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 10 /** 11 * struct pipe_buffer - a linux kernel pipe buffer 12 * @page: the page containing the data for the pipe buffer 13 * @offset: offset of data inside the @page 14 * @len: length of data inside the @page 15 * @ops: operations associated with this buffer. See @pipe_buf_operations. 16 * @flags: pipe buffer flags. See above. 17 * @private: private data owned by the ops. 18 **/ 19 struct pipe_buffer { 20 struct page *page; 21 unsigned int offset, len; 22 const struct pipe_buf_operations *ops; 23 unsigned int flags; 24 unsigned long private; 25 }; 26 27 /** 28 * struct pipe_inode_info - a linux kernel pipe 29 * @wait: reader/writer wait point in case of empty/full pipe 30 * @nrbufs: the number of non-empty pipe buffers in this pipe 31 * @buffers: total number of buffers (should be a power of 2) 32 * @curbuf: the current pipe buffer entry 33 * @tmp_page: cached released page 34 * @readers: number of current readers of this pipe 35 * @writers: number of current writers of this pipe 36 * @waiting_writers: number of writers blocked waiting for room 37 * @r_counter: reader counter 38 * @w_counter: writer counter 39 * @fasync_readers: reader side fasync 40 * @fasync_writers: writer side fasync 41 * @inode: inode this pipe is attached to 42 * @bufs: the circular array of pipe buffers 43 **/ 44 struct pipe_inode_info { 45 wait_queue_head_t wait; 46 unsigned int nrbufs, curbuf, buffers; 47 unsigned int readers; 48 unsigned int writers; 49 unsigned int waiting_writers; 50 unsigned int r_counter; 51 unsigned int w_counter; 52 struct page *tmp_page; 53 struct fasync_struct *fasync_readers; 54 struct fasync_struct *fasync_writers; 55 struct inode *inode; 56 struct pipe_buffer *bufs; 57 }; 58 59 /* 60 * Note on the nesting of these functions: 61 * 62 * ->confirm() 63 * ->steal() 64 * ... 65 * ->map() 66 * ... 67 * ->unmap() 68 * 69 * That is, ->map() must be called on a confirmed buffer, 70 * same goes for ->steal(). See below for the meaning of each 71 * operation. Also see kerneldoc in fs/pipe.c for the pipe 72 * and generic variants of these hooks. 73 */ 74 struct 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 * ->map() returns a virtual address mapping of the pipe buffer. 84 * The last integer flag reflects whether this should be an atomic 85 * mapping or not. The atomic map is faster, however you can't take 86 * page faults before calling ->unmap() again. So if you need to eg 87 * access user data through copy_to/from_user(), then you must get 88 * a non-atomic map. ->map() uses the KM_USER0 atomic slot for 89 * atomic maps, so you can't map more than one pipe_buffer at once 90 * and you have to be careful if mapping another page as source 91 * or destination for a copy (IOW, it has to use something else 92 * than KM_USER0). 93 */ 94 void * (*map)(struct pipe_inode_info *, struct pipe_buffer *, int); 95 96 /* 97 * Undoes ->map(), finishes the virtual mapping of the pipe buffer. 98 */ 99 void (*unmap)(struct pipe_inode_info *, struct pipe_buffer *, void *); 100 101 /* 102 * ->confirm() verifies that the data in the pipe buffer is there 103 * and that the contents are good. If the pages in the pipe belong 104 * to a file system, we may need to wait for IO completion in this 105 * hook. Returns 0 for good, or a negative error value in case of 106 * error. 107 */ 108 int (*confirm)(struct pipe_inode_info *, struct pipe_buffer *); 109 110 /* 111 * When the contents of this pipe buffer has been completely 112 * consumed by a reader, ->release() is called. 113 */ 114 void (*release)(struct pipe_inode_info *, struct pipe_buffer *); 115 116 /* 117 * Attempt to take ownership of the pipe buffer and its contents. 118 * ->steal() returns 0 for success, in which case the contents 119 * of the pipe (the buf->page) is locked and now completely owned 120 * by the caller. The page may then be transferred to a different 121 * mapping, the most often used case is insertion into different 122 * file address space cache. 123 */ 124 int (*steal)(struct pipe_inode_info *, struct pipe_buffer *); 125 126 /* 127 * Get a reference to the pipe buffer. 128 */ 129 void (*get)(struct pipe_inode_info *, struct pipe_buffer *); 130 }; 131 132 /* Differs from PIPE_BUF in that PIPE_SIZE is the length of the actual 133 memory allocation, whereas PIPE_BUF makes atomicity guarantees. */ 134 #define PIPE_SIZE PAGE_SIZE 135 136 /* Pipe lock and unlock operations */ 137 void pipe_lock(struct pipe_inode_info *); 138 void pipe_unlock(struct pipe_inode_info *); 139 void pipe_double_lock(struct pipe_inode_info *, struct pipe_inode_info *); 140 141 extern unsigned int pipe_max_size, pipe_min_size; 142 int pipe_proc_fn(struct ctl_table *, int, void __user *, size_t *, loff_t *); 143 144 145 /* Drop the inode semaphore and wait for a pipe event, atomically */ 146 void pipe_wait(struct pipe_inode_info *pipe); 147 148 struct pipe_inode_info * alloc_pipe_info(struct inode * inode); 149 void free_pipe_info(struct inode * inode); 150 void __free_pipe_info(struct pipe_inode_info *); 151 152 /* Generic pipe buffer ops functions */ 153 void *generic_pipe_buf_map(struct pipe_inode_info *, struct pipe_buffer *, int); 154 void generic_pipe_buf_unmap(struct pipe_inode_info *, struct pipe_buffer *, void *); 155 void generic_pipe_buf_get(struct pipe_inode_info *, struct pipe_buffer *); 156 int generic_pipe_buf_confirm(struct pipe_inode_info *, struct pipe_buffer *); 157 int generic_pipe_buf_steal(struct pipe_inode_info *, struct pipe_buffer *); 158 void generic_pipe_buf_release(struct pipe_inode_info *, struct pipe_buffer *); 159 160 /* for F_SETPIPE_SZ and F_GETPIPE_SZ */ 161 long pipe_fcntl(struct file *, unsigned int, unsigned long arg); 162 struct pipe_inode_info *get_pipe_info(struct file *file); 163 164 #endif 165