On Wed, Dec 01, 2010 at 05:52:07PM -0800, Michael Vrable wrote: > On Wed, Dec 01, 2010 at 03:09:52PM -0500, Josef Bacik wrote: > >On Wed, Dec 01, 2010 at 03:00:08PM -0500, J. Bruce Fields wrote: > >>I think you're already fine: > >> > >> # mkdir TMP > >> # dd if=/dev/zero of=TMP-image bs=1M count=512 > >> # mkfs.btrfs TMP-image > >> # mount -oloop TMP-image TMP/ > >> # btrfs subvolume create sub-a > >> # btrfs subvolume create sub-b > >> ../readdir-inos . > >> . 256 256 > >> .. 256 4130609 > >> sub-a 256 256 > >> sub-b 257 256 > >> > >>Where readdir-inos is my silly test program below, and the first > >>number is from readdir, the second from stat. > >> > > > >Heh as soon as I typed my email I went and actually looked at the > >code, looks like for readdir we fill in the root id, which will be > >unique, so hotdamn we are good and I don't have to use a stupid > >incompat flag. Thanks for checking that :), > > Except, aren't the inode numbers within a filesystem and the > sunbvolume tree IDs allocated out of separate namespaces? I don't > think there's anything preventing a file/directory from having an > inode number that clashes with one of the snapshots. > > In fact, this already happens in the example above: "." (inode 256 > in the root subvolume) and "sub-a" (subvolume ID 256). Oof, yes, I overlooked that. > (Though I still don't understand the semantics well enough to say > whether we need all the inode numbers returned by readdir to be > distinct.) On normal mounts they're the number of the inode that was mounted over, so normally they'd be unique across the parent filesystem..... I don't know if anything depends on that. --b. -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
