[net-next-2.6.git] / include / linux / pipe_fs_i.h

#ifndef _LINUX_PIPE_FS_I_H
#define _LINUX_PIPE_FS_I_H

#define PIPEFS_MAGIC 0x50495045

#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 */

/**
 *	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
 *	@wait: reader/writer wait point in case of empty/full pipe
 *	@nrbufs: the number of non-empty pipe buffers in this pipe
 *	@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
 *	@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
 *	@inode: inode this pipe is attached to
 *	@bufs: the circular array of pipe buffers
 **/
struct pipe_inode_info {
	wait_queue_head_t wait;
	unsigned int nrbufs, curbuf, buffers;
	unsigned int readers;
	unsigned int writers;
	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 inode *inode;
	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;

	/*
	 * ->map() returns a virtual address mapping of the pipe buffer.
	 * The last integer flag reflects whether this should be an atomic
	 * mapping or not. The atomic map is faster, however you can't take
	 * page faults before calling ->unmap() again. So if you need to eg
	 * access user data through copy_to/from_user(), then you must get
	 * a non-atomic map. ->map() uses the KM_USER0 atomic slot for
	 * atomic maps, so you can't map more than one pipe_buffer at once
	 * and you have to be careful if mapping another page as source
	 * or destination for a copy (IOW, it has to use something else
	 * than KM_USER0).
	 */
	void * (*map)(struct pipe_inode_info *, struct pipe_buffer *, int);

	/*
	 * Undoes ->map(), finishes the virtual mapping of the pipe buffer.
	 */
	void (*unmap)(struct pipe_inode_info *, struct pipe_buffer *, void *);

	/*
	 * ->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(struct inode * inode);
void free_pipe_info(struct inode * inode);
void __free_pipe_info(struct pipe_inode_info *);

/* Generic pipe buffer ops functions */
void *generic_pipe_buf_map(struct pipe_inode_info *, struct pipe_buffer *, int);
void generic_pipe_buf_unmap(struct pipe_inode_info *, struct pipe_buffer *, void *);
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 *);

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

#endif
Commit	Line	Data
1da177e4 LT	1	#ifndef _LINUX_PIPE_FS_I_H
	2	#define _LINUX_PIPE_FS_I_H
	3
	4	#define PIPEFS_MAGIC 0x50495045
	5
35f3d14d	6	#define PIPE_DEF_BUFFERS 16
1da177e4	7
1432873a JA	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 */
3e7ee3e7	11
0845718d JA	12	/**
	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	**/
1da177e4 LT	21	struct pipe_buffer {
	22	struct page *page;
	23	unsigned int offset, len;
d4c3cca9	24	const struct pipe_buf_operations *ops;
3e7ee3e7	25	unsigned int flags;
497f9625	26	unsigned long private;
1da177e4 LT	27	};
1da177e4 LT	28
0845718d JA	29	/**
	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	**/
17374ff1 JA	45	struct pipe_inode_info {
17374ff1 JA	46	wait_queue_head_t wait;
35f3d14d	47	unsigned int nrbufs, curbuf, buffers;
17374ff1 JA	48	unsigned int readers;
	49	unsigned int writers;
	50	unsigned int waiting_writers;
	51	unsigned int r_counter;
	52	unsigned int w_counter;
35f3d14d	53	struct page *tmp_page;
17374ff1 JA	54	struct fasync_struct *fasync_readers;
	55	struct fasync_struct *fasync_writers;
	56	struct inode *inode;
35f3d14d	57	struct pipe_buffer *bufs;
17374ff1 JA	58	};
17374ff1 JA	59
f84d7519 JA	60	/*
	61	* Note on the nesting of these functions:
	62	*
cac36bb0	63	* ->confirm()
f84d7519 JA	64	* ->steal()
	65	* ...
	66	* ->map()
	67	* ...
	68	* ->unmap()
	69	*
cac36bb0	70	* That is, ->map() must be called on a confirmed buffer,
0845718d JA	71	* 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.
f84d7519	74	*/
1da177e4	75	struct pipe_buf_operations {
0845718d JA	76	/*
	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	*/
1da177e4	81	int can_merge;
0845718d JA	82
	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	*/
f6762b7a	95	void * (map)(struct pipe_inode_info , struct pipe_buffer *, int);
0845718d JA	96
	97	/*
	98	* Undoes ->map(), finishes the virtual mapping of the pipe buffer.
	99	*/
f6762b7a	100	void (unmap)(struct pipe_inode_info , struct pipe_buffer , void );
0845718d JA	101
	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	*/
cac36bb0	109	int (confirm)(struct pipe_inode_info , struct pipe_buffer *);
0845718d JA	110
	111	/*
	112	* When the contents of this pipe buffer has been completely
	113	* consumed by a reader, ->release() is called.
	114	*/
1da177e4	115	void (release)(struct pipe_inode_info , struct pipe_buffer *);
0845718d JA	116
	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	*/
5abc97aa	125	int (steal)(struct pipe_inode_info , struct pipe_buffer *);
0845718d JA	126
	127	/*
	128	* Get a reference to the pipe buffer.
	129	*/
70524490	130	void (get)(struct pipe_inode_info , struct pipe_buffer *);
1da177e4 LT	131	};
1da177e4 LT	132
1da177e4 LT	133	/* 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
61e0d47c MS	137	/* Pipe lock and unlock operations */
	138	void pipe_lock(struct pipe_inode_info *);
	139	void pipe_unlock(struct pipe_inode_info *);
	140	void pipe_double_lock(struct pipe_inode_info , struct pipe_inode_info );
	141
ff9da691 JA	142	extern unsigned int pipe_max_size, pipe_min_size;
	143	int pipe_proc_fn(struct ctl_table , int, void __user , size_t , loff_t );
	144
b492e95b	145
1da177e4	146	/* Drop the inode semaphore and wait for a pipe event, atomically */
3a326a2c	147	void pipe_wait(struct pipe_inode_info *pipe);
1da177e4	148
3a326a2c IM	149	struct pipe_inode_info * alloc_pipe_info(struct inode * inode);
3a326a2c IM	150	void free_pipe_info(struct inode * inode);
b92ce558	151	void __free_pipe_info(struct pipe_inode_info *);
1da177e4	152
f84d7519	153	/* Generic pipe buffer ops functions */
f6762b7a JA	154	void generic_pipe_buf_map(struct pipe_inode_info , struct pipe_buffer *, int);
f6762b7a JA	155	void generic_pipe_buf_unmap(struct pipe_inode_info , struct pipe_buffer , void *);
f84d7519	156	void generic_pipe_buf_get(struct pipe_inode_info , struct pipe_buffer );
cac36bb0	157	int generic_pipe_buf_confirm(struct pipe_inode_info , struct pipe_buffer );
330ab716	158	int generic_pipe_buf_steal(struct pipe_inode_info , struct pipe_buffer );
6818173b	159	void generic_pipe_buf_release(struct pipe_inode_info , struct pipe_buffer );
f84d7519	160
35f3d14d JA	161	/* for F_SETPIPE_SZ and F_GETPIPE_SZ */
	162	long pipe_fcntl(struct file *, unsigned int, unsigned long arg);
	163
1da177e4	164	#endif