XFS, empty files after a crash

[kadafax at gmail.com]

Le 23/02/12 23:15, Nathaniel W. Turner a écrit :
> On 02/23/2012 03:07 PM, kadafax at gmail.com wrote:
>>
>>> kfx, try getting the inode number of the file (via stat or ls -i) 
>>> and then doing something like this:
>>>
>>> xfs_db -r $DEV -c "inode $INO" -c "bmap" 
>>
>>
>> # xfs_db -r /dev/sdc1 -c "inode 114748" -c "bmap"
>> data offset 0 startblock 1881705728 (7/2657536) count 6460 flag 0
>>
>> # xfs_db -r /dev/sdc1 -c "inode 114754" -c "bmap"
>> data offset 0 startblock 1077794560 (4/4052736) count 6582 flag 0
>
> If you want to see what's behind those data extents (which are 
> probably partially written), you could do something along these lines:
>
> # Determine the AG size
> agblocks=$(xfs_db -r /dev/sdc1 -c sb -c p | grep ^agblocks | sed 's/.* 
> = //')
>
> # Copy the extent in the first file, which consists of 6460 blocks 
> (~26MB)
> # in AG 7 starting at AG-relative block 2657536:
> dd if=/dev/sdc1 bs=4096 skip=$(($agblocks * 7 + 2657536)) count=6460 
> of=./blob
> # examine ./blob

Awesome, it's working for each file with non-null data extents.

I guess that for inode for which the command "xfs_db -r $DEV -c "inode 
$INO" -c "bmap"" returns a null result there is no hope ?

Anyway, thanks a lot Nathaniel !