Re: [Qemu-devel] [PATCH 4/4] scsi: add persistent reservation manager using qemu-pr-helper

["Daniel P. Berrange" <berrange@redhat.com>]

On Tue, Sep 19, 2017 at 12:24:34PM +0200, Paolo Bonzini wrote:
> This adds a concrete subclass of pr-manager that talks to qemu-pr-helper.
> 
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
> v1->v2: fixed string property double-free
>         fixed/cleaned up error handling
>         handle buffer underrun
> 
>  scsi/Makefile.objs       |   2 +-
>  scsi/pr-manager-helper.c | 302 +++++++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 303 insertions(+), 1 deletion(-)
>  create mode 100644 scsi/pr-manager-helper.c
> 
> diff --git a/scsi/Makefile.objs b/scsi/Makefile.objs
> index 5496d2ae6a..4d25e476cf 100644
> --- a/scsi/Makefile.objs
> +++ b/scsi/Makefile.objs
> @@ -1,3 +1,3 @@
>  block-obj-y += utils.o
>  
> -block-obj-$(CONFIG_LINUX) += pr-manager.o
> +block-obj-$(CONFIG_LINUX) += pr-manager.o pr-manager-helper.o
> diff --git a/scsi/pr-manager-helper.c b/scsi/pr-manager-helper.c
> new file mode 100644
> index 0000000000..063fd35dee
> --- /dev/null
> +++ b/scsi/pr-manager-helper.c

> +/* Called with lock held.  */
> +static int pr_manager_helper_read(PRManagerHelper *pr_mgr,
> +                                  void *buf, int sz, Error **errp)
> +{
> +    ssize_t r = qio_channel_read_all(pr_mgr->ioc, buf, sz, errp);

The return value isn't ssize_t - it just returns 0 on success, -1 on
error, never a bytes count since it always reads all requested bytes
and treats EOF as an error condition.

> +
> +    if (r < 0) {
> +        object_unref(OBJECT(pr_mgr->ioc));
> +        pr_mgr->ioc = NULL;
> +        return -EINVAL;
> +    }
> +
> +    return 0;
> +}
> +

Regards,
Daniel
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