include/linux/pipe_fs_i.h

   1 #ifndef _LINUX_PIPE_FS_I_H
   2 #define _LINUX_PIPE_FS_I_H
   3
   4 #define PIPEFS_MAGIC 0x50495045
   5
   6 #define PIPE_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 struct pipe_buffer {
  13         struct page *page;
  14         unsigned int offset, len;
  15         const struct pipe_buf_operations *ops;
  16         unsigned int flags;
  17         unsigned long private;
  18 };
  19
  20 struct pipe_inode_info {
  21         wait_queue_head_t wait;
  22         unsigned int nrbufs, curbuf;
  23         struct page *tmp_page;
  24         unsigned int readers;
  25         unsigned int writers;
  26         unsigned int waiting_writers;
  27         unsigned int r_counter;
  28         unsigned int w_counter;
  29         struct fasync_struct *fasync_readers;
  30         struct fasync_struct *fasync_writers;
  31         struct inode *inode;
  32         struct pipe_buffer bufs[PIPE_BUFFERS];
  33 };
  34
  35 /*
  36  * Note on the nesting of these functions:
  37  *
  38  * ->confirm()
  39  *      ->steal()
  40  *      ...
  41  *      ->map()
  42  *      ...
  43  *      ->unmap()
  44  *
  45  * That is, ->map() must be called on a confirmed buffer,
  46  * same goes for ->steal().
  47  */
  48 struct pipe_buf_operations {
  49         int can_merge;
  50         void * (*map)(struct pipe_inode_info *, struct pipe_buffer *, int);
  51         void (*unmap)(struct pipe_inode_info *, struct pipe_buffer *, void *);
  52         int (*confirm)(struct pipe_inode_info *, struct pipe_buffer *);
  53         void (*release)(struct pipe_inode_info *, struct pipe_buffer *);
  54         int (*steal)(struct pipe_inode_info *, struct pipe_buffer *);
  55         void (*get)(struct pipe_inode_info *, struct pipe_buffer *);
  56 };
  57
  58 /* Differs from PIPE_BUF in that PIPE_SIZE is the length of the actual
  59    memory allocation, whereas PIPE_BUF makes atomicity guarantees.  */
  60 #define PIPE_SIZE               PAGE_SIZE
  61
  62 /* Drop the inode semaphore and wait for a pipe event, atomically */
  63 void pipe_wait(struct pipe_inode_info *pipe);
  64
  65 struct pipe_inode_info * alloc_pipe_info(struct inode * inode);
  66 void free_pipe_info(struct inode * inode);
  67 void __free_pipe_info(struct pipe_inode_info *);
  68
  69 /* Generic pipe buffer ops functions */
  70 void *generic_pipe_buf_map(struct pipe_inode_info *, struct pipe_buffer *, int);
  71 void generic_pipe_buf_unmap(struct pipe_inode_info *, struct pipe_buffer *, void *);
  72 void generic_pipe_buf_get(struct pipe_inode_info *, struct pipe_buffer *);
  73 int generic_pipe_buf_confirm(struct pipe_inode_info *, struct pipe_buffer *);
  74 int generic_pipe_buf_steal(struct pipe_inode_info *, struct pipe_buffer *);
  75
  76 #endif