[RFC PATCH 0/2] Allow changing bs->file on reopen

[Alberto Garcia <berto@igalia.com>]

Hi,

during the past months we talked about making x-blockdev-reopen stable
API, and one of the missing things was having support for changing
bs->file. See here for the discusssion (I can't find the message from
Kashyap that started the thread in the web archives):

   https://lists.gnu.org/archive/html/qemu-block/2020-10/msg00922.html

I was testing this and one of the problems that I found was that
removing a filter node using this command is tricky because of the
permission system, see here for details:

   https://lists.gnu.org/archive/html/qemu-block/2020-12/msg00092.html

The good news is that Vladimir posted a set of patches that changes
the way that permissions are updated on reopen:

   https://lists.gnu.org/archive/html/qemu-block/2020-11/msg00745.html

I was testing if this would be useful to solve the problem that I
mentioned earlier and it seems to be the case so I wrote a patch to
add support for changing bs->file, along with a couple of test cases.

This is still an RFC but you can see the idea.

These patches apply on top of Vladimir's branch:

git: https://src.openvz.org/scm/~vsementsov/qemu.git
tag: up-block-topologic-perm-v2

Opinions are very welcome!

Berto

Alberto Garcia (2):
  block: Allow changing bs->file on reopen
  iotests: Update 245 to support replacing files with x-blockdev-reopen

 include/block/block.h      |  1 +
 block.c                    | 61 ++++++++++++++++++++++++++++++++++++++
 tests/qemu-iotests/245     | 61 +++++++++++++++++++++++++++++++++++---
 tests/qemu-iotests/245.out |  4 +--
 4 files changed, 121 insertions(+), 6 deletions(-)

-- 
2.20.1