req->rq_state |= RQ_LOCAL_COMPLETED;
req->rq_state &= ~RQ_LOCAL_PENDING;
D_ASSERT(!(req->rq_state & RQ_NET_MASK));
__drbd_chk_io_error(mdev, false);
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
* req_may_be_completed() */
D_ASSERT(drbd_interval_empty(&req->i));
drbd_insert_interval(&mdev->read_requests, &req->i);
set_bit(UNPLUG_REMOTE, &mdev->flags);
D_ASSERT(req->rq_state & RQ_NET_PENDING);
D_ASSERT((req->rq_state & RQ_LOCAL_MASK) == 0);
req->rq_state |= RQ_NET_QUEUED;
req->w.cb = w_send_read_req;
drbd_queue_work(&mdev->tconn->data.work, &req->w);
break;
case QUEUE_FOR_NET_WRITE:
/* assert something? */
/* from __drbd_make_request only */
/* Corresponding drbd_remove_request_interval is in
* req_may_be_completed() */
D_ASSERT(drbd_interval_empty(&req->i));
drbd_insert_interval(&mdev->write_requests, &req->i);
/* NOTE
* In case the req ended up on the transfer log before being
* queued on the worker, it could lead to this request being
* missed during cleanup after connection loss.
* So we have to do both operations here,
* within the same lock that protects the transfer log.
*
* _req_add_to_epoch(req); this has to be after the
* _maybe_start_new_epoch(req); which happened in
* __drbd_make_request, because we now may set the bit
* again ourselves to close the current epoch.
*
* Add req to the (now) current epoch (barrier). */
/* otherwise we may lose an unplug, which may cause some remote
* io-scheduler timeout to expire, increasing maximum latency,
* hurting performance. */
set_bit(UNPLUG_REMOTE, &mdev->flags);
/* see __drbd_make_request,
* just after it grabs the req_lock */
D_ASSERT(test_bit(CREATE_BARRIER, &mdev->tconn->flags) == 0);
req->epoch = mdev->tconn->newest_tle->br_number;
/* increment size of current epoch */
mdev->tconn->newest_tle->n_writes++;
/* queue work item to send data */
D_ASSERT(req->rq_state & RQ_NET_PENDING);
req->rq_state |= RQ_NET_QUEUED;
req->w.cb = w_send_dblock;
drbd_queue_work(&mdev->tconn->data.work, &req->w);
/* close the epoch, in case it outgrew the limit */
rcu_read_lock();
nc = rcu_dereference(mdev->tconn->net_conf);
p = nc->max_epoch_size;
rcu_read_unlock();
if (mdev->tconn->newest_tle->n_writes >= p)
queue_barrier(mdev);
break;
case QUEUE_FOR_SEND_OOS:
req->rq_state |= RQ_NET_QUEUED;
req->w.cb = w_send_out_of_sync;
drbd_queue_work(&mdev->tconn->data.work, &req->w);
break;
case 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 */
req->rq_state &= ~RQ_NET_QUEUED;
/* if we did it right, tl_clear should be scheduled only after
* this, so this should not be necessary! */
req_may_be_completed_not_susp(req, m);
break;
case HANDED_OVER_TO_NETWORK:
/* assert something? */
if (bio_data_dir(req->master_bio) == WRITE)
atomic_add(req->i.size >> 9, &mdev->ap_in_flight);
if (bio_data_dir(req->master_bio) == WRITE &&
!(req->rq_state & (RQ_EXP_RECEIVE_ACK | RQ_EXP_WRITE_ACK))) {
/* this is what is dangerous about protocol A:
* pretend it was successfully written on the peer. */
if (req->rq_state & RQ_NET_PENDING) {
dec_ap_pending(mdev);
req->rq_state &= ~RQ_NET_PENDING;
req->rq_state |= RQ_NET_OK;
} /* else: neg-ack was faster... */
/* it is still not yet RQ_NET_DONE until the
* corresponding epoch barrier got acked as well,
* so we know what to dirty on connection loss */
}
req->rq_state &= ~RQ_NET_QUEUED;
req->rq_state |= RQ_NET_SENT;
req_may_be_completed_not_susp(req, m);
break;
case OOS_HANDED_TO_NETWORK:
