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Linus Torvalds1da177e2005-04-16 15:20:36 -07001#ifndef _LINUX_PIPE_FS_I_H
2#define _LINUX_PIPE_FS_I_H
3
Jens Axboe35f3d142010-05-20 10:43:18 +02004#define PIPE_DEF_BUFFERS 16
Linus Torvalds1da177e2005-04-16 15:20:36 -07005
Jens Axboe14328732006-05-03 10:35:26 +02006#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 */
Linus Torvalds98830352012-04-29 13:12:42 -07009#define PIPE_BUF_FLAG_PACKET 0x08 /* read() as a packet */
Jens Axboe3e7ee3e2006-04-02 23:11:04 +020010
Jens Axboe08457182007-06-12 20:51:32 +020011/**
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 **/
Linus Torvalds1da177e2005-04-16 15:20:36 -070020struct pipe_buffer {
21 struct page *page;
22 unsigned int offset, len;
Eric Dumazetd4c3cca2006-12-13 00:34:04 -080023 const struct pipe_buf_operations *ops;
Jens Axboe3e7ee3e2006-04-02 23:11:04 +020024 unsigned int flags;
Jens Axboe497f9622007-06-11 12:00:45 +020025 unsigned long private;
Linus Torvalds1da177e2005-04-16 15:20:36 -070026};
27
Jens Axboe08457182007-06-12 20:51:32 +020028/**
29 * struct pipe_inode_info - a linux kernel pipe
Al Viro72b0d9a2013-03-21 02:32:24 -040030 * @mutex: mutex protecting the whole thing
Jens Axboe08457182007-06-12 20:51:32 +020031 * @wait: reader/writer wait point in case of empty/full pipe
32 * @nrbufs: the number of non-empty pipe buffers in this pipe
Randy Dunlap0dc14882011-01-08 19:40:33 -080033 * @buffers: total number of buffers (should be a power of 2)
Jens Axboe08457182007-06-12 20:51:32 +020034 * @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
Masanari Iidae2278672014-02-18 22:54:36 +090038 * @files: number of struct file referring this pipe (protected by ->i_lock)
Jens Axboe08457182007-06-12 20:51:32 +020039 * @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
Jens Axboe08457182007-06-12 20:51:32 +020044 * @bufs: the circular array of pipe buffers
Willy Tarreau759c0112016-01-18 16:36:09 +010045 * @user: the user who created this pipe
Jens Axboe08457182007-06-12 20:51:32 +020046 **/
Jens Axboe17374ff2007-06-04 15:03:12 +020047struct pipe_inode_info {
Al Viro72b0d9a2013-03-21 02:32:24 -040048 struct mutex mutex;
Jens Axboe17374ff2007-06-04 15:03:12 +020049 wait_queue_head_t wait;
Jens Axboe35f3d142010-05-20 10:43:18 +020050 unsigned int nrbufs, curbuf, buffers;
Jens Axboe17374ff2007-06-04 15:03:12 +020051 unsigned int readers;
52 unsigned int writers;
Al Viroba5bb142013-03-21 02:21:19 -040053 unsigned int files;
Jens Axboe17374ff2007-06-04 15:03:12 +020054 unsigned int waiting_writers;
55 unsigned int r_counter;
56 unsigned int w_counter;
Jens Axboe35f3d142010-05-20 10:43:18 +020057 struct page *tmp_page;
Jens Axboe17374ff2007-06-04 15:03:12 +020058 struct fasync_struct *fasync_readers;
59 struct fasync_struct *fasync_writers;
Jens Axboe35f3d142010-05-20 10:43:18 +020060 struct pipe_buffer *bufs;
Willy Tarreau759c0112016-01-18 16:36:09 +010061 struct user_struct *user;
Jens Axboe17374ff2007-06-04 15:03:12 +020062};
63
Jens Axboef84d7512006-05-01 19:59:03 +020064/*
65 * Note on the nesting of these functions:
66 *
Jens Axboecac36bb02007-06-14 13:10:48 +020067 * ->confirm()
Jens Axboef84d7512006-05-01 19:59:03 +020068 * ->steal()
Jens Axboef84d7512006-05-01 19:59:03 +020069 *
Miklos Szeredia949e632016-09-27 10:45:13 +020070 * That is, ->steal() must be called on a confirmed buffer.
