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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
Jens Axboe35f3d142010-05-20 10:43:18 +02004#define PIPE_DEF_BUFFERS 16
Linus Torvalds1da177e2005-04-16 15:20:36 -07005
Jens Axboe14328732006-05-03 10:35:26 +02006#define PIPE_BUF_FLAG_LRU 0x01 /* page is on the LRU */
7#define PIPE_BUF_FLAG_ATOMIC 0x02 /* was atomically mapped */
8#define PIPE_BUF_FLAG_GIFT 0x04 /* page is a gift */
Linus Torvalds98830352012-04-29 13:12:42 -07009#define PIPE_BUF_FLAG_PACKET 0x08 /* read() as a packet */
Jens Axboe3e7ee3e2006-04-02 23:11:04 +020010
Jens Axboe08457182007-06-12 20:51:32 +020011/**
12 * struct pipe_buffer - a linux kernel pipe buffer
13 * @page: the page containing the data for the pipe buffer
14 * @offset: offset of data inside the @page
15 * @len: length of data inside the @page
16 * @ops: operations associated with this buffer. See @pipe_buf_operations.
17 * @flags: pipe buffer flags. See above.
18 * @private: private data owned by the ops.
19 **/
Linus Torvalds1da177e2005-04-16 15:20:36 -070020struct pipe_buffer {
21 struct page *page;
22 unsigned int offset, len;
Eric Dumazetd4c3cca2006-12-13 00:34:04 -080023 const struct pipe_buf_operations *ops;
Jens Axboe3e7ee3e2006-04-02 23:11:04 +020024 unsigned int flags;
Jens Axboe497f9622007-06-11 12:00:45 +020025 unsigned long private;
Linus Torvalds1da177e2005-04-16 15:20:36 -070026};
27
Jens Axboe08457182007-06-12 20:51:32 +020028/**
29 * struct pipe_inode_info - a linux kernel pipe
Al Viro72b0d9a2013-03-21 02:32:24 -040030 * @mutex: mutex protecting the whole thing
Jens Axboe08457182007-06-12 20:51:32 +020031 * @wait: reader/writer wait point in case of empty/full pipe
32 * @nrbufs: the number of non-empty pipe buffers in this pipe
Randy Dunlap0dc14882011-01-08 19:40:33 -080033 * @buffers: total number of buffers (should be a power of 2)
Jens Axboe08457182007-06-12 20:51:32 +020034 * @curbuf: the current pipe buffer entry
35 * @tmp_page: cached released page
36 * @readers: number of current readers of this pipe
37 * @writers: number of current writers of this pipe
Al Viroba5bb142013-03-21 02:21:19 -040038 * @files: number of struct file refering this pipe (protected by ->i_lock)
Jens Axboe08457182007-06-12 20:51:32 +020039 * @waiting_writers: number of writers blocked waiting for room
40 * @r_counter: reader counter
41 * @w_counter: writer counter
42 * @fasync_readers: reader side fasync
43 * @fasync_writers: writer side fasync
Jens Axboe08457182007-06-12 20:51:32 +020044 * @bufs: the circular array of pipe buffers
45 **/
Jens Axboe17374ff2007-06-04 15:03:12 +020046struct pipe_inode_info {
Al Viro72b0d9a2013-03-21 02:32:24 -040047 struct mutex mutex;
Jens Axboe17374ff2007-06-04 15:03:12 +020048 wait_queue_head_t wait;
Jens Axboe35f3d142010-05-20 10:43:18 +020049 unsigned int nrbufs, curbuf, buffers;
Jens Axboe17374ff2007-06-04 15:03:12 +020050 unsigned int readers;
51 unsigned int writers;
Al Viroba5bb142013-03-21 02:21:19 -040052 unsigned int files;
Jens Axboe17374ff2007-06-04 15:03:12 +020053 unsigned int waiting_writers;
54 unsigned int r_counter;
55 unsigned int w_counter;
Jens Axboe35f3d142010-05-20 10:43:18 +020056 struct page *tmp_page;
Jens Axboe17374ff2007-06-04 15:03:12 +020057 struct fasync_struct *fasync_readers;
58 struct fasync_struct *fasync_writers;
Jens Axboe35f3d142010-05-20 10:43:18 +020059 struct pipe_buffer *bufs;
Jens Axboe17374ff2007-06-04 15:03:12 +020060};
61
Jens Axboef84d7512006-05-01 19:59:03 +020062/*
63 * Note on the nesting of these functions:
64 *
Jens Axboecac36bb02007-06-14 13:10:48 +020065 * ->confirm()
Jens Axboef84d7512006-05-01 19:59:03 +020066 * ->steal()
67 * ...
