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										 |  |  | /* include/linux/aio_abi.h
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										 |  |  |  * | 
					
						
							|  |  |  |  * Copyright 2000,2001,2002 Red Hat. | 
					
						
							|  |  |  |  * | 
					
						
							|  |  |  |  * Written by Benjamin LaHaise <bcrl@kvack.org> | 
					
						
							|  |  |  |  * | 
					
						
							|  |  |  |  * Distribute under the terms of the GPLv2 (see ../../COPYING) or under  | 
					
						
							|  |  |  |  * the following terms. | 
					
						
							|  |  |  |  * | 
					
						
							|  |  |  |  * Permission to use, copy, modify, and distribute this software and its | 
					
						
							|  |  |  |  * documentation is hereby granted, provided that the above copyright | 
					
						
							|  |  |  |  * notice appears in all copies.  This software is provided without any | 
					
						
							|  |  |  |  * warranty, express or implied.  Red Hat makes no representations about | 
					
						
							|  |  |  |  * the suitability of this software for any purpose. | 
					
						
							|  |  |  |  * | 
					
						
							|  |  |  |  * IN NO EVENT SHALL RED HAT BE LIABLE TO ANY PARTY FOR DIRECT, INDIRECT, | 
					
						
							|  |  |  |  * SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OF | 
					
						
							|  |  |  |  * THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF RED HAT HAS BEEN ADVISED | 
					
						
							|  |  |  |  * OF THE POSSIBILITY OF SUCH DAMAGE. | 
					
						
							|  |  |  |  * | 
					
						
							|  |  |  |  * RED HAT DISCLAIMS ANY WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE | 
					
						
							|  |  |  |  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR | 
					
						
							|  |  |  |  * PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS ON AN "AS IS" BASIS, AND | 
					
						
							|  |  |  |  * RED HAT HAS NO OBLIGATION TO PROVIDE MAINTENANCE, SUPPORT, UPDATES, | 
					
						
							|  |  |  |  * ENHANCEMENTS, OR MODIFICATIONS. | 
					
						
							|  |  |  |  */ | 
					
						
							|  |  |  | #ifndef __LINUX__AIO_ABI_H
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							|  |  |  | #define __LINUX__AIO_ABI_H
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							|  |  |  | 
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										 |  |  | #include <linux/types.h>
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										 |  |  | #include <asm/byteorder.h>
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							|  |  |  | 
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										 |  |  | typedef __kernel_ulong_t aio_context_t; | 
					
						
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							|  |  |  | enum { | 
					
						
							|  |  |  | 	IOCB_CMD_PREAD = 0, | 
					
						
							|  |  |  | 	IOCB_CMD_PWRITE = 1, | 
					
						
							|  |  |  | 	IOCB_CMD_FSYNC = 2, | 
					
						
							|  |  |  | 	IOCB_CMD_FDSYNC = 3, | 
					
						
							|  |  |  | 	/* These two are experimental.
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							|  |  |  | 	 * IOCB_CMD_PREADX = 4, | 
					
						
							|  |  |  | 	 * IOCB_CMD_POLL = 5, | 
					
						
							|  |  |  | 	 */ | 
					
						
							|  |  |  | 	IOCB_CMD_NOOP = 6, | 
					
						
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										 |  |  | 	IOCB_CMD_PREADV = 7, | 
					
						
							|  |  |  | 	IOCB_CMD_PWRITEV = 8, | 
					
						
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										 |  |  | }; | 
					
						
							|  |  |  | 
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							| 
									
										
											  
											
												signal/timer/event: KAIO eventfd support example
This is an example about how to add eventfd support to the current KAIO code,
in order to enable KAIO to post readiness events to a pollable fd (hence
compatible with POSIX select/poll).  The KAIO code simply signals the eventfd
fd when events are ready, and this triggers a POLLIN in the fd.  This patch
uses a reserved for future use member of the struct iocb to pass an eventfd
file descriptor, that KAIO will use to post events every time a request
completes.  At that point, an aio_getevents() will return the completed result
to a struct io_event.  I made a quick test program to verify the patch, and it
runs fine here:
http://www.xmailserver.org/eventfd-aio-test.c
The test program uses poll(2), but it'd, of course, work with select and epoll
too.
This can allow to schedule both block I/O and other poll-able devices
requests, and wait for results using select/poll/epoll.  In a typical
scenario, an application would submit KAIO request using aio_submit(), and
will also use epoll_ctl() on the whole other class of devices (that with the
addition of signals, timers and user events, now it's pretty much complete),
and then would:
	epoll_wait(...);
	for_each_event {
		if (curr_event_is_kaiofd) {
			aio_getevents();
			dispatch_aio_events();
		} else {
			dispatch_epoll_event();
		}
	}
Signed-off-by: Davide Libenzi <davidel@xmailserver.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
											
