[linux-2.6-block.git] / include / linux / pipe_fs_i.h

#ifndef _LINUX_PIPE_FS_I_H
#define _LINUX_PIPE_FS_I_H

#define PIPE_DEF_BUFFERS	16

#define PIPE_BUF_FLAG_LRU	0x01	/* page is on the LRU */
#define PIPE_BUF_FLAG_ATOMIC	0x02	/* was atomically mapped */
#define PIPE_BUF_FLAG_GIFT	0x04	/* page is a gift */
#define PIPE_BUF_FLAG_PACKET	0x08	/* read() as a packet */

/**
 *	struct pipe_buffer - a linux kernel pipe buffer
 *	@page: the page containing the data for the pipe buffer
 *	@offset: offset of data inside the @page
 *	@len: length of data inside the @page
 *	@ops: operations associated with this buffer. See @pipe_buf_operations.
 *	@flags: pipe buffer flags. See above.
 *	@private: private data owned by the ops.
 **/
struct pipe_buffer {
	struct page *page;
	unsigned int offset, len;
	const struct pipe_buf_operations *ops;
	unsigned int flags;
	unsigned long private;
};

/**
 *	struct pipe_inode_info - a linux kernel pipe
 *	@mutex: mutex protecting the whole thing
 *	@wait: reader/writer wait point in case of empty/full pipe
 *	@nrbufs: the number of non-empty pipe buffers in this pipe
 *	@buffers: total number of buffers (should be a power of 2)
 *	@curbuf: the current pipe buffer entry
 *	@tmp_page: cached released page
 *	@readers: number of current readers of this pipe
 *	@writers: number of current writers of this pipe
 *	@files: number of struct file referring this pipe (protected by ->i_lock)
 *	@waiting_writers: number of writers blocked waiting for room
 *	@r_counter: reader counter
 *	@w_counter: writer counter
 *	@fasync_readers: reader side fasync
 *	@fasync_writers: writer side fasync
 *	@bufs: the circular array of pipe buffers
 **/
struct pipe_inode_info {
	struct mutex mutex;
	wait_queue_head_t wait;
	unsigned int nrbufs, curbuf, buffers;
	unsigned int readers;
	unsigned int writers;
	unsigned int files;
	unsigned int waiting_writers;
	unsigned int r_counter;
	unsigned int w_counter;
	struct page *tmp_page;
	struct fasync_struct *fasync_readers;
	struct fasync_struct *fasync_writers;
	struct pipe_buffer *bufs;
};

/*
 * Note on the nesting of these functions:
 *
 * ->confirm()
 *	->steal()
 *	...
 *	->map()
 *	...
 *	->unmap()
 *
 * That is, ->map() must be called on a confirmed buffer,
 * same goes for ->steal(). See below for the meaning of each
 * operation. Also see kerneldoc in fs/pipe.c for the pipe
 * and generic variants of these hooks.
 */
struct pipe_buf_operations {
	/*
	 * This is set to 1, if the generic pipe read/write may coalesce
	 * data into an existing buffer. If this is set to 0, a new pipe
	 * page segment is always used for new data.
	 */
	int can_merge;

	/*
	 * ->confirm() verifies that the data in the pipe buffer is there
	 * and that the contents are good. If the pages in the pipe belong
	 * to a file system, we may need to wait for IO completion in this
	 * hook. Returns 0 for good, or a negative error value in case of
	 * error.
	 */
	int (*confirm)(struct pipe_inode_info *, struct pipe_buffer *);

	/*
	 * When the contents of this pipe buffer has been completely
	 * consumed by a reader, ->release() is called.
	 */
	void (*release)(struct pipe_inode_info *, struct pipe_buffer *);

	/*
	 * Attempt to take ownership of the pipe buffer and its contents.
	 * ->steal() returns 0 for success, in which case the contents
	 * of the pipe (the buf->page) is locked and now completely owned
	 * by the caller. The page may then be transferred to a different
	 * mapping, the most often used case is insertion into different
	 * file address space cache.
	 */
	int (*steal)(struct pipe_inode_info *, struct pipe_buffer *);

