1#ifndef _LINUX_PIPE_FS_I_H
2#define _LINUX_PIPE_FS_I_H
3
4#define PIPE_DEF_BUFFERS	16
5
6#define PIPE_BUF_FLAG_LRU	0x01	/* page is on the LRU */
7#define PIPE_BUF_FLAG_ATOMIC	0x02	/* was atomically mapped */
8#define PIPE_BUF_FLAG_GIFT	0x04	/* page is a gift */
9#define PIPE_BUF_FLAG_PACKET	0x08	/* read() as a packet */
10
11/**
12 *	struct pipe_buffer - a linux kernel pipe buffer
13 *	@page: the page containing the data for the pipe buffer
14 *	@offset: offset of data inside the @page
15 *	@len: length of data inside the @page
16 *	@ops: operations associated with this buffer. See @pipe_buf_operations.
17 *	@flags: pipe buffer flags. See above.
18 *	@private: private data owned by the ops.
19 **/
20struct pipe_buffer {
21	struct page *page;
22	unsigned int offset, len;
23	const struct pipe_buf_operations *ops;
24	unsigned int flags;
25	unsigned long private;
26};
27
28/**
29 *	struct pipe_inode_info - a linux kernel pipe
30 *	@mutex: mutex protecting the whole thing
31 *	@wait: reader/writer wait point in case of empty/full pipe
32 *	@nrbufs: the number of non-empty pipe buffers in this pipe
33 *	@buffers: total number of buffers (should be a power of 2)
34 *	@curbuf: the current pipe buffer entry
35 *	@tmp_page: cached released page
36 *	@readers: number of current readers of this pipe
37 *	@writers: number of current writers of this pipe
38 *	@files: number of struct file referring this pipe (protected by ->i_lock)
39 *	@waiting_writers: number of writers blocked waiting for room
40 *	@r_counter: reader counter
41 *	@w_counter: writer counter
42 *	@fasync_readers: reader side fasync
43 *	@fasync_writers: writer side fasync
44 *	@bufs: the circular array of pipe buffers
45 **/
46struct pipe_inode_info {
47	struct mutex mutex;
48	wait_queue_head_t wait;
49	unsigned int nrbufs, curbuf, buffers;
50	unsigned int readers;
51	unsigned int writers;
52	unsigned int files;
53	unsigned int waiting_writers;
54	unsigned int r_counter;
55	unsigned int w_counter;
56	struct page *tmp_page;
57	struct fasync_struct *fasync_readers;
58	struct fasync_struct *fasync_writers;
59	struct pipe_buffer *bufs;
60};
61
62/*
63 * Note on the nesting of these functions:
64 *
65 * ->confirm()
66 *	->steal()
67 *	...
68 *	->map()
69 *	...
70 *	->unmap()
71 *
72 * That is, ->map() must be called on a confirmed buffer,
73 * same goes for ->steal(). See below for the meaning of each
74 * operation. Also see kerneldoc in fs/pipe.c for the pipe
75 * and generic variants of these hooks.
76 */
77struct pipe_buf_operations {
78	/*
79	 * This is set to 1, if the generic pipe read/write may coalesce
80	 * data into an existing buffer. If this is set to 0, a new pipe
81	 * page segment is always used for new data.
82	 */
83	int can_merge;
84
85	/*
86	 * ->confirm() verifies that the data in the pipe buffer is there
87	 * and that the contents are good. If the pages in the pipe belong
88	 * to a file system, we may need to wait for IO completion in this
89	 * hook. Returns 0 for good, or a negative error value in case of
90	 * error.
91	 */
92	int (*confirm)(struct pipe_inode_info *, struct pipe_buffer *);
93
94	/*
95	 * When the contents of this pipe buffer has been completely
96	 * consumed by a reader, ->release() is called.
97	 */
98	void (*release)(struct pipe_inode_info *, struct pipe_buffer *);
99
100	/*
101	 * Attempt to take ownership of the pipe buffer and its contents.
102	 * ->steal() returns 0 for success, in which case the contents
103	 * of the pipe (the buf->page) is locked and now completely owned
104	 * by the caller. The page may then be transferred to a different
105	 * mapping, the most often used case is insertion into different
106	 * file address space cache.
107	 */
108	int (*steal)(struct pipe_inode_info *, struct pipe_buffer *);
109
110	/*
111	 * Get a reference to the pipe buffer.
112	 */
113	void (*get)(struct pipe_inode_info *, struct pipe_buffer *);
114};
115
116/* Differs from PIPE_BUF in that PIPE_SIZE is the length of the actual
117   memory allocation, whereas PIPE_BUF makes atomicity guarantees.  */
118#define PIPE_SIZE		PAGE_SIZE
119
120/* Pipe lock and unlock operations */
121void pipe_lock(struct pipe_inode_info *);
122void pipe_unlock(struct pipe_inode_info *);
123void pipe_double_lock(struct pipe_inode_info *, struct pipe_inode_info *);
124
125extern unsigned int pipe_max_size, pipe_min_size;
126int pipe_proc_fn(struct ctl_table *, int, void __user *, size_t *, loff_t *);
127
128
129/* Drop the inode semaphore and wait for a pipe event, atomically */
130void pipe_wait(struct pipe_inode_info *pipe);
131
132struct pipe_inode_info *alloc_pipe_info(void);
133void free_pipe_info(struct pipe_inode_info *);
134
135/* Generic pipe buffer ops functions */
136void generic_pipe_buf_get(struct pipe_inode_info *, struct pipe_buffer *);
137int generic_pipe_buf_confirm(struct pipe_inode_info *, struct pipe_buffer *);
138int generic_pipe_buf_steal(struct pipe_inode_info *, struct pipe_buffer *);
139void generic_pipe_buf_release(struct pipe_inode_info *, struct pipe_buffer *);
140
141extern const struct pipe_buf_operations nosteal_pipe_buf_ops;
142
143/* for F_SETPIPE_SZ and F_GETPIPE_SZ */
144long pipe_fcntl(struct file *, unsigned int, unsigned long arg);
145struct pipe_inode_info *get_pipe_info(struct file *file);
146
147int create_pipe_files(struct file **, int);
148
149#endif
150