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From: Kevin Wolf <kwolf@redhat.com>
To: qemu-block@nongnu.org
Date: Fri, 22 Dec 2017 16:18:30 +0100
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Subject: [Qemu-devel] [PULL v3 19/35] block: Make bdrv_drain() driver
callbacks non-recursive
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bdrv_drained_begin() doesn't increase bs->quiesce_counter recursively
and also doesn't notify other parent nodes of children, which both means
that the child nodes are not actually drained, and bdrv_drained_begin()
is providing useful functionality only on a single node.
To keep things consistent, we also shouldn't call the block driver
callbacks recursively.
A proper recursive drain version that provides an actually working
drained section for child nodes will be introduced later.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
---
block/io.c | 16 +++++++++-------
1 file changed, 9 insertions(+), 7 deletions(-)
diff --git a/block/io.c b/block/io.c
index b94740b8ff..91a52e2d82 100644
--- a/block/io.c
+++ b/block/io.c
@@ -158,7 +158,7 @@ static void coroutine_fn bdrv_drain_invoke_entry(void *=
opaque)
}
=20
/* Recursively call BlockDriver.bdrv_co_drain_begin/end callbacks */
-static void bdrv_drain_invoke(BlockDriverState *bs, bool begin)
+static void bdrv_drain_invoke(BlockDriverState *bs, bool begin, bool recur=
sive)
{
BdrvChild *child, *tmp;
BdrvCoDrainData data =3D { .bs =3D bs, .done =3D false, .begin =3D beg=
in};
@@ -172,8 +172,10 @@ static void bdrv_drain_invoke(BlockDriverState *bs, bo=
ol begin)
bdrv_coroutine_enter(bs, data.co);
BDRV_POLL_WHILE(bs, !data.done);
=20
- QLIST_FOREACH_SAFE(child, &bs->children, next, tmp) {
- bdrv_drain_invoke(child->bs, begin);
+ if (recursive) {
+ QLIST_FOREACH_SAFE(child, &bs->children, next, tmp) {
+ bdrv_drain_invoke(child->bs, begin, true);
+ }
}
}
=20
@@ -265,7 +267,7 @@ void bdrv_drained_begin(BlockDriverState *bs)
bdrv_parent_drained_begin(bs);
}
=20
- bdrv_drain_invoke(bs, true);
+ bdrv_drain_invoke(bs, true, false);
bdrv_drain_recurse(bs);
}
=20
@@ -281,7 +283,7 @@ void bdrv_drained_end(BlockDriverState *bs)
}
=20
/* Re-enable things in child-to-parent order */
- bdrv_drain_invoke(bs, false);
+ bdrv_drain_invoke(bs, false, false);
bdrv_parent_drained_end(bs);
aio_enable_external(bdrv_get_aio_context(bs));
}
@@ -345,7 +347,7 @@ void bdrv_drain_all_begin(void)
aio_context_acquire(aio_context);
aio_disable_external(aio_context);
bdrv_parent_drained_begin(bs);
- bdrv_drain_invoke(bs, true);
+ bdrv_drain_invoke(bs, true, true);
aio_context_release(aio_context);
=20
if (!g_slist_find(aio_ctxs, aio_context)) {
@@ -388,7 +390,7 @@ void bdrv_drain_all_end(void)
=20
/* Re-enable things in child-to-parent order */
aio_context_acquire(aio_context);
- bdrv_drain_invoke(bs, false);
+ bdrv_drain_invoke(bs, false, true);
bdrv_parent_drained_end(bs);
aio_enable_external(aio_context);
aio_context_release(aio_context);
--=20
2.13.6