/* Was not set PENDING, no longer QUEUED, so is now DONE
* as far as this connection is concerned. */
req->rq_state &= ~RQ_NET_QUEUED;
req->rq_state |= RQ_NET_DONE;
req_may_be_completed_not_susp(req, m);
break;
case CONNECTION_LOST_WHILE_PENDING:
/* transfer log cleanup after connection loss */
/* assert something? */
if (req->rq_state & RQ_NET_PENDING)
dec_ap_pending(mdev);
p = !(req->rq_state & RQ_WRITE) && req->rq_state & RQ_NET_PENDING;
req->rq_state &= ~(RQ_NET_OK|RQ_NET_PENDING);
req->rq_state |= RQ_NET_DONE;
if (req->rq_state & RQ_NET_SENT && req->rq_state & RQ_WRITE)
atomic_sub(req->i.size >> 9, &mdev->ap_in_flight);
req_may_be_completed(req, m); /* Allowed while state.susp */
break;
case DISCARD_WRITE:
/* for discarded conflicting writes of multiple primaries,
* there is no need to keep anything in the tl, potential
* node crashes are covered by the activity log. */
req->rq_state |= RQ_NET_DONE;
/* fall through */
case WRITE_ACKED_BY_PEER_AND_SIS:
case WRITE_ACKED_BY_PEER:
if (what == WRITE_ACKED_BY_PEER_AND_SIS)
req->rq_state |= RQ_NET_SIS;
D_ASSERT(req->rq_state & RQ_EXP_WRITE_ACK);
/* protocol C; successfully written on peer.
* 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(req->rq_state & RQ_EXP_RECEIVE_ACK);
/* protocol B; pretends to be successfully written on peer.
* see also notes above in HANDED_OVER_TO_NETWORK about
* protocol != C */
ack_common:
req->rq_state |= RQ_NET_OK;
D_ASSERT(req->rq_state & RQ_NET_PENDING);
dec_ap_pending(mdev);
atomic_sub(req->i.size >> 9, &mdev->ap_in_flight);
req->rq_state &= ~RQ_NET_PENDING;
maybe_wakeup_conflicting_requests(req);
req_may_be_completed_not_susp(req, m);
break;
case POSTPONE_WRITE:
D_ASSERT(req->rq_state & RQ_EXP_WRITE_ACK);
/* If this node has already detected the write conflict, the
* worker will be waiting on misc_wait. Wake it up once this
* request has completed locally.
*/
D_ASSERT(req->rq_state & RQ_NET_PENDING);
req->rq_state |= RQ_POSTPONED;
maybe_wakeup_conflicting_requests(req);
req_may_be_completed_not_susp(req, m);
break;
case NEG_ACKED:
/* assert something? */
if (req->rq_state & RQ_NET_PENDING) {
dec_ap_pending(mdev);
if (req->rq_state & RQ_WRITE)
atomic_sub(req->i.size >> 9, &mdev->ap_in_flight);
}
req->rq_state &= ~(RQ_NET_OK|RQ_NET_PENDING);
req->rq_state |= RQ_NET_DONE;
maybe_wakeup_conflicting_requests(req);
req_may_be_completed_not_susp(req, m);
/* else: done by HANDED_OVER_TO_NETWORK */
break;
case FAIL_FROZEN_DISK_IO:
if (!(req->rq_state & RQ_LOCAL_COMPLETED))
break;
req_may_be_completed(req, m); /* Allowed while state.susp */
break;
case RESTART_FROZEN_DISK_IO:
if (!(req->rq_state & RQ_LOCAL_COMPLETED))
break;
req->rq_state &= ~RQ_LOCAL_COMPLETED;
rv = MR_READ;
if (bio_data_dir(req->master_bio) == WRITE)
rv = MR_WRITE;
get_ldev(mdev);
req->w.cb = w_restart_disk_io;
drbd_queue_work(&mdev->tconn->data.work, &req->w);
break;
case RESEND:
/* If RQ_NET_OK is already set, we got a P_WRITE_ACK or P_RECV_ACK
before the connection loss (B&C only); only P_BARRIER_ACK was missing.
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)) {
if (req->w.cb) {
drbd_queue_work(&mdev->tconn->data.work, &req->w);
rv = req->rq_state & RQ_WRITE ? MR_WRITE : MR_READ;
}
break;
}
/* else, fall through to BARRIER_ACKED */
case BARRIER_ACKED:
if (!(req->rq_state & RQ_WRITE))
break;
if (req->rq_state & RQ_NET_PENDING) {
/* barrier came in before all requests were acked.
