• new_inode(): creates a new inode, sets the i_nlink field to 1 and initializes i_blkbits, i_sb and i_dev;

• insert_inode_hash(): adds the inode to the hash table of inodes; an interesting effect of this call is that the inode will be written to the disk if it is marked as dirty;

• mark_inode_dirty(): marks the inode as dirty; at a later moment, it will be written on the disc;

• iget_locked(): loads the inode with the given number from the disk, if it is not already loaded;

• unlock_new_inode(): used in conjunction with iget_locked(), releases the lock on the inode;

• iput(): tells the kernel that the work on the inode is finished; if no one else uses it, it will be destroyed (after being written on the disk if it is maked as dirty);

• make_bad_inode(): tells the kernel that the inode can not be used; It is generally used from the function that reads the inode when the inode could not be read from the disk, being invalid.

struct inode *ubifs_iget(struct super_block *sb, unsigned long inum)

{

    int err;

    union ubifs_key key;

    struct ubifs_ino_node *ino;

    struct ubifs_info *c = sb->s_fs_info;

    struct inode *inode;

    struct ubifs_inode *ui;



    dbg_gen("inode %lu", inum);



    inode = iget_locked(sb, inum);

    if (!inode)

        return ERR_PTR(-ENOMEM);

    if (!(inode->i_state & I_NEW))

        return inode;

    ui = ubifs_inode(inode);



    ino = kmalloc(UBIFS_MAX_INO_NODE_SZ, GFP_NOFS);

    if (!ino) {

        err = -ENOMEM;

        goto out;

    }



    ...

}

• alloc_inode: 分配一个inode. 通常, 这个函数分配一个struct _inode_info 结构和执行基本的VFS inode 初始化(调用inode_init_once()); minix uses for allocation the kmem_cache_alloc() function that interacts with the SLAB subsystem. For each allocation, the cache construction is called, which in the case of minix is the init_once() function. Alternatively, kmalloc() can be used, in which case the inode_init_once() function should be called. The alloc_inode() function will be called by the new_inode() and iget_locked() functions.
• write_inode : saves/updates the inode received as a parameter on disk; to update the inode, though inefficient, for beginners it is recommended to use the following sequence of operations:
  • load the inode from the disk using the sb_bread() function;
  • modify the buffer according to the saved inode;
  • mark the buffer as dirty using mark_buffer_dirty(); the kernel will then handle its writing on the disk;
  • an example is the minix_write_inode() function in the minix file system
• evict_inode: removes any information about the inode with the number received in the i_ino field from the disk and memory (both the inode on the disk and the associated data blocks). This involves performing the following operations:
  • delete the inode from the disk;
  • updates disk bitmaps (if any);
  • delete the inode from the page cache by calling truncate_inode_pages();
  • delete the inode from memory by calling clear_inode() ;
  • an example is the minix_evict_inode() function from the minix file system.
• destroy_inode releases the memory occupied by inode

inode_operations

ubifs_setattr()的实现。