block: Add bdrv_co_enter()/leave()

Add a pair of functions to temporarily move the current coroutine to the
AioContext of a given BlockDriverState.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20201005155855.256490-13-kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
This commit is contained in:
Kevin Wolf 2020-10-05 17:58:53 +02:00 committed by Markus Armbruster
parent 26b0b698c0
commit e336fd4c4b
2 changed files with 40 additions and 0 deletions

View file

@ -640,6 +640,23 @@ bool bdrv_debug_is_suspended(BlockDriverState *bs, const char *tag);
*/
AioContext *bdrv_get_aio_context(BlockDriverState *bs);
/**
* Move the current coroutine to the AioContext of @bs and return the old
* AioContext of the coroutine. Increase bs->in_flight so that draining @bs
* will wait for the operation to proceed until the corresponding
* bdrv_co_leave().
*
* Consequently, you can't call drain inside a bdrv_co_enter/leave() section as
* this will deadlock.
*/
AioContext *coroutine_fn bdrv_co_enter(BlockDriverState *bs);
/**
* Ends a section started by bdrv_co_enter(). Move the current coroutine back
* to old_ctx and decrease bs->in_flight again.
*/
void coroutine_fn bdrv_co_leave(BlockDriverState *bs, AioContext *old_ctx);
/**
* Transfer control to @co in the aio context of @bs
*/