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 *	@wait: reader/writer wait point in case of empty/full pipe
31 *	@nrbufs: the number of non-empty pipe buffers in this pipe
32 *	@buffers: total number of buffers (should be a power of 2)
33 *	@curbuf: the current pipe buffer entry
34 *	@tmp_page: cached released page
35 *	@readers: number of current readers of this pipe
36 *	@writers: number of current writers of this pipe
37 *	@waiting_writers: number of writers blocked waiting for room
38 *	@r_counter: reader counter
39 *	@w_counter: writer counter
40 *	@fasync_readers: reader side fasync
41 *	@fasync_writers: writer side fasync
42 *	@inode: inode this pipe is attached to
43 *	@bufs: the circular array of pipe buffers
44 **/
45struct pipe_inode_info {
46	wait_queue_head_t wait;
47	unsigned int nrbufs, curbuf, buffers;
48	unsigned int readers;
49	unsigned int writers;
50	unsigned int waiting_writers;
51	unsigned int r_counter;
52	unsigned int w_counter;
53	struct page *tmp_page;
54	struct fasync_struct *fasync_readers;
55	struct fasync_struct *fasync_writers;
56	struct inode *inode;
57	struct pipe_buffer *bufs;
58};
59
60/*
61 * Note on the nesting of these functions:
62 *
63 * ->confirm()
64 *	->steal()
65 *	...
66 *	->map()
67 *	...
68 *	->unmap()
69 *
70 * That is, ->map() must be called on a confirmed buffer,
71 * same goes for ->steal(). See below for the meaning of each
72 * operation. Also see kerneldoc in fs/pipe.c for the pipe
73 * and generic variants of these hooks.
74 */
75struct pipe_buf_operations {
76	/*
77	 * This is set to 1, if the generic pipe read/write may coalesce
78	 * data into an existing buffer. If this is set to 0, a new pipe
79	 * page segment is always used for new data.
80	 */
81	int can_merge;
82
83	/*
84	 * ->map() returns a virtual address mapping of the pipe buffer.
85	 * The last integer flag reflects whether this should be an atomic
86	 * mapping or not. The atomic map is faster, however you can't take
87	 * page faults before calling ->unmap() again. So if you need to eg
88	 * access user data through copy_to/from_user(), then you must get
89	 * a non-atomic map. ->map() uses the KM_USER0 atomic slot for
90	 * atomic maps, so you can't map more than one pipe_buffer at once
91	 * and you have to be careful if mapping another page as source
92	 * or destination for a copy (IOW, it has to use something else
93	 * than KM_USER0).
94	 */
95	void * (*map)(struct pipe_inode_info *, struct pipe_buffer *, int);
96
97	/*
98	 * Undoes ->map(), finishes the virtual mapping of the pipe buffer.
99	 */
100	void (*unmap)(struct pipe_inode_info *, struct pipe_buffer *, void *);
101
102	/*
103	 * ->confirm() verifies that the data in the pipe buffer is there
104	 * and that the contents are good. If the pages in the pipe belong
105	 * to a file system, we may need to wait for IO completion in this
106	 * hook. Returns 0 for good, or a negative error value in case of
107	 * error.
108	 */
109	int (*confirm)(struct pipe_inode_info *, struct pipe_buffer *);
110
111	/*
112	 * When the contents of this pipe buffer has been completely
113	 * consumed by a reader, ->release() is called.
114	 */
115	void (*release)(struct pipe_inode_info *, struct pipe_buffer *);
116
117	/*
118	 * Attempt to take ownership of the pipe buffer and its contents.
119	 * ->steal() returns 0 for success, in which case the contents
120	 * of the pipe (the buf->page) is locked and now completely owned
121	 * by the caller. The page may then be transferred to a different
122	 * mapping, the most often used case is insertion into different
123	 * file address space cache.
124	 */
125	int (*steal)(struct pipe_inode_info *, struct pipe_buffer *);
126
127	/*
128	 * Get a reference to the pipe buffer.
129	 */
130	void (*get)(struct pipe_inode_info *, struct pipe_buffer *);
131};
132
133/* Differs from PIPE_BUF in that PIPE_SIZE is the length of the actual
134   memory allocation, whereas PIPE_BUF makes atomicity guarantees.  */
135#define PIPE_SIZE		PAGE_SIZE
136
137/* Pipe lock and unlock operations */
138void pipe_lock(struct pipe_inode_info *);
139void pipe_unlock(struct pipe_inode_info *);
140void pipe_double_lock(struct pipe_inode_info *, struct pipe_inode_info *);
141
142extern unsigned int pipe_max_size, pipe_min_size;
143int pipe_proc_fn(struct ctl_table *, int, void __user *, size_t *, loff_t *);
144
145
146/* Drop the inode semaphore and wait for a pipe event, atomically */
147void pipe_wait(struct pipe_inode_info *pipe);
148
149struct pipe_inode_info * alloc_pipe_info(struct inode * inode);
150void free_pipe_info(struct inode * inode);
151void __free_pipe_info(struct pipe_inode_info *);
152
153/* Generic pipe buffer ops functions */
154void *generic_pipe_buf_map(struct pipe_inode_info *, struct pipe_buffer *, int);
155void generic_pipe_buf_unmap(struct pipe_inode_info *, struct pipe_buffer *, void *);
156void generic_pipe_buf_get(struct pipe_inode_info *, struct pipe_buffer *);
157int generic_pipe_buf_confirm(struct pipe_inode_info *, struct pipe_buffer *);
158int generic_pipe_buf_steal(struct pipe_inode_info *, struct pipe_buffer *);
159void generic_pipe_buf_release(struct pipe_inode_info *, struct pipe_buffer *);
160
161/* for F_SETPIPE_SZ and F_GETPIPE_SZ */
162long pipe_fcntl(struct file *, unsigned int, unsigned long arg);
163struct pipe_inode_info *get_pipe_info(struct file *file);
164
165#endif
166