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[Qemu-devel] [PULL 29/48] block: Rewrite bdrv_close_all()
From: |
Kevin Wolf |
Subject: |
[Qemu-devel] [PULL 29/48] block: Rewrite bdrv_close_all() |
Date: |
Fri, 29 Jan 2016 18:37:35 +0100 |
From: Max Reitz <address@hidden>
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>
Signed-off-by: Kevin Wolf <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);
}
}
--
1.8.3.1
- [Qemu-devel] [PULL 19/48] virtio-blk: Functions for op blocker management, (continued)
- [Qemu-devel] [PULL 19/48] virtio-blk: Functions for op blocker management, Kevin Wolf, 2016/01/29
- [Qemu-devel] [PULL 20/48] virtio-scsi: Catch BDS-BB removal/insertion, Kevin Wolf, 2016/01/29
- [Qemu-devel] [PULL 25/48] block: Make bdrv_close() static, Kevin Wolf, 2016/01/29
- [Qemu-devel] [PULL 30/48] iotests: Add test for multiple BB on BDS tree, Kevin Wolf, 2016/01/29
- [Qemu-devel] [PULL 26/48] block: Add list of all BlockDriverStates, Kevin Wolf, 2016/01/29
- [Qemu-devel] [PULL 34/48] qcow: Assign bs->file->bs to file in qcow_co_get_block_status, Kevin Wolf, 2016/01/29
- [Qemu-devel] [PULL 37/48] iscsi: Assign bs to file in iscsi_co_get_block_status, Kevin Wolf, 2016/01/29
- [Qemu-devel] [PULL 39/48] qed: Assign bs->file->bs to file in bdrv_qed_co_get_block_status, Kevin Wolf, 2016/01/29
- [Qemu-devel] [PULL 32/48] block: acquire in bdrv_query_image_info, Kevin Wolf, 2016/01/29
- [Qemu-devel] [PULL 35/48] qcow2: Assign bs->file->bs to file in qcow2_co_get_block_status, Kevin Wolf, 2016/01/29
- [Qemu-devel] [PULL 29/48] block: Rewrite bdrv_close_all(),
Kevin Wolf <=
- [Qemu-devel] [PULL 27/48] blockdev: Keep track of monitor-owned BDS, Kevin Wolf, 2016/01/29
- [Qemu-devel] [PULL 36/48] raw: Assign bs to file in raw_co_get_block_status, Kevin Wolf, 2016/01/29
- [Qemu-devel] [PULL 41/48] vdi: Assign bs->file->bs to file in vdi_co_get_block_status, Kevin Wolf, 2016/01/29
- [Qemu-devel] [PULL 28/48] block: Add blk_remove_all_bs(), Kevin Wolf, 2016/01/29
- [Qemu-devel] [PULL 40/48] sheepdog: Assign bs to file in sd_co_get_block_status, Kevin Wolf, 2016/01/29
- [Qemu-devel] [PULL 38/48] parallels: Assign bs->file->bs to file in parallels_co_get_block_status, Kevin Wolf, 2016/01/29
- [Qemu-devel] [PULL 42/48] vpc: Assign bs->file->bs to file in vpc_co_get_block_status, Kevin Wolf, 2016/01/29
- [Qemu-devel] [PULL 44/48] vmdk: Return extent's file in bdrv_get_block_status, Kevin Wolf, 2016/01/29
- [Qemu-devel] [PULL 33/48] block: Add "file" output parameter to block status query functions, Kevin Wolf, 2016/01/29
- [Qemu-devel] [PULL 31/48] iotests: Add test for block jobs and BDS ejection, Kevin Wolf, 2016/01/29