Re: [PATCH 1/2 v2] AOSP: erofs-utils: pass a parameter to write tail end in block list

[Gao Xiang <hsiangkao@linux.alibaba.com>]

On 2023/8/15 14:45, Yue Hu wrote:
> On Tue, 15 Aug 2023 14:18:08 +0800
> Gao Xiang <hsiangkao@linux.alibaba.com> wrote:
> 
>> On 2023/8/15 14:21, Yue Hu wrote:
>>> On Tue, 15 Aug 2023 13:36:46 +0800
>>> Gao Xiang <hsiangkao@linux.alibaba.com> wrote:
>>>    
>>>> On 2023/8/15 13:40, Yue Hu wrote:
>>>>> On Tue, 15 Aug 2023 12:59:56 +0800
>>>>> Gao Xiang <hsiangkao@linux.alibaba.com> wrote:
>>>>>       
>>>>>> On 2023/8/15 12:55, Yue Hu wrote:
>>>>>>> From: Yue Hu <huyue2@coolpad.com>
>>>>>>>
>>>>>>> We can determine whether the tail block is the first one or not during
>>>>>>> the writing process.  Therefore, instead of internally checking the
>>>>>>> block number for the tail block map, just simply pass the flag.
>>>>>>>
>>>>>>> Also, add the missing sbi argument to macro erofs_blknr.
>>>>>>
>>>>>> Could you submit a patch to fix this issue first?
>>>>>
>>>>> ok, will do that.
>>>>>       
>>>>>>      
>>>>>>>
>>>>>>> Signed-off-by: Yue Hu <huyue2@coolpad.com>
>>>>>>> ---
>>>>>>> v2: change commit message a bit
>>>>>>>
>>>>>>>      include/erofs/block_list.h | 4 ++--
>>>>>>>      lib/block_list.c           | 5 ++---
>>>>>>>      lib/inode.c                | 9 +++++++--
>>>>>>>      3 files changed, 11 insertions(+), 7 deletions(-)
>>>>>>>
>>>>>>> diff --git a/include/erofs/block_list.h b/include/erofs/block_list.h
>>>>>>> index 78fab44..e0dced8 100644
>>>>>>> --- a/include/erofs/block_list.h
>>>>>>> +++ b/include/erofs/block_list.h
>>>>>>> @@ -19,7 +19,7 @@ void erofs_droid_blocklist_fclose(void);
>>>>>>>      void erofs_droid_blocklist_write(struct erofs_inode *inode,
>>>>>>>      				 erofs_blk_t blk_start, erofs_blk_t nblocks);
>>>>>>>      void erofs_droid_blocklist_write_tail_end(struct erofs_inode *inode,
>>>>>>> -					  erofs_blk_t blkaddr);
>>>>>>> +					  erofs_blk_t blkaddr, bool first_block);
>>>>>>
>>>>>> I still have no idea why we need this, could you describe the Android
>>>>>> block map details for discussion?
>>>>>
>>>>> Android block map is just adding file blocks to a range.
>>>>>
>>>>> So, the tail block should be needed in this range as well.
>>>>> I think one simple way is just appending the tail block address in it as below:
>>>>>
>>>>> /`file_path` `block1_address`-`blockn_address` `tail_block_address`
>>>>
>>>> why `tail_block_address` needs a seperate field?
>>>
>>> Well, `erofs_write_tail_end()` is a separate logic and i think appending this block is
>>> simple enough since i don't need to consider whether the block address is contiguous
>>> with previous one.
>>>
>>> And i think Android block map can handle this since i have saw below in ext4:
>>>
>>> /system/.../libclang_rt.ubsan_standalone-arm-android.so 51276-51309 0 51310-51403
>>
>> What's the meaning of 0 here?
> 
> I have not check that yet, maybe i need to find time...
> 
> And check this: "/.../libxxx.so 87378-88630 0 0 0 88631 0 0 88632-88637 0 0 0 88638-88663"
> 
> so, i guess it looks like null block.

So here erofs_droid_blocklist_write_tail_end is not actually needed in principle?
0 is just used for sparse block?

Thanks,
Gao Xiang