file-posix: Add image locking to perm operations
This extends the permission bits of op blocker API to external using Linux OFD locks. Each permission in @perm and @shared_perm is represented by a locked byte in the image file. Requesting a permission in @perm is translated to a shared lock of the corresponding byte; rejecting to share the same permission is translated to a shared lock of a separate byte. With that, we use 2x number of bytes of distinct permission types. virtlockd in libvirt locks the first byte, so we do locking from a higher offset. Suggested-by: NKevin Wolf <kwolf@redhat.com> Signed-off-by: NFam Zheng <famz@redhat.com> Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Showing
想要评论请 注册 或 登录