71 * See below for the meaning of each operation. Also see kerneldoc
72 * in fs/pipe.c for the pipe and generic variants of these hooks.
Jens Axboef84d7512006-05-01 19:59:03 +020073 */
Linus Torvalds1da177e2005-04-16 15:20:36 -070074struct pipe_buf_operations {
Jens Axboe08457182007-06-12 20:51:32 +020075 /*
76 * This is set to 1, if the generic pipe read/write may coalesce
77 * data into an existing buffer. If this is set to 0, a new pipe
78 * page segment is always used for new data.
79 */
Linus Torvalds1da177e2005-04-16 15:20:36 -070080 int can_merge;
Jens Axboe08457182007-06-12 20:51:32 +020081
82 /*
Jens Axboe08457182007-06-12 20:51:32 +020083 * ->confirm() verifies that the data in the pipe buffer is there
84 * and that the contents are good. If the pages in the pipe belong
85 * to a file system, we may need to wait for IO completion in this
86 * hook. Returns 0 for good, or a negative error value in case of
87 * error.
88 */
Jens Axboecac36bb02007-06-14 13:10:48 +020089 int (*confirm)(struct pipe_inode_info *, struct pipe_buffer *);
Jens Axboe08457182007-06-12 20:51:32 +020090
91 /*
92 * When the contents of this pipe buffer has been completely
93 * consumed by a reader, ->release() is called.
94 */
Linus Torvalds1da177e2005-04-16 15:20:36 -070095 void (*release)(struct pipe_inode_info *, struct pipe_buffer *);
Jens Axboe08457182007-06-12 20:51:32 +020096
97 /*
98 * Attempt to take ownership of the pipe buffer and its contents.
99 * ->steal() returns 0 for success, in which case the contents
100 * of the pipe (the buf->page) is locked and now completely owned
101 * by the caller. The page may then be transferred to a different
102 * mapping, the most often used case is insertion into different
103 * file address space cache.
104 */
Jens Axboe5abc97a2006-03-30 15:16:46 +0200105 int (*steal)(struct pipe_inode_info *, struct pipe_buffer *);
Jens Axboe08457182007-06-12 20:51:32 +0200106
107 /*
108 * Get a reference to the pipe buffer.
109 */
Jens Axboe70524492006-04-11 15:51:17 +0200110 void (*get)(struct pipe_inode_info *, struct pipe_buffer *);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700111};
112
Miklos Szeredi7bf2d1d2016-09-27 10:45:12 +0200113/**
114 * pipe_buf_get - get a reference to a pipe_buffer
115 * @pipe: the pipe that the buffer belongs to
116 * @buf: the buffer to get a reference to
117 */
118static inline void pipe_buf_get(struct pipe_inode_info *pipe,
119 struct pipe_buffer *buf)
120{
121 buf->ops->get(pipe, buf);
122}
123
Miklos Szeredia7796382016-09-27 10:45:12 +0200124/**
125 * pipe_buf_release - put a reference to a pipe_buffer
126 * @pipe: the pipe that the buffer belongs to
127 * @buf: the buffer to put a reference to
128 */
129static inline void pipe_buf_release(struct pipe_inode_info *pipe,
130 struct pipe_buffer *buf)
131{
132 const struct pipe_buf_operations *ops = buf->ops;
133
134 buf->ops = NULL;
135 ops->release(pipe, buf);
136}
137
Miklos Szeredifba597d2016-09-27 10:45:12 +0200138/**
139 * pipe_buf_confirm - verify contents of the pipe buffer
140 * @pipe: the pipe that the buffer belongs to
