I don't know, maybe. This is not a new file system, clearly, it has
half million+ generations.
backup_roots[4]:
backup 0:
backup_tree_root: 29360128 gen: 593817 level: 1
backup_chunk_root: 20971520 gen: 591139 level: 1
backup_extent_root: 29376512 gen: 593817 level: 1
backup_fs_root: 132562944 gen: 593815 level: 0
backup_dev_root: 29409280 gen: 593817 level: 0
backup_csum_root: 29491200 gen: 593817 level: 0
backup_total_bytes: 254007050240
backup_bytes_used: 43532288
backup_num_devices: 1
backup 1:
backup_tree_root: 138821632 gen: 593818 level: 0
backup_chunk_root: 21020672 gen: 593818 level: 0
backup_extent_root: 138805248 gen: 593818 level: 0
backup_fs_root: 132562944 gen: 593815 level: 0
backup_dev_root: 132841472 gen: 593818 level: 0
backup_csum_root: 138870784 gen: 593818 level: 0
backup_total_bytes: 254007050240
backup_bytes_used: 655360
backup_num_devices: 1
The old chunk root and tree root might come in handy, from backup0,
which is the generation prior to the one currently set in the super
blocks. The bytes_used vs dev_item.bytes_used is also interesting,
huge difference. So it looks like this was umounted very soon after
you realized what you did.
What do you get for
btrfs restore -l <dev>
Maybe just try this, which is the oldest generation we know about
right now, which is found in backup root 2.
sudo btrfs restore -D -v -t 138788864 /dev/mapper/brick1 .
That's a dry run so the path to save stuff to doesn't matter, so I'm
just using . for that. But what you'll get is a file listing. If
there's nothing listed, then it's a dead end. But if it's listing
everything you want, it's a win. Just point to a proper destination
and remove -D. However, another possibility is that it's a partial -
i.e. it might be a generation in between the cleaner running, so some
stuff is restored but not all of it.
Yeah, maybe there's a way to get an older generation and root with an
older copy of btrfs-progs. I think the current one isn't working very
well...on yet another file system I have that is very new (week) but
has hours of writes on it,
[chris@f25s ~]$ sudo btrfs-find-root /dev/mapper/brick1
Superblock thinks the generation is 5727
Superblock thinks the level is 1
Found tree root at 426847567872 gen 5727 level 1
That's it. So no hang, but only one tree root which is just bogus.
Even the superblock has more information than this. I'm used to seeing
dozens or more.
Chris Murphy
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