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

[Yue Hu <zbestahu@gmail.com>]

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.

> 
> Thanks,
> Gao Xiang
>