[Yaffs] record block info

as subject,every block has its current state and when some operation is
done the state will be changed . In ram ,yaffs uses struct block_info to
record it,but if a thunder power loss happened,the state will loss,so
when restarts how to determine every block's state? i know yaffs uses
query_block_fn() to do this work ,but i'm not sure how to achieve that?


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Best wishes,
Ezio