2012/12/7 Ashish Sangwan <ashishsangwan2@xxxxxxxxx>:
> On Thu, Dec 6, 2012 at 8:06 PM, Forrest Liu <forrestl@xxxxxxxxxxxx> wrote:
>> Hi Ashish,
>>
>> There have a chance to do a trivial update, and this case will be
>> covered in ext4_ext_remove_space.
>>
>> + if (err == 0 && eh->eh_entries == 0 && path[depth].p_bh != NULL) {
>> err = ext4_ext_rm_idx(handle, inode, path + depth);
>> + /* If this was the first extent index in node,
>> + * propagates the ei_block updation info to top */
>> + if(!err) {
>> + --depth;
>> + path = path + depth;
>> + while (--depth >= 0) {
>> + if (path->p_idx != EXT_FIRST_INDEX(path->p_hdr))
>> + break;
>> + path--;
>> + err = ext4_ext_get_access(handle, inode, path);
>> + if (err)
>> + break;
>>
>> trivial update, when (path + 1)->p_idx->eh_entries == 0
>>
>> + path->p_idx->ei_block =(path +
>> 1)->p_idx->ei_block ;
>> + err = ext4_ext_dirty(handle, inode, path);
>> + if (err)
>> + break;
>> + }
>> + }
>> + }
>> +
>>
>> I will trying to reproduce the problem tomorrow.
> I think it will work fine atleast till depth = 2.
> It would be great if you could check with depth > 2.
> If still having this problem, we can think more.
Hi Ashish,
First, create a file lager than 4GB, and then punch out every even blocks;
Use ex command in debugfs to dump extents, belowing is the result.
Level Entries Logical Physical Length Flags
0/ 3 1/ 1 1 - 1048575 40013 1048575
1/ 3 1/ 5 1 - 231160 40012 231160
2/ 3 1/340 1 - 680 40011 680
3/ 3 1/340 1 - 1 2228225 - 2228225 1
3/ 3 2/340 3 - 3 2228227 - 2228227 1
3/ 3 3/340 5 - 5 2228229 - 2228229 1
punch out 231159, 231157, ..., 1..
Level Entries Logical Physical Length Flags
0/ 3 1/ 1 1 - 1048575 40013 1048575
1/ 3 1/ 4 231161 - 462320 2457604 231160
2/ 3 1/340 231161 - 231840 2457606 680
3/ 3 1/340 231161 - 231161 2459385 - 2459385 1
Then, we get incorrect logical index, if only do correction in ext4_ext_rm_leaf.
Thanks,
Forrest
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