[PATCH v3] erofs-utils: lib: treat data blocks filled with 0s as a hole

[Gao Xiang]

On Wed, Apr 17, 2024 at 04:48:44PM -0700, Sandeep Dhavale wrote:
> Add optimization to treat data blocks filled with 0s as a hole.
> Even though diskspace savings are comparable to chunk based or dedupe,
> having no block assigned saves us redundant disk IOs during read.
> 
> To detect blocks filled with zeros during chunking, we insert block
> filled with zeros (zerochunk) in the hashmap. If we detect a possible
> dedupe, we map it to the hole so there is no physical block assigned.
> 
> Signed-off-by: Sandeep Dhavale <dhavale at google.com>

Reviewed-by: Gao Xiang <hsiangkao at linux.alibaba.com>

Thanks,
Gao Xiang