On 27.05.2011 10:01, Stephane Chazelas wrote: > 2011-05-26 22:22:03 +0100, Stephane Chazelas: [...] >> I get a btrfs sub list output that I don't understand: >> >> # btrfs sub list /backup/ ID 257 top level 5 path >> u1/linux/lvm+btrfs/storage/data/data ID 260 top level 5 path >> u2/linux/lvm/linux/var/data ID 262 top level 5 path >> u1/linux/lvm+btrfs/storage/data/snapshots/2010-10-11 ID 263 top >> level 5 path u2/linux/lvm/linux/home/snapshots/2011-04-07 ID 264 >> top level 5 path u2/linux/lvm/linux/root/snapshots/2011-04-07 ID >> 265 top level 5 path u2/linux/lvm/linux/var/snapshots/2011-04-07 >> ID 266 top level 5 path >> u1/linux/lvm+btrfs/storage/data/snapshots/2010-10-26 ID 267 top >> level 5 path u1/linux/lvm+btrfs/storage/data/snapshots/2010-11-08 >> ID 268 top level 5 path >> u1/linux/lvm+btrfs/storage/data/snapshots/2010-11-22 ID 269 top >> level 5 path u1/linux/lvm+btrfs/storage/data/snapshots/2010-12-15 >> ID 270 top level 5 path >> u2/linux/lvm/linux/home/snapshots/2011-04-14 ID 271 top level 5 >> path u2/linux/lvm/linux/root/snapshots/2011-04-14 ID 272 top >> level 5 path u2/linux/lvm/linux/var/snapshots/2011-04-14 ID 273 >> top level 5 path >> u1/linux/lvm+btrfs/storage/data/snapshots/2010-12-29 ID 274 top >> level 5 path u1/linux/lvm+btrfs/storage/data/snapshots/2011-01-26 >> ID 275 top level 5 path >> u1/linux/lvm+btrfs/storage/data/snapshots/2011-03-07 ID 276 top >> level 5 path u1/linux/lvm+btrfs/storage/data/snapshots/2011-04-01 >> ID 277 top level 5 path u2/linux/lvm/linux/home/data ID 278 top >> level 5 path u2/linux/lvm/linux/home/snapshots/2011-04-27 ID 279 >> top level 5 path u2/linux/lvm/linux/root/snapshots/2011-04-27 ID >> 280 top level 5 path u2/linux/lvm/linux/var/snapshots/2011-04-27 >> ID 281 top level 5 path u3:10022/vm+xfs@u9/xvda1/g1/v4/data ID >> 282 top level 5 path >> u3:10022/vm+xfs@u9/xvda1/g1/v4/snapshots/2011-05-19 ID 283 top >> level 5 path u5/vm+xfs@u9/xvda1/g1/v5/data ID 284 top level 5 >> path u6:10022/vm+xfs@u8/xvda1/g8/v3/data ID 286 top level 5 path >> u5/vm+xfs@u9/xvda1/g1/v5/snapshots/2011-05-24 ID 287 top level >> 285 path data ID 288 top level 5 path >> u4/vm+xfs@u9/xvda1/g1/v1/data ID 289 top level 5 path >> u4/vm+xfs@u9/xvda1/g1/v1/snapshots/2011-03-11 ID 290 top level 5 >> path u4/vm+xfs@u9/xvda1/g1/v2/data ID 291 top level 5 path >> u4/vm+xfs@u9/xvda1/g1/v2/snapshots/2011-05-11 ID 292 top level 5 >> path u4/vm+xfs@u9/xvda1/g1/v1/snapshots/2011-05-11 > [...] >> There is no "/backup/data" directory. There is however a >> /backup/u6:10022/vm+xfs@u8/xvda1/g8/v3/snapshots/2011-03-30 that >> contains the same thing as what I get if I mount the fs with >> subvolid=287. And I did do a btrfs sub snap data >> snapshots/2011-03/30 there. >> >> What could be the cause of that? How to fix it? >> >> In case that matters, there used to be more components in the >> path of u6:10022/vm+xfs@u8/xvda1/g8/v3/data. > [...] > > I tried deleting the > /backup/u6:10022/vm+xfs@u8/xvda1/g8/v3/snapshots/2011-03-30 > subvolume (what seems to be id 287) and I get: > > # btrfs sub delete snapshots/2011-03-30 Delete subvolume > '/backup/u6:10022/vm+xfs@u8/xvda1/g8/v3/snapshots/2011-03-30' > ERROR: cannot delete > '/backup/u6:10022/vm+xfs@u8/xvda1/g8/v3/snapshots/2011-03-30' > > With a strace, it tells me: > > ioctl(3, 0x5000940f, 0x7fffc7841a80) = -1 ENOTEMPTY (Directory > not empty) > > Then I realised that there was a "data" directory in there and > that snapshots/2011-03-30 was actually id 285 (which doesn't appear > in the btrfs sub list) and "snapshots/2011-03-30/data" is id 287. > > What do those top-level IDs mean by the way? The top-level ID associated with a subvolume is NOT the ID of this particular subvolume but of the subvolume containing it. Since the "root/initial" (sub-)volume has always ID 0, the subvolumes of "depth" 1 will all have top-level ID set to 0. You need those top-level IDs to correctly mount a specific subvolume by name.
# mount /dev/dummy -o subvol=<subvolume>,subvolrootid=<top-level ID> /mountpoint Of course, you do need them, if you specify the subvolume to mount by its ID. Cheers, Andreas Philipp > > Then I was able to delete snapshots/2011-03-30/data, but > snapshots/2011-03-30 still didn't appear in the list. > > Then I was able to delete snapshots/2011-03-30 and recreate it, > and this time it was fine. > > Still don't know what happened there. > -- 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
