On Tue, Oct 11, 2016 at 02:48:09PM +0200, David Sterba wrote:
> Hi,
> 
> looks like a lot of random bitflips.
> 
> On Mon, Oct 10, 2016 at 11:50:14PM +0200, [email protected] wrote:
> > item 109 has a few strange chars in its name (and it's truncated): 
> > 1-x86_64.pkg.tar.xz 0x62 0x14 0x0a 0x0a
> > 
> >     item 105 key (261 DIR_ITEM 54556048) itemoff 11723 itemsize 72
> >             location key (606286 INODE_ITEM 0) type FILE
> >             namelen 42 datalen 0 name: 
> > python2-gobject-3.20.1-1-x86_64.pkg.tar.xz
> >     item 106 key (261 DIR_ITEM 56363628) itemoff 11660 itemsize 63
> >             location key (894298 INODE_ITEM 0) type FILE
> >             namelen 33 datalen 0 name: unrar-1:5.4.5-1-x86_64.pkg.tar.xz
> >     item 107 key (261 DIR_ITEM 66963651) itemoff 11600 itemsize 60
> >             location key (1178 INODE_ITEM 0) type FILE
> >             namelen 30 datalen 0 name: glibc-2.23-5-x86_64.pkg.tar.xz
> >     item 108 key (261 DIR_ITEM 68561395) itemoff 11532 itemsize 68
> >             location key (660578 INODE_ITEM 0) type FILE
> >             namelen 38 datalen 0 name: 
> > squashfs-tools-4.3-4-x86_64.pkg.tar.xz
> >     item 109 key (261 DIR_ITEM 76859450) itemoff 11483 itemsize 65
> >             location key (2397184 UNKNOWN.0 7091317839824617472) type 45
> >             namelen 13102 datalen 13358 name: 1-x86_64.pkg.tar.xzb
> 
> namelen must be smaller than 255, but the number itself does not look
> like a bitflip (0x332e), the name looks like a fragment of.
> 
> The location key is random garbage, likely an overwritten memory,
> 7091317839824617472 == 0x62696c0100230000 contains ascii 'bil', the key
> type is unknown but should be INODE_ITEM.
> 
> >             data
> >     item 110 key (261 DIR_ITEM 9799832789237604651) itemoff 11405 itemsize 
> > 62
> >             location key (388547 INODE_ITEM 0) type FILE
> >             namelen 32 datalen 0 name: intltool-0.51.0-1-any.pkg.tar.xz
> >     item 111 key (261 DIR_ITEM 81211850) itemoff 11344 itemsize 131133
> 
> itemsize 131133 == 0x2003d is a clear bitflip, 0x3d == 61, corresponds
> to the expected item size.
> 
> There's possibly other random bitflips in the keys or other structures.
> It's hard to estimate the damage and thus the scope of restorable data.

It makes sense since this's a ssd we may have only one copy for metadata.

Thanks,

-liubo
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