qemu-kvm/SOURCES/kvm-block-Remove-bdrv_drain_recurse.patch

92 lines
3.2 KiB
Diff

From e6d8bc54a031c61c1fce2c9e1ccdb821b5991c1a Mon Sep 17 00:00:00 2001
From: Kevin Wolf <kwolf@redhat.com>
Date: Wed, 10 Oct 2018 20:08:42 +0100
Subject: [PATCH 11/49] block: Remove bdrv_drain_recurse()
RH-Author: Kevin Wolf <kwolf@redhat.com>
Message-id: <20181010200843.6710-9-kwolf@redhat.com>
Patchwork-id: 82588
O-Subject: [RHEL-8 qemu-kvm PATCH 08/44] block: Remove bdrv_drain_recurse()
Bugzilla: 1637976
RH-Acked-by: Max Reitz <mreitz@redhat.com>
RH-Acked-by: John Snow <jsnow@redhat.com>
RH-Acked-by: Thomas Huth <thuth@redhat.com>
For bdrv_drain(), recursively waiting for child node requests is
pointless because we didn't quiesce their parents, so new requests could
come in anyway. Letting the function work only on a single node makes it
more consistent.
For subtree drains and drain_all, we already have the recursion in
bdrv_do_drained_begin(), so the extra recursion doesn't add anything
either.
Remove the useless code.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
(cherry picked from commit d30b8e64b7b282da785307504ada59efa8096fb1)
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Danilo C. L. de Paula <ddepaula@redhat.com>
---
block/io.c | 36 +++---------------------------------
1 file changed, 3 insertions(+), 33 deletions(-)
diff --git a/block/io.c b/block/io.c
index e260394..a0e3461 100644
--- a/block/io.c
+++ b/block/io.c
@@ -218,38 +218,6 @@ static bool bdrv_drain_poll_top_level(BlockDriverState *bs,
return bdrv_drain_poll(bs, ignore_parent);
}
-static bool bdrv_drain_recurse(BlockDriverState *bs, BdrvChild *parent)
-{
- BdrvChild *child, *tmp;
- bool waited;
-
- /* Wait for drained requests to finish */
- waited = BDRV_POLL_WHILE(bs, bdrv_drain_poll_top_level(bs, parent));
-
- QLIST_FOREACH_SAFE(child, &bs->children, next, tmp) {
- BlockDriverState *bs = child->bs;
- bool in_main_loop =
- qemu_get_current_aio_context() == qemu_get_aio_context();
- assert(bs->refcnt > 0);
- if (in_main_loop) {
- /* In case the recursive bdrv_drain_recurse processes a
- * block_job_defer_to_main_loop BH and modifies the graph,
- * let's hold a reference to bs until we are done.
- *
- * IOThread doesn't have such a BH, and it is not safe to call
- * bdrv_unref without BQL, so skip doing it there.
- */
- bdrv_ref(bs);
- }
- waited |= bdrv_drain_recurse(bs, child);
- if (in_main_loop) {
- bdrv_unref(bs);
- }
- }
-
- return waited;
-}
-
static void bdrv_do_drained_begin(BlockDriverState *bs, bool recursive,
BdrvChild *parent);
static void bdrv_do_drained_end(BlockDriverState *bs, bool recursive,
@@ -317,7 +285,9 @@ void bdrv_do_drained_begin(BlockDriverState *bs, bool recursive,
bdrv_parent_drained_begin(bs, parent);
bdrv_drain_invoke(bs, true);
- bdrv_drain_recurse(bs, parent);
+
+ /* Wait for drained requests to finish */
+ BDRV_POLL_WHILE(bs, bdrv_drain_poll_top_level(bs, parent));
if (recursive) {
bs->recursive_quiesce_counter++;
--
1.8.3.1