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drbd: simplify retry path of failed READ requests

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If a local or remote READ request fails, just push it back to the retry
workqueue.  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.

This obsoletes w_read_retry_remote(),
and eliminates two goto...retry blocks in __req_mod()

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
This commit is contained in:
Lars Ellenberg
2012-03-26 17:29:30 +02:00
committed by Philipp Reisner
parent 2415308eb9
commit 4439c400ab
3 changed files with 19 additions and 67 deletions
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drivers/block/drbd/drbd_req.c
+19 -46
View File
@@ -263,7 +263,6 @@ 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;
int rw = req->rq_state & RQ_WRITE ? WRITE : READ;
/* we must not complete the master bio, while it is
* still being processed by _drbd_send_zc_bio (drbd_send_dblock)
@@ -282,6 +281,8 @@ void req_may_be_completed(struct drbd_request *req, struct bio_and_error *m)
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
@@ -326,7 +327,18 @@ void req_may_be_completed(struct drbd_request *req, struct bio_and_error *m)
/* Update disk stats */
_drbd_end_io_acct(mdev, req);
if (!(s & RQ_POSTPONED)) {
/* 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;
@@ -420,10 +432,7 @@ int __req_mod(struct drbd_request *req, enum drbd_req_event what,
case ABORT_DISK_IO:
req->rq_state |= RQ_LOCAL_ABORTED;
if (req->rq_state & RQ_WRITE)
req_may_be_completed_not_susp(req, m);
else
goto goto_queue_for_net_read;
req_may_be_completed_not_susp(req, m);
break;
case WRITE_COMPLETED_WITH_ERROR:
@@ -451,20 +460,7 @@ int __req_mod(struct drbd_request *req, enum drbd_req_event what,
D_ASSERT(!(req->rq_state & RQ_NET_MASK));
__drbd_chk_io_error(mdev, false);
goto_queue_for_net_read:
/* 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_completed_not_susp(req, m);
break;
}
/* _req_mod(req,TO_BE_SENT); oops, recursion... */
req->rq_state |= RQ_NET_PENDING;
inc_ap_pending(mdev);
/* fall through: _req_mod(req,QUEUE_FOR_NET_READ); */
break;
case QUEUE_FOR_NET_READ:
/* READ or READA, and
@@ -483,10 +479,9 @@ int __req_mod(struct drbd_request *req, enum drbd_req_event what,
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 = (req->rq_state & RQ_LOCAL_MASK)
? w_read_retry_remote
: w_send_read_req;
req->w.cb = w_send_read_req;
drbd_queue_work(&mdev->tconn->data.work, &req->w);
break;
@@ -604,13 +599,7 @@ int __req_mod(struct drbd_request *req, enum drbd_req_event what,
if (req->rq_state & RQ_NET_SENT && req->rq_state & RQ_WRITE)
atomic_sub(req->i.size >> 9, &mdev->ap_in_flight);
/* if it is still queued, we may not complete it here.
* it will be canceled soon. */
if (!(req->rq_state & RQ_NET_QUEUED)) {
if (p)
goto goto_read_retry_local;
req_may_be_completed(req, m); /* Allowed while state.susp */
}
req_may_be_completed(req, m); /* Allowed while state.susp */
break;
case DISCARD_WRITE:
@@ -668,27 +657,11 @@ int __req_mod(struct drbd_request *req, enum drbd_req_event what,
req->rq_state |= RQ_NET_DONE;
if (!(req->rq_state & RQ_WRITE))
goto goto_read_retry_local;
maybe_wakeup_conflicting_requests(req);
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_completed_not_susp(req, m);
break;
}
D_ASSERT(!(req->rq_state & RQ_LOCAL_PENDING));
req->rq_state |= RQ_LOCAL_PENDING;
get_ldev(mdev);
req->w.cb = w_restart_disk_io;
drbd_queue_work(&mdev->tconn->data.work, &req->w);
break;
case FAIL_FROZEN_DISK_IO:
if (!(req->rq_state & RQ_LOCAL_COMPLETED))
break;