Re: corrupt leaf, slot offset bad

[Liu Bo <bo.li.liu@oracle.com>]

On Mon, Oct 10, 2016 at 08:57:19PM +0200, aron@aron.ws wrote:
> Hi all,
> 
> I've been using btrfs for a few months now, without any problems. During
> work, I've noticed segfaults, when accessing my root directory. As my home
> directory contents was readable, I've decided to reboot. That was the worst
> decision, as now I can't copy my data off the SSD. It seems like a memory
> isse. I have backups, but its ~2 weeks old. What I did is a dd dump
> immediately. Have latest kernel and latest progs built from source now, but
> :S ...
> 
> This is what I've got:
> 
> When mounting:
> 
> BTRFS critical (device: sdb2): corrupt leaf, slot offset bad:
> block=610107392,root=1, slot=108

This indicates that leaf 610107392 is corrupted somehow because its slot
108's 'start offset in leaf' and slot 109's 'end offset in leaf' doesn't
match with each other, the cause is not shown though.

> 
> find-root prints nothing to the stdout ofter 2 hours.
> 
> running btrfs inspect-internal dump-tree -b 610107392 /dev/sdb2

> 
> leaf 610107392 items 188 free space 1690 generation 90792 owner 5

owner 5 means that it's not a tree root leaf, it's a fs tree leaf.

> fs uuid 2cc75a87-b22b-448e-80d4-383a9f42deed
> chunk uuid a5b09a2a-da3d-4049-91ba-4fe66932907b
> 	item 0 key (256 INODE_ITEM 0) itemoff 16123 itemsize 160
> 		inode generation 3 transid 90769 size 144 nbytes 16384
> 		block group 0 mode 40755 links 1 uid 0 gid 0
> 		rdev 0 flags 0x0(none)
> 	item 1 key (256 INODE_REF 256) itemoff 16111 itemsize 12
> 		inode ref index 0 namelen 2 name: ..
> 	item 2 key (256 DIR_ITEM 145260132) itemoff 16078 itemsize 33
> 		location key (265 INODE_ITEM 0) type DIR
> 		namelen 3 datalen 0 name: dev
> 	item 3 key (256 DIR_ITEM 217684952) itemoff 16045 itemsize 33
> 		location key (266 INODE_ITEM 0) type DIR
> 		namelen 3 datalen 0 name: run
> 	item 4 key (256 DIR_ITEM 308198373) itemoff 16011 itemsize 34
> 		location key (257 INODE_ITEM 0) type DIR
> 
> ...

Maybe we can check the content of item 108 and item 109 in this output from
'dump-tree'?

Thanks,

-liubo

> 	item 111 key (261 DIR_ITEM 81211850) itemoff 11344 itemsize 131133
> 		location key (893669 INODE_ITEM 0) type FILE
> 		namelen 31 datalen 0 name: babl-0.1.16-1-x86_64.pkg.tar.xz
> 		location key (388547 INODE_ITEM 0) type FILE
> 		namelen 32 datalen 0 name: intltool-0.51.0-1-any.pkg.tar.xz
> ...
> 		namelen 30 datalen 0 name: glibc-2.24-2-x86_64.pkg.tar.xz
> 		location key (893658 INODE_ITEM 0) type FILE
> 		namelen 36 datalen 0 name: procps-ng-3.3.12-1-x86_64.pkg.tar.xz
> 		location key (EXTENT_TREE UNKNOWN.3 36094832640) type 12
> 		namelen 0 datalen 0 name:
> 		location key (291 UNKNOWN.0 0) type 0
> 		namelen 0 datalen 0 name:
> 		location key (18556457741975552 UNKNOWN.0 0) type 0
> 		namelen 0 datalen 7134 name:
> 		data
> 		location key (0 UNKNOWN.0 0) type 0
> 		namelen 0 datalen 0 name:
> 		location key (0 UNKNOWN.0 0) type 0
> 		namelen 0 datalen 0 name:
> 		location key (0 UNKNOWN.0 0) type 0
> 		namelen 0 datalen 0 name:
> 		location key (0 UNKNOWN.0 0) type 0
> 		namelen 0 datalen 0 name:
> 		location key (0 UNKNOWN.0 0) type 0
> 		namelen 0 datalen 0 name:
> 		location key (0 UNKNOWN.0 0) type 0
> 		namelen 0 datalen 0 name:
> 		location key (0 UNKNOWN.0 0) type 0
> 		namelen 0 datalen 0 name:
> 		location key (0 UNKNOWN.0 0) type 0
> 		namelen 0 datalen 0 name:
> 		location key (0 UNKNOWN.0 0) type 0
> 		namelen 0 datalen 0 name:
> 
> ....
> 
> segfault
> 
> 
> running restore:
> 
> incorrect offsets 11532 11548
> Error searching -1
> 
> Tried every rescue, check commands, in different variations ... nothing. It
> seems that the root leaf (?) has some garbage, tried using the corrupt-block
> utility, to mark the item dirty got the same error: incorrect offsets.
> 
> The only thing I've managed is to restore a part of the /etc directory,
> with: btrfs restore -i -f 610123776 -vvvv -d /dev/sdb2 /mnt/restore
> 
> I'm still trying to learn how the data is structured now, but my problem is
> that I can't figure out how to calculate the leaf positions, using the
> dump-tree output ...
> 
> I need some kind tool/script that can recursively rescue the structure from
> a defined leaf. (can this be done?)
> 
> Any help would be appreciated! :)
> 
> Thanks!
> 
> Yours,
> Aron
> 
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