1 | /* SPDX-License-Identifier: GPL-2.0 */ |
2 | #ifndef _LINUX_PIPE_FS_I_H |
3 | #define _LINUX_PIPE_FS_I_H |
4 | |
5 | #define PIPE_DEF_BUFFERS 16 |
6 | |
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 */ |
15 | #endif |
16 | |
17 | /** |
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. |
25 | **/ |
26 | struct pipe_buffer { |
27 | struct page *page; |
28 | unsigned int offset, len; |
29 | const struct pipe_buf_operations *ops; |
30 | unsigned int flags; |
31 | unsigned long private; |
32 | }; |
33 | |
34 | /** |
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 | * @poll_usage: is this pipe used for epoll, which has crazy wakeups? |
52 | * @fasync_readers: reader side fasync |
53 | * @fasync_writers: writer side fasync |
54 | * @bufs: the circular array of pipe buffers |
55 | * @user: the user who created this pipe |
56 | * @watch_queue: If this pipe is a watch_queue, this is the stuff for that |
57 | **/ |
58 | struct pipe_inode_info { |
59 | struct mutex mutex; |
60 | wait_queue_head_t rd_wait, wr_wait; |
61 | unsigned int head; |
62 | unsigned int tail; |
63 | unsigned int max_usage; |
64 | unsigned int ring_size; |
65 | unsigned int nr_accounted; |
66 | unsigned int readers; |
67 | unsigned int writers; |
68 | unsigned int files; |
69 | unsigned int r_counter; |
70 | unsigned int w_counter; |
71 | bool poll_usage; |
72 | #ifdef CONFIG_WATCH_QUEUE |
73 | bool note_loss; |
74 | #endif |
75 | struct page *tmp_page; |
76 | struct fasync_struct *fasync_readers; |
77 | struct fasync_struct *fasync_writers; |
78 | struct pipe_buffer *bufs; |
79 | struct user_struct *user; |
80 | #ifdef CONFIG_WATCH_QUEUE |
81 | struct watch_queue *watch_queue; |
82 | #endif |
83 | }; |
84 | |
85 | /* |
86 | * Note on the nesting of these functions: |
87 | * |
88 | * ->confirm() |
89 | * ->try_steal() |
90 | * |
91 | * That is, ->try_steal() must be called on a confirmed buffer. See below for |
92 | * the meaning of each operation. Also see the kerneldoc in fs/pipe.c for the |
93 | * pipe and generic variants of these hooks. |
94 | */ |
95 | struct pipe_buf_operations { |
96 | /* |
97 | * ->confirm() verifies that the data in the pipe buffer is there |
98 | * and that the contents are good. If the pages in the pipe belong |
99 | * to a file system, we may need to wait for IO completion in this |
100 | * hook. Returns 0 for good, or a negative error value in case of |
101 | * error. If not present all pages are considered good. |
102 | */ |
103 | int (*confirm)(struct pipe_inode_info *, struct pipe_buffer *); |
104 | |
105 | /* |
106 | * When the contents of this pipe buffer has been completely |
107 | * consumed by a reader, ->release() is called. |
108 | */ |
109 | void (*release)(struct pipe_inode_info *, struct pipe_buffer *); |
110 | |
111 | /* |
112 | * Attempt to take ownership of the pipe buffer and its contents. |
113 | * ->try_steal() returns %true for success, in which case the contents |
114 | * of the pipe (the buf->page) is locked and now completely owned by the |
115 | * caller. The page may then be transferred to a different mapping, the |
116 | * most often used case is insertion into different file address space |
117 | * cache. |
118 | */ |
119 | bool (*try_steal)(struct pipe_inode_info *, struct pipe_buffer *); |
120 | |
121 | /* |
122 | * Get a reference to the pipe buffer. |
123 | */ |
124 | bool (*get)(struct pipe_inode_info *, struct pipe_buffer *); |
125 | }; |
126 | |
127 | /** |
128 | * pipe_has_watch_queue - Check whether the pipe is a watch_queue, |
129 | * i.e. it was created with O_NOTIFICATION_PIPE |
130 | * @pipe: The pipe to check |
131 | * |
132 | * Return: true if pipe is a watch queue, false otherwise. |
133 | */ |
134 | static inline bool pipe_has_watch_queue(const struct pipe_inode_info *pipe) |
135 | { |
136 | #ifdef CONFIG_WATCH_QUEUE |
137 | return pipe->watch_queue != NULL; |
138 | #else |
139 | return false; |
140 | #endif |
141 | } |
142 | |
143 | /** |
144 | * pipe_empty - Return true if the pipe is empty |
145 | * @head: The pipe ring head pointer |
146 | * @tail: The pipe ring tail pointer |
147 | */ |
148 | static inline bool pipe_empty(unsigned int head, unsigned int tail) |
149 | { |
150 | return head == tail; |
151 | } |
152 | |
153 | /** |
154 | * pipe_occupancy - Return number of slots used in the pipe |
155 | * @head: The pipe ring head pointer |
156 | * @tail: The pipe ring tail pointer |
157 | */ |
158 | static inline unsigned int pipe_occupancy(unsigned int head, unsigned int tail) |
159 | { |
160 | return head - tail; |
161 | } |
162 | |
163 | /** |
164 | * pipe_full - Return true if the pipe is full |
165 | * @head: The pipe ring head pointer |
166 | * @tail: The pipe ring tail pointer |
167 | * @limit: The maximum amount of slots available. |
168 | */ |