* this is bad, because if the connection is lost now,
* we won't be able to clean them up... */
dev_err(DEV, "FIXME (BARRIER_ACKED but pending)\n");
list_move(&req->tl_requests, &mdev->tconn->out_of_sequence_requests);
}
if ((req->rq_state & RQ_NET_MASK) != 0) {
req->rq_state |= RQ_NET_DONE;
if (!(req->rq_state & (RQ_EXP_RECEIVE_ACK | RQ_EXP_WRITE_ACK)))
atomic_sub(req->i.size>>9, &mdev->ap_in_flight);
}
req_may_be_done(req); /* Allowed while state.susp */
break;
case DATA_RECEIVED:
D_ASSERT(req->rq_state & RQ_NET_PENDING);
dec_ap_pending(mdev);
req->rq_state &= ~RQ_NET_PENDING;
req->rq_state |= (RQ_NET_OK|RQ_NET_DONE);
req_may_be_completed_not_susp(req, m);
break;
};
return rv;
}
/* we may do a local read if:
* - we are consistent (of course),
* - or we are generally inconsistent,
* BUT we are still/already IN SYNC for this area.
* since size may be bigger than BM_BLOCK_SIZE,
* we may need to check several bits.
*/
static bool drbd_may_do_local_read(struct drbd_conf *mdev, sector_t sector, int size)
{
unsigned long sbnr, ebnr;
sector_t esector, nr_sectors;
if (mdev->state.disk == D_UP_TO_DATE)
return true;
if (mdev->state.disk != D_INCONSISTENT)
return false;
esector = sector + (size >> 9) - 1;
nr_sectors = drbd_get_capacity(mdev->this_bdev);
D_ASSERT(sector < nr_sectors);
D_ASSERT(esector < nr_sectors);
sbnr = BM_SECT_TO_BIT(sector);
ebnr = BM_SECT_TO_BIT(esector);
return drbd_bm_count_bits(mdev, sbnr, ebnr) == 0;
}
static bool remote_due_to_read_balancing(struct drbd_conf *mdev, sector_t sector)
{
enum drbd_read_balancing rbm;
struct backing_dev_info *bdi;
int stripe_shift;
if (mdev->state.pdsk < D_UP_TO_DATE)
return false;
rcu_read_lock();
rbm = rcu_dereference(mdev->ldev->disk_conf)->read_balancing;
rcu_read_unlock();
switch (rbm) {
case RB_CONGESTED_REMOTE:
bdi = &mdev->ldev->backing_bdev->bd_disk->queue->backing_dev_info;
return bdi_read_congested(bdi);
case RB_LEAST_PENDING:
return atomic_read(&mdev->local_cnt) >
atomic_read(&mdev->ap_pending_cnt) + atomic_read(&mdev->rs_pending_cnt);
case RB_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, &mdev->flags);
case RB_PREFER_REMOTE:
return true;
case RB_PREFER_LOCAL:
default:
return false;
}
}
/*
* complete_conflicting_writes - wait for any conflicting write requests
*
* The write_requests tree contains all active write requests which we
* currently know about. Wait for any requests to complete which conflict with
* the new one.
*
* Only way out: remove the conflicting intervals from the tree.
*/
static void complete_conflicting_writes(struct drbd_request *req)
{
DEFINE_WAIT(wait);
struct drbd_conf *mdev = req->w.mdev;
struct drbd_interval *i;
sector_t sector = req->i.sector;
int size = req->i.size;
i = drbd_find_overlap(&mdev->write_requests, sector, size);
if (!i)
return;
for (;;) {
prepare_to_wait(&mdev->misc_wait, &wait, TASK_UNINTERRUPTIBLE);
i = drbd_find_overlap(&mdev->write_requests, sector, size);
if (!i)
break;
/* Indicate to wake up device->misc_wait on progress. */
i->waiting = true;
spin_unlock_irq(&mdev->tconn->req_lock);
schedule();
spin_lock_irq(&mdev->tconn->req_lock);
}
finish_wait(&mdev->misc_wait, &wait);
}
int __drbd_make_request(struct drbd_conf *mdev, struct bio *bio, unsigned long start_time)
{
const int rw = bio_rw(bio);
const int size = bio->bi_size;
const sector_t sector = bio->bi_sector;
struct drbd_tl_epoch *b = NULL;
struct drbd_request *req;
struct net_conf *nc;
int local, remote, send_oos = 0;
int err = 0;
int ret = 0;
union drbd_dev_state s;
/* allocate outside of all locks; */
req = drbd_req_new(mdev, bio);
if (!req) {
dec_ap_bio(mdev);
/* only pass the error to the upper layers.
