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>

1 files changed, 1 insertions, 6 deletions

diff --git a/qemu-io-cmds.c b/qemu-io-cmds.c
index e8d862a426..46593d632d 100644
--- a/qemu-io-cmds.c
+++ b/qemu-io-cmds.c
@@ -2116,8 +2116,6 @@ static int reopen_f(BlockBackend *blk, int argc, char **argv)
     bool writethrough = !blk_enable_write_cache(blk);
     bool has_rw_option = false;
     bool has_cache_option = false;
-
-    BlockReopenQueue *brq;
     Error *local_err = NULL;
 
     while ((c = getopt(argc, argv, "c:o:rw")) != -1) {
@@ -2210,10 +2208,7 @@ static int reopen_f(BlockBackend *blk, int argc, char **argv)
         qdict_put_bool(opts, BDRV_OPT_CACHE_NO_FLUSH, flags & BDRV_O_NO_FLUSH);
     }
 
-    bdrv_subtree_drained_begin(bs);
-    brq = bdrv_reopen_queue(NULL, bs, opts, true);
-    bdrv_reopen_multiple(brq, &local_err);
-    bdrv_subtree_drained_end(bs);
+    bdrv_reopen(bs, opts, true, &local_err);
 
     if (local_err) {
         error_report_err(local_err);