FS ext2_super_block
2015-10-12 00:50
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super_block:用于记录文件系统和管理信息,特定的文件系统定义了特定的超级块。第一个超级块=start_sect(分区表里ext2文件系统开始的扇区)+2
struct ext2_super_block { __le32 s_inodes_count; /* Inodes count */ __le32 s_blocks_count; /* Blocks count */ __le32 s_r_blocks_count; /* Reserved blocks count */ __le32 s_free_blocks_count; /* Free blocks count */ __le32 s_free_inodes_count; /* Free inodes count */ __le32 s_first_data_block; /* First Data Block */ __le32 s_log_block_size; /* Block size */ __le32 s_log_frag_size; /* Fragment size */ __le32 s_blocks_per_group; /* # Blocks per group */ __le32 s_frags_per_group; /* # Fragments per group */ __le32 s_inodes_per_group; /* # Inodes per group */ __le32 s_mtime; /* Mount time */ __le32 s_wtime; /* Write time */ __le16 s_mnt_count; /* Mount count */ __le16 s_max_mnt_count; /* Maximal mount count */ __le16 s_magic; /* Magic signature */ __le16 s_state; /* File system state */ __le16 s_errors; /* Behaviour when detecting errors */ __le16 s_minor_rev_level; /* minor revision level */ __le32 s_lastcheck; /* time of last check */ __le32 s_checkinterval; /* max. time between checks */ __le32 s_creator_os; /* OS */ __le32 s_rev_level; /* Revision level */ __le16 s_def_resuid; /* Default uid for reserved blocks */ __le16 s_def_resgid; /* Default gid for reserved blocks */ /* * These fields are for EXT2_DYNAMIC_REV superblocks only. * * Note: the difference between the compatible feature set and * the incompatible feature set is that if there is a bit set * in the incompatible feature set that the kernel doesn't * know about, it should refuse to mount the filesystem. * * e2fsck's requirements are more strict; if it doesn't know * about a feature in either the compatible or incompatible * feature set, it must abort and not try to meddle with * things it doesn't understand... */ __le32 s_first_ino; /* First non-reserved inode */ __le16 s_inode_size; /* size of inode structure */ __le16 s_block_group_nr; /* block group # of this superblock */ __le32 s_feature_compat; /* compatible feature set */ __le32 s_feature_incompat; /* incompatible feature set */ __le32 s_feature_ro_compat; /* readonly-compatible feature set */ __u8 s_uuid[16]; /* 128-bit uuid for volume */ char s_volume_name[16]; /* volume name */ char s_last_mounted[64]; /* directory where last mounted */ __le32 s_algorithm_usage_bitmap; /* For compression */ /* * Performance hints. Directory preallocation should only * happen if the EXT2_COMPAT_PREALLOC flag is on. */ __u8 s_prealloc_blocks; /* Nr of blocks to try to preallocate*/ __u8 s_prealloc_dir_blocks; /* Nr to preallocate for dirs */ __u16 s_padding1; /* * Journaling support valid if EXT3_FEATURE_COMPAT_HAS_JOURNAL set. */ __u8 s_journal_uuid[16]; /* uuid of journal superblock */ __u32 s_journal_inum; /* inode number of journal file */ __u32 s_journal_dev; /* device number of journal file */ __u32 s_last_orphan; /* start of list of inodes to delete */ __u32 s_hash_seed[4]; /* HTREE hash seed */ __u8 s_def_hash_version; /* Default hash version to use */ __u8 s_reserved_char_pad; __u16 s_reserved_word_pad; __le32 s_default_mount_opts; __le32 s_first_meta_bg; /* First metablock block group */ __u32 s_reserved[190]; /* Padding to the end of the block */ };
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 group */ unsigned long s_gdb_count; /* Number of group descriptor blocks */ unsigned long s_desc_per_block; /* Number of group descriptors per block */ unsigned long s_groups_count; /* Number of groups in the fs */ unsigned long s_overhead_last; /* Last calculated overhead */ unsigned long s_blocks_last; /* Last seen block count */ struct buffer_head * s_sbh; /* Buffer containing the super block */ struct ext2_super_block * s_es; /* Pointer to the super block in the buffer */ struct buffer_head ** s_group_desc; unsigned long s_mount_opt; unsigned long s_sb_block; 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; spinlock_t s_next_gen_lock; u32 s_next_generation; unsigned long s_dir_count; u8 *s_debts; struct percpu_counter s_freeblocks_counter; struct percpu_counter s_freeinodes_counter; struct percpu_counter s_dirs_counter; struct blockgroup_lock *s_blockgroup_lock; /* root of the per fs reservation window tree */ spinlock_t s_rsv_window_lock; struct rb_root s_rsv_window_root; struct ext2_reserve_window_node s_rsv_window_head; };
static int __init init_ext2_fs(void) { int err = init_ext2_xattr(); if (err) return err; err = init_inodecache(); if (err) goto out1; err = register_filesystem(&ext2_fs_type); if (err) goto out; return 0; out: destroy_inodecache(); out1: exit_ext2_xattr(); return err; }
const struct file_operations ext2_file_operations = { .llseek = generic_file_llseek, .read = do_sync_read, .write = do_sync_write, .aio_read = generic_file_aio_read, .aio_write = generic_file_aio_write, .unlocked_ioctl = ext2_ioctl, #ifdef CONFIG_COMPAT .compat_ioctl = ext2_compat_ioctl, #endif .mmap = generic_file_mmap, .open = generic_file_open, .release = ext2_release_file, .fsync = simple_fsync, .splice_read = generic_file_splice_read, .splice_write = generic_file_splice_write, };
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