169 | static inline bool pipe_full(unsigned int head, unsigned int tail, |
170 | unsigned int limit) |
171 | { |
172 | return pipe_occupancy(head, tail) >= limit; |
173 | } |
174 | |
175 | /** |
176 | * pipe_buf - Return the pipe buffer for the specified slot in the pipe ring |
177 | * @pipe: The pipe to access |
178 | * @slot: The slot of interest |
179 | */ |
180 | static inline struct pipe_buffer *pipe_buf(const struct pipe_inode_info *pipe, |
181 | unsigned int slot) |
182 | { |
183 | return &pipe->bufs[slot & (pipe->ring_size - 1)]; |
184 | } |
185 | |
186 | /** |
187 | * pipe_head_buf - Return the pipe buffer at the head of the pipe ring |
188 | * @pipe: The pipe to access |
189 | */ |
190 | static inline struct pipe_buffer *pipe_head_buf(const struct pipe_inode_info *pipe) |
191 | { |
192 | return pipe_buf(pipe, slot: pipe->head); |
193 | } |
194 | |
195 | /** |
196 | * pipe_buf_get - get a reference to a pipe_buffer |
197 | * @pipe: the pipe that the buffer belongs to |
198 | * @buf: the buffer to get a reference to |
199 | * |
200 | * Return: %true if the reference was successfully obtained. |
201 | */ |
202 | static inline __must_check bool pipe_buf_get(struct pipe_inode_info *pipe, |
203 | struct pipe_buffer *buf) |
204 | { |
205 | return buf->ops->get(pipe, buf); |
206 | } |
207 | |
208 | /** |
209 | * pipe_buf_release - put a reference to a pipe_buffer |
210 | * @pipe: the pipe that the buffer belongs to |
211 | * @buf: the buffer to put a reference to |
212 | */ |
213 | static inline void pipe_buf_release(struct pipe_inode_info *pipe, |
214 | struct pipe_buffer *buf) |
215 | { |
216 | const struct pipe_buf_operations *ops = buf->ops; |
217 | |
218 | buf->ops = NULL; |
219 | ops->release(pipe, buf); |
220 | } |
221 | |
222 | /** |
223 | * pipe_buf_confirm - verify contents of the pipe buffer |
224 | * @pipe: the pipe that the buffer belongs to |
225 | * @buf: the buffer to confirm |
226 | */ |
227 | static inline int pipe_buf_confirm(struct pipe_inode_info *pipe, |
228 | struct pipe_buffer *buf) |
229 | { |
230 | if (!buf->ops->confirm) |
231 | return 0; |
232 | return buf->ops->confirm(pipe, buf); |
233 | } |
234 | |
235 | /** |
236 | * pipe_buf_try_steal - attempt to take ownership of a pipe_buffer |
237 | * @pipe: the pipe that the buffer belongs to |
238 | * @buf: the buffer to attempt to steal |
239 | */ |
240 | static inline bool pipe_buf_try_steal(struct pipe_inode_info *pipe, |
241 | struct pipe_buffer *buf) |
242 | { |
243 | if (!buf->ops->try_steal) |
244 | return false; |
245 | return buf->ops->try_steal(pipe, buf); |
246 | } |
247 | |
248 | static inline void pipe_discard_from(struct pipe_inode_info *pipe, |
249 | unsigned int old_head) |
250 | { |
251 | unsigned int mask = pipe->ring_size - 1; |
252 | |
253 | while (pipe->head > old_head) |
254 | pipe_buf_release(pipe, buf: &pipe->bufs[--pipe->head & mask]); |
255 | } |
256 | |
257 | /* Differs from PIPE_BUF in that PIPE_SIZE is the length of the actual |
258 | memory allocation, whereas PIPE_BUF makes atomicity guarantees. */ |
259 | #define PIPE_SIZE PAGE_SIZE |
260 | |
261 | /* Pipe lock and unlock operations */ |
262 | void pipe_lock(struct pipe_inode_info *); |
263 | void pipe_unlock(struct pipe_inode_info *); |
264 | void pipe_double_lock(struct pipe_inode_info *, struct pipe_inode_info *); |
265 | |
266 | /* Wait for a pipe to be readable/writable while dropping the pipe lock */ |
267 | void pipe_wait_readable(struct pipe_inode_info *); |
268 | void pipe_wait_writable(struct pipe_inode_info *); |
269 | |
270 | struct pipe_inode_info *alloc_pipe_info(void); |
271 | void free_pipe_info(struct pipe_inode_info *); |
272 | |
273 | /* Generic pipe buffer ops functions */ |
274 | bool generic_pipe_buf_get(struct pipe_inode_info *, struct pipe_buffer *); |
275 | bool generic_pipe_buf_try_steal(struct pipe_inode_info *, struct pipe_buffer *); |
276 | void generic_pipe_buf_release(struct pipe_inode_info *, struct pipe_buffer *); |
277 | |
278 | extern const struct pipe_buf_operations nosteal_pipe_buf_ops; |
279 | |
280 | unsigned long account_pipe_buffers(struct user_struct *user, |
281 | unsigned long old, unsigned long new); |
282 | bool too_many_pipe_buffers_soft(unsigned long user_bufs); |
283 | bool too_many_pipe_buffers_hard(unsigned long user_bufs); |
284 | bool pipe_is_unprivileged_user(void); |
285 | |
286 | /* for F_SETPIPE_SZ and F_GETPIPE_SZ */ |
287 | int pipe_resize_ring(struct pipe_inode_info *pipe, unsigned int nr_slots); |
288 | long pipe_fcntl(struct file *, unsigned int, unsigned int arg); |
289 | struct pipe_inode_info *get_pipe_info(struct file *file, bool for_splice); |
290 | |
291 | int create_pipe_files(struct file **, int); |
292 | unsigned int round_pipe_size(unsigned int size); |
293 | |
294 | #endif |
295 | |