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 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

> 
> > 
> > or
> > 
> > /`file_path` `tail_block_address`   //only one block  
> 
> how about recording the previous inode pointer as an internal global variable?
> if it's not the same inode, trigger "\n" immediately.
> 
> and generate files as:
> " `block1_address`-`blockn_address`"  for many blocks;
> " `block1_address`" for a single block?

Let me check.

> 
> Thanks,
> Gao Xiang