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[Qemu-block] [PATCH 08/19] block: Remove bdrv_drain_recurse()
From: |
Kevin Wolf |
Subject: |
[Qemu-block] [PATCH 08/19] block: Remove bdrv_drain_recurse() |
Date: |
Wed, 11 Apr 2018 18:39:29 +0200 |
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 <address@hidden>
---
block/io.c | 36 +++---------------------------------
1 file changed, 3 insertions(+), 33 deletions(-)
diff --git a/block/io.c b/block/io.c
index 0a778eeff4..f24f39c278 100644
--- a/block/io.c
+++ b/block/io.c
@@ -211,38 +211,6 @@ bool bdrv_drain_poll(BlockDriverState *bs, bool top_level)
return atomic_read(&bs->in_flight);
}
-static bool bdrv_drain_recurse(BlockDriverState *bs)
-{
- BdrvChild *child, *tmp;
- bool waited;
-
- /* Wait for drained requests to finish */
- waited = BDRV_POLL_WHILE(bs, bdrv_drain_poll(bs, true));
-
- 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);
- 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,
@@ -310,7 +278,9 @@ void bdrv_do_drained_begin(BlockDriverState *bs, bool
recursive,
bdrv_parent_drained_begin(bs, parent);
bdrv_drain_invoke(bs, true);
- bdrv_drain_recurse(bs);
+
+ /* Wait for drained requests to finish */
+ BDRV_POLL_WHILE(bs, bdrv_drain_poll(bs, true));
if (recursive) {
bs->recursive_quiesce_counter++;
--
2.13.6
- [Qemu-block] [PATCH 00/19] Drain fixes and cleanups, part 3, Kevin Wolf, 2018/04/11
- [Qemu-block] [PATCH 03/19] block: Remove 'recursive' parameter from bdrv_drain_invoke(), Kevin Wolf, 2018/04/11
- [Qemu-block] [PATCH 02/19] block: Use bdrv_do_drain_begin/end in bdrv_drain_all(), Kevin Wolf, 2018/04/11
- [Qemu-block] [PATCH 05/19] tests/test-bdrv-drain: bdrv_drain_all() works in coroutines now, Kevin Wolf, 2018/04/11
- [Qemu-block] [PATCH 08/19] block: Remove bdrv_drain_recurse(),
Kevin Wolf <=
- [Qemu-block] [PATCH 07/19] block: Really pause block jobs on drain, Kevin Wolf, 2018/04/11
- Re: [Qemu-block] [PATCH 07/19] block: Really pause block jobs on drain, Paolo Bonzini, 2018/04/12
- Re: [Qemu-block] [PATCH 07/19] block: Really pause block jobs on drain, Kevin Wolf, 2018/04/12
- Re: [Qemu-block] [PATCH 07/19] block: Really pause block jobs on drain, Paolo Bonzini, 2018/04/12
- Re: [Qemu-block] [PATCH 07/19] block: Really pause block jobs on drain, Kevin Wolf, 2018/04/12
- Re: [Qemu-block] [PATCH 07/19] block: Really pause block jobs on drain, Paolo Bonzini, 2018/04/12
- Re: [Qemu-block] [PATCH 07/19] block: Really pause block jobs on drain, Kevin Wolf, 2018/04/12
- Re: [Qemu-block] [PATCH 07/19] block: Really pause block jobs on drain, Paolo Bonzini, 2018/04/12