* if user cannot handle io errors, that's not our business. */
dev_err(DEV, "could not kmalloc() req\n");
bio_endio(bio, -ENOMEM);
return 0;
}
req->start_time = start_time;
local = get_ldev(mdev);
if (!local) {
bio_put(req->private_bio); /* or we get a bio leak */
req->private_bio = NULL;
}
if (rw == WRITE) {
remote = 1;
} else {
/* READ || READA */
if (local) {
if (!drbd_may_do_local_read(mdev, sector, size) ||
remote_due_to_read_balancing(mdev, sector)) {
/* we could kick the syncer to
* sync this extent asap, wait for
* it, then continue locally.
* Or just issue the request remotely.
*/
local = 0;
bio_put(req->private_bio);
req->private_bio = NULL;
put_ldev(mdev);
}
}
remote = !local && mdev->state.pdsk >= D_UP_TO_DATE;
}
/* If we have a disk, but a READA request is mapped to remote,
* we are R_PRIMARY, D_INCONSISTENT, SyncTarget.
* Just fail that READA request right here.
*
* THINK: maybe fail all READA when not local?
* or make this configurable...
* if network is slow, READA won't do any good.
*/
if (rw == READA && mdev->state.disk >= D_INCONSISTENT && !local) {
err = -EWOULDBLOCK;
goto fail_and_free_req;
}
/* For WRITES going to the local disk, grab a reference on the target
* extent. This waits for any resync activity in the corresponding
* resync extent to finish, and, if necessary, pulls in the target
* extent into the activity log, which involves further disk io because
* of transactional on-disk meta data updates. */
if (rw == WRITE && local && !test_bit(AL_SUSPENDED, &mdev->flags)) {
req->rq_state |= RQ_IN_ACT_LOG;
drbd_al_begin_io(mdev, &req->i);
}
s = mdev->state;
remote = remote && drbd_should_do_remote(s);
send_oos = rw == WRITE && drbd_should_send_out_of_sync(s);
D_ASSERT(!(remote && send_oos));
if (!(local || remote) && !drbd_suspended(mdev)) {
if (__ratelimit(&drbd_ratelimit_state))
dev_err(DEV, "IO ERROR: neither local nor remote disk\n");
err = -EIO;
goto fail_free_complete;
}
/* For WRITE request, we have to make sure that we have an
* unused_spare_tle, in case we need to start a new epoch.
* I try to be smart and avoid to pre-allocate always "just in case",
* but there is a race between testing the bit and pointer outside the
* spinlock, and grabbing the spinlock.
* if we lost that race, we retry. */
if (rw == WRITE && (remote || send_oos) &&
mdev->tconn->unused_spare_tle == NULL &&
test_bit(CREATE_BARRIER, &mdev->tconn->flags)) {
allocate_barrier:
b = kmalloc(sizeof(struct drbd_tl_epoch), GFP_NOIO);
if (!b) {
dev_err(DEV, "Failed to alloc barrier.\n");
err = -ENOMEM;
goto fail_free_complete;
}
}
/* GOOD, everything prepared, grab the spin_lock */
spin_lock_irq(&mdev->tconn->req_lock);
if (rw == WRITE) {
/* 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);
}
if (drbd_suspended(mdev)) {
/* If we got suspended, use the retry mechanism in
drbd_make_request() to restart processing of this
bio. In the next call to drbd_make_request
we sleep in inc_ap_bio() */
ret = 1;
spin_unlock_irq(&mdev->tconn->req_lock);
goto fail_free_complete;
}
if (remote || send_oos) {
remote = drbd_should_do_remote(mdev->state);
send_oos = rw == WRITE && drbd_should_send_out_of_sync(mdev->state);
D_ASSERT(!(remote && send_oos));
if (!(remote || send_oos))
dev_warn(DEV, "lost connection while grabbing the req_lock!\n");
if (!(local || remote)) {
dev_err(DEV, "IO ERROR: neither local nor remote disk\n");
spin_unlock_irq(&mdev->tconn->req_lock);
err = -EIO;
goto fail_free_complete;
}
}
if (b && mdev->tconn->unused_spare_tle == NULL) {
mdev->tconn->unused_spare_tle = b;
b = NULL;
}
if (rw == WRITE && (remote || send_oos) &&
mdev->tconn->unused_spare_tle == NULL &&
test_bit(CREATE_BARRIER, &mdev->tconn->flags)) {
/* someone closed the current epoch
* while we were grabbing the spinlock */
spin_unlock_irq(&mdev->tconn->req_lock);
goto allocate_barrier;
}
/* Update disk stats */
_drbd_start_io_acct(mdev, req, bio);
/* _maybe_start_new_epoch(mdev);
* If we need to generate a write barrier packet, we have to add the
* new epoch (barrier) object, and queue the barrier packet for sending,
* and queue the req's data after it _within the same lock_, otherwise
* we have race conditions were the reorder domains could be mixed up.
