Re: [Jfs-discussion] Ideas on how to recover a trashed JFS volume.

[Dave K. <sh...@au...>]

On Fri, 2006-10-27 at 22:45 +0200, lu...@ik... wrote:
> It was the unallocated inodes that fooled me. When I take them into
> account its no problem to detect inode extents. I guess this is quite a
> good filter.
> 
> The program does check for duplicate di_numbers, and I am not sure what to
> do with these duplicates. The di_number must be unique in the inode set to
> be recovered (or else its impossible to decide which inode whould be used
> as parent etc.). But how do I choose which inode to keep of two, seemingly
> sane, but not identical, inodes? I will attach an example at the end of
> this mail.

I guess the decision should be made on an entire inode extent.  I'm sure
one was freed at one point, and a new extent was allocated for the same
group of inodes.  I think it's pretty safe to choose the one with the
larger otime timestamp.  The other timestamps can be touched back by cp
-p or something, but otime is set when the inode is allocated, and there
currently is no interface to change it.

> How do I detect which inode that was the original root? In normal cases I
> get a set of orphaned trees, but one of this should be the original root.
> In the filesystems I have tried it seems that the inode with di_number ==
> 2 is the root. Is that always true?

Yes.  The root is always 2.

> The program slowly progresses towards something that might be usable by
> others than me. I would be very happy with releasing it under the GPL or
> some other open source license. But, as I have copied some code from xpeek
> I'm not sure weather it is possible. The program is not based on anything
> from any jfs package, its only parts from xpeek that has been copied and
> modified (the extent walk for instance).

The xpeek code is GPL, so that's probably your only option, other than
replacing the xpeek code and releasing it under anything you like.

> 
> Best regards,
> Simon
> 
> 
> I have no idea why these two inodes have the same di_number. They also
> have the same inostamp.
> 
> Non-unique di_number found! 680576
> [1] di_inostamp:        0x44da3d75      [19] di_mtime.tv_nsec:  0x00000000
> [2] di_fileset:         16              [20] di_otime.tv_sec:   0x45072082
> [3] di_number:          680576          [21] di_otime.tv_nsec:  0x00000000
> [4] di_gen:             7214231         [22] di_acl.flag:       0x00
> [5] di_ixpxd.len:       4               [23] di_acl.rsrvd:      Not Displayed
> [6] di_ixpxd.addr1:     0x00            [24] di_acl.size:       0x00000000
> [7] di_ixpxd.addr2:     0x000925e8      [25] di_acl.len:        0
>      di_ixpxd.address:  599528          [26] di_acl.addr1:      0x00
> [8] di_size:    0x0000000000001000      [27] di_acl.addr2:      0x00000000
> [9] di_nblocks: 0x0000000000000002           di_acl.address:    0
> [10] di_nlink:          2               [28] di_ea.flag:        0x00
> [11] di_uid:            0               [29] di_ea.rsrvd:       Not Displayed
> [12] di_gid:            0               [30] di_ea.size:        0x00000000
> [13] di_mode:           0x200041ed      [31] di_ea.len:         0
> [32] di_ea.addr1:       0x00
> [14] di_atime.tv_sec:   0x45072082      [33] di_ea.addr2:       0x00000000
> [15] di_atime.tv_nsec:  0x00000000           di_ea.address:     0
> [16] di_ctime.tv_sec:   0x45072087      [34] di_next_index:     27
> [17] di_ctime.tv_nsec:  0x234a7068      [35] di_acltype:        0x00000000
> [18] di_mtime.tv_sec:   0x45072085
> 
> 
> 
> 
> [1] di_inostamp:        0x44da3d75      [19] di_mtime.tv_nsec:  0x00000000
> [2] di_fileset:         16              [20] di_otime.tv_sec:   0x44dfbb92
> [3] di_number:          680576          [21] di_otime.tv_nsec:  0x00000000
> [4] di_gen:             1703739         [22] di_acl.flag:       0x00
> [5] di_ixpxd.len:       4               [23] di_acl.rsrvd:      Not Displayed
> [6] di_ixpxd.addr1:     0x00            [24] di_acl.size:       0x00000000
> [7] di_ixpxd.addr2:     0x000c507c      [25] di_acl.len:        0
>      di_ixpxd.address:  807036          [26] di_acl.addr1:      0x00
> [8] di_size:    0x0000000000000010      [27] di_acl.addr2:      0x00000000
> [9] di_nblocks: 0x0000000000000000           di_acl.address:    0
> [10] di_nlink:          2               [28] di_ea.flag:        0x00
> [11] di_uid:            1000            [29] di_ea.rsrvd:       Not Displayed
> [12] di_gid:            100             [30] di_ea.size:        0x00000000
> [13] di_mode:           0x200041ed      [31] di_ea.len:         0
> [32] di_ea.addr1:       0x00
> [14] di_atime.tv_sec:   0x44dfc505      [33] di_ea.addr2:       0x00000000
> [15] di_atime.tv_nsec:  0x00000000           di_ea.address:     0
> [16] di_ctime.tv_sec:   0x44dfc505      [34] di_next_index:     4
> [17] di_ctime.tv_nsec:  0x1185292c      [35] di_acltype:        0x00000000
> [18] di_mtime.tv_sec:   0x44d2c8db
> 
> 
> 
-- 
David Kleikamp
IBM Linux Technology Center