diff mbox series

[17/97] block: Drain source node in bdrv_replace_node()

Message ID 20191001234616.7825-18-mdroth@linux.vnet.ibm.com
State New
Headers show
Series Patch Round-up for stable 4.0.1, freeze on 2019-10-10 | expand

Commit Message

Michael Roth Oct. 1, 2019, 11:44 p.m. UTC 
From: Kevin Wolf <kwolf@redhat.com>

Instead of just asserting that no requests are in flight in
bdrv_replace_node(), which is a requirement that most callers ignore, we
can just drain the source node right there. This fixes at least starting
a commit job while I/O is active on the backing chain, but probably
other callers, too.

Having requests in flight on the target node isn't a problem because the
target just gets new parents, but the call path of running requests
isn't modified. So we can just drop this assertion without a replacement.

Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1711643
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
(cherry picked from commit f871abd60f4b67547e62c57c9bec19420052be39)
*prereq for d81e1efb tests
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
---
 block.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)
diff mbox series

Patch

diff --git a/block.c b/block.c
index 9ae5c0ed2f..c0e1c86911 100644
--- a/block.c
+++ b/block.c
@@ -3987,13 +3987,13 @@  void bdrv_replace_node(BlockDriverState *from, BlockDriverState *to,
     uint64_t perm = 0, shared = BLK_PERM_ALL;
     int ret;
 
-    assert(!atomic_read(&from->in_flight));
-    assert(!atomic_read(&to->in_flight));
-
     /* Make sure that @from doesn't go away until we have successfully attached
      * all of its parents to @to. */
     bdrv_ref(from);
 
+    assert(qemu_get_current_aio_context() == qemu_get_aio_context());
+    bdrv_drained_begin(from);
+
     /* Put all parents into @list and calculate their cumulative permissions */
     QLIST_FOREACH_SAFE(c, &from->parents, next_parent, next) {
         assert(c->bs == from);
@@ -4034,6 +4034,7 @@  void bdrv_replace_node(BlockDriverState *from, BlockDriverState *to,
 
 out:
     g_slist_free(list);
+    bdrv_drained_end(from);
     bdrv_unref(from);
 }