On Thu, Jun 01 2023 at 3:28P -0400, Christoph Hellwig <hch@xxxxxx> wrote: > Hi all, > > I've recently got a report where a file system can write to a read-only > block device, and while I've not found the root cause yet, it is very > clear that we should not prevents writes to read-only at all. > > This did in fact get fixed 5 years ago, but Linus reverted it as older > lvm2 tools relying on this broken behavior. This series tries to > restore it, although I'm still worried about thee older lvm2 tools > to be honest. Question to the device mapper maintainers: is the > any good way to work around that behavior in device mapper if needed > instead of leaving the core block layer and drivers exposed? Given the block core change (in patch 3) _and_ old lvm2 code: it'll obviously fail. Not sure of a crafty hack to workaround. Hopefully 5 year old lvm2 remains tightly coupled to kernels of the same vintage and we get lucky moving forward. So I agree with Linus, worth trying this simple change again and seeing if there is fallout. Revert/worry about it again as needed. Mike
