[PATCH v2] qemu: Revoke access to mirror on failed blockcopy

[Pavel Mores]

On Thu, Apr 16, 2020 at 09:42:46AM +0200, Michal Privoznik wrote:
> When preparing to do a blockcopy, the mirror image is modified so
> that QEMU can access it. For instance, the mirror has seclabels
> set, if it is a NVMe disk it is detached from the host and so on.
> And usually, the restore is done upon successful finish of the
> blockcopy operation. But, if something fails then we need to
> explicitly revoke the access to the mirror image (and thus
> reattach NVMe disk back to the host).
> 
> Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1822538
> 
> Signed-off-by: Michal Privoznik <mprivozn at redhat.com>
> ---
> 
> diff to v1:
> - Fix call of qemuDomainStorageSourceChainAccessRevoke() so that it is
> called even if data = crdata = NULL.
> 
>  src/qemu/qemu_driver.c | 21 +++++++++++++--------
>  1 file changed, 13 insertions(+), 8 deletions(-)
> 
> diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
> index 31f199fdef..dfe0adaad8 100644
> --- a/src/qemu/qemu_driver.c
> +++ b/src/qemu/qemu_driver.c
> @@ -17950,6 +17950,7 @@ qemuDomainBlockCopyCommon(virDomainObjPtr vm,
>      virDomainDiskDefPtr disk = NULL;
>      int ret = -1;
>      bool need_unlink = false;
> +    bool need_revoke = false;
>      g_autoptr(virQEMUDriverConfig) cfg = virQEMUDriverGetConfig(driver);
>      const char *format = NULL;
>      bool mirror_reuse = !!(flags & VIR_DOMAIN_BLOCK_COPY_REUSE_EXT);
> @@ -18124,6 +18125,7 @@ qemuDomainBlockCopyCommon(virDomainObjPtr vm,
>  
>      if (qemuDomainStorageSourceChainAccessAllow(driver, vm, mirror) < 0)
>          goto endjob;
> +    need_revoke = true;
>  
>      if (blockdev) {
>          if (mirror_reuse) {
> @@ -18232,14 +18234,17 @@ qemuDomainBlockCopyCommon(virDomainObjPtr vm,
>  
>   endjob:
>      if (ret < 0 &&
> -        virDomainObjIsActive(vm) &&
> -        (data || crdata)) {
> -        qemuDomainObjEnterMonitor(driver, vm);
> -        if (data)
> -            qemuBlockStorageSourceChainDetach(priv->mon, data);
> -        if (crdata)
> -            qemuBlockStorageSourceAttachRollback(priv->mon, crdata->srcdata[0]);
> -        ignore_value(qemuDomainObjExitMonitor(driver, vm));
> +        virDomainObjIsActive(vm)) {
> +        if (data || crdata) {
> +            qemuDomainObjEnterMonitor(driver, vm);
> +            if (data)
> +                qemuBlockStorageSourceChainDetach(priv->mon, data);
> +            if (crdata)
> +                qemuBlockStorageSourceAttachRollback(priv->mon, crdata->srcdata[0]);
> +            ignore_value(qemuDomainObjExitMonitor(driver, vm));
> +        }
> +        if (need_revoke)
> +            qemuDomainStorageSourceChainAccessRevoke(driver, vm, mirror);
>      }
>      if (need_unlink && virStorageFileUnlink(mirror) < 0)
>          VIR_WARN("%s", _("unable to remove just-created copy target"));
> -- 
> 2.25.3
> 

Reviewed-by: Pavel Mores <pmores at redhat.com>