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_ATOMIC    0x01    /* was atomically mapped */
   9 #define PIPE_BUF_FLAG_GIFT      0x02    /* page is a gift */
  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 /*
  19  * Note on the nesting of these functions:
  20  *
  21  * ->pin()
  22  *      ->steal()
  23  *      ...
  24  *      ->map()
  25  *      ...
  26  *      ->unmap()
  27  *
  28  * That is, ->map() must be called on a pinned buffer, same goes for ->steal().
  29  */
  30 struct pipe_buf_operations {
  31         int can_merge;
  32         void * (*map)(struct pipe_inode_info *, struct pipe_buffer *, int);
  33         void (*unmap)(struct pipe_inode_info *, struct pipe_buffer *, void *);
  34         int (*pin)(struct pipe_inode_info *, struct pipe_buffer *);
  35         void (*release)(struct pipe_inode_info *, struct pipe_buffer *);
  36         int (*steal)(struct pipe_inode_info *, struct pipe_buffer *);
  37         void (*get)(struct pipe_inode_info *, struct pipe_buffer *);
  38 };
  39
  40 struct pipe_inode_info {
  41         wait_queue_head_t wait;
  42         unsigned int nrbufs, curbuf;
  43         struct pipe_buffer bufs[PIPE_BUFFERS];
  44         struct page *tmp_page;
  45         unsigned int start;
  46         unsigned int readers;
  47         unsigned int writers;
  48         unsigned int waiting_writers;
  49         unsigned int r_counter;
  50         unsigned int w_counter;
  51         struct fasync_struct *fasync_readers;
  52         struct fasync_struct *fasync_writers;
  53         struct inode *inode;
  54 };
  55
  56 /* Differs from PIPE_BUF in that PIPE_SIZE is the length of the actual
  57    memory allocation, whereas PIPE_BUF makes atomicity guarantees.  */
  58 #define PIPE_SIZE               PAGE_SIZE
  59
  60 /* Drop the inode semaphore and wait for a pipe event, atomically */
  61 void pipe_wait(struct pipe_inode_info *pipe);
  62
  63 struct pipe_inode_info * alloc_pipe_info(struct inode * inode);
  64 void free_pipe_info(struct inode * inode);
  65 void __free_pipe_info(struct pipe_inode_info *);
  66
  67 /* Generic pipe buffer ops functions */
  68 void *generic_pipe_buf_map(struct pipe_inode_info *, struct pipe_buffer *, int);
  69 void generic_pipe_buf_unmap(struct pipe_inode_info *, struct pipe_buffer *, void *);
  70 void generic_pipe_buf_get(struct pipe_inode_info *, struct pipe_buffer *);
  71 int generic_pipe_buf_pin(struct pipe_inode_info *, struct pipe_buffer *);
  72 int generic_pipe_buf_steal(struct pipe_inode_info *, struct pipe_buffer *);
  73
  74 /*
  75  * splice is tied to pipes as a transport (at least for now), so we'll just
  76  * add the splice flags here.
  77  */
  78 #define SPLICE_F_MOVE   (0x01)  /* move pages instead of copying */
  79 #define SPLICE_F_NONBLOCK (0x02) /* don't block on the pipe splicing (but */
  80                                  /* we may still block on the fd we splice */
  81                                  /* from/to, of course */
  82 #define SPLICE_F_MORE   (0x04)  /* expect more data */
  83 #define SPLICE_F_GIFT   (0x08)  /* pages passed in are a gift */
  84
  85 /*
  86  * Passed to the actors
  87  */
  88 struct splice_desc {
  89         unsigned int len, total_len;    /* current and remaining length */
  90         unsigned int flags;             /* splice flags */
  91         struct file *file;              /* file to read/write */
  92         loff_t pos;                     /* file position */
  93 };
  94
  95 typedef int (splice_actor)(struct pipe_inode_info *, struct pipe_buffer *,
  96                            struct splice_desc *);
  97
  98 extern ssize_t splice_from_pipe(struct pipe_inode_info *, struct file *,
  99                                 loff_t *, size_t, unsigned int,
 100                                 splice_actor *);
 101
 102 #endif