On Wed, Oct 24, 2018 at 03:24:29PM -0400, Mikulas Patocka wrote: > What about allocating a big file, using the FIEMAP ioctl to find the For reference, dmfilemapd in the lvm2 tree (in daemons/) uses FIEMAP (in libdm/libdm-stats.c) for monitoring I/O by file. > If you decide that rollback is no longer needed, you just unload the > snapshot target and delete the big file. If you decide that you want to > rollback, you can use the snapshot merge functionality (or you can write a > userspace utility that does offline merge). There's some old code from Mark McLoughlin for userspace snapshot merging here: https://people.gnome.org/~markmc/code/merge-dm-snapshot.c Alasdair
