OK this is screwy. The super has a totally different generation for
the root tree than any of the backup roots.
$ sudo btrfs rescue super -v /dev/mapper/sdd
All Devices:
Device: id = 1, name = /dev/mapper/sdc
Device: id = 2, name = /dev/mapper/sdd
Before Recovering:
[All good supers]:
device name = /dev/mapper/sdc
superblock bytenr = 65536
device name = /dev/mapper/sdc
superblock bytenr = 67108864
device name = /dev/mapper/sdc
superblock bytenr = 274877906944
device name = /dev/mapper/sdd
superblock bytenr = 65536
device name = /dev/mapper/sdd
superblock bytenr = 67108864
device name = /dev/mapper/sdd
superblock bytenr = 274877906944
[All bad supers]:
All supers are valid, no need to recover
$ sudo btrfs insp dump-s -f /dev/mapper/sdd
superblock: bytenr=65536, device=/dev/mapper/sdd
---------------------------------------------------------
csum_type 0 (crc32c)
csum_size 4
csum 0x312a8b5e [match]
bytenr 65536
flags 0x1
( WRITTEN )
magic _BHRfS_M [match]
fsid f5adc913-bbea-4340-8b5f-3411e2cda642
label second
generation 4514
root 29392896
sys_array_size 258
chunk_root_generation 3823
root_level 1
chunk_root 822549151744
chunk_root_level 1
log_root 0
log_root_transid 0
log_root_level 0
total_bytes 1500308553728
bytes_used 735327125504
sectorsize 4096
nodesize 16384
leafsize (deprecated) 16384
stripesize 4096
root_dir 6
num_devices 2
compat_flags 0x0
compat_ro_flags 0x0
incompat_flags 0x161
( MIXED_BACKREF |
BIG_METADATA |
EXTENDED_IREF |
SKINNY_METADATA )
cache_generation 4076
uuid_tree_generation 4076
dev_item.uuid 2fbaa023-7cf8-4f48-b4ed-c6e18c99d2bd
dev_item.fsid f5adc913-bbea-4340-8b5f-3411e2cda642 [match]
dev_item.type 0
dev_item.total_bytes 750154276864
dev_item.bytes_used 737702576128
dev_item.io_align 4096
dev_item.io_width 4096
dev_item.sector_size 4096
dev_item.devid 2
dev_item.dev_group 0
dev_item.seek_speed 0
dev_item.bandwidth 0
dev_item.generation 0
sys_chunk_array[2048]:
item 0 key (FIRST_CHUNK_TREE CHUNK_ITEM 20971520)
length 8388608 owner 2 stripe_len 65536 type SYSTEM|RAID1
io_align 65536 io_width 65536 sector_size 4096
num_stripes 2 sub_stripes 0
stripe 0 devid 2 offset 1048576
dev_uuid 2fbaa023-7cf8-4f48-b4ed-c6e18c99d2bd
stripe 1 devid 1 offset 20971520
dev_uuid d071b0ca-1d27-48cb-826e-63c5e9972339
item 1 key (FIRST_CHUNK_TREE CHUNK_ITEM 822549151744)
length 33554432 owner 2 stripe_len 65536 type SYSTEM|RAID1
io_align 65536 io_width 65536 sector_size 4096
num_stripes 2 sub_stripes 1
stripe 0 devid 2 offset 737670070272
dev_uuid 2fbaa023-7cf8-4f48-b4ed-c6e18c99d2bd
stripe 1 devid 1 offset 737689993216
dev_uuid d071b0ca-1d27-48cb-826e-63c5e9972339
backup_roots[4]:
backup 0:
backup_tree_root: 931053568 gen: 4075 level: 1
backup_chunk_root: 822549151744 gen: 3823 level: 1
backup_extent_root: 931086336 gen: 4075 level: 2
backup_fs_root: 537116672 gen: 3806 level: 0
backup_dev_root: 721174528 gen: 3823 level: 1
backup_csum_root: 932249600 gen: 4075 level: 2
backup_total_bytes: 1500308553728
backup_bytes_used: 735441764352
backup_num_devices: 2
backup 1:
backup_tree_root: 930086912 gen: 4076 level: 1
backup_chunk_root: 822549151744 gen: 3823 level: 1
backup_extent_root: 930447360 gen: 4076 level: 2
backup_fs_root: 537116672 gen: 3806 level: 0
backup_dev_root: 930856960 gen: 4076 level: 1
backup_csum_root: 932118528 gen: 4076 level: 2
backup_total_bytes: 1500308553728
backup_bytes_used: 735441764352
backup_num_devices: 2
backup 2:
backup_tree_root: 930070528 gen: 4073 level: 1
backup_chunk_root: 822549151744 gen: 3823 level: 1
backup_extent_root: 930365440 gen: 4073 level: 2
backup_fs_root: 537116672 gen: 3806 level: 0
backup_dev_root: 721174528 gen: 3823 level: 1
backup_csum_root: 931086336 gen: 4073 level: 2
backup_total_bytes: 1500308553728
backup_bytes_used: 735441764352
backup_num_devices: 2
backup 3:
backup_tree_root: 930086912 gen: 4074 level: 1
backup_chunk_root: 822549151744 gen: 3823 level: 1
backup_extent_root: 930447360 gen: 4074 level: 2
backup_fs_root: 537116672 gen: 3806 level: 0
backup_dev_root: 721174528 gen: 3823 level: 1
backup_csum_root: 932052992 gen: 4074 level: 2
backup_total_bytes: 1500308553728
backup_bytes_used: 735441764352
backup_num_devices: 2
$
Super says root tree generation 4514; but the most recent backup says
4076. What?
# btrfs insp dump-t -b 930086912 /dev/mapper/sdd
btrfs-progs v4.19.1
node 930086912 level 1 items 19 free 474 generation 4076 owner ROOT_TREE
fs uuid f5adc913-bbea-4340-8b5f-3411e2cda642
chunk uuid 4af0d265-00fa-4a2b-9ea9-59c06a372284
key (EXTENT_TREE ROOT_ITEM 0) block 931102720 gen 4076
key (279 INODE_ITEM 0) block 535216128 gen 3802
key (307 INODE_ITEM 0) block 715111579648 gen 3511
key (368 EXTENT_DATA 0) block 715103928320 gen 3510
key (430 INODE_ITEM 0) block 715111612416 gen 3511
key (491 EXTENT_DATA 0) block 715111677952 gen 3511
key (553 INODE_ITEM 0) block 715111841792 gen 3511
key (652 EXTENT_DATA 0) block 714560716800 gen 3523
key (711 INODE_ITEM 0) block 934019072 gen 4076
key (773 INODE_ITEM 0) block 934887424 gen 4076
key (829 INODE_ITEM 0) block 671989760 gen 3808
key (884 INODE_ITEM 0) block 714619404288 gen 3525
key (939 ROOT_ITEM 1889) block 715035377664 gen 3506
key (981 ROOT_ITEM 3330) block 933658624 gen 4067
key (1034 INODE_ITEM 0) block 172621824 gen 3546
key (1095 EXTENT_DATA 0) block 934232064 gen 4076
key (FREE_SPACE UNTYPED 11840520192) block 934248448 gen 4076
key (FREE_SPACE UNTYPED 275981008896) block 934658048 gen 4076
key (FREE_SPACE UNTYPED 568038785024) block 933724160 gen 4067
# btrfs insp dump-t -b 29392896 /dev/mapper/sdd
btrfs-progs v4.19.1
node 29392896 level 1 items 10 free 483 generation 4514 owner ROOT_TREE
fs uuid f5adc913-bbea-4340-8b5f-3411e2cda642
chunk uuid 4af0d265-00fa-4a2b-9ea9-59c06a372284
key (EXTENT_TREE ROOT_ITEM 0) block 712994078720 gen 4514
key (773 INODE_ITEM 0) block 29442048 gen 4470
key (829 INODE_ITEM 0) block 671989760 gen 3808
key (884 INODE_ITEM 0) block 714619404288 gen 3525
key (939 ROOT_ITEM 1889) block 715035377664 gen 3506
key (981 ROOT_ITEM 3330) block 933658624 gen 4067
key (1034 INODE_ITEM 0) block 172621824 gen 3546
key (1095 EXTENT_DATA 0) block 29409280 gen 4514
key (FREE_SPACE UNTYPED 559448850432) block 29376512 gen 4483
key (FREE_SPACE UNTYPED 568038785024) block 933724160 gen 4067
#
I guess I don't understand why 'btrfs check' would have successfully
written six updated copies of the super, when the operation hadn't yet
succeeded. I guess this isn't an atomic operation, and perhaps it
can't be.
---
Chris Murphy
