fileaio-linux.cpp@ 78359

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1	/* $Id: fileaio-linux.cpp 76553 2019-01-01 01:45:53Z vboxsync $ */
2	/** @file
3	* IPRT - File async I/O, native implementation for the Linux host platform.
4	*/
5
6	/*
7	* Copyright (C) 2006-2019 Oracle Corporation
8	*
9	* This file is part of VirtualBox Open Source Edition (OSE), as
10	* available from http://www.virtualbox.org. This file is free software;
11	* you can redistribute it and/or modify it under the terms of the GNU
12	* General Public License (GPL) as published by the Free Software
13	* Foundation, in version 2 as it comes in the "COPYING" file of the
14	* VirtualBox OSE distribution. VirtualBox OSE is distributed in the
15	* hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
16	*
17	* The contents of this file may alternatively be used under the terms
18	* of the Common Development and Distribution License Version 1.0
19	* (CDDL) only, as it comes in the "COPYING.CDDL" file of the
20	* VirtualBox OSE distribution, in which case the provisions of the
21	* CDDL are applicable instead of those of the GPL.
22	*
23	* You may elect to license modified versions of this file under the
24	* terms and conditions of either the GPL or the CDDL or both.
25	*/
26
27	/** @page pg_rtfileaio_linux RTFile Async I/O - Linux Implementation Notes
28	* @internal
29	*
30	* Linux implements the kernel async I/O API through the io_* syscalls. They are
31	* not exposed in the glibc (the aio_* API uses userspace threads and blocking
32	* I/O operations to simulate async behavior). There is an external library
33	* called libaio which implements these syscalls but because we don't want to
34	* have another dependency and this library is not installed by default and the
35	* interface is really simple we use the kernel interface directly using wrapper
36	* functions.
37	*
38	* The interface has some limitations. The first one is that the file must be
39	* opened with O_DIRECT. This disables caching done by the kernel which can be
40	* compensated if the user of this API implements caching itself. The next
41	* limitation is that data buffers must be aligned at a 512 byte boundary or the
42	* request will fail.
43	*/
44	/** @todo r=bird: What's this about "must be opened with O_DIRECT"? An
45	* explanation would be nice, esp. seeing what Linus is quoted saying
46	* about it in the open man page... */
47
48
49	/*********************************************************************************************************************************
50	* Header Files *
51	*********************************************************************************************************************************/
52	#define LOG_GROUP RTLOGGROUP_FILE
53	#include <iprt/asm.h>
54	#include <iprt/mem.h>
55	#include <iprt/assert.h>
56	#include <iprt/string.h>
57	#include <iprt/err.h>
58	#include <iprt/log.h>
59	#include <iprt/thread.h>
60	#include "internal/fileaio.h"
61
62	#include <unistd.h>
63	#include <sys/syscall.h>
64	#include <errno.h>
65
66	#include <iprt/file.h>
67
68
69	/*********************************************************************************************************************************
70	* Structures and Typedefs *
71	*********************************************************************************************************************************/
72	/** The async I/O context handle */
73	typedef unsigned long LNXKAIOCONTEXT;
74
75	/**
76	* Supported commands for the iocbs
77	*/
78	enum
79	{
80	LNXKAIO_IOCB_CMD_READ = 0,
81	LNXKAIO_IOCB_CMD_WRITE = 1,
82	LNXKAIO_IOCB_CMD_FSYNC = 2,
83	LNXKAIO_IOCB_CMD_FDSYNC = 3
84	};
85
86	/**
87	* The iocb structure of a request which is passed to the kernel.
88	*
89	* We redefined this here because the version in the header lacks padding
90	* for 32bit.
