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[Qemu-devel] [PATCH v9 14/16] block: Rewrite bdrv_close_all()
From: |
Max Reitz |
Subject: |
[Qemu-devel] [PATCH v9 14/16] block: Rewrite bdrv_close_all() |
Date: |
Fri, 29 Jan 2016 16:36:14 +0100 |
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 | 34 ++++++++++++++++++++++++++--------
1 file changed, 26 insertions(+), 8 deletions(-)
diff --git a/block.c b/block.c
index d687d2c..ff1aafc 100644
--- a/block.c
+++ b/block.c
@@ -2145,9 +2145,7 @@ static void bdrv_close(BlockDriverState *bs)
{
BdrvAioNotifier *ban, *ban_next;
- if (bs->job) {
- block_job_cancel_sync(bs->job);
- }
+ assert(!bs->job);
/* Disable I/O limits and drain all pending throttled requests */
if (bs->throttle_state) {
@@ -2214,13 +2212,33 @@ 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);
+ /* Drop references from requests still in flight, such as canceled block
+ * jobs whose AIO context has not been polled yet */
+ bdrv_drain_all();
- aio_context_acquire(aio_context);
- bdrv_close(bs);
- aio_context_release(aio_context);
+ blk_remove_all_bs();
+ blockdev_close_all_bdrv_states();
+
+ /* Cancel all block jobs */
+ 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);
+ }
+
+ /* All the remaining BlockDriverStates are referenced directly or
+ * indirectly from block jobs, so there needs to be at least one BDS
+ * directly used by a block job */
+ assert(bs);
}
}
--
2.7.0
- [Qemu-devel] [PATCH v9 03/16] block: Add BB-BDS remove/insert notifiers, (continued)
- [Qemu-devel] [PATCH v9 03/16] block: Add BB-BDS remove/insert notifiers, Max Reitz, 2016/01/29
- [Qemu-devel] [PATCH v9 02/16] iotests: Add test for eject under NBD server, Max Reitz, 2016/01/29
- [Qemu-devel] [PATCH v9 05/16] virtio-scsi: Catch BDS-BB removal/insertion, Max Reitz, 2016/01/29
- [Qemu-devel] [PATCH v9 06/16] nbd: Switch from close to eject notifier, Max Reitz, 2016/01/29
- [Qemu-devel] [PATCH v9 07/16] block: Remove BDS close notifier, Max Reitz, 2016/01/29
- [Qemu-devel] [PATCH v9 08/16] block: Use blk_remove_bs() in blk_delete(), Max Reitz, 2016/01/29
- [Qemu-devel] [PATCH v9 09/16] blockdev: Use blk_remove_bs() in do_drive_del(), Max Reitz, 2016/01/29
- [Qemu-devel] [PATCH v9 11/16] block: Add list of all BlockDriverStates, Max Reitz, 2016/01/29
- [Qemu-devel] [PATCH v9 13/16] block: Add blk_remove_all_bs(), Max Reitz, 2016/01/29
- [Qemu-devel] [PATCH v9 10/16] block: Make bdrv_close() static, Max Reitz, 2016/01/29
- [Qemu-devel] [PATCH v9 14/16] block: Rewrite bdrv_close_all(),
Max Reitz <=
- [Qemu-devel] [PATCH v9 12/16] blockdev: Keep track of monitor-owned BDS, Max Reitz, 2016/01/29
- [Qemu-devel] [PATCH v9 15/16] iotests: Add test for multiple BB on BDS tree, Max Reitz, 2016/01/29
- [Qemu-devel] [PATCH v9 16/16] iotests: Add test for block jobs and BDS ejection, Max Reitz, 2016/01/29