On Thu, Aug 2, 2018 at 8:16 AM WGH <wgh@xxxxxxxxx> wrote: > > On 08/02/2018 04:31 PM, Ilya Dryomov wrote: > > > > From a quick look, --permission r sets DM_READONLY_FLAG, which makes dm > > mark the disk read-only with set_disk_ro(dm_disk(md), 1) in do_resume(). > > A bit later it tries to write to the disk from write_header(): > > > > return chunk_io(ps, ps->header_area, 0, REQ_OP_WRITE, 0, 1); > > > > Thanks, > > > > Ilya > > After further investigation, this was fixed on lvm2 side (userspace) in > https://sourceware.org/git/?p=lvm2.git;a=commit;h=a6fdb9d9d70f51c49ad11a87ab4243344e6701a3 > (snapshot: keep COW writable for read-only volumes). > > So I guess that's it. Time to poke my distribution package maintainers > to bump the package version. That is *not* how kernel development is supposed to work. If your script used to work, it should continue to work. Why did it use to work despite that read-only flag? And what was it that actually broke this? We remain bug-for-bug compatible with older kernel versions when people depend on the bugs. Unless the old bugs are security issues, and even then we try to make it _look_ like we work the same way. Or was it a user-space lvm tool that broke in the first place, and the kernel release update was a red herring? Linus
