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 */
11 #define PIPE_BUF_FLAG_CAN_MERGE 0x10 /* can merge buffers */
12 #define PIPE_BUF_FLAG_WHOLE 0x20 /* read() must return entire buffer or error */
13 #ifdef CONFIG_WATCH_QUEUE
14 #define PIPE_BUF_FLAG_LOSS 0x40 /* Message loss happened after this buffer */
18 * struct pipe_buffer - a linux kernel pipe buffer
19 * @page: the page containing the data for the pipe buffer
20 * @offset: offset of data inside the @page
21 * @len: length of data inside the @page
22 * @ops: operations associated with this buffer. See @pipe_buf_operations.
23 * @flags: pipe buffer flags. See above.
24 * @private: private data owned by the ops.
28 unsigned int offset
, len
;
29 const struct pipe_buf_operations
*ops
;
31 unsigned long private;
35 * struct pipe_inode_info - a linux kernel pipe
36 * @mutex: mutex protecting the whole thing
37 * @rd_wait: reader wait point in case of empty pipe
38 * @wr_wait: writer wait point in case of full pipe
39 * @head: The point of buffer production
40 * @tail: The point of buffer consumption
41 * @note_loss: The next read() should insert a data-lost message
42 * @max_usage: The maximum number of slots that may be used in the ring
43 * @ring_size: total number of buffers (should be a power of 2)
44 * @nr_accounted: The amount this pipe accounts for in user->pipe_bufs
45 * @tmp_page: cached released page
46 * @readers: number of current readers of this pipe
47 * @writers: number of current writers of this pipe
48 * @files: number of struct file referring this pipe (protected by ->i_lock)
49 * @r_counter: reader counter
50 * @w_counter: writer counter
51 * @fasync_readers: reader side fasync
52 * @fasync_writers: writer side fasync
53 * @bufs: the circular array of pipe buffers
54 * @user: the user who created this pipe
55 * @watch_queue: If this pipe is a watch_queue, this is the stuff for that
57 struct pipe_inode_info
{
59 wait_queue_head_t rd_wait
, wr_wait
;
62 unsigned int max_usage
;
63 unsigned int ring_size
;
64 #ifdef CONFIG_WATCH_QUEUE
67 unsigned int nr_accounted
;
71 unsigned int r_counter
;
72 unsigned int w_counter
;
73 struct page
*tmp_page
;
74 struct fasync_struct
*fasync_readers
;
75 struct fasync_struct
*fasync_writers
;
76 struct pipe_buffer
*bufs
;
77 struct user_struct
*user
;
78 #ifdef CONFIG_WATCH_QUEUE
79 struct watch_queue
*watch_queue
;
84 * Note on the nesting of these functions:
89 * That is, ->try_steal() must be called on a confirmed buffer. See below for
90 * the meaning of each operation. Also see the kerneldoc in fs/pipe.c for the
91 * pipe and generic variants of these hooks.
93 struct pipe_buf_operations
{
95 * ->confirm() verifies that the data in the pipe buffer is there
96 * and that the contents are good. If the pages in the pipe belong
97 * to a file system, we may need to wait for IO completion in this
98 * hook. Returns 0 for good, or a negative error value in case of
99 * error. If not present all pages are considered good.
101 int (*confirm
)(struct pipe_inode_info
*, struct pipe_buffer
*);
104 * When the contents of this pipe buffer has been completely
105 * consumed by a reader, ->release() is called.
107 void (*release
)(struct pipe_inode_info
*, struct pipe_buffer
*);
110 * Attempt to take ownership of the pipe buffer and its contents.
111 * ->try_steal() returns %true for success, in which case the contents
112 * of the pipe (the buf->page) is locked and now completely owned by the
113 * caller. The page may then be transferred to a different mapping, the
114 * most often used case is insertion into different file address space
117 bool (*try_steal
)(struct pipe_inode_info
*, struct pipe_buffer
*);
120 * Get a reference to the pipe buffer.
122 bool (*get
)(struct pipe_inode_info
*, struct pipe_buffer
*);
126 * pipe_empty - Return true if the pipe is empty
127 * @head: The pipe ring head pointer
128 * @tail: The pipe ring tail pointer
130 static inline bool pipe_empty(unsigned int head
, unsigned int tail
)
136 * pipe_occupancy - Return number of slots used in the pipe
137 * @head: The pipe ring head pointer
138 * @tail: The pipe ring tail pointer
140 static inline unsigned int pipe_occupancy(unsigned int head
, unsigned int tail
)
146 * pipe_full - Return true if the pipe is full
147 * @head: The pipe ring head pointer
148 * @tail: The pipe ring tail pointer
149 * @limit: The maximum amount of slots available.
