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         struct pipe_buf_operations *ops;
  16         unsigned int flags;
  17 };
  18
  19 /*
  20  * Note on the nesting of these functions:
  21  *
  22  * ->pin()
  23  *      ->steal()
  24  *      ...
  25  *      ->map()
  26  *      ...
  27  *      ->unmap()
  28  *
  29  * That is, ->map() must be called on a pinned buffer, same goes for ->steal().
  30  */
  31 struct pipe_buf_operations {
  32         int can_merge;
  33         void * (*map)(struct pipe_inode_info *, struct pipe_buffer *, int);
  34         void (*unmap)(struct pipe_inode_info *, struct pipe_buffer *, void *);
  35         int (*pin)(struct pipe_inode_info *, struct pipe_buffer *);
  36         void (*release)(struct pipe_inode_info *, struct pipe_buffer *);
  37         int (*steal)(struct pipe_inode_info *, struct pipe_buffer *);
  38         void (*get)(struct pipe_inode_info *, struct pipe_buffer *);
  39 };
  40
  41 struct pipe_inode_info {
  42         wait_queue_head_t wait;
  43         unsigned int nrbufs, curbuf;
  44         struct pipe_buffer bufs[PIPE_BUFFERS];
  45         struct page *tmp_page;
  46         unsigned int start;
  47         unsigned int readers;
  48         unsigned int writers;
  49         unsigned int waiting_writers;
  50         unsigned int r_counter;
  51         unsigned int w_counter;
  52         struct fasync_struct *fasync_readers;
  53         struct fasync_struct *fasync_writers;
  54         struct inode *inode;
  55 };
  56
  57 /* Differs from PIPE_BUF in that PIPE_SIZE is the length of the actual
  58    memory allocation, whereas PIPE_BUF makes atomicity guarantees.  */
  59 #define PIPE_SIZE               PAGE_SIZE
  60
  61 /* Drop the inode semaphore and wait for a pipe event, atomically */
  62 void pipe_wait(struct pipe_inode_info *pipe);
  63
  64 struct pipe_inode_info * alloc_pipe_info(struct inode * inode);
  65 void free_pipe_info(struct inode * inode);
  66 void __free_pipe_info(struct pipe_inode_info *);
  67
  68 /* Generic pipe buffer ops functions */
  69 void *generic_pipe_buf_map(struct pipe_inode_info *, struct pipe_buffer *, int);
  70 void generic_pipe_buf_unmap(struct pipe_inode_info *, struct pipe_buffer *, void *);
  71 void generic_pipe_buf_get(struct pipe_inode_info *, struct pipe_buffer *);
  72 int generic_pipe_buf_pin(struct pipe_inode_info *, struct pipe_buffer *);
  73 int generic_pipe_buf_steal(struct pipe_inode_info *, struct pipe_buffer *);
  74
  75 /*
  76  * splice is tied to pipes as a transport (at least for now), so we'll just
  77  * add the splice flags here.
  78  */
  79 #define SPLICE_F_MOVE   (0x01)  /* move pages instead of copying */
  80 #define SPLICE_F_NONBLOCK (0x02) /* don't block on the pipe splicing (but */
  81                                  /* we may still block on the fd we splice */
  82                                  /* from/to, of course */
  83 #define SPLICE_F_MORE   (0x04)  /* expect more data */
  84 #define SPLICE_F_GIFT   (0x08)  /* pages passed in are a gift */
  85
  86 /*
  87  * Passed to the actors
  88  */
  89 struct splice_desc {
  90         unsigned int len, total_len;    /* current and remaining length */
  91         unsigned int flags;             /* splice flags */
  92         struct file *file;              /* file to read/write */
  93         loff_t pos;                     /* file position */
  94 };
  95
  96 typedef int (splice_actor)(struct pipe_inode_info *, struct pipe_buffer *,
  97                            struct splice_desc *);
  98
  99 extern ssize_t splice_from_pipe(struct pipe_inode_info *, struct file *,
 100                                 loff_t *, size_t, unsigned int,
 101                                 splice_actor *);
 102
 103 #endif