Re: [Qemu-devel] [PATCH 19/27] block/parallels: implement incorrect close detection

[Roman Kagan]

On Tue, Mar 10, 2015 at 11:51:13AM +0300, Denis V. Lunev wrote:
> The software driver must set inuse field in Parallels header to
> 0x746F6E59 when the image is opened in read-write mode. The presence of
> this magic in the header on open forces image consistency check.
> 
> There is an unfortunate trick here. We can not check for inuse in
> parallels_check as this will happen too late. It is possible to do
> that for simple check, but during the fix this would always report
> an error as the image was opened in BDRV_O_RDWR mode. Thus we save
> the flag in BDRVParallelsState for this.
> 
> On the other hand, nothing should be done to clear inuse in
> parallels_check. Generic close will do the job right.
> 
> Signed-off-by: Denis V. Lunev <address@hidden>
> CC: Roman Kagan <address@hidden>
> CC: Kevin Wolf <address@hidden>
> CC: Stefan Hajnoczi <address@hidden>
> ---
>  block/parallels.c | 50 ++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 50 insertions(+)

> @@ -462,6 +487,25 @@ static int parallels_open(BlockDriverState *bs, QDict 
> *options, int flags,
>      }
>      s->bat_bitmap = (uint32_t *)(s->header + 1);
>  
> +    if (le32_to_cpu(ph.inuse) == HEADER_INUSE_MAGIC) {
> +        /* Image was not closed correctly. The check is mandatory */
> +        s->header_unclean = true;
> +        if ((flags & BDRV_O_RDWR) && !(flags & BDRV_O_CHECK)) {
> +            error_setg(errp, "parallels: Image was not closed correctly; "
> +                       "cannot be opened read/write");
> +            ret = -EACCES;

-EBUSY?

Otherwise looks ok.

Roman.