	/*
	 * Get a reference to the pipe buffer.
	 */
	void (*get)(struct pipe_inode_info *, struct pipe_buffer *);
};

/* Differs from PIPE_BUF in that PIPE_SIZE is the length of the actual
   memory allocation, whereas PIPE_BUF makes atomicity guarantees.  */
#define PIPE_SIZE		PAGE_SIZE

/* Pipe lock and unlock operations */
void pipe_lock(struct pipe_inode_info *);
void pipe_unlock(struct pipe_inode_info *);
void pipe_double_lock(struct pipe_inode_info *, struct pipe_inode_info *);

extern unsigned int pipe_max_size, pipe_min_size;
int pipe_proc_fn(struct ctl_table *, int, void __user *, size_t *, loff_t *);


/* Drop the inode semaphore and wait for a pipe event, atomically */
void pipe_wait(struct pipe_inode_info *pipe);

struct pipe_inode_info *alloc_pipe_info(void);
void free_pipe_info(struct pipe_inode_info *);

/* Generic pipe buffer ops functions */
void generic_pipe_buf_get(struct pipe_inode_info *, struct pipe_buffer *);
int generic_pipe_buf_confirm(struct pipe_inode_info *, struct pipe_buffer *);
int generic_pipe_buf_steal(struct pipe_inode_info *, struct pipe_buffer *);
void generic_pipe_buf_release(struct pipe_inode_info *, struct pipe_buffer *);

extern const struct pipe_buf_operations nosteal_pipe_buf_ops;

/* for F_SETPIPE_SZ and F_GETPIPE_SZ */
long pipe_fcntl(struct file *, unsigned int, unsigned long arg);
struct pipe_inode_info *get_pipe_info(struct file *file);

int create_pipe_files(struct file **, int);

