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Linus Torvalds1da177e2005-04-16 15:20:36 -07001#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
Jens Axboe14328732006-05-03 10:35:26 +02008#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 */
Jens Axboe3e7ee3e2006-04-02 23:11:04 +020011
Jens Axboe08457182007-06-12 20:51:32 +020012/**
13 * struct pipe_buffer - a linux kernel pipe buffer
14 * @page: the page containing the data for the pipe buffer
15 * @offset: offset of data inside the @page
16 * @len: length of data inside the @page
17 * @ops: operations associated with this buffer. See @pipe_buf_operations.
18 * @flags: pipe buffer flags. See above.
19 * @private: private data owned by the ops.
20 **/
Linus Torvalds1da177e2005-04-16 15:20:36 -070021struct pipe_buffer {
22 struct page *page;
23 unsigned int offset, len;
Eric Dumazetd4c3cca2006-12-13 00:34:04 -080024 const struct pipe_buf_operations *ops;
Jens Axboe3e7ee3e2006-04-02 23:11:04 +020025 unsigned int flags;
Jens Axboe497f9622007-06-11 12:00:45 +020026 unsigned long private;
Linus Torvalds1da177e2005-04-16 15:20:36 -070027};
28
Jens Axboe08457182007-06-12 20:51:32 +020029/**
30 * struct pipe_inode_info - a linux kernel pipe
31 * @wait: reader/writer wait point in case of empty/full pipe
32 * @nrbufs: the number of non-empty pipe buffers in this pipe
33 * @curbuf: the current pipe buffer entry
34 * @tmp_page: cached released page
35 * @readers: number of current readers of this pipe
36 * @writers: number of current writers of this pipe
37 * @waiting_writers: number of writers blocked waiting for room
38 * @r_counter: reader counter
39 * @w_counter: writer counter
40 * @fasync_readers: reader side fasync
41 * @fasync_writers: writer side fasync
42 * @inode: inode this pipe is attached to
43 * @bufs: the circular array of pipe buffers
44 **/
Jens Axboe17374ff2007-06-04 15:03:12 +020045struct pipe_inode_info {
46 wait_queue_head_t wait;
47 unsigned int nrbufs, curbuf;
48 struct page *tmp_page;
49 unsigned int readers;
50 unsigned int writers;
51 unsigned int waiting_writers;
52 unsigned int r_counter;
53 unsigned int w_counter;
54 struct fasync_struct *fasync_readers;
55 struct fasync_struct *fasync_writers;
56 struct inode *inode;
57 struct pipe_buffer bufs[PIPE_BUFFERS];
58};
59
Jens Axboef84d7512006-05-01 19:59:03 +020060/*
61 * Note on the nesting of these functions:
62 *
Jens Axboecac36bb02007-06-14 13:10:48 +020063 * ->confirm()
Jens Axboef84d7512006-05-01 19:59:03 +020064 * ->steal()
65 * ...
66 * ->map()
67 * ...
68 * ->unmap()
69 *
Jens Axboecac36bb02007-06-14 13:10:48 +020070 * That is, ->map() must be called on a confirmed buffer,
Jens Axboe08457182007-06-12 20:51:32 +020071 * same goes for ->steal(). See below for the meaning of each
72 * operation. Also see kerneldoc in fs/pipe.c for the pipe
73 * and generic variants of these hooks.
Jens Axboef84d7512006-05-01 19:59:03 +020074 */
Linus Torvalds1da177e2005-04-16 15:20:36 -070075struct pipe_buf_operations {
Jens Axboe08457182007-06-12 20:51:32 +020076 /*
77 * This is set to 1, if the generic pipe read/write may coalesce
78 * data into an existing buffer. If this is set to 0, a new pipe
79 * page segment is always used for new data.
80 */
Linus Torvalds1da177e2005-04-16 15:20:36 -070081 int can_merge;
Jens Axboe08457182007-06-12 20:51:32 +020082
83 /*
84 * ->map() returns a virtual address mapping of the pipe buffer.
85 * The last integer flag reflects whether this should be an atomic
86 * mapping or not. The atomic map is faster, however you can't take
87 * page faults before calling ->unmap() again. So if you need to eg
88 * access user data through copy_to/from_user(), then you must get
89 * a non-atomic map. ->map() uses the KM_USER0 atomic slot for
90 * atomic maps, so you can't map more than one pipe_buffer at once
91 * and you have to be careful if mapping another page as source
92 * or destination for a copy (IOW, it has to use something else
93 * than KM_USER0).
