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 struct pipe_buffer {
   9         struct page *page;
  10         unsigned int offset, len;
  11         struct pipe_buf_operations *ops;
  12 };
  13
  14 struct pipe_buf_operations {
  15         int can_merge;
  16         void * (*map)(struct file *, struct pipe_inode_info *, struct pipe_buffer *);
  17         void (*unmap)(struct pipe_inode_info *, struct pipe_buffer *);
  18         void (*release)(struct pipe_inode_info *, struct pipe_buffer *);
  19         int (*steal)(struct pipe_inode_info *, struct pipe_buffer *);
  20 };
  21
  22 struct pipe_inode_info {
  23         wait_queue_head_t wait;
  24         unsigned int nrbufs, curbuf;
  25         struct pipe_buffer bufs[PIPE_BUFFERS];
  26         struct page *tmp_page;
  27         unsigned int start;
  28         unsigned int readers;
  29         unsigned int writers;
  30         unsigned int waiting_writers;
  31         unsigned int r_counter;
  32         unsigned int w_counter;
  33         struct fasync_struct *fasync_readers;
  34         struct fasync_struct *fasync_writers;
  35 };
  36
  37 /* Differs from PIPE_BUF in that PIPE_SIZE is the length of the actual
  38    memory allocation, whereas PIPE_BUF makes atomicity guarantees.  */
  39 #define PIPE_SIZE               PAGE_SIZE
  40
  41 #define PIPE_MUTEX(inode)       (&(inode).i_mutex)
  42 #define PIPE_WAIT(inode)        (&(inode).i_pipe->wait)
  43 #define PIPE_READERS(inode)     ((inode).i_pipe->readers)
  44 #define PIPE_WRITERS(inode)     ((inode).i_pipe->writers)
  45 #define PIPE_WAITING_WRITERS(inode)     ((inode).i_pipe->waiting_writers)
  46 #define PIPE_RCOUNTER(inode)    ((inode).i_pipe->r_counter)
  47 #define PIPE_WCOUNTER(inode)    ((inode).i_pipe->w_counter)
  48 #define PIPE_FASYNC_READERS(inode)     (&((inode).i_pipe->fasync_readers))
  49 #define PIPE_FASYNC_WRITERS(inode)     (&((inode).i_pipe->fasync_writers))
  50
  51 /* Drop the inode semaphore and wait for a pipe event, atomically */
  52 void pipe_wait(struct inode * inode);
  53
  54 struct inode* pipe_new(struct inode* inode);
  55 void free_pipe_info(struct inode* inode);
  56
  57 /*
  58  * splice is tied to pipes as a transport (at least for now), so we'll just
  59  * add the splice flags here.
  60  */
  61 #define SPLICE_F_MOVE   (0x01)  /* move pages instead of copying */
  62 #define SPLICE_F_NONBLOCK (0x02) /* don't block on the pipe splicing (but */
  63                                  /* we may still block on the fd we splice */
  64                                  /* from/to, of course */
  65 #define SPLICE_F_MORE   (0x04)  /* expect more data */
  66
  67 #endif