On Thu, Apr 08, 2010 at 08:51:42AM -0700, David Brown wrote: > I am developing backup software (<http://github.com/d3zd3z/jpool> for > the curious), and have been doing some testing with btrfs. > > Jpool currently uses the blkid database to map between device numbers > (st_rdev) and the uuid of a particular filesystem. I originally > created this because LVM device numbers sometimes changed. Jpool > uses the uuid to track files within a tree. > > The subvolumes on btrfs seem to be getting ephemeral device numbers, > which aren't listed in the blkid output. The program falls back to > using the mountpoint, but that misses mountpoints changing. > > - Do subvolumes in btrfs even have separate uuids, and should they?
I think yes, in libblkid code is: blkid_probe_set_uuid(pr, bfs->fsid); blkid_probe_set_uuid_as(pr, bfs->dev_item.uuid, "UUID_SUB"); so there should be two UUIDs for the device. However, I'd like to see more information about btrfs UUIDs. BTW, see my old discussion with Andreas about UUIDs: http://marc.info/?l=linux-fsdevel&m=126754081900406&w=2 Karel -- Karel Zak <k...@redhat.com> http://karelzak.blogspot.com -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
