From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
To: qemu-block@nongnu.org
Cc: fam@euphon.net, kwolf@redhat.com, vsementsov@virtuozzo.com,
armbru@redhat.com, qemu-devel@nongnu.org, mreitz@redhat.com,
nsoffer@redhat.com, stefanha@redhat.com, den@openvz.org
Subject: [PATCH v5 03/10] block/io: split out bdrv_find_conflicting_request
Date: Fri, 21 Aug 2020 17:11:16 +0300 [thread overview]
Message-ID: <20200821141123.28538-4-vsementsov@virtuozzo.com> (raw)
In-Reply-To: <20200821141123.28538-1-vsementsov@virtuozzo.com>
To be reused in separate.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
---
block/io.c | 71 +++++++++++++++++++++++++++++++-----------------------
1 file changed, 41 insertions(+), 30 deletions(-)
diff --git a/block/io.c b/block/io.c
index b18680a842..5b96715058 100644
--- a/block/io.c
+++ b/block/io.c
@@ -727,43 +727,54 @@ static bool tracked_request_overlaps(BdrvTrackedRequest *req,
return true;
}
+/* Called with self->bs->reqs_lock held */
+static BdrvTrackedRequest *
+bdrv_find_conflicting_request(BdrvTrackedRequest *self)
+{
+ BdrvTrackedRequest *req;
+
+ QLIST_FOREACH(req, &self->bs->tracked_requests, list) {
+ if (req == self || (!req->serialising && !self->serialising)) {
+ continue;
+ }
+ if (tracked_request_overlaps(req, self->overlap_offset,
+ self->overlap_bytes))
+ {
+ /*
+ * Hitting this means there was a reentrant request, for
+ * example, a block driver issuing nested requests. This must
+ * never happen since it means deadlock.
+ */
+ assert(qemu_coroutine_self() != req->co);
+
+ /*
+ * If the request is already (indirectly) waiting for us, or
+ * will wait for us as soon as it wakes up, then just go on
+ * (instead of producing a deadlock in the former case).
+ */
+ if (!req->waiting_for) {
+ return req;
+ }
+ }
+ }
+
+ return NULL;
+}
+
static bool coroutine_fn
bdrv_wait_serialising_requests_locked(BlockDriverState *bs,
BdrvTrackedRequest *self)
{
BdrvTrackedRequest *req;
- bool retry;
bool waited = false;
- do {
- retry = false;
- QLIST_FOREACH(req, &bs->tracked_requests, list) {
- if (req == self || (!req->serialising && !self->serialising)) {
- continue;
- }
- if (tracked_request_overlaps(req, self->overlap_offset,
- self->overlap_bytes))
- {
- /* Hitting this means there was a reentrant request, for
- * example, a block driver issuing nested requests. This must
- * never happen since it means deadlock.
- */
- assert(qemu_coroutine_self() != req->co);
-
- /* If the request is already (indirectly) waiting for us, or
- * will wait for us as soon as it wakes up, then just go on
- * (instead of producing a deadlock in the former case). */
- if (!req->waiting_for) {
- self->waiting_for = req;
- qemu_co_queue_wait(&req->wait_queue, &bs->reqs_lock);
- self->waiting_for = NULL;
- retry = true;
- waited = true;
- break;
- }
- }
- }
- } while (retry);
+ while ((req = bdrv_find_conflicting_request(self))) {
+ self->waiting_for = req;
+ qemu_co_queue_wait(&req->wait_queue, &bs->reqs_lock);
+ self->waiting_for = NULL;
+ waited = true;
+ }
+
return waited;
}
--
2.21.3
next prev parent reply other threads:[~2020-08-21 14:16 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-21 14:11 [PATCH v5 00/10] preallocate filter Vladimir Sementsov-Ogievskiy
2020-08-21 14:11 ` [PATCH v5 01/10] block: simplify comment to BDRV_REQ_SERIALISING Vladimir Sementsov-Ogievskiy
2020-08-21 14:11 ` [PATCH v5 02/10] block/io.c: drop assertion on double waiting for request serialisation Vladimir Sementsov-Ogievskiy
2020-08-21 14:11 ` Vladimir Sementsov-Ogievskiy [this message]
2020-08-21 14:11 ` [PATCH v5 04/10] block/io: bdrv_wait_serialising_requests_locked: drop extra bs arg Vladimir Sementsov-Ogievskiy
2020-08-21 14:11 ` [PATCH v5 05/10] block: bdrv_mark_request_serialising: split non-waiting function Vladimir Sementsov-Ogievskiy
2020-08-25 12:43 ` Max Reitz
2020-08-21 14:11 ` [PATCH v5 06/10] block: introduce BDRV_REQ_NO_WAIT flag Vladimir Sementsov-Ogievskiy
2020-08-25 13:10 ` Max Reitz
2020-08-26 6:26 ` Vladimir Sementsov-Ogievskiy
2020-08-26 8:36 ` Max Reitz
2020-08-26 8:57 ` Vladimir Sementsov-Ogievskiy
2020-08-21 14:11 ` [PATCH v5 07/10] block: introduce preallocate filter Vladimir Sementsov-Ogievskiy
2020-08-24 17:52 ` Vladimir Sementsov-Ogievskiy
2020-08-26 7:06 ` Vladimir Sementsov-Ogievskiy
2020-08-25 15:11 ` Max Reitz
2020-08-26 6:49 ` Vladimir Sementsov-Ogievskiy
2020-08-26 8:52 ` Max Reitz
2020-08-26 9:15 ` Vladimir Sementsov-Ogievskiy
2020-08-26 9:58 ` Max Reitz
2020-08-26 11:29 ` Vladimir Sementsov-Ogievskiy
2020-08-26 13:51 ` David Edmondson
2020-08-27 9:19 ` Vladimir Sementsov-Ogievskiy
2020-08-21 14:11 ` [PATCH v5 08/10] iotests.py: add verify_o_direct helper Vladimir Sementsov-Ogievskiy
2020-08-21 17:29 ` Nir Soffer
2020-08-21 14:11 ` [PATCH v5 09/10] iotests.py: add filter_img_check Vladimir Sementsov-Ogievskiy
2020-08-21 14:11 ` [PATCH v5 10/10] iotests: add 298 to test new preallocate filter driver Vladimir Sementsov-Ogievskiy
2020-08-27 21:08 ` [PATCH v5 00/10] preallocate filter Vladimir Sementsov-Ogievskiy
2020-09-01 15:07 ` Max Reitz
2020-09-17 9:00 ` Vladimir Sementsov-Ogievskiy
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