151 static inline bool pipe_full(unsigned int head
, unsigned int tail
,
154 return pipe_occupancy(head
, tail
) >= limit
;
158 * pipe_space_for_user - Return number of slots available to userspace
159 * @head: The pipe ring head pointer
160 * @tail: The pipe ring tail pointer
161 * @pipe: The pipe info structure
163 static inline unsigned int pipe_space_for_user(unsigned int head
, unsigned int tail
,
164 struct pipe_inode_info
*pipe
)
166 unsigned int p_occupancy
, p_space
;
168 p_occupancy
= pipe_occupancy(head
, tail
);
169 if (p_occupancy
>= pipe
->max_usage
)
171 p_space
= pipe
->ring_size
- p_occupancy
;
172 if (p_space
> pipe
->max_usage
)
173 p_space
= pipe
->max_usage
;
178 * pipe_buf_get - get a reference to a pipe_buffer
179 * @pipe: the pipe that the buffer belongs to
180 * @buf: the buffer to get a reference to
182 * Return: %true if the reference was successfully obtained.
184 static inline __must_check
bool pipe_buf_get(struct pipe_inode_info
*pipe
,
185 struct pipe_buffer
*buf
)
187 return buf
->ops
->get(pipe
, buf
);
191 * pipe_buf_release - put a reference to a pipe_buffer
192 * @pipe: the pipe that the buffer belongs to
193 * @buf: the buffer to put a reference to
195 static inline void pipe_buf_release(struct pipe_inode_info
*pipe
,
196 struct pipe_buffer
*buf
)
198 const struct pipe_buf_operations
*ops
= buf
->ops
;
201 ops
->release(pipe
, buf
);
205 * pipe_buf_confirm - verify contents of the pipe buffer
206 * @pipe: the pipe that the buffer belongs to
207 * @buf: the buffer to confirm
209 static inline int pipe_buf_confirm(struct pipe_inode_info
*pipe
,
210 struct pipe_buffer
*buf
)
212 if (!buf
->ops
->confirm
)
214 return buf
->ops
->confirm(pipe
, buf
);
218 * pipe_buf_try_steal - attempt to take ownership of a pipe_buffer
219 * @pipe: the pipe that the buffer belongs to
220 * @buf: the buffer to attempt to steal
222 static inline bool pipe_buf_try_steal(struct pipe_inode_info
*pipe
,
223 struct pipe_buffer
*buf
)
225 if (!buf
->ops
->try_steal
)
227 return buf
->ops
->try_steal(pipe
, buf
);
230 /* Differs from PIPE_BUF in that PIPE_SIZE is the length of the actual
231 memory allocation, whereas PIPE_BUF makes atomicity guarantees. */
232 #define PIPE_SIZE PAGE_SIZE
234 /* Pipe lock and unlock operations */
235 void pipe_lock(struct pipe_inode_info
*);
236 void pipe_unlock(struct pipe_inode_info
*);
237 void pipe_double_lock(struct pipe_inode_info
*, struct pipe_inode_info
*);
239 extern unsigned int pipe_max_size
;
240 extern unsigned long pipe_user_pages_hard
;
241 extern unsigned long pipe_user_pages_soft
;
243 /* Wait for a pipe to be readable/writable while dropping the pipe lock */
244 void pipe_wait_readable(struct pipe_inode_info
*);
245 void pipe_wait_writable(struct pipe_inode_info
*);
247 struct pipe_inode_info
*alloc_pipe_info(void);
248 void free_pipe_info(struct pipe_inode_info
*);
250 /* Generic pipe buffer ops functions */
251 bool generic_pipe_buf_get(struct pipe_inode_info
*, struct pipe_buffer
*);
252 bool generic_pipe_buf_try_steal(struct pipe_inode_info
*, struct pipe_buffer
*);
253 void generic_pipe_buf_release(struct pipe_inode_info
*, struct pipe_buffer
*);
255 extern const struct pipe_buf_operations nosteal_pipe_buf_ops
;
257 #ifdef CONFIG_WATCH_QUEUE
258 unsigned long account_pipe_buffers(struct user_struct
*user
,
259 unsigned long old
, unsigned long new);
260 bool too_many_pipe_buffers_soft(unsigned long user_bufs
);
261 bool too_many_pipe_buffers_hard(unsigned long user_bufs
);
262 bool pipe_is_unprivileged_user(void);
265 /* for F_SETPIPE_SZ and F_GETPIPE_SZ */
266 #ifdef CONFIG_WATCH_QUEUE
267 int pipe_resize_ring(struct pipe_inode_info
*pipe
, unsigned int nr_slots
);
269 long pipe_fcntl(struct file
*, unsigned int, unsigned long arg
);
270 struct pipe_inode_info
*get_pipe_info(struct file
*file
, bool for_splice
);
272 int create_pipe_files(struct file
**, int);
273 unsigned int round_pipe_size(unsigned long size
);