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[Qemu-devel] [PULL 08/35] block: Remove bdrv_drain_recurse()
From: |
Kevin Wolf |
Subject: |
[Qemu-devel] [PULL 08/35] block: Remove bdrv_drain_recurse() |
Date: |
Mon, 18 Jun 2018 18:44:37 +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>
Reviewed-by: Stefan Hajnoczi <address@hidden>
---
block/io.c | 36 +++---------------------------------
1 file changed, 3 insertions(+), 33 deletions(-)
diff --git a/block/io.c b/block/io.c
index 5820e73bb2..5f6d5eed52 100644
--- a/block/io.c
+++ b/block/io.c
@@ -219,38 +219,6 @@ 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,
@@ -318,7 +286,9 @@ 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++;
--
2.13.6
- [Qemu-devel] [PULL 03/35] block: Remove 'recursive' parameter from bdrv_drain_invoke(), (continued)
- [Qemu-devel] [PULL 03/35] block: Remove 'recursive' parameter from bdrv_drain_invoke(), Kevin Wolf, 2018/06/18
- [Qemu-devel] [PULL 05/35] tests/test-bdrv-drain: bdrv_drain_all() works in coroutines now, Kevin Wolf, 2018/06/18
- [Qemu-devel] [PULL 02/35] block: Use bdrv_do_drain_begin/end in bdrv_drain_all(), Kevin Wolf, 2018/06/18
- [Qemu-devel] [PULL 04/35] block: Don't manually poll in bdrv_drain_all(), Kevin Wolf, 2018/06/18
- [Qemu-devel] [PULL 06/35] block: Avoid unnecessary aio_poll() in AIO_WAIT_WHILE(), Kevin Wolf, 2018/06/18
- [Qemu-devel] [PULL 07/35] block: Really pause block jobs on drain, Kevin Wolf, 2018/06/18
- [Qemu-devel] [PULL 09/35] test-bdrv-drain: Add test for node deletion, Kevin Wolf, 2018/06/18
- [Qemu-devel] [PULL 11/35] test-bdrv-drain: Test node deletion in subtree recursion, Kevin Wolf, 2018/06/18
- [Qemu-devel] [PULL 01/35] test-bdrv-drain: bdrv_drain() works with cross-AioContext events, Kevin Wolf, 2018/06/18
- [Qemu-devel] [PULL 12/35] block: Don't poll in parent drain callbacks, Kevin Wolf, 2018/06/18
- [Qemu-devel] [PULL 08/35] block: Remove bdrv_drain_recurse(),
Kevin Wolf <=
- [Qemu-devel] [PULL 10/35] block: Drain recursively with a single BDRV_POLL_WHILE(), Kevin Wolf, 2018/06/18
- [Qemu-devel] [PULL 13/35] test-bdrv-drain: Graph change through parent callback, Kevin Wolf, 2018/06/18
- [Qemu-devel] [PULL 15/35] test-bdrv-drain: Test that bdrv_drain_invoke() doesn't poll, Kevin Wolf, 2018/06/18
- [Qemu-devel] [PULL 14/35] block: Defer .bdrv_drain_begin callback to polling phase, Kevin Wolf, 2018/06/18
- [Qemu-devel] [PULL 17/35] block: Move bdrv_drain_all_begin() out of coroutine context, Kevin Wolf, 2018/06/18
- [Qemu-devel] [PULL 16/35] block: Allow AIO_WAIT_WHILE with NULL ctx, Kevin Wolf, 2018/06/18
- [Qemu-devel] [PULL 20/35] test-bdrv-drain: Test graph changes in drain_all section, Kevin Wolf, 2018/06/18
- [Qemu-devel] [PULL 21/35] block: fix QEMU crash with scsi-hd and drive_del, Kevin Wolf, 2018/06/18
- [Qemu-devel] [PULL 18/35] block: ignore_bds_parents parameter for drain functions, Kevin Wolf, 2018/06/18
- [Qemu-devel] [PULL 19/35] block: Allow graph changes in bdrv_drain_all_begin/end sections, Kevin Wolf, 2018/06/18