Re: [PATCH 08/20] block: .bdrv_open is non-coroutine and unlocked

[Stefan Hajnoczi]

On Tue, Apr 25, 2023 at 07:31:46PM +0200, Kevin Wolf wrote:
> Drivers were a bit confused about whether .bdrv_open can run in a
> coroutine and whether or not it holds a graph lock.
> 
> It cannot keep a graph lock from the caller across the whole function
> because it both changes the graph (requires a writer lock) and does I/O
> (requires a reader lock). Therefore, it should take these locks
> internally as needed.
> 
> The functions used to be called in coroutine context during image
> creation. This was buggy for other reasons, and as of commit 32192301,
> all block drivers go through no_co_wrappers. So it is not called in
> coroutine context any more.
> 
> Fix qcow2 and qed to work with the correct assumptions: The graph lock
> needs to be taken internally instead of just assuming it's already
> there, and the coroutine path is dead code that can be removed.
> 
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
>  include/block/block_int-common.h |  8 ++++----
>  block.c                          |  6 +++---
>  block/qcow2.c                    | 15 ++++++---------
>  block/qed.c                      | 18 ++++++++----------
>  4 files changed, 21 insertions(+), 26 deletions(-)

Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>

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