On Wed, Apr 27, 2011 at 08:19:13PM -0400, Mike Snitzer wrote: > Discards pose a problem for the snapshot-origin target because they are > treated as writes. Treating a discard as a write would trigger a > copyout to the snapshot. Such copyout can prove too costly in the face > of otherwise benign scenarios (e.g. create a snapshot and then mkfs.ext4 > the origin -- mkfs.ext4 discards the entire volume by default, which > would copyout the entire origin volume to the snapshot). You also need to make sure that we don't claim discard_zeroes_data for the origin volume in this case. Especially as ext4 started to rely on this actually working (very bad idea IMHO, but that's another story) -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
