ext4 mount流程

目录

​​1.mount流程​​

​​2. ext4_file_super​​

​​ext4同步磁盘模式​​

​​jbd提交日志间隔​​

​​journal_inode日志索引节点​​

​​mount参数解析​​

​​ext4_load_journal​​

​​ext4_register_sysfs​​

1.mount流程

路径：fs\ext4\super.c

static struct dentry *ext4_mount(struct file_system_type *fs_type, int flags,
               const char *dev_name, void *data)
{
    return mount_bdev(fs_type, flags, dev_name, data, ext4_fill_super);
}

static struct file_system_type ext4_fs_type = {
    .owner      = THIS_MODULE,
    .name       = "ext4",
    .mount      = ext4_mount,
    .kill_sb    = kill_block_super,
    .fs_flags   = FS_REQUIRES_DEV,
};
MODULE_ALIAS_FS("ext4");

static int __init ext4_init_fs(void)
{
    int i, err;

    ratelimit_state_init(&ext4_mount_msg_ratelimit, 30 * HZ, 64);
    ext4_li_info = NULL;
    mutex_init(&ext4_li_mtx);

    /* Build-time check for flags consistency */
    ext4_check_flag_values();

    for (i = 0; i < EXT4_WQ_HASH_SZ; i++)
        init_waitqueue_head(&ext4__ioend_wq[i]);

    err = ext4_init_es();
    if (err)
        return err;

    err = ext4_init_pending();
    if (err)
        goto out7;

    err = ext4_init_post_read_processing();
    if (err)
        goto out6;

    err = ext4_init_pageio();
    if (err)
        goto out5;

    err = ext4_init_system_zone();
    if (err)
        goto out4;

    err = ext4_init_sysfs();
    if (err)
        goto out3;

    err = ext4_init_mballoc();
    if (err)
        goto out2;
    err = init_inodecache();
    if (err)
        goto out1;

    err = ext4_fc_init_dentry_cache();
    if (err)
        goto out05;

    register_as_ext3();
    register_as_ext2();
    err = register_filesystem(&ext4_fs_type);
    if (err)
        goto out;

    return 0;
out:
    unregister_as_ext2();
    unregister_as_ext3();
    ext4_fc_destroy_dentry_cache();
out05:
    destroy_inodecache();
out1:
    ext4_exit_mballoc();
out2:
    ext4_exit_sysfs();
out3:
    ext4_exit_system_zone();
out4:
    ext4_exit_pageio();
out5:
    ext4_exit_post_read_processing();
out6:
    ext4_exit_pending();
out7:
    ext4_exit_es();

    return err;
}

其中ext4_fs_type结构体定义

static struct file_system_type ext4_fs_type = {
    .owner      = THIS_MODULE,
    .name       = "ext4",
    .mount      = ext4_mount,
    .kill_sb    = kill_block_super,
    .fs_flags   = FS_REQUIRES_DEV,
};
MODULE_ALIAS_FS("ext4");

2. ext4_file_super

ext4同步磁盘模式

if ((def_mount_opts & EXT4_DEFM_JMODE) == EXT4_DEFM_JMODE_DATA)

set_opt(sb, JOURNAL_DATA);

else if ((def_mount_opts & EXT4_DEFM_JMODE) == EXT4_DEFM_JMODE_ORDERED)

set_opt(sb, ORDERED_DATA);

else if ((def_mount_opts & EXT4_DEFM_JMODE) == EXT4_DEFM_JMODE_WBACK)

set_opt(sb, WRITEBACK_DATA);

jbd提交日志间隔

sbi->s_commit_interval = JBD2_DEFAULT_MAX_COMMIT_AGE * HZ; //5*HZ

sbi->s_min_batch_time = EXT4_DEF_MIN_BATCH_TIME;

sbi->s_max_batch_time = EXT4_DEF_MAX_BATCH_TIME;

journal_inode日志索引节点

journal_inode = d_inode(path.dentry);
    if (!S_ISBLK(journal_inode->i_mode)) {
      ext4_msg(sb, KERN_ERR, "error: journal path %s "
        "is not a block device", journal_path);
      path_put(&path);
      kfree(journal_path);
      return -1;
    }

mount参数解析

if (sbi->s_es->s_mount_opts[0]) {
    char *s_mount_opts = kstrndup(sbi->s_es->s_mount_opts,
                sizeof(sbi->s_es->s_mount_opts),
                GFP_KERNEL);
    if (!s_mount_opts)
      goto failed_mount;
    if (!parse_options(s_mount_opts, sb, &journal_devnum,
           &journal_ioprio, 0)) {
      ext4_msg(sb, KERN_WARNING,
         "failed to parse options in superblock: %s",
         s_mount_opts);
    }
    kfree(s_mount_opts);
  }
  sbi->s_def_mount_opt = sbi->s_mount_opt;
  if (!parse_options((char *) data, sb, &journal_devnum,
         &journal_ioprio, 0))
    goto failed_mount;

ext4_load_journal

if (!test_opt(sb, NOLOAD) && ext4_has_feature_journal(sb)) {
    err = ext4_load_journal(sb, es, journal_devnum);
    if (err)
      goto failed_mount3a;
  } else if (test_opt(sb, NOLOAD) && !sb_rdonly(sb) &&

ext4_register_sysfs

err = ext4_register_sysfs(sb);
  if (err)
    goto failed_mount7;