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_STOLEN    0x01
   9 #define PIPE_BUF_FLAG_LRU       0x02
  10
  11 struct pipe_buffer {
  12         struct page *page;
  13         unsigned int offset, len;
  14         struct pipe_buf_operations *ops;
  15         unsigned int flags;
  16 };
  17
  18 struct pipe_buf_operations {
  19         int can_merge;
  20         void * (*map)(struct file *, struct pipe_inode_info *, struct pipe_buffer *);
  21         void (*unmap)(struct pipe_inode_info *, struct pipe_buffer *);
  22         void (*release)(struct pipe_inode_info *, struct pipe_buffer *);
  23         int (*steal)(struct pipe_inode_info *, struct pipe_buffer *);
  24         void (*get)(struct pipe_inode_info *, struct pipe_buffer *);
  25 };
  26
  27 struct pipe_inode_info {
  28         wait_queue_head_t wait;
  29         unsigned int nrbufs, curbuf;
  30         struct pipe_buffer bufs[PIPE_BUFFERS];
  31         struct page *tmp_page;
  32         unsigned int start;
  33         unsigned int readers;
  34         unsigned int writers;
  35         unsigned int waiting_writers;
  36         unsigned int r_counter;
  37         unsigned int w_counter;
  38         struct fasync_struct *fasync_readers;
  39         struct fasync_struct *fasync_writers;
  40         struct inode *inode;
  41 };
  42
  43 /* Differs from PIPE_BUF in that PIPE_SIZE is the length of the actual
  44    memory allocation, whereas PIPE_BUF makes atomicity guarantees.  */
  45 #define PIPE_SIZE               PAGE_SIZE
  46
  47 /* Drop the inode semaphore and wait for a pipe event, atomically */
  48 void pipe_wait(struct pipe_inode_info *pipe);
  49
  50 struct pipe_inode_info * alloc_pipe_info(struct inode * inode);
  51 void free_pipe_info(struct inode * inode);
  52 void __free_pipe_info(struct pipe_inode_info *);
  53
  54 /*
  55  * splice is tied to pipes as a transport (at least for now), so we'll just
  56  * add the splice flags here.
  57  */
  58 #define SPLICE_F_MOVE   (0x01)  /* move pages instead of copying */
  59 #define SPLICE_F_NONBLOCK (0x02) /* don't block on the pipe splicing (but */
  60                                  /* we may still block on the fd we splice */
  61                                  /* from/to, of course */
  62 #define SPLICE_F_MORE   (0x04)  /* expect more data */
  63
  64 /*
  65  * Passed to the actors
  66  */
  67 struct splice_desc {
  68         unsigned int len, total_len;    /* current and remaining length */
  69         unsigned int flags;             /* splice flags */
  70         struct file *file;              /* file to read/write */
  71         loff_t pos;                     /* file position */
  72 };
  73
  74 typedef int (splice_actor)(struct pipe_inode_info *, struct pipe_buffer *,
  75                            struct splice_desc *);
  76
  77 extern ssize_t splice_from_pipe(struct pipe_inode_info *, struct file *,
  78                                 loff_t *, size_t, unsigned int,
  79                                 splice_actor *);
  80
  81 #endif