On Tue, Aug 25, 2020 at 10:41:37AM +0200, Jan Kara wrote: > On Tue 25-08-20 10:11:29, yebin wrote: > > Your patch certainly can fix the problem with my testcases, but I don't > > think it's a good way. There are other paths that can call > > do_invalidatepage , for instance block ioctl to discard and zero_range. > > OK, good point! So my patch is a cleanup that stands on its own and we > should do it regardless. But I agree we need more to completely fix this. > I don't quite like the callback you've added just for this special case > (furthermore it grows size of every buffer_head and there can be lots of > those). But I agree with the general idea that we shouldn't discard buffers > that the filesystem is working with. > > In fact I believe that fallocate(2) and zeroout/discard ioctls should > return EBUSY if they are run against a mounted device because with 99% > probability something went wrong and you're accidentally discarding the > wrong device. But maybe I'm wrong. I'll run this idea through other fs > developers. I'm going through old patches, and I'm trying to figure out where did we end up on this issue? Did we come to a conclusion on this? One other thing which I noticed when looking at the original patch was shouldn't lvreduce not be allowed to run on a LV which has a mounted file system on its block device? - Ted
