When trying to repair a btrfs root filesystem I get the following error
message:
# losetup -f /home/fturco/Buffer/root-20160616.img
# btrfs check --repair /dev/loop0
enabling repair mode
warning, device 4 is missing
Checking filesystem on /dev/loop0
UUID: 34fb5b58-f50f-47c3-a5b8-91d81a30eade
checking extents
Unable to find block group for 0
extent-tree.c:289: find_search_start: Assertion `1` failed.
btrfs[0x44882e]
btrfs(btrfs_reserve_extent+0xaa9)[0x44d639]
btrfs(btrfs_alloc_free_block+0x5f)[0x44d6ff]
btrfs(__btrfs_cow_block+0xc4)[0x43e9d4]
btrfs(btrfs_cow_block+0x35)[0x43efd5]
btrfs[0x4442e6]
btrfs(btrfs_commit_transaction+0x95)[0x446115]
btrfs[0x42b58e]
btrfs(cmd_check+0x76c)[0x42c60c]
btrfs(main+0x7b)[0x40ac3b]
/usr/lib/libc.so.6(__libc_start_main+0xf1)[0x7f272f658741]
btrfs(_start+0x29)[0x40ad39]
This is an unmountable filesystem:
# mount /dev/loop0 /mnt/
mount: wrong fs type, bad option, bad superblock on /dev/loop0,
missing codepage or helper program, or other error
In some cases useful info is found in syslog - try
dmesg | tail or so.
# dmesg | tail
[ 9185.503571] scsi 8:0:0:1: Direct-Access Samsung File-CD Gadget
0000 PQ: 0 ANSI: 2
[ 9185.513943] sd 8:0:0:0: [sdb] Attached SCSI removable disk
[ 9185.514565] sd 8:0:0:1: [sdc] Attached SCSI removable disk
[13773.533435] usb 1-4: USB disconnect, device number 8
[31454.672925] loop: module loaded
[31455.600069] BTRFS: device fsid 34fb5b58-f50f-47c3-a5b8-91d81a30eade
devid 1 transid 81460 /dev/loop0
[32584.640398] BTRFS info (device loop0): disk space caching is enabled
[32584.640403] BTRFS: has skinny extents
[32584.654196] BTRFS: failed to read the system array on loop0
[32584.666774] BTRFS: open_ctree failed
Fortunately I have no valuable content in that image file and I restored
the system from a recent backup, but I still wonder if there's a bug
somewhere in btrfs-check.
Do you need other debug informations perhaps?
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Website: http://www.fturco.net/
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