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long do_unlinkat(int dfd, const char __user *pathname){	struct dentry *dentry;	struct nameidata nd;	struct inode *inode = NULL;	error = user_path_parent(dfd, pathname, &nd, &name);		dentry = lookup_hash(&nd);		inode = dentry->d_inode;	if (inode)		atomic_inc(&inode->i_count);	error = mnt_want_write(nd.path.mnt);		error = vfs_unlink(nd.path.dentry->d_inode, dentry);		mnt_drop_write(nd.path.mnt);		dput(dentry);		if (inode)		iput(inode);	/* truncate the inode here */		=>void iput(struct inode *inode)		{			if (inode) {				BUG_ON(inode->i_state == I_CLEAR);				if (atomic_dec_and_lock(&inode->i_count, &inode_lock))					iput_final(inode);					=>void iput_final(struct inode *inode)					{						const struct super_operations *op = inode->i_sb->s_op;						void (*drop)(struct inode *) = generic_drop_inode;						if (op && op->drop_inode)							drop = op->drop_inode;						drop(inode);						=>void generic_drop_inode(struct inode *inode)						{							if (!inode->i_nlink)								generic_delete_inode(inode);//Super.c (fs\ext2):	.delete_inode	= ext2_delete_inode,								=>void ext2_delete_inode (struct inode * inode)								{									if (!is_bad_inode(inode))										dquot_initialize(inode);									truncate_inode_pages(&inode->i_data, 0);									if (is_bad_inode(inode))										goto no_delete;									EXT2_I(inode)->i_dtime	= get_seconds();									mark_inode_dirty(inode);									__ext2_write_inode(inode, inode_needs_sync(inode));									inode->i_size = 0;									if (inode->i_blocks)										ext2_truncate (inode);									ext2_free_inode (inode);//真正释放文件节点									return;								no_delete:									clear_inode(inode);	/* We must guarantee clearing of inode... */								}							else								generic_forget_inode(inode);						}					}			}		}			path_put(&nd.path);	putname(name);	return error;}

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