141 * @buf: the buffer to confirm
142 */
143static inline int pipe_buf_confirm(struct pipe_inode_info *pipe,
144 struct pipe_buffer *buf)
145{
146 return buf->ops->confirm(pipe, buf);
147}
148
Miklos Szeredica76f5b2016-09-27 10:45:12 +0200149/**
150 * pipe_buf_steal - attempt to take ownership of a pipe_buffer
151 * @pipe: the pipe that the buffer belongs to
152 * @buf: the buffer to attempt to steal
153 */
154static inline int pipe_buf_steal(struct pipe_inode_info *pipe,
155 struct pipe_buffer *buf)
156{
157 return buf->ops->steal(pipe, buf);
158}
159
Linus Torvalds1da177e2005-04-16 15:20:36 -0700160/* Differs from PIPE_BUF in that PIPE_SIZE is the length of the actual
161 memory allocation, whereas PIPE_BUF makes atomicity guarantees. */
162#define PIPE_SIZE PAGE_SIZE
163
Miklos Szeredi61e0d472009-04-14 19:48:41 +0200164/* Pipe lock and unlock operations */
165void pipe_lock(struct pipe_inode_info *);
166void pipe_unlock(struct pipe_inode_info *);
167void pipe_double_lock(struct pipe_inode_info *, struct pipe_inode_info *);
168
Jens Axboeff9da692010-06-03 14:54:39 +0200169extern unsigned int pipe_max_size, pipe_min_size;
Willy Tarreau759c0112016-01-18 16:36:09 +0100170extern unsigned long pipe_user_pages_hard;
171extern unsigned long pipe_user_pages_soft;
Jens Axboeff9da692010-06-03 14:54:39 +0200172int pipe_proc_fn(struct ctl_table *, int, void __user *, size_t *, loff_t *);
173
Linus Torvalds1da177e2005-04-16 15:20:36 -0700174/* Drop the inode semaphore and wait for a pipe event, atomically */
Ingo Molnar3a326a22006-04-10 15:18:35 +0200175void pipe_wait(struct pipe_inode_info *pipe);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700176
Al Viro7bee1302013-03-21 11:04:15 -0400177struct pipe_inode_info *alloc_pipe_info(void);
Al Viro4b8a8f12013-03-21 11:06:46 -0400178void free_pipe_info(struct pipe_inode_info *);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700179
Jens Axboef84d7512006-05-01 19:59:03 +0200180/* Generic pipe buffer ops functions */
Jens Axboef84d7512006-05-01 19:59:03 +0200181void generic_pipe_buf_get(struct pipe_inode_info *, struct pipe_buffer *);
Jens Axboecac36bb02007-06-14 13:10:48 +0200182int generic_pipe_buf_confirm(struct pipe_inode_info *, struct pipe_buffer *);
Jens Axboe330ab712006-05-02 15:29:57 +0200183int generic_pipe_buf_steal(struct pipe_inode_info *, struct pipe_buffer *);
Miklos Szeredi68181732009-05-07 15:37:36 +0200184void generic_pipe_buf_release(struct pipe_inode_info *, struct pipe_buffer *);
Jens Axboef84d7512006-05-01 19:59:03 +0200185
Miklos Szeredi28a625c2014-01-22 19:36:57 +0100186extern const struct pipe_buf_operations nosteal_pipe_buf_ops;
187
Jens Axboe35f3d142010-05-20 10:43:18 +0200188/* for F_SETPIPE_SZ and F_GETPIPE_SZ */
189long pipe_fcntl(struct file *, unsigned int, unsigned long arg);
Linus Torvalds72083642010-11-28 16:27:19 -0800190struct pipe_inode_info *get_pipe_info(struct file *file);
Linus Torvaldsc66fb342010-11-28 14:09:57 -0800191
Al Viroe4fad8e2012-07-21 15:33:25 +0400192int create_pipe_files(struct file **, int);
193
Linus Torvalds1da177e2005-04-16 15:20:36 -0700194#endif