# sfs.h ```c #ifndef __KERN_FS_SFS_SFS_H__ #define __KERN_FS_SFS_SFS_H__ #include #include #include #include #include /* * Simple FS (SFS) definitions visible to ucore. This covers the on-disk format * and is used by tools that work on SFS volumes, such as mksfs. */ #define SFS_MAGIC 0x2f8dbe2a /* magic number for sfs */ #define SFS_BLKSIZE PGSIZE /* size of block */ #define SFS_NDIRECT 12 /* # of direct blocks in inode */ #define SFS_MAX_INFO_LEN 31 /* max length of infomation */ #define SFS_MAX_FNAME_LEN FS_MAX_FNAME_LEN /* max length of filename */ #define SFS_MAX_FILE_SIZE (1024UL * 1024 * 128) /* max file size (128M) */ #define SFS_BLKN_SUPER 0 /* block the superblock lives in */ #define SFS_BLKN_ROOT 1 /* location of the root dir inode */ #define SFS_BLKN_FREEMAP 2 /* 1st block of the freemap */ /* # of bits in a block */ #define SFS_BLKBITS (SFS_BLKSIZE * CHAR_BIT) /* # of entries in a block */ #define SFS_BLK_NENTRY (SFS_BLKSIZE / sizeof(uint32_t)) /* file types */ #define SFS_TYPE_INVAL 0 /* Should not appear on disk */ #define SFS_TYPE_FILE 1 #define SFS_TYPE_DIR 2 #define SFS_TYPE_LINK 3 /* * On-disk superblock */ struct sfs_super { uint32_t magic; /* magic number, should be SFS_MAGIC */ uint32_t blocks; /* # of blocks in fs */ uint32_t unused_blocks; /* # of unused blocks in fs */ char info[SFS_MAX_INFO_LEN + 1]; /* infomation for sfs */ }; /* inode (on disk) */ struct sfs_disk_inode { uint32_t size; /* size of the file (in bytes) */ uint16_t type; /* one of SYS_TYPE_* above */ uint16_t nlinks; /* # of hard links to this file */ uint32_t blocks; /* # of blocks */ uint32_t direct[SFS_NDIRECT]; /* direct blocks */ uint32_t indirect; /* indirect blocks */ // uint32_t db_indirect; /* double indirect blocks */ // unused }; /* file entry (on disk) */ struct sfs_disk_entry { uint32_t ino; /* inode number */ char name[SFS_MAX_FNAME_LEN + 1]; /* file name */ }; #define sfs_dentry_size \ sizeof(((struct sfs_disk_entry *)0)->name) /* inode for sfs */ struct sfs_inode { struct sfs_disk_inode *din; /* on-disk inode */ uint32_t ino; /* inode number */ bool dirty; /* true if inode modified */ int reclaim_count; /* kill inode if it hits zero */ semaphore_t sem; /* semaphore for din */ list_entry_t inode_link; /* entry for linked-list in sfs_fs */ list_entry_t hash_link; /* entry for hash linked-list in sfs_fs */ }; #define le2sin(le, member) \ to_struct((le), struct sfs_inode, member) /* filesystem for sfs */ struct sfs_fs { struct sfs_super super; /* on-disk superblock */ struct device *dev; /* device mounted on */ struct bitmap *freemap; /* blocks in use are mared 0 */ bool super_dirty; /* true if super/freemap modified */ void *sfs_buffer; /* buffer for non-block aligned io */ semaphore_t fs_sem; /* semaphore for fs */ semaphore_t io_sem; /* semaphore for io */ semaphore_t mutex_sem; /* semaphore for link/unlink and rename */ list_entry_t inode_list; /* inode linked-list */ list_entry_t *hash_list; /* inode hash linked-list */ }; /* hash for sfs */ #define SFS_HLIST_SHIFT 10 #define SFS_HLIST_SIZE (1 << SFS_HLIST_SHIFT) #define sin_hashfn(x) (hash32(x, SFS_HLIST_SHIFT)) /* size of freemap (in bits) */ #define sfs_freemap_bits(super) ROUNDUP((super)->blocks, SFS_BLKBITS) /* size of freemap (in blocks) */ #define sfs_freemap_blocks(super) ROUNDUP_DIV((super)->blocks, SFS_BLKBITS) struct fs; struct inode; void sfs_init(void); int sfs_mount(const char *devname); void lock_sfs_fs(struct sfs_fs *sfs); void lock_sfs_io(struct sfs_fs *sfs); void unlock_sfs_fs(struct sfs_fs *sfs); void unlock_sfs_io(struct sfs_fs *sfs); int sfs_rblock(struct sfs_fs *sfs, void *buf, uint32_t blkno, uint32_t nblks); int sfs_wblock(struct sfs_fs *sfs, void *buf, uint32_t blkno, uint32_t nblks); int sfs_rbuf(struct sfs_fs *sfs, void *buf, size_t len, uint32_t blkno, off_t offset); int sfs_wbuf(struct sfs_fs *sfs, void *buf, size_t len, uint32_t blkno, off_t offset); int sfs_sync_super(struct sfs_fs *sfs); int sfs_sync_freemap(struct sfs_fs *sfs); int sfs_clear_block(struct sfs_fs *sfs, uint32_t blkno, uint32_t nblks); int sfs_load_inode(struct sfs_fs *sfs, struct inode **node_store, uint32_t ino); #endif /* !__KERN_FS_SFS_SFS_H__ */ ``` --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://oscourse-tsinghua.gitbook.io/ucore-analysis/ucore/kern/fs/sfs/sfs_h.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.