Re: [PATCH 1/2] block/mirror: Fix mirror_top's permissions

[Eric Blake <eblake@redhat.com>]

On 2/11/21 11:22 AM, Max Reitz wrote:
> mirror_top currently shares all permissions, and takes only the WRITE
> permission (if some parent has taken that permission, too).
> 
> That is wrong, though; mirror_top is a filter, so it should take
> permissions like any other filter does.  For example, if the parent
> needs CONSISTENT_READ, we need to take that, too, and if it cannot share
> the WRITE permission, we cannot share it either.
> 
> The exception is when mirror_top is used for active commit, where we
> cannot take CONSISTENT_READ (because it is deliberately unshared above
> the base node) and where we must share WRITE (so that it is shared for
> all images in the backing chain, so the mirror job can take it for the
> target BB).
> 
> Signed-off-by: Max Reitz <mreitz@redhat.com>
> ---
>  block/mirror.c | 32 +++++++++++++++++++++++++-------
>  1 file changed, 25 insertions(+), 7 deletions(-)
> 

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

-- 
Eric Blake, Principal Software Engineer
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