1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _LINUX_PIPE_FS_I_H
3 #define _LINUX_PIPE_FS_I_H
5 #define PIPE_DEF_BUFFERS 16
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 */
10 #define PIPE_BUF_FLAG_PACKET 0x08 /* read() as a packet */
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.
23 unsigned int offset
, len
;
24 const struct pipe_buf_operations
*ops
;
26 unsigned long private;
30 * struct pipe_inode_info - a linux kernel pipe
31 * @mutex: mutex protecting the whole thing
32 * @wait: reader/writer wait point in case of empty/full pipe
33 * @nrbufs: the number of non-empty pipe buffers in this pipe
34 * @buffers: total number of buffers (should be a power of 2)
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
39 * @files: number of struct file referring this pipe (protected by ->i_lock)
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
45 * @bufs: the circular array of pipe buffers
46 * @user: the user who created this pipe
48 struct pipe_inode_info
{
50 wait_queue_head_t wait
;
51 unsigned int nrbufs
, curbuf
, buffers
;
55 unsigned int waiting_writers
;
56 unsigned int r_counter
;
57 unsigned int w_counter
;
58 struct page
*tmp_page
;
59 struct fasync_struct
*fasync_readers
;
60 struct fasync_struct
*fasync_writers
;
61 struct pipe_buffer
*bufs
;
62 struct user_struct
*user
;
66 * Note on the nesting of these functions:
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.
75 struct pipe_buf_operations
{
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.
84 * ->confirm() verifies that the data in the pipe buffer is there
85 * and that the contents are good. If the pages in the pipe belong
86 * to a file system, we may need to wait for IO completion in this
87 * hook. Returns 0 for good, or a negative error value in case of
90 int (*confirm
)(struct pipe_inode_info
*, struct pipe_buffer
*);
93 * When the contents of this pipe buffer has been completely
94 * consumed by a reader, ->release() is called.
96 void (*release
)(struct pipe_inode_info
*, struct pipe_buffer
*);
99 * Attempt to take ownership of the pipe buffer and its contents.
100 * ->steal() returns 0 for success, in which case the contents
101 * of the pipe (the buf->page) is locked and now completely owned
102 * by the caller. The page may then be transferred to a different
103 * mapping, the most often used case is insertion into different
104 * file address space cache.
106 int (*steal
)(struct pipe_inode_info
*, struct pipe_buffer
*);
109 * Get a reference to the pipe buffer.
111 bool (*get
)(struct pipe_inode_info
*, struct pipe_buffer
*);
115 * pipe_buf_get - get a reference to a pipe_buffer
116 * @pipe: the pipe that the buffer belongs to
117 * @buf: the buffer to get a reference to
119 * Return: %true if the reference was successfully obtained.
121 static inline __must_check
bool pipe_buf_get(struct pipe_inode_info
*pipe
,
122 struct pipe_buffer
*buf
)
124 return buf
->ops
->get(pipe
, buf
);
128 * pipe_buf_release - put a reference to a pipe_buffer
129 * @pipe: the pipe that the buffer belongs to
130 * @buf: the buffer to put a reference to
132 static inline void pipe_buf_release(struct pipe_inode_info
*pipe
,
133 struct pipe_buffer
*buf
)
135 const struct pipe_buf_operations
*ops
= buf
->ops
;
138 ops
->release(pipe
, buf
);
142 * pipe_buf_confirm - verify contents of the pipe buffer
143 * @pipe: the pipe that the buffer belongs to
144 * @buf: the buffer to confirm
146 static inline int pipe_buf_confirm(struct pipe_inode_info
*pipe
,
147 struct pipe_buffer
*buf
)
149 return buf
->ops
->confirm(pipe
, buf
);
153 * pipe_buf_steal - attempt to take ownership of a pipe_buffer
154 * @pipe: the pipe that the buffer belongs to
155 * @buf: the buffer to attempt to steal
157 static inline int pipe_buf_steal(struct pipe_inode_info
*pipe
,
158 struct pipe_buffer
*buf
)
160 return buf
->ops
->steal(pipe
, buf
);
163 /* Differs from PIPE_BUF in that PIPE_SIZE is the length of the actual
164 memory allocation, whereas PIPE_BUF makes atomicity guarantees. */
165 #define PIPE_SIZE PAGE_SIZE
167 /* Pipe lock and unlock operations */
168 void pipe_lock(struct pipe_inode_info
*);
169 void pipe_unlock(struct pipe_inode_info
*);
170 void pipe_double_lock(struct pipe_inode_info
*, struct pipe_inode_info
*);
172 extern unsigned int pipe_max_size
, pipe_min_size
;
173 extern unsigned long pipe_user_pages_hard
;
174 extern unsigned long pipe_user_pages_soft
;
175 int pipe_proc_fn(struct ctl_table
*, int, void __user
*, size_t *, loff_t
*);
177 /* Drop the inode semaphore and wait for a pipe event, atomically */
178 void pipe_wait(struct pipe_inode_info
*pipe
);
180 struct pipe_inode_info
*alloc_pipe_info(void);
181 void free_pipe_info(struct pipe_inode_info
*);
183 /* Generic pipe buffer ops functions */
184 bool generic_pipe_buf_get(struct pipe_inode_info
*, struct pipe_buffer
*);
185 int generic_pipe_buf_confirm(struct pipe_inode_info
*, struct pipe_buffer
*);
186 int generic_pipe_buf_steal(struct pipe_inode_info
*, struct pipe_buffer
*);
187 int generic_pipe_buf_nosteal(struct pipe_inode_info
*, struct pipe_buffer
*);
188 void generic_pipe_buf_release(struct pipe_inode_info
*, struct pipe_buffer
*);
189 void pipe_buf_mark_unmergeable(struct pipe_buffer
*buf
);
191 extern const struct pipe_buf_operations nosteal_pipe_buf_ops
;
193 /* for F_SETPIPE_SZ and F_GETPIPE_SZ */
194 long pipe_fcntl(struct file
*, unsigned int, unsigned long arg
);
195 struct pipe_inode_info
*get_pipe_info(struct file
*file
);
197 int create_pipe_files(struct file
**, int);
198 unsigned int round_pipe_size(unsigned int size
);