yaffs2源码文件

YAFFS is a log-structured filesystem. It is designed particularly for NAND (as opposed to NOR) flash, to be flash-friendly, robust due to journalling, and to have low RAM and boot time overheads. File data is stored in 'chunks'. Chunks are the same size as NAND pages. Each page is marked with file id and chunk number. These marking 'tags' are stored in the OOB (or 'spare') region of the flash. The chunk number is determined by dividing the file position by the chunk size. Each chunk has a number of valid bytes, which equals the page size for all except the last chunk in a file.