#endif
Commit	Line	Data
1da177e4 LT	1	#ifndef _LINUX_PIPE_FS_I_H
	2	#define _LINUX_PIPE_FS_I_H
	3
35f3d14d	4	#define PIPE_DEF_BUFFERS 16
1da177e4	5
1432873a JA	6	#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 */
9883035a	9	#define PIPE_BUF_FLAG_PACKET 0x08 /* read() as a packet */
3e7ee3e7	10
0845718d JA	11	/**
	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	**/
1da177e4 LT	20	struct pipe_buffer {
	21	struct page *page;
	22	unsigned int offset, len;
d4c3cca9	23	const struct pipe_buf_operations *ops;
3e7ee3e7	24	unsigned int flags;
497f9625	25	unsigned long private;
1da177e4 LT	26	};
1da177e4 LT	27
0845718d JA	28	/**
0845718d JA	29	* struct pipe_inode_info - a linux kernel pipe
72b0d9aa	30	* @mutex: mutex protecting the whole thing
0845718d JA	31	* @wait: reader/writer wait point in case of empty/full pipe
0845718d JA	32	* @nrbufs: the number of non-empty pipe buffers in this pipe
0dc14885	33	* @buffers: total number of buffers (should be a power of 2)
0845718d JA	34	* @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
e227867f	38	* @files: number of struct file referring this pipe (protected by ->i_lock)
0845718d JA	39	* @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
0845718d JA	44	* @bufs: the circular array of pipe buffers
0845718d JA	45	**/
17374ff1	46	struct pipe_inode_info {
72b0d9aa	47	struct mutex mutex;
17374ff1	48	wait_queue_head_t wait;
35f3d14d	49	unsigned int nrbufs, curbuf, buffers;
17374ff1 JA	50	unsigned int readers;
17374ff1 JA	51	unsigned int writers;
ba5bb147	52	unsigned int files;
17374ff1 JA	53	unsigned int waiting_writers;
	54	unsigned int r_counter;
	55	unsigned int w_counter;
35f3d14d	56	struct page *tmp_page;
17374ff1 JA	57	struct fasync_struct *fasync_readers;
17374ff1 JA	58	struct fasync_struct *fasync_writers;
35f3d14d	59	struct pipe_buffer *bufs;
17374ff1 JA	60	};
17374ff1 JA	61
f84d7519 JA	62	/*
	63	* Note on the nesting of these functions:
	64	*
cac36bb0	65	* ->confirm()
f84d7519 JA	66	* ->steal()
	67	* ...
	68	* ->map()
	69	* ...
	70	* ->unmap()
	71	*
cac36bb0	72	* That is, ->map() must be called on a confirmed buffer,
0845718d JA	73	* 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.
f84d7519	76	*/
1da177e4	77	struct pipe_buf_operations {
0845718d JA	78	/*
	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	*/
1da177e4	83	int can_merge;
0845718d	84
0845718d JA	85	/*
	86	* ->confirm() verifies that the data in the pipe buffer is there
	87	* and that the contents are good. If the pages in the pipe belong
	88	* to a file system, we may need to wait for IO completion in this
	89	* hook. Returns 0 for good, or a negative error value in case of
	90	* error.
	91	*/
cac36bb0	92	int (confirm)(struct pipe_inode_info , struct pipe_buffer *);
0845718d JA	93
	94	/*
	95	* When the contents of this pipe buffer has been completely
	96	* consumed by a reader, ->release() is called.
	97	*/
1da177e4	98	void (release)(struct pipe_inode_info , struct pipe_buffer *);
0845718d JA	99
	100	/*
	101	* Attempt to take ownership of the pipe buffer and its contents.
	102	* ->steal() returns 0 for success, in which case the contents
	103	* of the pipe (the buf->page) is locked and now completely owned
	104	* by the caller. The page may then be transferred to a different
	105	* mapping, the most often used case is insertion into different
	106	* file address space cache.
	107	*/
5abc97aa	108	int (steal)(struct pipe_inode_info , struct pipe_buffer *);
0845718d JA	109
	110	/*
	111	* Get a reference to the pipe buffer.
	112	*/
70524490	113	void (get)(struct pipe_inode_info , struct pipe_buffer *);
1da177e4 LT	114	};
1da177e4 LT	115
1da177e4 LT	116	/* Differs from PIPE_BUF in that PIPE_SIZE is the length of the actual
	117	memory allocation, whereas PIPE_BUF makes atomicity guarantees. */
	118	#define PIPE_SIZE PAGE_SIZE
	119
61e0d47c MS	120	/* Pipe lock and unlock operations */
	121	void pipe_lock(struct pipe_inode_info *);
	122	void pipe_unlock(struct pipe_inode_info *);
	123	void pipe_double_lock(struct pipe_inode_info , struct pipe_inode_info );
	124
ff9da691 JA	125	extern unsigned int pipe_max_size, pipe_min_size;
	126	int pipe_proc_fn(struct ctl_table , int, void __user , size_t , loff_t );
	127
b492e95b	128
1da177e4	129	/* Drop the inode semaphore and wait for a pipe event, atomically */
3a326a2c	130	void pipe_wait(struct pipe_inode_info *pipe);
1da177e4	131
7bee130e	132	struct pipe_inode_info *alloc_pipe_info(void);
4b8a8f1e	133	void free_pipe_info(struct pipe_inode_info *);
1da177e4	134
f84d7519	135	/* Generic pipe buffer ops functions */
f84d7519	136	void generic_pipe_buf_get(struct pipe_inode_info , struct pipe_buffer );
cac36bb0	137	int generic_pipe_buf_confirm(struct pipe_inode_info , struct pipe_buffer );
330ab716	138	int generic_pipe_buf_steal(struct pipe_inode_info , struct pipe_buffer );
6818173b	139	void generic_pipe_buf_release(struct pipe_inode_info , struct pipe_buffer );
f84d7519	140
28a625cb MS	141	extern const struct pipe_buf_operations nosteal_pipe_buf_ops;
28a625cb MS	142
35f3d14d JA	143	/* for F_SETPIPE_SZ and F_GETPIPE_SZ */
35f3d14d JA	144	long pipe_fcntl(struct file *, unsigned int, unsigned long arg);
72083646	145	struct pipe_inode_info get_pipe_info(struct file file);
c66fb347	146
e4fad8e5 AV	147	int create_pipe_files(struct file **, int);
e4fad8e5 AV	148
1da177e4	149	#endif