block: protect tracked_requests and flush_queue with reqs_lock
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20170605123908.18777-14-pbonzini@redhat.com>
Signed-off-by: Fam Zheng <famz@redhat.com>
diff --git a/block.c b/block.c
index 361005c..a5cbd45 100644
--- a/block.c
+++ b/block.c
@@ -320,6 +320,7 @@
QLIST_INIT(&bs->op_blockers[i]);
}
notifier_with_return_list_init(&bs->before_write_notifiers);
+ qemu_co_mutex_init(&bs->reqs_lock);
bs->refcnt = 1;
bs->aio_context = qemu_get_aio_context();
diff --git a/block/io.c b/block/io.c
index 036f5a4..91611ff 100644
--- a/block/io.c
+++ b/block/io.c
@@ -378,8 +378,10 @@
atomic_dec(&req->bs->serialising_in_flight);
}
+ qemu_co_mutex_lock(&req->bs->reqs_lock);
QLIST_REMOVE(req, list);
qemu_co_queue_restart_all(&req->wait_queue);
+ qemu_co_mutex_unlock(&req->bs->reqs_lock);
}
/**
@@ -404,7 +406,9 @@
qemu_co_queue_init(&req->wait_queue);
+ qemu_co_mutex_lock(&bs->reqs_lock);
QLIST_INSERT_HEAD(&bs->tracked_requests, req, list);
+ qemu_co_mutex_unlock(&bs->reqs_lock);
}
static void mark_request_serialising(BdrvTrackedRequest *req, uint64_t align)
@@ -526,6 +530,7 @@
do {
retry = false;
+ qemu_co_mutex_lock(&bs->reqs_lock);
QLIST_FOREACH(req, &bs->tracked_requests, list) {
if (req == self || (!req->serialising && !self->serialising)) {
continue;
@@ -544,7 +549,7 @@
* (instead of producing a deadlock in the former case). */
if (!req->waiting_for) {
self->waiting_for = req;
- qemu_co_queue_wait(&req->wait_queue, NULL);
+ qemu_co_queue_wait(&req->wait_queue, &bs->reqs_lock);
self->waiting_for = NULL;
retry = true;
waited = true;
@@ -552,6 +557,7 @@
}
}
}
+ qemu_co_mutex_unlock(&bs->reqs_lock);
} while (retry);
return waited;
@@ -2291,14 +2297,17 @@
goto early_exit;
}
+ qemu_co_mutex_lock(&bs->reqs_lock);
current_gen = atomic_read(&bs->write_gen);
/* Wait until any previous flushes are completed */
while (bs->active_flush_req) {
- qemu_co_queue_wait(&bs->flush_queue, NULL);
+ qemu_co_queue_wait(&bs->flush_queue, &bs->reqs_lock);
}
+ /* Flushes reach this point in nondecreasing current_gen order. */
bs->active_flush_req = true;
+ qemu_co_mutex_unlock(&bs->reqs_lock);
/* Write back all layers by calling one driver function */
if (bs->drv->bdrv_co_flush) {
@@ -2370,9 +2379,12 @@
if (ret == 0) {
bs->flushed_gen = current_gen;
}
+
+ qemu_co_mutex_lock(&bs->reqs_lock);
bs->active_flush_req = false;
/* Return value is ignored - it's ok if wait queue is empty */
qemu_co_queue_next(&bs->flush_queue);
+ qemu_co_mutex_unlock(&bs->reqs_lock);
early_exit:
bdrv_dec_in_flight(bs);
diff --git a/include/block/block_int.h b/include/block/block_int.h
index b7d0dfb..ae74df9 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -609,11 +609,6 @@
uint64_t write_threshold_offset;
NotifierWithReturn write_threshold_notifier;
- QLIST_HEAD(, BdrvTrackedRequest) tracked_requests;
- CoQueue flush_queue; /* Serializing flush queue */
- bool active_flush_req; /* Flush request in flight? */
- unsigned int flushed_gen; /* Flushed write generation */
-
QLIST_HEAD(, BdrvDirtyBitmap) dirty_bitmaps;
/* Offset after the highest byte written to */
@@ -647,6 +642,15 @@
/* Accessed with atomic ops. */
int quiesce_counter;
unsigned int write_gen; /* Current data generation */
+
+ /* Protected by reqs_lock. */
+ CoMutex reqs_lock;
+ QLIST_HEAD(, BdrvTrackedRequest) tracked_requests;
+ CoQueue flush_queue; /* Serializing flush queue */
+ bool active_flush_req; /* Flush request in flight? */
+
+ /* Only read/written by whoever has set active_flush_req to true. */
+ unsigned int flushed_gen; /* Flushed write generation */
};
struct BlockBackendRootState {
