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[PATCH v2 05/11] block: Fix AioContext locking in bdrv_attach_child_comm
From: |
Kevin Wolf |
Subject: |
[PATCH v2 05/11] block: Fix AioContext locking in bdrv_attach_child_common() |
Date: |
Mon, 5 Jun 2023 10:57:05 +0200 |
The function can move the child node to a different AioContext. In this
case, it also must take the AioContext lock for the new context before
calling functions that require the caller to hold the AioContext for the
child node.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
block.c | 21 ++++++++++++++++++++-
1 file changed, 20 insertions(+), 1 deletion(-)
diff --git a/block.c b/block.c
index 3ed943467a..508e0e396b 100644
--- a/block.c
+++ b/block.c
@@ -2989,6 +2989,10 @@ static TransactionActionDrv bdrv_attach_child_common_drv
= {
* Function doesn't update permissions, caller is responsible for this.
*
* Returns new created child.
+ *
+ * The caller must hold the AioContext lock for @child_bs. Both @parent_bs and
+ * @child_bs can move to a different AioContext in this function. Callers must
+ * make sure that their AioContext locking is still correct after this.
*/
static BdrvChild *bdrv_attach_child_common(BlockDriverState *child_bs,
const char *child_name,
@@ -2999,7 +3003,7 @@ static BdrvChild
*bdrv_attach_child_common(BlockDriverState *child_bs,
Transaction *tran, Error **errp)
{
BdrvChild *new_child;
- AioContext *parent_ctx;
+ AioContext *parent_ctx, *new_child_ctx;
AioContext *child_ctx = bdrv_get_aio_context(child_bs);
assert(child_class->get_parent_desc);
@@ -3050,6 +3054,12 @@ static BdrvChild
*bdrv_attach_child_common(BlockDriverState *child_bs,
}
}
+ new_child_ctx = bdrv_get_aio_context(child_bs);
+ if (new_child_ctx != child_ctx) {
+ aio_context_release(child_ctx);
+ aio_context_acquire(new_child_ctx);
+ }
+
bdrv_ref(child_bs);
/*
* Let every new BdrvChild start with a drained parent. Inserting the child
@@ -3079,11 +3089,20 @@ static BdrvChild
*bdrv_attach_child_common(BlockDriverState *child_bs,
};
tran_add(tran, &bdrv_attach_child_common_drv, s);
+ if (new_child_ctx != child_ctx) {
+ aio_context_release(new_child_ctx);
+ aio_context_acquire(child_ctx);
+ }
+
return new_child;
}
/*
* Function doesn't update permissions, caller is responsible for this.
+ *
+ * The caller must hold the AioContext lock for @child_bs. Both @parent_bs and
+ * @child_bs can move to a different AioContext in this function. Callers must
+ * make sure that their AioContext locking is still correct after this.
*/
static BdrvChild *bdrv_attach_child_noperm(BlockDriverState *parent_bs,
BlockDriverState *child_bs,
--
2.40.1
- [PATCH v2 00/11] block: Re-enable the graph lock, Kevin Wolf, 2023/06/05
- [PATCH v2 01/11] iotests: Test active commit with iothread and background I/O, Kevin Wolf, 2023/06/05
- [PATCH v2 03/11] test-block-iothread: Lock AioContext for blk_insert_bs(), Kevin Wolf, 2023/06/05
- [PATCH v2 04/11] block: Fix AioContext locking in bdrv_open_child(), Kevin Wolf, 2023/06/05
- [PATCH v2 06/11] block: Fix AioContext locking in bdrv_reopen_parse_file_or_backing(), Kevin Wolf, 2023/06/05
- [PATCH v2 07/11] block: Fix AioContext locking in bdrv_open_inherit(), Kevin Wolf, 2023/06/05
- [PATCH v2 09/11] blockjob: Fix AioContext locking in block_job_add_bdrv(), Kevin Wolf, 2023/06/05
- [PATCH v2 02/11] qdev-properties-system: Lock AioContext for blk_insert_bs(), Kevin Wolf, 2023/06/05
- [PATCH v2 05/11] block: Fix AioContext locking in bdrv_attach_child_common(),
Kevin Wolf <=
- [PATCH v2 11/11] Revert "graph-lock: Disable locking for now", Kevin Wolf, 2023/06/05
- [PATCH v2 10/11] graph-lock: Unlock the AioContext while polling, Kevin Wolf, 2023/06/05
- [PATCH v2 08/11] block: Fix AioContext locking in bdrv_open_backing_file(), Kevin Wolf, 2023/06/05
- Re: [PATCH v2 00/11] block: Re-enable the graph lock, Stefan Hajnoczi, 2023/06/07