										 
											2007-05-10 22:23:21 -07:00
										 |  |  | /*
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							|  |  |  |  * Valid flags for the "aio_flags" member of the "struct iocb". | 
					
						
							|  |  |  |  * | 
					
						
							|  |  |  |  * IOCB_FLAG_RESFD - Set if the "aio_resfd" member of the "struct iocb" | 
					
						
							|  |  |  |  *                   is valid. | 
					
						
							|  |  |  |  */ | 
					
						
							|  |  |  | #define IOCB_FLAG_RESFD		(1 << 0)
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							|  |  |  | 
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										 |  |  | /* read() from /dev/aio returns these structures. */ | 
					
						
							|  |  |  | struct io_event { | 
					
						
							|  |  |  | 	__u64		data;		/* the data field from the iocb */ | 
					
						
							|  |  |  | 	__u64		obj;		/* what iocb this event came from */ | 
					
						
							|  |  |  | 	__s64		res;		/* result code for this event */ | 
					
						
							|  |  |  | 	__s64		res2;		/* secondary result */ | 
					
						
							|  |  |  | }; | 
					
						
							|  |  |  | 
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							|  |  |  | #if defined(__LITTLE_ENDIAN)
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							|  |  |  | #define PADDED(x,y)	x, y
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							|  |  |  | #elif defined(__BIG_ENDIAN)
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							|  |  |  | #define PADDED(x,y)	y, x
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							|  |  |  | #else
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							|  |  |  | #error edit for your odd byteorder.
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							|  |  |  | #endif
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							|  |  |  | 
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							|  |  |  | /*
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							|  |  |  |  * we always use a 64bit off_t when communicating | 
					
						
							|  |  |  |  * with userland.  its up to libraries to do the | 
					
						
							|  |  |  |  * proper padding and aio_error abstraction | 
					
						
							|  |  |  |  */ | 
					
						
							|  |  |  | 
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							|  |  |  | struct iocb { | 
					
						
							|  |  |  | 	/* these are internal to the kernel/libc. */ | 
					
						
							|  |  |  | 	__u64	aio_data;	/* data to be returned in event's data */ | 
					
						
							|  |  |  | 	__u32	PADDED(aio_key, aio_reserved1); | 
					
						
							|  |  |  | 				/* the kernel sets aio_key to the req # */ | 
					
						
							|  |  |  | 
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							|  |  |  | 	/* common fields */ | 
					
						
							|  |  |  | 	__u16	aio_lio_opcode;	/* see IOCB_CMD_ above */ | 
					
						
							|  |  |  | 	__s16	aio_reqprio; | 
					
						
							|  |  |  | 	__u32	aio_fildes; | 
					
						
							|  |  |  | 
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							|  |  |  | 	__u64	aio_buf; | 
					
						
							|  |  |  | 	__u64	aio_nbytes; | 
					
						
							|  |  |  | 	__s64	aio_offset; | 
					
						
							|  |  |  | 
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							|  |  |  | 	/* extra parameters */ | 
					
						
							|  |  |  | 	__u64	aio_reserved2;	/* TODO: use this for a (struct sigevent *) */ | 
					
						
							| 
									
										
											  
											
												signal/timer/event: KAIO eventfd support example
This is an example about how to add eventfd support to the current KAIO code,
in order to enable KAIO to post readiness events to a pollable fd (hence
compatible with POSIX select/poll).  The KAIO code simply signals the eventfd
fd when events are ready, and this triggers a POLLIN in the fd.  This patch
uses a reserved for future use member of the struct iocb to pass an eventfd
file descriptor, that KAIO will use to post events every time a request
completes.  At that point, an aio_getevents() will return the completed result
to a struct io_event.  I made a quick test program to verify the patch, and it
runs fine here:
http://www.xmailserver.org/eventfd-aio-test.c
The test program uses poll(2), but it'd, of course, work with select and epoll
too.
This can allow to schedule both block I/O and other poll-able devices
requests, and wait for results using select/poll/epoll.  In a typical
scenario, an application would submit KAIO request using aio_submit(), and
will also use epoll_ctl() on the whole other class of devices (that with the
addition of signals, timers and user events, now it's pretty much complete),
and then would:
	epoll_wait(...);
	for_each_event {
		if (curr_event_is_kaiofd) {
			aio_getevents();
			dispatch_aio_events();
		} else {
			dispatch_epoll_event();
		}
	}
Signed-off-by: Davide Libenzi <davidel@xmailserver.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
											
										 
											2007-05-10 22:23:21 -07:00
										 |  |  | 
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							|  |  |  | 	/* flags for the "struct iocb" */ | 
					
						
							|  |  |  | 	__u32	aio_flags; | 
					
						
							|  |  |  | 
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							|  |  |  | 	/*
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							|  |  |  | 	 * if the IOCB_FLAG_RESFD flag of "aio_flags" is set, this is an | 
					
						
							|  |  |  | 	 * eventfd to signal AIO readiness to | 
					
						
							|  |  |  | 	 */ | 
					
						
							|  |  |  | 	__u32	aio_resfd; | 
					
						
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										 |  |  | }; /* 64 bytes */ | 
					
						
							|  |  |  | 
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							|  |  |  | #undef IFBIG
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							|  |  |  | #undef IFLITTLE
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							|  |  |  | 
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							|  |  |  | #endif /* __LINUX__AIO_ABI_H */
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							|  |  |  | 
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