ext2_fs_sb.h.txt

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相关文件
	include/linux/fs.h


#define EXT2_MAX_GROUP_LOADED   32	//ext2文件系统最大可以同时装载到内存中组数量(?)


这个结构属于fs.h中vfs的super_block中的u成员的，也就是当系统从磁盘中把ext2文件系统的超级块读出来
以后，就用读出来的数据对这个数据结构进行赋值，这个是linux系统实际使用的真正的超级块
struct ext2_sb_info {
        unsigned long s_frag_size;      /* Size of a fragment in bytes */
        unsigned long s_frags_per_block;/* Number of fragments per block */
        unsigned long s_inodes_per_block;/* Number of inodes per block */
        unsigned long s_frags_per_group;/* Number of fragments in a group */
        unsigned long s_blocks_per_group;/* Number of blocks in a group */
        unsigned long s_inodes_per_group;/* Number of inodes in a group */
        unsigned long s_itb_per_group;  /* Number of inode table blocks per grop */
        unsigned long s_gdb_count;      /* Number of group descriptor blocks */
        unsigned long s_desc_per_block; /* Number of group descriptors per bloc */
        unsigned long s_groups_count;   /* 当前文件系统的组数量 */
        struct buffer_head * s_sbh;     /* 纪录一个buffer，其中包含s_es */
        struct ext2_super_block * s_es; /* 从磁盘上读出来的ext2超级块就存在这里 */
        struct buffer_head ** s_group_desc;
        unsigned short s_loaded_inode_bitmaps;
        unsigned short s_loaded_block_bitmaps;
        unsigned long s_inode_bitmap_number[EXT2_MAX_GROUP_LOADED];	//装载的块组缓存(inode)
        struct buffer_head * s_inode_bitmap[EXT2_MAX_GROUP_LOADED];
        unsigned long s_block_bitmap_number[EXT2_MAX_GROUP_LOADED];
        struct buffer_head * s_block_bitmap[EXT2_MAX_GROUP_LOADED];
	unsigned long  s_mount_opt;
        uid_t s_resuid;
        gid_t s_resgid;
        unsigned short s_mount_state;
        unsigned short s_pad;
        int s_addr_per_block_bits;
        int s_desc_per_block_bits;
        int s_inode_size;
        int s_first_ino;
};