1 files changed, 274 insertions, 0 deletions
diff --git a/include/linux/pipe_fs_i.h b/include/linux/pipe_fs_i.h
new file mode 100644
index 000000000..1f1e7ae95
--- /dev/null
+++ b/include/linux/pipe_fs_i.h
@@ -0,0 +1,274 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_PIPE_FS_I_H
+#define _LINUX_PIPE_FS_I_H
+
+#define PIPE_DEF_BUFFERS	16
+
+#define PIPE_BUF_FLAG_LRU	0x01	/* page is on the LRU */
+#define PIPE_BUF_FLAG_ATOMIC	0x02	/* was atomically mapped */
+#define PIPE_BUF_FLAG_GIFT	0x04	/* page is a gift */
+#define PIPE_BUF_FLAG_PACKET	0x08	/* read() as a packet */
+#define PIPE_BUF_FLAG_CAN_MERGE	0x10	/* can merge buffers */
+#define PIPE_BUF_FLAG_WHOLE	0x20	/* read() must return entire buffer or error */
+#ifdef CONFIG_WATCH_QUEUE
+#define PIPE_BUF_FLAG_LOSS	0x40	/* Message loss happened after this buffer */
+#endif
+
+/**
+ *	struct pipe_buffer - a linux kernel pipe buffer
+ *	@page: the page containing the data for the pipe buffer
+ *	@offset: offset of data inside the @page
+ *	@len: length of data inside the @page
+ *	@ops: operations associated with this buffer. See @pipe_buf_operations.
+ *	@flags: pipe buffer flags. See above.
+ *	@private: private data owned by the ops.
+ **/
+struct pipe_buffer {
+	struct page *page;
+	unsigned int offset, len;
+	const struct pipe_buf_operations *ops;
+	unsigned int flags;
+	unsigned long private;
+};
+
+/**
+ *	struct pipe_inode_info - a linux kernel pipe
+ *	@mutex: mutex protecting the whole thing
+ *	@rd_wait: reader wait point in case of empty pipe
+ *	@wr_wait: writer wait point in case of full pipe
+ *	@head: The point of buffer production
+ *	@tail: The point of buffer consumption
+ *	@note_loss: The next read() should insert a data-lost message
+ *	@max_usage: The maximum number of slots that may be used in the ring
+ *	@ring_size: total number of buffers (should be a power of 2)
+ *	@nr_accounted: The amount this pipe accounts for in user->pipe_bufs
+ *	@tmp_page: cached released page
+ *	@readers: number of current readers of this pipe
+ *	@writers: number of current writers of this pipe
+ *	@files: number of struct file referring this pipe (protected by ->i_lock)
+ *	@r_counter: reader counter
+ *	@w_counter: writer counter
+ *	@poll_usage: is this pipe used for epoll, which has crazy wakeups?
+ *	@fasync_readers: reader side fasync
+ *	@fasync_writers: writer side fasync
+ *	@bufs: the circular array of pipe buffers
+ *	@user: the user who created this pipe
+ *	@watch_queue: If this pipe is a watch_queue, this is the stuff for that
+ **/
+struct pipe_inode_info {
+	struct mutex mutex;
+	wait_queue_head_t rd_wait, wr_wait;
+	unsigned int head;
+	unsigned int tail;
+	unsigned int max_usage;
+	unsigned int ring_size;
+#ifdef CONFIG_WATCH_QUEUE
+	bool note_loss;
+#endif
+	unsigned int nr_accounted;
+	unsigned int readers;
+	unsigned int writers;
+	unsigned int files;
+	unsigned int r_counter;
+	unsigned int w_counter;
+	bool poll_usage;
+	struct page *tmp_page;
+	struct fasync_struct *fasync_readers;
+	struct fasync_struct *fasync_writers;
+	struct pipe_buffer *bufs;
+	struct user_struct *user;
+#ifdef CONFIG_WATCH_QUEUE
+	struct watch_queue *watch_queue;
+#endif
+};
+
+/*
+ * Note on the nesting of these functions:
+ *
+ * ->confirm()
+ *	->try_steal()
+ *
+ * That is, ->try_steal() must be called on a confirmed buffer.  See below for
+ * the meaning of each operation.  Also see the kerneldoc in fs/pipe.c for the
+ * pipe and generic variants of these hooks.
+ */
+struct pipe_buf_operations {
+	/*
+	 * ->confirm() verifies that the data in the pipe buffer is there
+	 * and that the contents are good. If the pages in the pipe belong
+	 * to a file system, we may need to wait for IO completion in this
+	 * hook. Returns 0 for good, or a negative error value in case of
+	 * error.  If not present all pages are considered good.
+	 */
+	int (*confirm)(struct pipe_inode_info *, struct pipe_buffer *);
+
+	/*
+	 * When the contents of this pipe buffer has been completely
+	 * consumed by a reader, ->release() is called.
+	 */
+	void (*release)(struct pipe_inode_info *, struct pipe_buffer *);
+
+	/*
+	 * Attempt to take ownership of the pipe buffer and its contents.
+	 * ->try_steal() returns %true for success, in which case the contents
+	 * of the pipe (the buf->page) is locked and now completely owned by the
+	 * caller. The page may then be transferred to a different mapping, the
+	 * most often used case is insertion into different file address space
+	 * cache.
+	 */
+	bool (*try_steal)(struct pipe_inode_info *, struct pipe_buffer *);
+
+	/*
+	 * Get a reference to the pipe buffer.