94 */
Jens Axboef6762b72006-05-01 20:02:05 +020095 void * (*map)(struct pipe_inode_info *, struct pipe_buffer *, int);
Jens Axboe08457182007-06-12 20:51:32 +020096
97 /*
98 * Undoes ->map(), finishes the virtual mapping of the pipe buffer.
99 */
Jens Axboef6762b72006-05-01 20:02:05 +0200100 void (*unmap)(struct pipe_inode_info *, struct pipe_buffer *, void *);
Jens Axboe08457182007-06-12 20:51:32 +0200101
102 /*
103 * ->confirm() verifies that the data in the pipe buffer is there
104 * and that the contents are good. If the pages in the pipe belong
105 * to a file system, we may need to wait for IO completion in this
106 * hook. Returns 0 for good, or a negative error value in case of
107 * error.
108 */
Jens Axboecac36bb02007-06-14 13:10:48 +0200109 int (*confirm)(struct pipe_inode_info *, struct pipe_buffer *);
Jens Axboe08457182007-06-12 20:51:32 +0200110
111 /*
112 * When the contents of this pipe buffer has been completely
113 * consumed by a reader, ->release() is called.
114 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700115 void (*release)(struct pipe_inode_info *, struct pipe_buffer *);
Jens Axboe08457182007-06-12 20:51:32 +0200116
117 /*
118 * Attempt to take ownership of the pipe buffer and its contents.
119 * ->steal() returns 0 for success, in which case the contents
120 * of the pipe (the buf->page) is locked and now completely owned
121 * by the caller. The page may then be transferred to a different
122 * mapping, the most often used case is insertion into different
123 * file address space cache.
124 */
Jens Axboe5abc97a2006-03-30 15:16:46 +0200125 int (*steal)(struct pipe_inode_info *, struct pipe_buffer *);
Jens Axboe08457182007-06-12 20:51:32 +0200126
127 /*
128 * Get a reference to the pipe buffer.
129 */
Jens Axboe70524492006-04-11 15:51:17 +0200130 void (*get)(struct pipe_inode_info *, struct pipe_buffer *);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700131};
132
Linus Torvalds1da177e2005-04-16 15:20:36 -0700133/* Differs from PIPE_BUF in that PIPE_SIZE is the length of the actual
134 memory allocation, whereas PIPE_BUF makes atomicity guarantees. */
135#define PIPE_SIZE PAGE_SIZE
136
Miklos Szeredi61e0d472009-04-14 19:48:41 +0200137/* Pipe lock and unlock operations */
138void pipe_lock(struct pipe_inode_info *);
139void pipe_unlock(struct pipe_inode_info *);
140void pipe_double_lock(struct pipe_inode_info *, struct pipe_inode_info *);
141
Linus Torvalds1da177e2005-04-16 15:20:36 -0700142/* Drop the inode semaphore and wait for a pipe event, atomically */
Ingo Molnar3a326a22006-04-10 15:18:35 +0200143void pipe_wait(struct pipe_inode_info *pipe);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700144
Ingo Molnar3a326a22006-04-10 15:18:35 +0200145struct pipe_inode_info * alloc_pipe_info(struct inode * inode);
146void free_pipe_info(struct inode * inode);
Jens Axboeb92ce552006-04-11 13:52:07 +0200147void __free_pipe_info(struct pipe_inode_info *);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700148
Jens Axboef84d7512006-05-01 19:59:03 +0200149/* Generic pipe buffer ops functions */
Jens Axboef6762b72006-05-01 20:02:05 +0200150void *generic_pipe_buf_map(struct pipe_inode_info *, struct pipe_buffer *, int);
151void generic_pipe_buf_unmap(struct pipe_inode_info *, struct pipe_buffer *, void *);
Jens Axboef84d7512006-05-01 19:59:03 +0200152void generic_pipe_buf_get(struct pipe_inode_info *, struct pipe_buffer *);
Jens Axboecac36bb02007-06-14 13:10:48 +0200153int generic_pipe_buf_confirm(struct pipe_inode_info *, struct pipe_buffer *);
Jens Axboe330ab712006-05-02 15:29:57 +0200154int generic_pipe_buf_steal(struct pipe_inode_info *, struct pipe_buffer *);
Jens Axboef84d7512006-05-01 19:59:03 +0200155
Linus Torvalds1da177e2005-04-16 15:20:36 -0700156#endif