file: Implement task_lookup_fd_rcu (3a879fb3) · Commits · 戴 / test

As a companion to lookup_fd_rcu implement task_lookup_fd_rcu for querying an arbitrary process about a specific file. Acked-by:

fs/file.c

+15 −0

Original line number	Diff line number	Diff line
		@@ -865,6 +865,21 @@ struct file fget_task(struct task_struct task, unsigned int fd)
		return file;
		}

		struct file task_lookup_fd_rcu(struct task_struct task, unsigned int fd)
		{
		/* Must be called with rcu_read_lock held */
		struct files_struct *files;
		struct file *file = NULL;

		task_lock(task);
		files = task->files;
		if (files)
		file = files_lookup_fd_rcu(files, fd);
		task_unlock(task);

		return file;
		}

		/*
		* Lightweight file lookup - no refcnt increment if fd table isn't shared.
		*

+2 −0

Original line number	Diff line number	Diff line
		@@ -110,6 +110,8 @@ static inline struct file *lookup_fd_rcu(unsigned int fd)
		return files_lookup_fd_rcu(current->files, fd);
		}

		struct file task_lookup_fd_rcu(struct task_struct task, unsigned int fd);

		struct task_struct;

		struct files_struct get_files_struct(struct task_struct );