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drbd: factor out master_bio completion and drbd_request destruction p…
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…aths

In preparation for multiple connections and reference counting,
separate the code paths for completion of the master bio
and destruction of the request object.

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
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Lars Ellenberg authored and Philipp Reisner committed Nov 8, 2012
1 parent 8d6cdd7 commit 6870ca6
Showing 1 changed file with 58 additions and 36 deletions.
94 changes: 58 additions & 36 deletions drivers/block/drbd/drbd_req.c
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Original file line number Diff line number Diff line change
Expand Up @@ -222,13 +222,44 @@ static void maybe_wakeup_conflicting_requests(struct drbd_request *req)
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.
*/
void _req_may_be_done(struct drbd_request *req, struct bio_and_error *m)
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;
Expand Down Expand Up @@ -309,26 +340,15 @@ void _req_may_be_done(struct drbd_request *req, struct bio_and_error *m)
D_ASSERT(s & RQ_NET_DONE);
}
}

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... */
req_may_be_done(req);
}

static void _req_may_be_done_not_susp(struct drbd_request *req, struct bio_and_error *m)
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_done(req, m);
req_may_be_completed(req, m);
}

/* obviously this could be coded as many single functions
Expand Down Expand Up @@ -395,14 +415,14 @@ int __req_mod(struct drbd_request *req, enum drbd_req_event what,
req->rq_state &= ~RQ_LOCAL_PENDING;

maybe_wakeup_conflicting_requests(req);
_req_may_be_done_not_susp(req, m);
req_may_be_completed_not_susp(req, m);
put_ldev(mdev);
break;

case ABORT_DISK_IO:
req->rq_state |= RQ_LOCAL_ABORTED;
if (req->rq_state & RQ_WRITE)
_req_may_be_done_not_susp(req, m);
req_may_be_completed_not_susp(req, m);
else
goto goto_queue_for_net_read;
break;
Expand All @@ -413,15 +433,15 @@ int __req_mod(struct drbd_request *req, enum drbd_req_event what,

__drbd_chk_io_error(mdev, false);
maybe_wakeup_conflicting_requests(req);
_req_may_be_done_not_susp(req, m);
req_may_be_completed_not_susp(req, m);
put_ldev(mdev);
break;

case READ_AHEAD_COMPLETED_WITH_ERROR:
/* it is legal to fail READA */
req->rq_state |= RQ_LOCAL_COMPLETED;
req->rq_state &= ~RQ_LOCAL_PENDING;
_req_may_be_done_not_susp(req, m);
req_may_be_completed_not_susp(req, m);
put_ldev(mdev);
break;

Expand All @@ -441,7 +461,7 @@ int __req_mod(struct drbd_request *req, enum drbd_req_event what,
/* no point in retrying if there is no good remote data,
* or we have no connection. */
if (mdev->state.pdsk != D_UP_TO_DATE) {
_req_may_be_done_not_susp(req, m);
req_may_be_completed_not_susp(req, m);
break;
}

Expand All @@ -458,8 +478,9 @@ int __req_mod(struct drbd_request *req, enum drbd_req_event what,
/* from __drbd_make_request
* or from bio_endio during read io-error recovery */

/* so we can verify the handle in the answer packet
* corresponding hlist_del is in _req_may_be_done() */
/* 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);

Expand All @@ -477,7 +498,8 @@ int __req_mod(struct drbd_request *req, enum drbd_req_event what,
/* assert something? */
/* from __drbd_make_request only */

/* corresponding hlist_del is in _req_may_be_done() */
/* 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);

Expand Down Expand Up @@ -539,7 +561,7 @@ int __req_mod(struct drbd_request *req, enum drbd_req_event what,
req->rq_state &= ~RQ_NET_QUEUED;
/* if we did it right, tl_clear should be scheduled only after
* this, so this should not be necessary! */
_req_may_be_done_not_susp(req, m);
req_may_be_completed_not_susp(req, m);
break;

case HANDED_OVER_TO_NETWORK:
Expand All @@ -562,15 +584,15 @@ int __req_mod(struct drbd_request *req, enum drbd_req_event what,
}
req->rq_state &= ~RQ_NET_QUEUED;
req->rq_state |= RQ_NET_SENT;
_req_may_be_done_not_susp(req, m);
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_done_not_susp(req, m);
req_may_be_completed_not_susp(req, m);
break;

case CONNECTION_LOST_WHILE_PENDING:
Expand All @@ -591,7 +613,7 @@ int __req_mod(struct drbd_request *req, enum drbd_req_event what,
if (!(req->rq_state & RQ_NET_QUEUED)) {
if (p)
goto goto_read_retry_local;
_req_may_be_done(req, m); /* Allowed while state.susp */
req_may_be_completed(req, m); /* Allowed while state.susp */
}
break;

Expand Down Expand Up @@ -624,7 +646,7 @@ int __req_mod(struct drbd_request *req, enum drbd_req_event what,
atomic_sub(req->i.size >> 9, &mdev->ap_in_flight);
req->rq_state &= ~RQ_NET_PENDING;
maybe_wakeup_conflicting_requests(req);
_req_may_be_done_not_susp(req, m);
req_may_be_completed_not_susp(req, m);
break;

case POSTPONE_WRITE:
Expand All @@ -636,7 +658,7 @@ int __req_mod(struct drbd_request *req, enum drbd_req_event what,
D_ASSERT(req->rq_state & RQ_NET_PENDING);
req->rq_state |= RQ_POSTPONED;
maybe_wakeup_conflicting_requests(req);
_req_may_be_done_not_susp(req, m);
req_may_be_completed_not_susp(req, m);
break;

case NEG_ACKED:
Expand All @@ -654,13 +676,13 @@ int __req_mod(struct drbd_request *req, enum drbd_req_event what,
goto goto_read_retry_local;

maybe_wakeup_conflicting_requests(req);
_req_may_be_done_not_susp(req, m);
req_may_be_completed_not_susp(req, m);
/* else: done by HANDED_OVER_TO_NETWORK */
break;

goto_read_retry_local:
if (!drbd_may_do_local_read(mdev, req->i.sector, req->i.size)) {
_req_may_be_done_not_susp(req, m);
req_may_be_completed_not_susp(req, m);
break;
}
D_ASSERT(!(req->rq_state & RQ_LOCAL_PENDING));
Expand All @@ -675,7 +697,7 @@ int __req_mod(struct drbd_request *req, enum drbd_req_event what,
if (!(req->rq_state & RQ_LOCAL_COMPLETED))
break;

_req_may_be_done(req, m); /* Allowed while state.susp */
req_may_be_completed(req, m); /* Allowed while state.susp */
break;

case RESTART_FROZEN_DISK_IO:
Expand All @@ -696,8 +718,8 @@ int __req_mod(struct drbd_request *req, enum drbd_req_event what,
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.
Trowing them out of the TL here by pretending we got a BARRIER_ACK
We ensure that the peer was not rebooted */
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);
Expand All @@ -723,15 +745,15 @@ int __req_mod(struct drbd_request *req, enum drbd_req_event what,
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, m); /* Allowed while state.susp */
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_done_not_susp(req, m);
req_may_be_completed_not_susp(req, m);
break;
};

Expand Down

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