block: Acquire AioContexts during bdrv_reopen_multiple()
As the BlockReopenQueue can contain nodes in multiple AioContexts, only
one of which may be locked when AIO_WAIT_WHILE() can be called, we can't
let the caller lock the right contexts. Instead, individually lock the
AioContext of a single node when iterating the queue.
Reintroduce bdrv_reopen() as a wrapper for reopening a single node that
drains the node and temporarily drops the AioContext lock for
bdrv_reopen_multiple().
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20210708114709.206487-4-kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
diff --git a/block.c b/block.c
index a26465e..be083f3 100644
--- a/block.c
+++ b/block.c
@@ -4124,19 +4124,26 @@
*
* All affected nodes must be drained between bdrv_reopen_queue() and
* bdrv_reopen_multiple().
+ *
+ * To be called from the main thread, with all other AioContexts unlocked.
*/
int bdrv_reopen_multiple(BlockReopenQueue *bs_queue, Error **errp)
{
int ret = -1;
BlockReopenQueueEntry *bs_entry, *next;
+ AioContext *ctx;
Transaction *tran = tran_new();
g_autoptr(GHashTable) found = NULL;
g_autoptr(GSList) refresh_list = NULL;
+ assert(qemu_get_current_aio_context() == qemu_get_aio_context());
assert(bs_queue != NULL);
QTAILQ_FOREACH(bs_entry, bs_queue, entry) {
+ ctx = bdrv_get_aio_context(bs_entry->state.bs);
+ aio_context_acquire(ctx);
ret = bdrv_flush(bs_entry->state.bs);
+ aio_context_release(ctx);
if (ret < 0) {
error_setg_errno(errp, -ret, "Error flushing drive");
goto abort;
@@ -4145,7 +4152,10 @@
QTAILQ_FOREACH(bs_entry, bs_queue, entry) {
assert(bs_entry->state.bs->quiesce_counter > 0);
+ ctx = bdrv_get_aio_context(bs_entry->state.bs);
+ aio_context_acquire(ctx);
ret = bdrv_reopen_prepare(&bs_entry->state, bs_queue, tran, errp);
+ aio_context_release(ctx);
if (ret < 0) {
goto abort;
}
@@ -4188,7 +4198,10 @@
* to first element.
*/
QTAILQ_FOREACH_REVERSE(bs_entry, bs_queue, entry) {
+ ctx = bdrv_get_aio_context(bs_entry->state.bs);
+ aio_context_acquire(ctx);
bdrv_reopen_commit(&bs_entry->state);
+ aio_context_release(ctx);
}
tran_commit(tran);
@@ -4197,7 +4210,10 @@
BlockDriverState *bs = bs_entry->state.bs;
if (bs->drv->bdrv_reopen_commit_post) {
+ ctx = bdrv_get_aio_context(bs);
+ aio_context_acquire(ctx);
bs->drv->bdrv_reopen_commit_post(&bs_entry->state);
+ aio_context_release(ctx);
}
}
@@ -4208,7 +4224,10 @@
tran_abort(tran);
QTAILQ_FOREACH_SAFE(bs_entry, bs_queue, entry, next) {
if (bs_entry->prepared) {
+ ctx = bdrv_get_aio_context(bs_entry->state.bs);
+ aio_context_acquire(ctx);
bdrv_reopen_abort(&bs_entry->state);
+ aio_context_release(ctx);
}
}
@@ -4218,21 +4237,37 @@
return ret;
}
+int bdrv_reopen(BlockDriverState *bs, QDict *opts, bool keep_old_opts,
+ Error **errp)
+{
+ AioContext *ctx = bdrv_get_aio_context(bs);
+ BlockReopenQueue *queue;
+ int ret;
+
+ bdrv_subtree_drained_begin(bs);
+ if (ctx != qemu_get_aio_context()) {
+ aio_context_release(ctx);
+ }
+
+ queue = bdrv_reopen_queue(NULL, bs, opts, keep_old_opts);
+ ret = bdrv_reopen_multiple(queue, errp);
+
+ if (ctx != qemu_get_aio_context()) {
+ aio_context_acquire(ctx);
+ }
+ bdrv_subtree_drained_end(bs);
+
+ return ret;
+}
+
int bdrv_reopen_set_read_only(BlockDriverState *bs, bool read_only,
Error **errp)
{
- int ret;
- BlockReopenQueue *queue;
QDict *opts = qdict_new();
qdict_put_bool(opts, BDRV_OPT_READ_ONLY, read_only);
- bdrv_subtree_drained_begin(bs);
- queue = bdrv_reopen_queue(NULL, bs, opts, true);
- ret = bdrv_reopen_multiple(queue, errp);
- bdrv_subtree_drained_end(bs);
-
- return ret;
+ return bdrv_reopen(bs, opts, true, errp);
}
/*