*
* Even read requests may start a new epoch and queue the corresponding
* barrier packet. To get the write ordering right, we only have to
* make sure that, if this is a write request and it triggered a
* barrier packet, this request is queued within the same spinlock. */
if ((remote || send_oos) && mdev->tconn->unused_spare_tle &&
test_and_clear_bit(CREATE_BARRIER, &mdev->tconn->flags)) {
_tl_add_barrier(mdev->tconn, mdev->tconn->unused_spare_tle);
mdev->tconn->unused_spare_tle = NULL;
} else {
D_ASSERT(!(remote && rw == WRITE &&
test_bit(CREATE_BARRIER, &mdev->tconn->flags)));
}
/* NOTE
* Actually, 'local' may be wrong here already, since we may have failed
* to write to the meta data, and may become wrong anytime because of
* local io-error for some other request, which would lead to us
* "detaching" the local disk.
*
* 'remote' may become wrong any time because the network could fail.
*
* This is a harmless race condition, though, since it is handled
* correctly at the appropriate places; so it just defers the failure
* of the respective operation.
*/
/* mark them early for readability.
* this just sets some state flags. */
if (remote)
_req_mod(req, TO_BE_SENT);
if (local)
_req_mod(req, TO_BE_SUBMITTED);
list_add_tail(&req->tl_requests, &mdev->tconn->newest_tle->requests);
/* NOTE remote first: to get the concurrent write detection right,
* we must register the request before start of local IO. */
if (remote) {
/* either WRITE and C_CONNECTED,
* or READ, and no local disk,
* or READ, but not in sync.
*/
_req_mod(req, (rw == WRITE)
? QUEUE_FOR_NET_WRITE
: QUEUE_FOR_NET_READ);
}
if (send_oos && drbd_set_out_of_sync(mdev, sector, size))
_req_mod(req, QUEUE_FOR_SEND_OOS);
rcu_read_lock();
nc = rcu_dereference(mdev->tconn->net_conf);
if (remote &&
nc->on_congestion != OC_BLOCK && mdev->tconn->agreed_pro_version >= 96) {
int congested = 0;
if (nc->cong_fill &&
atomic_read(&mdev->ap_in_flight) >= nc->cong_fill) {
dev_info(DEV, "Congestion-fill threshold reached\n");
congested = 1;
}
if (mdev->act_log->used >= nc->cong_extents) {
dev_info(DEV, "Congestion-extents threshold reached\n");
congested = 1;
}
if (congested) {
queue_barrier(mdev); /* last barrier, after mirrored writes */
if (nc->on_congestion == OC_PULL_AHEAD)
_drbd_set_state(_NS(mdev, conn, C_AHEAD), 0, NULL);
else /*nc->on_congestion == OC_DISCONNECT */
_drbd_set_state(_NS(mdev, conn, C_DISCONNECTING), 0, NULL);
}
}
rcu_read_unlock();
spin_unlock_irq(&mdev->tconn->req_lock);
kfree(b); /* if someone else has beaten us to it... */
if (local) {
req->private_bio->bi_bdev = mdev->ldev->backing_bdev;
/* State may have changed since we grabbed our reference on the
* mdev->ldev member. Double check, and short-circuit to endio.
