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[Qemu-devel] [PATCH v5 12/13] block: Rewrite bdrv_close_all()
From: |
Max Reitz |
Subject: |
[Qemu-devel] [PATCH v5 12/13] block: Rewrite bdrv_close_all() |
Date: |
Tue, 3 Mar 2015 15:13:10 -0500 |
This patch rewrites bdrv_close_all(): Until now, all root BDSs have been
force-closed. This is bad because it can lead to cached data not being
flushed to disk.
Instead, try to make all reference holders relinquish their reference
voluntarily:
1. All BlockBackend users are handled by making all BBs simply eject
their BDS tree. Since a BDS can never be on top of a BB, this will
not cause any of the issues as seen with the force-closing of BDSs.
The references will be relinquished and any further access to the BB
will fail gracefully.
2. All BDSs which are owned by the monitor itself (because they do not
have a BB) are relinquished next.
3. Besides BBs and the monitor, block jobs and other BDSs are the only
things left that can hold a reference to BDSs. After every remaining
block job has been canceled, there should not be any BDSs left (and
the loop added here will always terminate (as long as NDEBUG is not
defined), because either all_bdrv_states will be empty or there will
not be any block job left to cancel, failing the assertion).
Signed-off-by: Max Reitz <address@hidden>
---
block.c | 26 ++++++++++++++++++--------
1 file changed, 18 insertions(+), 8 deletions(-)
diff --git a/block.c b/block.c
index fce9d5d..fe44bd2 100644
--- a/block.c
+++ b/block.c
@@ -1893,9 +1893,8 @@ static void bdrv_close(BlockDriverState *bs)
{
BdrvAioNotifier *ban, *ban_next;
- if (bs->job) {
- block_job_cancel_sync(bs->job);
- }
+ assert(!bs->job);
+
bdrv_drain_all(); /* complete I/O */
bdrv_flush(bs);
bdrv_drain_all(); /* in case flush left pending I/O */
@@ -1947,13 +1946,24 @@ static void bdrv_close(BlockDriverState *bs)
void bdrv_close_all(void)
{
BlockDriverState *bs;
+ AioContext *aio_context;
- QTAILQ_FOREACH(bs, &bdrv_states, device_list) {
- AioContext *aio_context = bdrv_get_aio_context(bs);
+ blockdev_close_all_bdrv_states();
+ blk_remove_all_bs();
- aio_context_acquire(aio_context);
- bdrv_close(bs);
- aio_context_release(aio_context);
+ while (!QTAILQ_EMPTY(&all_bdrv_states)) {
+ QTAILQ_FOREACH(bs, &all_bdrv_states, bs_list) {
+ aio_context = bdrv_get_aio_context(bs);
+
+ aio_context_acquire(aio_context);
+ if (bs->job) {
+ block_job_cancel_sync(bs->job);
+ aio_context_release(aio_context);
+ break;
+ }
+ aio_context_release(aio_context);
+ }
+ assert(bs);
}
}
--
2.1.0
- [Qemu-devel] [PATCH v5 02/13] iotests: Make redirecting qemu's stderr optional, (continued)
- [Qemu-devel] [PATCH v5 02/13] iotests: Make redirecting qemu's stderr optional, Max Reitz, 2015/03/03
- [Qemu-devel] [PATCH v5 06/13] block: Use blk_remove_bs() in blk_delete(), Max Reitz, 2015/03/03
- [Qemu-devel] [PATCH v5 13/13] iotests: Add test for multiple BB on BDS tree, Max Reitz, 2015/03/03
- [Qemu-devel] [PATCH v5 05/13] block: Move BDS close notifiers into BB, Max Reitz, 2015/03/03
- [Qemu-devel] [PATCH v5 10/13] blockdev: Keep track of monitor-owned BDS, Max Reitz, 2015/03/03
- [Qemu-devel] [PATCH v5 12/13] block: Rewrite bdrv_close_all(),
Max Reitz <=
- [Qemu-devel] [PATCH v5 09/13] block: Add list of all BlockDriverStates, Max Reitz, 2015/03/03
- [Qemu-devel] [PATCH v5 04/13] quorum: Fix close path, Max Reitz, 2015/03/03
- [Qemu-devel] [PATCH v5 11/13] block: Add blk_remove_all_bs(), Max Reitz, 2015/03/03
- Re: [Qemu-devel] [PATCH v5 00/13] block: Rework bdrv_close_all(), Kevin Wolf, 2015/03/04