FS 数据结构

linux-5.14.3/fs/fat/namei_vfat.c

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

static struct file_system_type vfat_fs_type = {
    .owner        = THIS_MODULE,
    .name        = "vfat",
    .mount        = vfat_mount,
    .kill_sb    = kill_block_super,
    .fs_flags    = FS_REQUIRES_DEV | FS_ALLOW_IDMAP,
};
MODULE_ALIAS_FS("vfat");

static int __init init_vfat_fs(void)
{
    return register_filesystem(&vfat_fs_type);
}

static void __exit exit_vfat_fs(void)
{
    unregister_filesystem(&vfat_fs_type);
}

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("VFAT filesystem support");
MODULE_AUTHOR("Gordon Chaffee");

module_init(init_vfat_fs)
module_exit(exit_vfat_fs)

linux-5.14.3/fs/filesystems.c

/*
 * Handling of filesystem drivers list.
 * Rules:
 *    Inclusion to/removals from/scanning of list are protected by spinlock.
 *    During the unload module must call unregister_filesystem().
 *    We can access the fields of list element if:
 *        1) spinlock is held or
 *        2) we hold the reference to the module.
 *    The latter can be guaranteed by call of try_module_get(); if it
 *    returned 0 we must skip the element, otherwise we got the reference.
 *    Once the reference is obtained we can drop the spinlock.
 */

static struct file_system_type *file_systems;

struct mount {
  struct vfsmount   mnt
  struct dentry    *mnt_mountpoint
}

struct dentry {
  struct qstr         d_name;
  struct super_block *d_sb;
  ......
}

struct vfsmount {
  struct dentry      *mnt_root;
  struct super_block *mnt_sb;
  ......
}


struct super_block {
  struct file_system_type    *s_type;
  const struct super_operations    *s_op;
  struct dentry        *s_root;
  ......
}

3.

/* super_block => dentry => vfsmount => mount */
vfs_kern_mount()
struct dentry *root = mount_fs(type, flags, name, data);