* In case the last activity log transaction failed to get on
* stable storage, and this is a WRITE, we may not even submit
* this bio. */
if (get_ldev(mdev)) {
if (drbd_insert_fault(mdev, rw == WRITE ? DRBD_FAULT_DT_WR
: rw == READ ? DRBD_FAULT_DT_RD
: DRBD_FAULT_DT_RA))
bio_endio(req->private_bio, -EIO);
else
generic_make_request(req->private_bio);
put_ldev(mdev);
} else
bio_endio(req->private_bio, -EIO);
}
return 0;
fail_free_complete:
if (req->rq_state & RQ_IN_ACT_LOG)
drbd_al_complete_io(mdev, &req->i);
fail_and_free_req:
if (local) {
bio_put(req->private_bio);
req->private_bio = NULL;
put_ldev(mdev);
}
if (!ret)
bio_endio(bio, err);
drbd_req_free(req);
dec_ap_bio(mdev);
kfree(b);
return ret;
}
int drbd_make_request(struct request_queue *q, struct bio *bio)
{
struct drbd_conf *mdev = (struct drbd_conf *) q->queuedata;
unsigned long start_time;
start_time = jiffies;
/*
* what we "blindly" assume:
*/
D_ASSERT(bio->bi_size > 0);
D_ASSERT(IS_ALIGNED(bio->bi_size, 512));
do {
inc_ap_bio(mdev);
} while (__drbd_make_request(mdev, bio, start_time));
return 0;
}
/* This is called by bio_add_page().
*
* q->max_hw_sectors and other global limits are already enforced there.
*
* We need to call down to our lower level device,
* in case it has special restrictions.
*
* We also may need to enforce configured max-bio-bvecs limits.
*
* As long as the BIO is empty we have to allow at least one bvec,
* regardless of size and offset, so no need to ask lower levels.
*/
int drbd_merge_bvec(struct request_queue *q, struct bvec_merge_data *bvm, struct bio_vec *bvec)
{
struct drbd_conf *mdev = (struct drbd_conf *) q->queuedata;
unsigned int bio_size = bvm->bi_size;
int limit = DRBD_MAX_BIO_SIZE;
int backing_limit;
if (bio_size && get_ldev(mdev)) {
struct request_queue * const b =
mdev->ldev->backing_bdev->bd_disk->queue;
if (b->merge_bvec_fn) {
backing_limit = b->merge_bvec_fn(b, bvm, bvec);
limit = min(limit, backing_limit);
}
put_ldev(mdev);
}
return limit;
}
void request_timer_fn(unsigned long data)
{
struct drbd_conf *mdev = (struct drbd_conf *) data;
struct drbd_tconn *tconn = mdev->tconn;
struct drbd_request *req; /* oldest request */
struct list_head *le;
struct net_conf *nc;
unsigned long ent = 0, dt = 0, et, nt; /* effective timeout = ko_count * timeout */
unsigned long now;
rcu_read_lock();
nc = rcu_dereference(tconn->net_conf);
if (nc && mdev->state.conn >= C_WF_REPORT_PARAMS)
ent = nc->timeout * HZ/10 * nc->ko_count;
if (get_ldev(mdev)) { /* implicit state.disk >= D_INCONSISTENT */
dt = rcu_dereference(mdev->ldev->disk_conf)->disk_timeout * HZ / 10;
put_ldev(mdev);
}
rcu_read_unlock();
et = min_not_zero(dt, ent);
if (!et)
return; /* Recurring timer stopped */
now = jiffies;
spin_lock_irq(&tconn->req_lock);
le = &tconn->oldest_tle->requests;
if (list_empty(le)) {
spin_unlock_irq(&tconn->req_lock);
mod_timer(&mdev->request_timer, now + et);
return;
}
le = le->prev;
req = list_entry(le, struct drbd_request, tl_requests);
/* 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->rq_state & RQ_NET_PENDING &&
time_after(now, req->start_time + ent) &&
!time_in_range(now, tconn->last_reconnect_jif, tconn->last_reconnect_jif + ent)) {
dev_warn(DEV, "Remote failed to finish a request within ko-count * timeout\n");
_drbd_set_state(_NS(mdev, conn, C_TIMEOUT), CS_VERBOSE | CS_HARD, NULL);
}
if (dt && req->rq_state & RQ_LOCAL_PENDING && req->w.mdev == mdev &&
time_after(now, req->start_time + dt) &&
!time_in_range(now, mdev->last_reattach_jif, mdev->last_reattach_jif + dt)) {
dev_warn(DEV, "Local backing device failed to meet the disk-timeout\n");
__drbd_chk_io_error(mdev, 1);
}
nt = (time_after(now, req->start_time + et) ? now : req->start_time) + et;
spin_unlock_irq(&tconn->req_lock);
mod_timer(&mdev->request_timer, nt);
}
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