/**
* sysfs_get_inode - get inode for sysfs_dirent
* @sb: super block
* @sd: sysfs_dirent to allocate inode for
*
* Get inode for @sd. If such inode doesn't exist, a new inode
* is allocated and basics are initialized. New inode is
* returned locked.
*
* LOCKING:
* Kernel thread context (may sleep).
*
* RETURNS:
* Pointer to allocated inode on success, NULL on failure.
*/
struct inode * sysfs_get_inode(struct super_block *sb, struct sysfs_dirent *sd)
{
struct inode *inode;
inode = iget_locked(sb, sd->s_ino);
if (inode && (inode->i_state & I_NEW))
sysfs_init_inode(sd, inode);
return inode;
}
/**
* sysfs_get_inode - get inode for sysfs_dirent
* @sd: sysfs_dirent to allocate inode for
*
* Get inode for @sd. If such inode doesn't exist, a new inode
* is allocated and basics are initialized. New inode is
* returned locked.
*
* LOCKING:
* Kernel thread context (may sleep).
*
* RETURNS:
* Pointer to allocated inode on success, NULL on failure.
*/
struct inode * sysfs_get_inode(struct sysfs_dirent *sd)
{
struct inode *inode;
/*
对于一个目录文件，有两个数据结构 dentry 和inode咯.
sysfs_dirent->s_ino指向了这个目录文件的inode号。
对于一个文件系统来说，超级块+inode号可以找到inode数据结构.
根据sb + ino计算hash值.
*/
/*
如果没有存在于当前的hash表中，那么就需要分配一个新的inode数据结构咯。
同时设置i_state为I_NEW标记.还有I_LOCK标记，代表还不可用..因为它还没初始化完成.
避免说，有另外的地方也去查找了hash表，得到后直接使用。因此，需要在初始化完成后，
需要对I_NEW和I_LOCK进行clear掉.
*/
inode = iget_locked(sysfs_sb, sd->s_ino);
if (inode && (inode->i_state & I_NEW))
sysfs_init_inode(sd, inode);
return inode;
}
