On Wed, Oct 05, 2016 at 01:40:05AM +0100, Alasdair G Kergon wrote: > On Tue, Oct 04, 2016 at 04:39:28PM -0700, Andy Grover wrote: > > devicemapper is using uevents for: > > a. dm-verity detected corruption > > b. dm-multipath: path failed or reinstated > > c. dm device renamed > > d. there's also some use in md and bcache. > > > > devicemapper uses DM_EVENT ioctl (yuck) for: > > 1. dm-thin pool data/metadata filling up (hit a threshold) > > 2. dm-cache is now clean > > 3. dm-log flushed or log failed > > 4. dm-raid error detected or sync complete > > > there doesn't seem to be much technical differentiation between the > > two lists. > > The distinction in dm is that events in the first category may affect > the availability of the device: they represent major (and hopefully > rare) changes. > > Events in the second category are just notifications: no impact on /dev, > no need to trigger udev rules, and their use will continue to be > extended, and (rarely at the moment) could be frequent (which is no > problem for the existing polling-based mechanism). > > > Instead of using uevent for everything, we could go to a separate > > genetlink for 1-4 instead of making them use uevent like a-d, but we'd > > end up with two different userspace notification techniques. > > We see these as two different categories of notifications, and prefer > the greater flexibility a mechanism independent of uevents would > provide. The team has discussed several alternatives over the years but > didn't make a decision as we've not yet reached a point where we're > straining the existing mechanism too far. So, no changes need to be made? I'm confused here, who is wanting this changed? greg k-h -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
