[Lower Layer] Inode

Operation System final project -- inode

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What is inode?

• Matedata of a file or directory
• Following are the object included

Structs

struct inode_entry{}

total length limitation: 128byte

設計num[12]的子表，用於num[]用盡的時候另開block儲存資料

寬度	型態	命名	用途
2byte	short	id	inode id
4byte	int	filesize	filesize(更動file內容時需要一並更新)
2byte	short	uid	UID
2byte	short	gid	GID
2byte	short	filemode	檔案類型與權限 (e.g. 4664 == drw-rw-r--)
4byte	time_t	timestamp	最後修改日期(更動此inode時需要一並更新)
2byte	short	filetype
2byte	short	name_len
15*4byte	int	num[15]	block number (file) or inode number (directory)
32byte	char[32]	filename	filename

檔案類型改存於inode -> filetype (1 = Regular file, 2 = Directory, 詳見inode_entry.h) , 不放在filemode

num[12] 子表

用途：當num用盡時的儲存表，indirect block map size limit: 1 block

寬度	型態	命名	用途
2byte	short	num12[512]	block number

superblock _2

用途：存和indoe相關的資訊 size limit: 1 block

寬度	型態	命名	用途
2byte	Short	block_used	已用block數
2byte	Short	block_unuse	未用block數
2byte	Short	inode_used	已用inode數
2byte	Short	inode_unuse	未用inode數
512byte	bitmap	inode_bitmap	inode bitmap (共4096個inode)