68 * ->map()
69 * ...
70 * ->unmap()
71 *
Jens Axboecac36bb02007-06-14 13:10:48 +020072 * That is, ->map() must be called on a confirmed buffer,
Jens Axboe08457182007-06-12 20:51:32 +020073 * same goes for ->steal(). See below for the meaning of each
74 * operation. Also see kerneldoc in fs/pipe.c for the pipe
75 * and generic variants of these hooks.
Jens Axboef84d7512006-05-01 19:59:03 +020076 */
Linus Torvalds1da177e2005-04-16 15:20:36 -070077struct pipe_buf_operations {
Jens Axboe08457182007-06-12 20:51:32 +020078 /*
79 * This is set to 1, if the generic pipe read/write may coalesce
80 * data into an existing buffer. If this is set to 0, a new pipe
81 * page segment is always used for new data.
82 */
Linus Torvalds1da177e2005-04-16 15:20:36 -070083 int can_merge;
Jens Axboe08457182007-06-12 20:51:32 +020084
85 /*
86 * ->map() returns a virtual address mapping of the pipe buffer.
87 * The last integer flag reflects whether this should be an atomic
88 * mapping or not. The atomic map is faster, however you can't take
89 * page faults before calling ->unmap() again. So if you need to eg
90 * access user data through copy_to/from_user(), then you must get
Cong Wang2164d332012-06-23 11:33:51 +080091 * a non-atomic map. ->map() uses the kmap_atomic slot for
92 * atomic maps, you have to be careful if mapping another page as
93 * source or destination for a copy.
Jens Axboe08457182007-06-12 20:51:32 +020094 */
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
Jens Axboeff9da692010-06-03 14:54:39 +0200142extern unsigned int pipe_max_size, pipe_min_size;
143int pipe_proc_fn(struct ctl_table *, int, void __user *, size_t *, loff_t *);
144
Jens Axboeb492e952010-05-19 21:03:16 +0200145
Linus Torvalds1da177e2005-04-16 15:20:36 -0700146/* Drop the inode semaphore and wait for a pipe event, atomically */
Ingo Molnar3a326a22006-04-10 15:18:35 +0200147void pipe_wait(struct pipe_inode_info *pipe);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700148
Al Viro7bee1302013-03-21 11:04:15 -0400149struct pipe_inode_info *alloc_pipe_info(void);
Al Viro4b8a8f12013-03-21 11:06:46 -0400150void free_pipe_info(struct pipe_inode_info *);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700151
Jens Axboef84d7512006-05-01 19:59:03 +0200152/* Generic pipe buffer ops functions */
Jens Axboef6762b72006-05-01 20:02:05 +0200153void *generic_pipe_buf_map(struct pipe_inode_info *, struct pipe_buffer *, int);
154void generic_pipe_buf_unmap(struct pipe_inode_info *, struct pipe_buffer *, void *);
Jens Axboef84d7512006-05-01 19:59:03 +0200155void generic_pipe_buf_get(struct pipe_inode_info *, struct pipe_buffer *);
Jens Axboecac36bb02007-06-14 13:10:48 +0200156int generic_pipe_buf_confirm(struct pipe_inode_info *, struct pipe_buffer *);
Jens Axboe330ab712006-05-02 15:29:57 +0200157int generic_pipe_buf_steal(struct pipe_inode_info *, struct pipe_buffer *);
Miklos Szeredi68181732009-05-07 15:37:36 +0200158void generic_pipe_buf_release(struct pipe_inode_info *, struct pipe_buffer *);
Jens Axboef84d7512006-05-01 19:59:03 +0200159
Miklos Szeredi28a625c2014-01-22 19:36:57 +0100160extern const struct pipe_buf_operations nosteal_pipe_buf_ops;
161
Jens Axboe35f3d142010-05-20 10:43:18 +0200162/* for F_SETPIPE_SZ and F_GETPIPE_SZ */
163long pipe_fcntl(struct file *, unsigned int, unsigned long arg);
Linus Torvalds72083642010-11-28 16:27:19 -0800164struct pipe_inode_info *get_pipe_info(struct file *file);
Linus Torvaldsc66fb342010-11-28 14:09:57 -0800165
Al Viroe4fad8e2012-07-21 15:33:25 +0400166int create_pipe_files(struct file **, int);
167
Linus Torvalds1da177e2005-04-16 15:20:36 -0700168#endif