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 **/ 20 struct 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 refering 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 **/ 46 struct pipe_inode_info { 47 struct mutex mutex; 48 wait_queue_head_t wait; 49 unsigned int nrbufs, curbuf, buffers; 50 unsigned int readers; 51 unsigned int writers; 52 unsigned int files; 53 unsigned int waiting_writers; 54 unsigned int r_counter; 55 unsigned int w_counter; 56 struct page *tmp_page; 57 struct fasync_struct *fasync_readers; 58 struct fasync_struct *fasync_writers; 59 struct pipe_buffer *bufs; 60 }; 61 62 /* 63 * Note on the nesting of these functions: 64 * 65 * ->confirm() 66 * ->steal() 67 * ... 68 * ->map() 69 * ... 70 * ->unmap() 71 * 72 * That is, ->map() must be called on a confirmed buffer, 73 * same goes for ->steal(). See below for the meaning of each 74 * operation. Also see kerneldoc in fs/pipe.c for the pipe 75 * and generic variants of these hooks. 76 */ 77 struct pipe_buf_operations { 78 /* 79 * This is set to 1, if the generic pipe read/write may coalesce 80 * data into an existing buffer. If this is set to 0, a new pipe 81 * page segment is always used for new data. 82 */ 83 int can_merge; 84 85 /* 86 * ->map() returns a virtual address mapping of the pipe buffer. 87 * The last integer flag reflects whether this should be an atomic 88 * mapping or not. The atomic map is faster, however you can't take 89 * page faults before calling ->unmap() again. So if you need to eg 90 * access user data through copy_to/from_user(), then you must get 91 * a non-atomic map. ->map() uses the kmap_atomic slot for 92 * atomic maps, you have to be careful if mapping another page as 93 * source or destination for a copy. 94 */ 95 void * (*map)(struct pipe_inode_info *, struct pipe_buffer *, int); 96 97 /* 98 * Undoes ->map(), finishes the virtual mapping of the pipe buffer. 99 */ 100 void (*unmap)(struct pipe_inode_info *, struct pipe_buffer *, void *); 101 102 /* 103 * ->confirm() verifies that the data in the pipe buffer is there 104 * and that the contents are good. If the pages in the pipe belong 105 * to a file system, we may need to wait for IO completion in this 106 * hook. Returns 0 for good, or a negative error value in case of 107 * error. 108 */ 109 int (*confirm)(struct pipe_inode_info *, struct pipe_buffer *); 110 111 /* 112 * When the contents of this pipe buffer has been completely 113 * consumed by a reader, ->release() is called. 114 */ 115 void (*release)(struct pipe_inode_info *, struct pipe_buffer *); 116 117 /* 118 * Attempt to take ownership of the pipe buffer and its contents. 119 * ->steal() returns 0 for success, in which case the contents 120 * of the pipe (the buf->page) is locked and now completely owned 121 * by the caller. The page may then be transferred to a different 122 * mapping, the most often used case is insertion into different 123 * file address space cache. 124 */ 125 int (*steal)(struct pipe_inode_info *, struct pipe_buffer *); 126 127 /* 128 * Get a reference to the pipe buffer. 129 */ 130 void (*get)(struct pipe_inode_info *, struct pipe_buffer *); 131 }; 132 133 /* Differs from PIPE_BUF in that PIPE_SIZE is the length of the actual 134 memory allocation, whereas PIPE_BUF makes atomicity guarantees. */ 135 #define PIPE_SIZE PAGE_SIZE 136 137 /* Pipe lock and unlock operations */ 138 void pipe_lock(struct pipe_inode_info *); 139 void pipe_unlock(struct pipe_inode_info *); 140 void pipe_double_lock(struct pipe_inode_info *, struct pipe_inode_info *); 141 142 extern unsigned int pipe_max_size, pipe_min_size; 143 int pipe_proc_fn(struct ctl_table *, int, void __user *, size_t *, loff_t *); 144 145 146 /* Drop the inode semaphore and wait for a pipe event, atomically */ 147 void pipe_wait(struct pipe_inode_info *pipe); 148 149 struct pipe_inode_info *alloc_pipe_info(void); 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 int create_pipe_files(struct file **, int); 165 166 #endif 167