91	*/
92	typedef struct LNXKAIOIOCB
93	{
94	/** Opaque pointer to data which is returned on an I/O event. */
95	void *pvUser;
96	#ifdef RT_ARCH_X86
97	uint32_t u32Padding0;
98	#endif
99	/** Contains the request number and is set by the kernel. */
100	uint32_t u32Key;
101	/** Reserved. */
102	uint32_t u32Reserved0;
103	/** The I/O opcode. */
104	uint16_t u16IoOpCode;
105	/** Request priority. */
106	int16_t i16Priority;
107	/** The file descriptor. */
108	uint32_t uFileDesc;
109	/** The userspace pointer to the buffer containing/receiving the data. */
110	void *pvBuf;
111	#ifdef RT_ARCH_X86
112	uint32_t u32Padding1;
113	#endif
114	/** How many bytes to transfer. */
115	#ifdef RT_ARCH_X86
116	uint32_t cbTransfer;
117	uint32_t u32Padding2;
118	#elif defined(RT_ARCH_AMD64)
119	uint64_t cbTransfer;
120	#else
121	# error "Unknown architecture"
122	#endif
123	/** At which offset to start the transfer. */
124	int64_t off;
125	/** Reserved. */
126	uint64_t u64Reserved1;
127	/** Flags */
128	uint32_t fFlags;
129	/** Readyness signal file descriptor. */
130	uint32_t u32ResFd;
131	} LNXKAIOIOCB, *PLNXKAIOIOCB;
132
133	/**
134	* I/O event structure to notify about completed requests.
135	* Redefined here too because of the padding.
136	*/
137	typedef struct LNXKAIOIOEVENT
138	{
139	/** The pvUser field from the iocb. */
140	void *pvUser;
141	#ifdef RT_ARCH_X86
142	uint32_t u32Padding0;
143	#endif
144	/** The LNXKAIOIOCB object this event is for. */
145	PLNXKAIOIOCB *pIoCB;
146	#ifdef RT_ARCH_X86
147	uint32_t u32Padding1;
148	#endif
149	/** The result code of the operation .*/
150	#ifdef RT_ARCH_X86
151	int32_t rc;
152	uint32_t u32Padding2;
153	#elif defined(RT_ARCH_AMD64)
154	int64_t rc;
155	#else
156	# error "Unknown architecture"
157	#endif
158	/** Secondary result code. */
159	#ifdef RT_ARCH_X86
160	int32_t rc2;
161	uint32_t u32Padding3;
162	#elif defined(RT_ARCH_AMD64)
163	int64_t rc2;
164	#else
165	# error "Unknown architecture"
166	#endif
167	} LNXKAIOIOEVENT, *PLNXKAIOIOEVENT;
168
169
170	/**
171	* Async I/O completion context state.
172	*/
173	typedef struct RTFILEAIOCTXINTERNAL
174	{
175	/** Handle to the async I/O context. */
176	LNXKAIOCONTEXT AioContext;
177	/** Maximum number of requests this context can handle. */
178	int cRequestsMax;
179	/** Current number of requests active on this context. */
180	volatile int32_t cRequests;
181	/** The ID of the thread which is currently waiting for requests. */
182	volatile RTTHREAD hThreadWait;
183	/** Flag whether the thread was woken up. */
184	volatile bool fWokenUp;
185	/** Flag whether the thread is currently waiting in the syscall. */
186	volatile bool fWaiting;
187	/** Flags given during creation. */
188	uint32_t fFlags;
189	/** Magic value (RTFILEAIOCTX_MAGIC). */
190	uint32_t u32Magic;
191	} RTFILEAIOCTXINTERNAL;
192	/** Pointer to an internal context structure. */
193	typedef RTFILEAIOCTXINTERNAL *PRTFILEAIOCTXINTERNAL;
194
195	/**
196	* Async I/O request state.
197	*/
198	typedef struct RTFILEAIOREQINTERNAL
199	{
200	/** The aio control block. This must be the FIRST elment in
201	* the structure! (see notes below) */
202	LNXKAIOIOCB AioCB;
203	/** Current state the request is in. */
204	RTFILEAIOREQSTATE enmState;
205	/** The I/O context this request is associated with. */
206	LNXKAIOCONTEXT AioContext;
207	/** Return code the request completed with. */
208	int Rc;
209	/** Number of bytes actually transferred. */
210	size_t cbTransfered;
211	/** Completion context we are assigned to. */
212	PRTFILEAIOCTXINTERNAL pCtxInt;
213	/** Magic value (RTFILEAIOREQ_MAGIC). */
214	uint32_t u32Magic;
215	} RTFILEAIOREQINTERNAL;
216	/** Pointer to an internal request structure. */
217	typedef RTFILEAIOREQINTERNAL *PRTFILEAIOREQINTERNAL;
218
219
220	/*********************************************************************************************************************************
221	* Defined Constants And Macros *
222	*********************************************************************************************************************************/
223	/** The max number of events to get in one call. */
224	#define AIO_MAXIMUM_REQUESTS_PER_CONTEXT 64
225
226
227	/**
228	* Creates a new async I/O context.
