2014-02-27 1:48 GMT+09:00, Theodore Ts'o <ty...@mit.edu>:
> On Mon, Feb 24, 2014 at 10:22:10AM +0900, Namjae Jeon wrote:
>> >> + ret = ext4_es_remove_extent(inode, punch_start,
>> >> + EXT_MAX_BLOCKS - punch_start - 1);
>> >> + if (ret) {
>> >> + up_write(&EXT4_I(inode)->i_data_sem);
>> >> + goto out_stop;
>> >> + }
>> >
>> > Doing this at first is probably a bad idea; you should do this at the
>> > end, and then completely invalidate the es cache for that inode. That
>> > way, the right thing happens if you get an error in the middle
>> > releasing the boxes and shifting the extents:
>> Okay, I see.
>
> Actually, thinking about this some more, we do want to do this first,
> since if we error out, we do need to make sure the extent cache is
> flushed.
Okay.
>
>> If there is error in the middle of extent shifting, the hole will
>> present between the last shifted extent and the extent at which error
>> happen so this will be consistent state.
>> IMHO even if there is error in between the shift, filesystem will be
>> in consistent state.
>> Am I missing something?
>
> No, I was wrong about that; you're right. The file will be in an
> inconsistent statement, which will probably be highly confusing for
> the application, but the file system will be fine.
>
> So I withdraw my complaints. I'll do a bit more testing, but so far
> the patch looks fine to me. Thanks for your reply and your work!
Thanks for your review! I will fix these include Hugh's review points.
>
> - Ted
>
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