We introduced the auto-read-only option to fix the problem that block jobs that reopen a backing file read-write don't work any more when all nodes are created individually with -blockdev. The reason is that bs->file of these backing files doesn't inherit the read-only option from the format layer node any more if it's created separately.
The way auto-read-only was designed to fix this is that it just always opens the file node read-write if it can, so reopening the format layer node is enough to make the backing file writable when necessary. This works in principle, but not when libvirt uses sVirt: Then QEMU doesn't even have the permissions to open the image file read-write until libvirt performs an operation where write access is needed. This series changes auto-read-only so that it works dynamically and automatically reopens the file read-only or read-write depending on the permissions that users attached to the node requested. See also: https://bugzilla.redhat.com/show_bug.cgi?id=1685989 Kevin Wolf (8): tests/virtio-blk-test: Disable auto-read-only block: Avoid useless local_err block: Make permission changes in reopen less wrong file-posix: Factor out raw_reconfigure_getfd() file-posix: Store BDRVRawState.reopen_state during reopen file-posix: Lock new fd in raw_reopen_prepare() file-posix: Prepare permission code for fd switching file-posix: Make auto-read-only dynamic block.c | 39 +++--- block/file-posix.c | 243 ++++++++++++++++++++++++++----------- tests/virtio-blk-test.c | 2 +- tests/qemu-iotests/232.out | 12 +- 4 files changed, 203 insertions(+), 93 deletions(-) -- 2.20.1
