2012/12/9 Eric Sandeen <sandeen@xxxxxxxxxx>:
> On 12/4/12 6:29 AM, forrest wrote:
>> This problem is easily to reproduce
>>
>> Create a file with size larger than 1GB.
>>
>> dd if=/dev/zero of=/test_file bs=1M count=1024
>>
>> Punch every even block in test_file, and then use debugfs to dump
>> extents, followings is dumped result
>>
>> 2/ 2 339/340 231197 - 231197 3917597 - 3917597 1
>> 2/ 2 340/340 231199 - 231199 3917599 - 3917599 1
>> 0/ 2 2/ 2 231201 - 262143 3901486 30943
>> 1/ 2 1/ 46 231201 - 231880 3901488 680
>> 2/ 2 1/340 231201 - 231201 3917601 - 3917601 1
>> 2/ 2 2/340 231203 - 231203 3917603 - 3917603 1
>>
>> Punch blocks #231779 ~#231201 ,
>
> Can you explain what you mean by the above? Which blocks get punched?
Hi Eric,
At first, i found blowing code may have some problem
ext4_ext_rm_leaf ()
{
...
/////when eh->eh_entries equals to zero, logical start value
will not be update;
//// If parent is first index in block, this cause problem.
if (correct_index && eh->eh_entries)
err = ext4_ext_correct_indexes(handle, inode, path);
}
To prove that, I tried to trigger this case (eh->eh_entries = 0)
1) create a file which size greater than 1GB
2) punch all even blocks 0, 2, 4, 6, 8, ....... (blocks depends on
file size) one by one to make extent tree with depth equals to 2
3) use debugfs to find an extent index entry at level1 (assume leaf at
level2) witch logical start value is equals to is't parent node.
In example, founded entry is
1/ 2 1/ 46 231201 - 231880 3901488 680
4 ) punch blocks covered by extent index found by step3 one by one.
In example,
231879, 231877, ..., 231201..
5 ) Then, we can use debugfs to check if logical start value is correct or not
In example, 231201 is not equals to 231881.
0/ 2 2/ 2 231201 - 262143 3901486 30943
1/ 2 1/ 45 231881 - 232560 3901490 680
Thanks,
-Forrest
>
> -Eric
>
>> to remove extent index, and then use
>> debugfs to dump extents, followings is dumped result
>
>
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