1#ifndef _LINUX_PIPE_FS_I_H 2#define _LINUX_PIPE_FS_I_H 3 4#define PIPEFS_MAGIC 0x50495045 5 6#define PIPE_DEF_BUFFERS 16 7 8#define PIPE_BUF_FLAG_LRU 0x01 /* page is on the LRU */ 9#define PIPE_BUF_FLAG_ATOMIC 0x02 /* was atomically mapped */ 10#define PIPE_BUF_FLAG_GIFT 0x04 /* page is a gift */ 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 **/ 21struct 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 * @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 * @waiting_writers: number of writers blocked waiting for room 39 * @r_counter: reader counter 40 * @w_counter: writer counter 41 * @fasync_readers: reader side fasync 42 * @fasync_writers: writer side fasync 43 * @inode: inode this pipe is attached to 44 * @bufs: the circular array of pipe buffers 45 **/ 46struct pipe_inode_info { 47 wait_queue_head_t wait; 48 unsigned int nrbufs, curbuf, buffers; 49 unsigned int readers; 50 unsigned int writers; 51 unsigned int waiting_writers; 52 unsigned int r_counter; 53 unsigned int w_counter; 54 struct page *tmp_page; 55 struct fasync_struct *fasync_readers; 56 struct fasync_struct *fasync_writers; 57 struct inode *inode; 58 struct pipe_buffer *bufs; 59}; 60 61/* 62 * Note on the nesting of these functions: 63 * 64 * ->confirm() 65 * ->steal() 66 * ... 67 * ->map() 68 * ... 69 * ->unmap() 70 * 71 * That is, ->map() must be called on a confirmed buffer, 72 * same goes for ->steal(). See below for the meaning of each 73 * operation. Also see kerneldoc in fs/pipe.c for the pipe 74 * and generic variants of these hooks. 75 */ 76struct pipe_buf_operations { 77 /* 78 * This is set to 1, if the generic pipe read/write may coalesce 79 * data into an existing buffer. If this is set to 0, a new pipe 80 * page segment is always used for new data. 81 */ 82 int can_merge; 83 84 /* 85 * ->map() returns a virtual address mapping of the pipe buffer. 86 * The last integer flag reflects whether this should be an atomic 87 * mapping or not. The atomic map is faster, however you can't take 88 * page faults before calling ->unmap() again. So if you need to eg 89 * access user data through copy_to/from_user(), then you must get 90 * a non-atomic map. ->map() uses the KM_USER0 atomic slot for 91 * atomic maps, so you can't map more than one pipe_buffer at once 92 * and you have to be careful if mapping another page as source 93 * or destination for a copy (IOW, it has to use something else 94 * than KM_USER0). 95 */ 96 void * (*map)(struct pipe_inode_info *, struct pipe_buffer *, int); 97 98 /* 99 * Undoes ->map(), finishes the virtual mapping of the pipe buffer. 100 */ 101 void (*unmap)(struct pipe_inode_info *, struct pipe_buffer *, void *); 102 103 /* 104 * ->confirm() verifies that the data in the pipe buffer is there 105 * and that the contents are good. If the pages in the pipe belong 106 * to a file system, we may need to wait for IO completion in this 107 * hook. Returns 0 for good, or a negative error value in case of 108 * error. 109 */ 110 int (*confirm)(struct pipe_inode_info *, struct pipe_buffer *); 111 112 /* 113 * When the contents of this pipe buffer has been completely 114 * consumed by a reader, ->release() is called. 115 */ 116 void (*release)(struct pipe_inode_info *, struct pipe_buffer *); 117 118 /* 119 * Attempt to take ownership of the pipe buffer and its contents. 120 * ->steal() returns 0 for success, in which case the contents 121 * of the pipe (the buf->page) is locked and now completely owned 122 * by the caller. The page may then be transferred to a different 123 * mapping, the most often used case is insertion into different 124 * file address space cache. 125 */ 126 int (*steal)(struct pipe_inode_info *, struct pipe_buffer *); 127 128 /* 129 * Get a reference to the pipe buffer. 130 */ 131 void (*get)(struct pipe_inode_info *, struct pipe_buffer *); 132}; 133 134/* Differs from PIPE_BUF in that PIPE_SIZE is the length of the actual 135 memory allocation, whereas PIPE_BUF makes atomicity guarantees. */ 136#define PIPE_SIZE PAGE_SIZE 137 138/* Pipe lock and unlock operations */ 139void pipe_lock(struct pipe_inode_info *); 140void pipe_unlock(struct pipe_inode_info *); 141void pipe_double_lock(struct pipe_inode_info *, struct pipe_inode_info *); 142 143extern unsigned int pipe_max_size, pipe_min_size; 144int pipe_proc_fn(struct ctl_table *, int, void __user *, size_t *, loff_t *); 145 146 147/* Drop the inode semaphore and wait for a pipe event, atomically */ 148void pipe_wait(struct pipe_inode_info *pipe); 149 150struct pipe_inode_info * alloc_pipe_info(struct inode * inode); 151void free_pipe_info(struct inode * inode); 152void __free_pipe_info(struct pipe_inode_info *); 153 154/* Generic pipe buffer ops functions */ 155void *generic_pipe_buf_map(struct pipe_inode_info *, struct pipe_buffer *, int); 156void generic_pipe_buf_unmap(struct pipe_inode_info *, struct pipe_buffer *, void *); 157void generic_pipe_buf_get(struct pipe_inode_info *, struct pipe_buffer *); 158int generic_pipe_buf_confirm(struct pipe_inode_info *, struct pipe_buffer *); 159int generic_pipe_buf_steal(struct pipe_inode_info *, struct pipe_buffer *); 160void generic_pipe_buf_release(struct pipe_inode_info *, struct pipe_buffer *); 161 162/* for F_SETPIPE_SZ and F_GETPIPE_SZ */ 163long pipe_fcntl(struct file *, unsigned int, unsigned long arg); 164struct pipe_inode_info *get_pipe_info(struct file *file); 165 166#endif 167