229	*/
230	DECLINLINE(int) rtFileAsyncIoLinuxCreate(unsigned cEvents, LNXKAIOCONTEXT *pAioContext)
231	{
232	int rc = syscall(__NR_io_setup, cEvents, pAioContext);
233	if (RT_UNLIKELY(rc == -1))
234	{
235	if (errno == EAGAIN)
236	return VERR_FILE_AIO_INSUFFICIENT_EVENTS;
237	else
238	return RTErrConvertFromErrno(errno);
239	}
240
241	return VINF_SUCCESS;
242	}
243
244	/**
245	* Destroys a async I/O context.
246	*/
247	DECLINLINE(int) rtFileAsyncIoLinuxDestroy(LNXKAIOCONTEXT AioContext)
248	{
249	int rc = syscall(__NR_io_destroy, AioContext);
250	if (RT_UNLIKELY(rc == -1))
251	return RTErrConvertFromErrno(errno);
252
253	return VINF_SUCCESS;
254	}
255
256	/**
257	* Submits an array of I/O requests to the kernel.
258	*/
259	DECLINLINE(int) rtFileAsyncIoLinuxSubmit(LNXKAIOCONTEXT AioContext, long cReqs, LNXKAIOIOCB *ppIoCB, int pcSubmitted)
260	{
261	int rc = syscall(__NR_io_submit, AioContext, cReqs, ppIoCB);
262	if (RT_UNLIKELY(rc == -1))
263	return RTErrConvertFromErrno(errno);
264
265	*pcSubmitted = rc;
266
267	return VINF_SUCCESS;
268	}
269
270	/**
271	* Cancels a I/O request.
272	*/
273	DECLINLINE(int) rtFileAsyncIoLinuxCancel(LNXKAIOCONTEXT AioContext, PLNXKAIOIOCB pIoCB, PLNXKAIOIOEVENT pIoResult)
274	{
275	int rc = syscall(__NR_io_cancel, AioContext, pIoCB, pIoResult);
276	if (RT_UNLIKELY(rc == -1))
277	return RTErrConvertFromErrno(errno);
278
279	return VINF_SUCCESS;
280	}
281
282	/**
283	* Waits for I/O events.
284	* @returns Number of events (natural number w/ 0), IPRT error code (negative).
285	*/
286	DECLINLINE(int) rtFileAsyncIoLinuxGetEvents(LNXKAIOCONTEXT AioContext, long cReqsMin, long cReqs,
287	PLNXKAIOIOEVENT paIoResults, struct timespec *pTimeout)
288	{
289	int rc = syscall(__NR_io_getevents, AioContext, cReqsMin, cReqs, paIoResults, pTimeout);
290	if (RT_UNLIKELY(rc == -1))
291	return RTErrConvertFromErrno(errno);
292
293	return rc;
294	}
295
296	RTR3DECL(int) RTFileAioGetLimits(PRTFILEAIOLIMITS pAioLimits)
297	{
298	int rc = VINF_SUCCESS;
299	AssertPtrReturn(pAioLimits, VERR_INVALID_POINTER);
300
301	/*
302	* Check if the API is implemented by creating a
303	* completion port.
304	*/
305	LNXKAIOCONTEXT AioContext = 0;
306	rc = rtFileAsyncIoLinuxCreate(1, &AioContext);
307	if (RT_FAILURE(rc))
308	return rc;
309
310	rc = rtFileAsyncIoLinuxDestroy(AioContext);
311	if (RT_FAILURE(rc))
312	return rc;
313
314	/* Supported - fill in the limits. The alignment is the only restriction. */
315	pAioLimits->cReqsOutstandingMax = RTFILEAIO_UNLIMITED_REQS;
316	pAioLimits->cbBufferAlignment = 512;
317
318	return VINF_SUCCESS;
319	}
320
321
322	RTR3DECL(int) RTFileAioReqCreate(PRTFILEAIOREQ phReq)
323	{
324	AssertPtrReturn(phReq, VERR_INVALID_POINTER);
325
326	/*
327	* Allocate a new request and initialize it.
