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b2441318 1/* SPDX-License-Identifier: GPL-2.0 */
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2#ifndef _LINUX_PIPE_FS_I_H
3#define _LINUX_PIPE_FS_I_H
4
35f3d14d 5#define PIPE_DEF_BUFFERS 16
1da177e4 6
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7#define PIPE_BUF_FLAG_LRU 0x01 /* page is on the LRU */
8#define PIPE_BUF_FLAG_ATOMIC 0x02 /* was atomically mapped */
9#define PIPE_BUF_FLAG_GIFT 0x04 /* page is a gift */
9883035a 10#define PIPE_BUF_FLAG_PACKET 0x08 /* read() as a packet */
3e7ee3e7 11
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12/**
13 * struct pipe_buffer - a linux kernel pipe buffer
14 * @page: the page containing the data for the pipe buffer
15 * @offset: offset of data inside the @page
16 * @len: length of data inside the @page
17 * @ops: operations associated with this buffer. See @pipe_buf_operations.
18 * @flags: pipe buffer flags. See above.
19 * @private: private data owned by the ops.
20 **/
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21struct pipe_buffer {
22 struct page *page;
23 unsigned int offset, len;
d4c3cca9 24 const struct pipe_buf_operations *ops;
3e7ee3e7 25 unsigned int flags;
497f9625 26 unsigned long private;
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27};
28
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29/**
30 * struct pipe_inode_info - a linux kernel pipe
72b0d9aa 31 * @mutex: mutex protecting the whole thing
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32 * @wait: reader/writer wait point in case of empty/full pipe
33 * @nrbufs: the number of non-empty pipe buffers in this pipe
0dc14885 34 * @buffers: total number of buffers (should be a power of 2)
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35 * @curbuf: the current pipe buffer entry
36 * @tmp_page: cached released page
37 * @readers: number of current readers of this pipe
38 * @writers: number of current writers of this pipe
e227867f 39 * @files: number of struct file referring this pipe (protected by ->i_lock)
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40 * @waiting_writers: number of writers blocked waiting for room
41 * @r_counter: reader counter
42 * @w_counter: writer counter
43 * @fasync_readers: reader side fasync
44 * @fasync_writers: writer side fasync
0845718d 45 * @bufs: the circular array of pipe buffers
759c0114 46 * @user: the user who created this pipe
0845718d 47 **/
17374ff1 48struct pipe_inode_info {
72b0d9aa 49 struct mutex mutex;
17374ff1 50 wait_queue_head_t wait;
35f3d14d 51 unsigned int nrbufs, curbuf, buffers;
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52 unsigned int readers;
53 unsigned int writers;
ba5bb147 54 unsigned int files;
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55 unsigned int waiting_writers;
56 unsigned int r_counter;
57 unsigned int w_counter;
35f3d14d 58 struct page *tmp_page;
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59 struct fasync_struct *fasync_readers;
60 struct fasync_struct *fasync_writers;
35f3d14d 61 struct pipe_buffer *bufs;
759c0114 62 struct user_struct *user;
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63};
64
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65/*
66 * Note on the nesting of these functions:
67 *
cac36bb0 68 * ->confirm()
f84d7519 69 * ->steal()
f84d7519 70 *
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71 * That is, ->steal() must be called on a confirmed buffer.
72 * See below for the meaning of each operation. Also see kerneldoc
73 * in fs/pipe.c for the pipe and generic variants of these hooks.
f84d7519 74 */
1da177e4 75struct pipe_buf_operations {
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76 /*
77 * ->confirm() verifies that the data in the pipe buffer is there
78 * and that the contents are good. If the pages in the pipe belong
79 * to a file system, we may need to wait for IO completion in this
80 * hook. Returns 0 for good, or a negative error value in case of
81 * error.
82 */
cac36bb0 83 int (*confirm)(struct pipe_inode_info *, struct pipe_buffer *);
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84
85 /*
86 * When the contents of this pipe buffer has been completely
87 * consumed by a reader, ->release() is called.
88 */
1da177e4 89 void (*release)(struct pipe_inode_info *, struct pipe_buffer *);
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90
91 /*
92 * Attempt to take ownership of the pipe buffer and its contents.
93 * ->steal() returns 0 for success, in which case the contents
94 * of the pipe (the buf->page) is locked and now completely owned
95 * by the caller. The page may then be transferred to a different
96 * mapping, the most often used case is insertion into different
97 * file address space cache.
