1#ifndef _LINUX_PIPE_FS_I_H 2#define _LINUX_PIPE_FS_I_H 3 4#define PIPE_DEF_BUFFERS 16 5 6#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 */ 9#define PIPE_BUF_FLAG_PACKET 0x08 /* read() as a packet */ 10 11/** 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 **/ 20struct pipe_buffer { 21 struct page *page; 22 unsigned int offset, len; 23 const struct pipe_buf_operations *ops; 24 unsigned int flags; 25 unsigned long private; 26}; 27 28/** 29 * struct pipe_inode_info - a linux kernel pipe 30 * @mutex: mutex protecting the whole thing 31 * @wait: reader/writer wait point in case of empty/full pipe 32 * @nrbufs: the number of non-empty pipe buffers in this pipe 33 * @buffers: total number of buffers (should be a power of 2) 34 * @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 38 * @files: number of struct file referring this pipe (protected by ->i_lock) 39 * @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 44 * @bufs: the circular array of pipe buffers 45 * @user: the user who created this pipe 46 **/ 47struct pipe_inode_info { 48 struct mutex mutex; 49 wait_queue_head_t wait; 50 unsigned int nrbufs, curbuf, buffers; 51 unsigned int readers; 52 unsigned int writers; 53 unsigned int files; 54 unsigned int waiting_writers; 55 unsigned int r_counter; 56 unsigned int w_counter; 57 struct page *tmp_page; 58 struct fasync_struct *fasync_readers; 59 struct fasync_struct *fasync_writers; 60 struct pipe_buffer *bufs; 61 struct user_struct *user; 62}; 63 64/* 65 * Note on the nesting of these functions: 66 * 67 * ->confirm() 68 * ->steal() 69 * 70 * 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. 73 */ 74struct pipe_buf_operations { 75 /* 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 */ 80 int can_merge; 81 82 /* 83 * ->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 */ 89 int (*confirm)(struct pipe_inode_info *, struct pipe_buffer *); 90 91 /* 92 * When the contents of this pipe buffer has been completely 93 * consumed by a reader, ->release() is called. 94 */ 95 void (*release)(struct pipe_inode_info *, struct pipe_buffer *); 96 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 */ 105 int (*steal)(struct pipe_inode_info *, struct pipe_buffer *); 106 107 /* 108 * Get a reference to the pipe buffer. 109 */ 110 void (*get)(struct pipe_inode_info *, struct pipe_buffer *); 111}; 112 113/** 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} 123 124/** 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} 137 138/** 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} 148 149/** 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} 159 160/* 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 163 164/* 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 169extern unsigned int pipe_max_size, pipe_min_size; 170extern unsigned long pipe_user_pages_hard; 171extern unsigned long pipe_user_pages_soft; 172int pipe_proc_fn(struct ctl_table *, int, void __user *, size_t *, loff_t *); 173 174/* Drop the inode semaphore and wait for a pipe event, atomically */ 175void pipe_wait(struct pipe_inode_info *pipe); 176 177struct pipe_inode_info *alloc_pipe_info(void); 178void free_pipe_info(struct pipe_inode_info *); 179 180/* Generic pipe buffer ops functions */ 181void generic_pipe_buf_get(struct pipe_inode_info *, struct pipe_buffer *); 182int generic_pipe_buf_confirm(struct pipe_inode_info *, struct pipe_buffer *); 183int generic_pipe_buf_steal(struct pipe_inode_info *, struct pipe_buffer *); 184void generic_pipe_buf_release(struct pipe_inode_info *, struct pipe_buffer *); 185 186extern const struct pipe_buf_operations nosteal_pipe_buf_ops; 187 188/* for F_SETPIPE_SZ and F_GETPIPE_SZ */ 189long pipe_fcntl(struct file *, unsigned int, unsigned long arg); 190struct pipe_inode_info *get_pipe_info(struct file *file); 191 192int create_pipe_files(struct file **, int); 193 194#endif 195