Re: [PATCH 1/5] f2fs: fix to wait page writeback before update

[Chao Yu]

On 2020/6/20 6:47, Jaegeuk Kim wrote:
> > > > > > diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> > > > > > index 3268f8dd59bb..1862073b96d2 100644
> > > > > > --- a/fs/f2fs/file.c
> > > > > > +++ b/fs/f2fs/file.c
> > > > > > @@ -1250,6 +1250,7 @@ static int __clone_blkaddrs(struct inode *src_inode, struct inode *dst_inode,
> > > > > >   				f2fs_put_page(psrc, 1);
> > > > > >   				return PTR_ERR(pdst);
> > > > > >   			}
> > > > > > +			f2fs_wait_on_page_writeback(pdst, DATA, true, true);
>
> Do you mean pdst can be under writeback?

Jaegeuk,

Look back this again, is it possible that pdst is writebacking
in below race condition? or am I missing something?

Thread A				GC Thread
- f2fs_move_file_range
 - filemap_write_and_wait_range(dst)
					- gc_data_segment
					 - f2fs_down_write(dst)
					 - move_data_page
					  - set_page_writeback(dst_page)
					  - f2fs_submit_page_write
					 - f2fs_up_write(dst)
 - f2fs_down_write(dst)
 - __exchange_data_block
  - __clone_blkaddrs
   - f2fs_get_new_data_page
   - memcpy_page

Thanks,