98 */
5abc97aa 99 int (*steal)(struct pipe_inode_info *, struct pipe_buffer *);
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100
101 /*
102 * Get a reference to the pipe buffer.
103 */
15fab63e 104 bool (*get)(struct pipe_inode_info *, struct pipe_buffer *);
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105};
106
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107/**
108 * pipe_buf_get - get a reference to a pipe_buffer
109 * @pipe: the pipe that the buffer belongs to
110 * @buf: the buffer to get a reference to
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111 *
112 * Return: %true if the reference was successfully obtained.
7bf2d1df 113 */
15fab63e 114static inline __must_check bool pipe_buf_get(struct pipe_inode_info *pipe,
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115 struct pipe_buffer *buf)
116{
15fab63e 117 return buf->ops->get(pipe, buf);
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118}
119
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120/**
121 * pipe_buf_release - put a reference to a pipe_buffer
122 * @pipe: the pipe that the buffer belongs to
123 * @buf: the buffer to put a reference to
124 */
125static inline void pipe_buf_release(struct pipe_inode_info *pipe,
126 struct pipe_buffer *buf)
127{
128 const struct pipe_buf_operations *ops = buf->ops;
129
130 buf->ops = NULL;
131 ops->release(pipe, buf);
132}
133
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134/**
135 * pipe_buf_confirm - verify contents of the pipe buffer
136 * @pipe: the pipe that the buffer belongs to
137 * @buf: the buffer to confirm
138 */
139static inline int pipe_buf_confirm(struct pipe_inode_info *pipe,
140 struct pipe_buffer *buf)
141{
142 return buf->ops->confirm(pipe, buf);
143}
144
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145/**
146 * pipe_buf_steal - attempt to take ownership of a pipe_buffer
147 * @pipe: the pipe that the buffer belongs to
148 * @buf: the buffer to attempt to steal
149 */
150static inline int pipe_buf_steal(struct pipe_inode_info *pipe,
151 struct pipe_buffer *buf)
152{
153 return buf->ops->steal(pipe, buf);
154}
155
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156/* Differs from PIPE_BUF in that PIPE_SIZE is the length of the actual
157 memory allocation, whereas PIPE_BUF makes atomicity guarantees. */
158#define PIPE_SIZE PAGE_SIZE
159
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160/* Pipe lock and unlock operations */
161void pipe_lock(struct pipe_inode_info *);
162void pipe_unlock(struct pipe_inode_info *);
163void pipe_double_lock(struct pipe_inode_info *, struct pipe_inode_info *);
164
4c2e4bef 165extern unsigned int pipe_max_size;
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166extern unsigned long pipe_user_pages_hard;
167extern unsigned long pipe_user_pages_soft;
ff9da691 168
1da177e4 169/* Drop the inode semaphore and wait for a pipe event, atomically */
3a326a2c 170void pipe_wait(struct pipe_inode_info *pipe);
1da177e4 171
7bee130e 172struct pipe_inode_info *alloc_pipe_info(void);
4b8a8f1e 173void free_pipe_info(struct pipe_inode_info *);
1da177e4 174
f84d7519 175/* Generic pipe buffer ops functions */
15fab63e 176bool generic_pipe_buf_get(struct pipe_inode_info *, struct pipe_buffer *);
cac36bb0 177int generic_pipe_buf_confirm(struct pipe_inode_info *, struct pipe_buffer *);
330ab716 178int generic_pipe_buf_steal(struct pipe_inode_info *, struct pipe_buffer *);
b9872226 179int generic_pipe_buf_nosteal(struct pipe_inode_info *, struct pipe_buffer *);
6818173b 180void generic_pipe_buf_release(struct pipe_inode_info *, struct pipe_buffer *);
a0ce2f0a 181void pipe_buf_mark_unmergeable(struct pipe_buffer *buf);
f84d7519 182
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183extern const struct pipe_buf_operations nosteal_pipe_buf_ops;
184
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185/* for F_SETPIPE_SZ and F_GETPIPE_SZ */
186long pipe_fcntl(struct file *, unsigned int, unsigned long arg);
72083646 187struct pipe_inode_info *get_pipe_info(struct file *file);
c66fb347 188
e4fad8e5 189int create_pipe_files(struct file **, int);
96e99be4 190unsigned int round_pipe_size(unsigned long size);
e4fad8e5 191
1da177e4 192#endif