The block backend changed in a way that flushing empty CDROM drives now
crashes.  Amend IDE to avoid doing so until the root problem can be
addressed for 2.11.

Original patch by John Snow <jsnow@redhat.com>.

Reported-by: Kieron Shorrock <kshorrock@paloaltonetworks.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 hw/ide/core.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/hw/ide/core.c b/hw/ide/core.c
index 0b48b64d3a..bea39536b0 100644
--- a/hw/ide/core.c
+++ b/hw/ide/core.c
@@ -1063,7 +1063,15 @@ static void ide_flush_cache(IDEState *s)
     s->status |= BUSY_STAT;
     ide_set_retry(s);
     block_acct_start(blk_get_stats(s->blk), &s->acct, 0, BLOCK_ACCT_FLUSH);
-    s->pio_aiocb = blk_aio_flush(s->blk, ide_flush_cb, s);
+
+    if (blk_bs(s->blk)) {
+        s->pio_aiocb = blk_aio_flush(s->blk, ide_flush_cb, s);
+    } else {
+        /* XXX blk_aio_flush() crashes when blk_bs(blk) is NULL, remove this
+         * temporary workaround when blk_aio_*() functions handle NULL blk_bs.
+         */
+        ide_flush_cb(s, 0);
+    }
 }
 
 static void ide_cfata_metadata_inquiry(IDEState *s)
-- 
2.13.3

On 08/09/2017 11:02 AM, Stefan Hajnoczi wrote:
> The block backend changed in a way that flushing empty CDROM drives now
> crashes.  Amend IDE to avoid doing so until the root problem can be
> addressed for 2.11.
> 
> Original patch by John Snow <jsnow@redhat.com>.
> 
> Reported-by: Kieron Shorrock <kshorrock@paloaltonetworks.com>
> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
> ---
>  hw/ide/core.c | 10 +++++++++-
>  1 file changed, 9 insertions(+), 1 deletion(-)

Reviewed-by: Eric Blake <eblake@redhat.com>

> 
> diff --git a/hw/ide/core.c b/hw/ide/core.c
> index 0b48b64d3a..bea39536b0 100644
> --- a/hw/ide/core.c
> +++ b/hw/ide/core.c
> @@ -1063,7 +1063,15 @@ static void ide_flush_cache(IDEState *s)
>      s->status |= BUSY_STAT;
>      ide_set_retry(s);
>      block_acct_start(blk_get_stats(s->blk), &s->acct, 0, BLOCK_ACCT_FLUSH);
> -    s->pio_aiocb = blk_aio_flush(s->blk, ide_flush_cb, s);
> +
> +    if (blk_bs(s->blk)) {
> +        s->pio_aiocb = blk_aio_flush(s->blk, ide_flush_cb, s);
> +    } else {
> +        /* XXX blk_aio_flush() crashes when blk_bs(blk) is NULL, remove this
> +         * temporary workaround when blk_aio_*() functions handle NULL blk_bs.
> +         */
> +        ide_flush_cb(s, 0);
> +    }
>  }
>  
>  static void ide_cfata_metadata_inquiry(IDEState *s)
> 

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
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