Re: [Qemu-devel] [Qemu-block] [PATCH v2 1/1] block-backend: allow flush on devices with open tray

[Jeff Cody <jcody@redhat.com>]

On Thu, Sep 01, 2016 at 05:56:52PM -0400, John Snow wrote:
> If a device still has an attached BDS because the medium has not yet
> been removed, we will be unable to migrate to a new host because
> blk_flush will return an error for that backend.
> 
> Replace the call to blk_is_available to blk_is_inserted to weaken
> the check and allow flushes from the backend to work, while still
> disallowing flushes from the frontend/device model to work.
> 
> This fixes a regression present in 2.6.0 caused by the following commit:
> fe1a9cbc339bb54d20f1ca4c1e8788d16944d5cf
> block: Move some bdrv_*_all() functions to BB
> 
> Signed-off-by: John Snow <jsnow@redhat.com>

Reviewed-by: Jeff Cody <jcody@redhat.com>


I don't have any real suggestions for a test either, except to point you to
test 091 which does a live migration test (which is not very helpful, I
know).


> ---
>  block/block-backend.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/block/block-backend.c b/block/block-backend.c
> index effa038..36a32c3 100644
> --- a/block/block-backend.c
> +++ b/block/block-backend.c
> @@ -1058,7 +1058,7 @@ BlockAIOCB *blk_aio_pwritev(BlockBackend *blk, int64_t offset,
>  BlockAIOCB *blk_aio_flush(BlockBackend *blk,
>                            BlockCompletionFunc *cb, void *opaque)
>  {
> -    if (!blk_is_available(blk)) {
> +    if (!blk_is_inserted(blk)) {
>          return blk_abort_aio_request(blk, cb, opaque, -ENOMEDIUM);
>      }
>  
> @@ -1118,7 +1118,7 @@ int blk_co_pdiscard(BlockBackend *blk, int64_t offset, int count)
>  
>  int blk_co_flush(BlockBackend *blk)
>  {
> -    if (!blk_is_available(blk)) {
> +    if (!blk_is_inserted(blk)) {
>          return -ENOMEDIUM;
>      }
>  
> @@ -1127,7 +1127,7 @@ int blk_co_flush(BlockBackend *blk)
>  
>  int blk_flush(BlockBackend *blk)
>  {
> -    if (!blk_is_available(blk)) {
> +    if (!blk_is_inserted(blk)) {
>          return -ENOMEDIUM;
>      }
>  
> -- 
> 2.7.4
> 
>