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 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 **/ 21 struct pipe_buffer { 22 struct page *page; 23 unsigned int offset, len; 24 const struct pipe_buf_operations *ops; 25 unsigned int flags; 26 unsigned long private; 27 }; 28 29 /** 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 47 **/ 48 struct pipe_inode_info { 49 struct mutex mutex; 50 wait_queue_head_t wait; 51 unsigned int nrbufs, curbuf, buffers; 52 unsigned int readers; 53 unsigned int writers; 54 unsigned int files; 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; 63 }; 64 65 /* 66 * Note on the nesting of these functions: 67 * 68 * ->confirm() 69 * ->steal() 70 * 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. 74 */ 75 struct pipe_buf_operations { 76 /* 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. 80 */ 81 int can_merge; 82 83 /* 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 88 * error. 89 */ 90 int (*confirm)(struct pipe_inode_info *, struct pipe_buffer *); 91 92 /* 93 * When the contents of this pipe buffer has been completely 94 * consumed by a reader, ->release() is called. 95 */ 96 void (*release)(struct pipe_inode_info *, struct pipe_buffer *); 97 98 /* 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. 105 */ 106 int (*steal)(struct pipe_inode_info *, struct pipe_buffer *); 107 108 /* 109 * Get a reference to the pipe buffer. 110 */ 111 void (*get)(struct pipe_inode_info *, struct pipe_buffer *); 112 }; 113 114 /** 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 118 */ 119 static inline void pipe_buf_get(struct pipe_inode_info *pipe, 120 struct pipe_buffer *buf) 121 { 122 buf->ops->get(pipe, buf); 123 } 124 125 /** 126 * pipe_buf_release - put a reference to a pipe_buffer 127 * @pipe: the pipe that the buffer belongs to 128 * @buf: the buffer to put a reference to 129 */ 130 static inline void pipe_buf_release(struct pipe_inode_info *pipe, 131 struct pipe_buffer *buf) 132 { 133 const struct pipe_buf_operations *ops = buf->ops; 134 135 buf->ops = NULL; 136 ops->release(pipe, buf); 137 } 138 139 /** 140 * pipe_buf_confirm - verify contents of the pipe buffer 141 * @pipe: the pipe that the buffer belongs to 142 * @buf: the buffer to confirm 143 */ 144 static inline int pipe_buf_confirm(struct pipe_inode_info *pipe, 145 struct pipe_buffer *buf) 146 { 147 return buf->ops->confirm(pipe, buf); 148 } 149 150 /** 151 * pipe_buf_steal - attempt to take ownership of a pipe_buffer 152 * @pipe: the pipe that the buffer belongs to 153 * @buf: the buffer to attempt to steal 154 */ 155 static inline int pipe_buf_steal(struct pipe_inode_info *pipe, 156 struct pipe_buffer *buf) 157 { 158 return buf->ops->steal(pipe, buf); 159 } 160 161 /* Differs from PIPE_BUF in that PIPE_SIZE is the length of the actual 162 memory allocation, whereas PIPE_BUF makes atomicity guarantees. */ 163 #define PIPE_SIZE PAGE_SIZE 164 165 /* Pipe lock and unlock operations */ 166 void pipe_lock(struct pipe_inode_info *); 167 void pipe_unlock(struct pipe_inode_info *); 168 void pipe_double_lock(struct pipe_inode_info *, struct pipe_inode_info *); 169 170 extern unsigned int pipe_max_size; 171 extern unsigned long pipe_user_pages_hard; 172 extern unsigned long pipe_user_pages_soft; 173 174 /* Drop the inode semaphore and wait for a pipe event, atomically */ 175 void pipe_wait(struct pipe_inode_info *pipe); 176 177 struct pipe_inode_info *alloc_pipe_info(void); 178 void free_pipe_info(struct pipe_inode_info *); 179 180 /* Generic pipe buffer ops functions */ 181 void generic_pipe_buf_get(struct pipe_inode_info *, struct pipe_buffer *); 182 int generic_pipe_buf_confirm(struct pipe_inode_info *, struct pipe_buffer *); 183 int generic_pipe_buf_steal(struct pipe_inode_info *, struct pipe_buffer *); 184 void generic_pipe_buf_release(struct pipe_inode_info *, struct pipe_buffer *); 185 186 extern const struct pipe_buf_operations nosteal_pipe_buf_ops; 187 188 /* for F_SETPIPE_SZ and F_GETPIPE_SZ */ 189 long pipe_fcntl(struct file *, unsigned int, unsigned long arg); 190 struct pipe_inode_info *get_pipe_info(struct file *file); 191 192 int create_pipe_files(struct file **, int); 193 unsigned int round_pipe_size(unsigned long size); 194 195 #endif 196