Hey! I recently starting playing with btrfs and subvolume, but it has left me puzzled: Distribution is Archlinux, Kernel is 3.4.6. >>> root@horus /mnt # mkfs.btrfs -L test /dev/sdb1 WARNING! - Btrfs Btrfs v0.19 IS EXPERIMENTAL WARNING! - see http://btrfs.wiki.kernel.org before using fs created label test on /dev/sdb1 nodesize 4096 leafsize 4096 sectorsize 4096 size 2.73TB Btrfs Btrfs v0.19 root@horus /mnt # mount /dev/sdb1 test root@horus /mnt # cd test root@horus /mnt/test # btrfs subvolume create sv1 Create subvolume './sv1' root@horus /mnt/test # btrfs subvolume create sv2 Create subvolume './sv2' root@horus /mnt/test # touch sv1/sv1.file root@horus /mnt/test # touch sv2/sv2.file root@horus /mnt/test # btrfs subvolume get-default . ID 256 top level 5 path sv1 ID 259 top level 5 path sv2 <<< What is the default subvolume now? How can I tell? >>> root@horus /mnt/test # btrfs subvolume set-default 259 . root@horus /mnt/test # btrfs subvolume get-default . ID 256 top level 5 path sv1 ID 259 top level 5 path sv2 <<< Seems to have changed nothing....? >>> root@horus /mnt/test # cd .. root@horus /mnt # umount test && mount /dev/sdb1 test root@horus /mnt # ls test sv2.file <<< Ah, sv2 seems to be default, like I had set it. >>> root@horus /mnt # btrfs subvolume set-default 5 test root@horus /mnt # umount test && /mnt # mount /dev/sdb1 test root@horus /mnt # ls test sv1/ sv2/ <<< Ok, 5 seems to be the root subvolume id. Is it always like that? I remembered to have read somewhere it was 0 ? (which makes a kind of more sense for me) >>> root@horus /mnt # btrfs subvolume set-default 256 test root@horus /mnt # umount test && mount /dev/sdb1 test root@horus /mnt # ls test sv1.file <<< Fine! But: >>> root@horus /mnt # btrfs subvolume set-default 0 test root@horus /mnt # umount test && mount /dev/sdb1 test root@horus /mnt # ls test sv1.file <<< set-default 0 seems to do nothing but does not produce an error either. What about subvolume 0? Still I can do: >>> root@horus /mnt # umount test root@horus /mnt # mount -o subvolid=0 /dev/sdb1 test root@horus /mnt # ls test sv1/ sv2/ <<< Ok, here 0 as subvolid works. What about subvolid=5? >>> root@horus /mnt # umount test root@horus /mnt # mount -o subvolid=5 /dev/sdb1 test root@horus /mnt # ls test sv1/ sv2/ <<< Works too. Sorry for the lengthy posting, but writing this posting has puzzled me even more I was yesterday. I hope someone could shed some light on it. Thanks! Florian -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