+	 */
+	bool (*get)(struct pipe_inode_info *, struct pipe_buffer *);
+};
+
+/**
+ * pipe_has_watch_queue - Check whether the pipe is a watch_queue,
+ * i.e. it was created with O_NOTIFICATION_PIPE
+ * @pipe: The pipe to check
+ *
+ * Return: true if pipe is a watch queue, false otherwise.
+ */
+static inline bool pipe_has_watch_queue(const struct pipe_inode_info *pipe)
+{
+#ifdef CONFIG_WATCH_QUEUE
+	return pipe->watch_queue != NULL;
+#else
+	return false;
+#endif
+}
+
+/**
+ * pipe_empty - Return true if the pipe is empty
+ * @head: The pipe ring head pointer
+ * @tail: The pipe ring tail pointer
+ */
+static inline bool pipe_empty(unsigned int head, unsigned int tail)
+{
+	return head == tail;
+}
+
+/**
+ * pipe_occupancy - Return number of slots used in the pipe
+ * @head: The pipe ring head pointer
+ * @tail: The pipe ring tail pointer
+ */
+static inline unsigned int pipe_occupancy(unsigned int head, unsigned int tail)
+{
+	return head - tail;
+}
+
+/**
+ * pipe_full - Return true if the pipe is full
+ * @head: The pipe ring head pointer
+ * @tail: The pipe ring tail pointer
+ * @limit: The maximum amount of slots available.
+ */
+static inline bool pipe_full(unsigned int head, unsigned int tail,
+			     unsigned int limit)
+{
+	return pipe_occupancy(head, tail) >= limit;
+}
+
+/**
+ * pipe_buf_get - get a reference to a pipe_buffer
+ * @pipe:	the pipe that the buffer belongs to
+ * @buf:	the buffer to get a reference to
+ *
+ * Return: %true if the reference was successfully obtained.
+ */
+static inline __must_check bool pipe_buf_get(struct pipe_inode_info *pipe,
+				struct pipe_buffer *buf)
+{
+	return buf->ops->get(pipe, buf);
+}
+
+/**
+ * pipe_buf_release - put a reference to a pipe_buffer
+ * @pipe:	the pipe that the buffer belongs to
+ * @buf:	the buffer to put a reference to
+ */
+static inline void pipe_buf_release(struct pipe_inode_info *pipe,
+				    struct pipe_buffer *buf)
+{
+	const struct pipe_buf_operations *ops = buf->ops;
+
+	buf->ops = NULL;
+	ops->release(pipe, buf);
+}
+
+/**
+ * pipe_buf_confirm - verify contents of the pipe buffer
+ * @pipe:	the pipe that the buffer belongs to
+ * @buf:	the buffer to confirm
+ */
+static inline int pipe_buf_confirm(struct pipe_inode_info *pipe,
+				   struct pipe_buffer *buf)
+{
+	if (!buf->ops->confirm)
+		return 0;
+	return buf->ops->confirm(pipe, buf);
+}
+
+/**
+ * pipe_buf_try_steal - attempt to take ownership of a pipe_buffer
+ * @pipe:	the pipe that the buffer belongs to
+ * @buf:	the buffer to attempt to steal
+ */
+static inline bool pipe_buf_try_steal(struct pipe_inode_info *pipe,
+		struct pipe_buffer *buf)
+{
+	if (!buf->ops->try_steal)
+		return false;
+	return buf->ops->try_steal(pipe, buf);
+}
+
+static inline void pipe_discard_from(struct pipe_inode_info *pipe,
+		unsigned int old_head)
+{
+	unsigned int mask = pipe->ring_size - 1;
+
+	while (pipe->head > old_head)
+		pipe_buf_release(pipe, &pipe->bufs[--pipe->head & mask]);
+}
+
+/* Differs from PIPE_BUF in that PIPE_SIZE is the length of the actual
+   memory allocation, whereas PIPE_BUF makes atomicity guarantees.  */
+#define PIPE_SIZE		PAGE_SIZE
+
+/* Pipe lock and unlock operations */
+void pipe_lock(struct pipe_inode_info *);
+void pipe_unlock(struct pipe_inode_info *);
+void pipe_double_lock(struct pipe_inode_info *, struct pipe_inode_info *);
+
+/* Wait for a pipe to be readable/writable while dropping the pipe lock */
+void pipe_wait_readable(struct pipe_inode_info *);
+void pipe_wait_writable(struct pipe_inode_info *);
+
+struct pipe_inode_info *alloc_pipe_info(void);
+void free_pipe_info(struct pipe_inode_info *);
+
+/* Generic pipe buffer ops functions */
+bool generic_pipe_buf_get(struct pipe_inode_info *, struct pipe_buffer *);
+bool generic_pipe_buf_try_steal(struct pipe_inode_info *, struct pipe_buffer *);
+void generic_pipe_buf_release(struct pipe_inode_info *, struct pipe_buffer *);
+
+extern const struct pipe_buf_operations nosteal_pipe_buf_ops;
+
+unsigned long account_pipe_buffers(struct user_struct *user,
+				   unsigned long old, unsigned long new);
+bool too_many_pipe_buffers_soft(unsigned long user_bufs);
+bool too_many_pipe_buffers_hard(unsigned long user_bufs);
+bool pipe_is_unprivileged_user(void);
+
+/* for F_SETPIPE_SZ and F_GETPIPE_SZ */
+int pipe_resize_ring(struct pipe_inode_info *pipe, unsigned int nr_slots);
+long pipe_fcntl(struct file *, unsigned int, unsigned long arg);
+struct pipe_inode_info *get_pipe_info(struct file *file, bool for_splice);
+
+int create_pipe_files(struct file **, int);
+unsigned int round_pipe_size(unsigned long size);
+
+#endif