328	*/
329	PRTFILEAIOREQINTERNAL pReqInt = (PRTFILEAIOREQINTERNAL)RTMemAllocZ(sizeof(*pReqInt));
330	if (RT_UNLIKELY(!pReqInt))
331	return VERR_NO_MEMORY;
332
333	pReqInt->pCtxInt = NULL;
334	pReqInt->u32Magic = RTFILEAIOREQ_MAGIC;
335	RTFILEAIOREQ_SET_STATE(pReqInt, COMPLETED);
336
337	*phReq = (RTFILEAIOREQ)pReqInt;
338	return VINF_SUCCESS;
339	}
340
341
342	RTDECL(int) RTFileAioReqDestroy(RTFILEAIOREQ hReq)
343	{
344	/*
345	* Validate the handle and ignore nil.
346	*/
347	if (hReq == NIL_RTFILEAIOREQ)
348	return VINF_SUCCESS;
349	PRTFILEAIOREQINTERNAL pReqInt = hReq;
350	RTFILEAIOREQ_VALID_RETURN(pReqInt);
351	RTFILEAIOREQ_NOT_STATE_RETURN_RC(pReqInt, SUBMITTED, VERR_FILE_AIO_IN_PROGRESS);
352
353	/*
354	* Trash the magic and free it.
355	*/
356	ASMAtomicUoWriteU32(&pReqInt->u32Magic, ~RTFILEAIOREQ_MAGIC);
357	RTMemFree(pReqInt);
358	return VINF_SUCCESS;
359	}
360
361
362	/**
363	* Worker setting up the request.
364	*/
365	DECLINLINE(int) rtFileAioReqPrepareTransfer(RTFILEAIOREQ hReq, RTFILE hFile,
366	uint16_t uTransferDirection,
367	RTFOFF off, void *pvBuf, size_t cbTransfer,
368	void *pvUser)
369	{
370	/*
371	* Validate the input.
372	*/
373	PRTFILEAIOREQINTERNAL pReqInt = hReq;
374	RTFILEAIOREQ_VALID_RETURN(pReqInt);
375	RTFILEAIOREQ_NOT_STATE_RETURN_RC(pReqInt, SUBMITTED, VERR_FILE_AIO_IN_PROGRESS);
376	Assert(hFile != NIL_RTFILE);
377
378	if (uTransferDirection != LNXKAIO_IOCB_CMD_FSYNC)
379	{
380	AssertPtr(pvBuf);
381	Assert(off >= 0);
382	Assert(cbTransfer > 0);
383	}
384
385	/*
386	* Setup the control block and clear the finished flag.
387	*/
388	pReqInt->AioCB.u16IoOpCode = uTransferDirection;
389	pReqInt->AioCB.uFileDesc = RTFileToNative(hFile);
390	pReqInt->AioCB.off = off;
391	pReqInt->AioCB.cbTransfer = cbTransfer;
392	pReqInt->AioCB.pvBuf = pvBuf;
393	pReqInt->AioCB.pvUser = pvUser;
394
395	pReqInt->pCtxInt = NULL;
396	RTFILEAIOREQ_SET_STATE(pReqInt, PREPARED);
397
398	return VINF_SUCCESS;
399	}
400
401
402	RTDECL(int) RTFileAioReqPrepareRead(RTFILEAIOREQ hReq, RTFILE hFile, RTFOFF off,
403	void pvBuf, size_t cbRead, void pvUser)
404	{
405	return rtFileAioReqPrepareTransfer(hReq, hFile, LNXKAIO_IOCB_CMD_READ,
406	off, pvBuf, cbRead, pvUser);
407	}
408
409
410	RTDECL(int) RTFileAioReqPrepareWrite(RTFILEAIOREQ hReq, RTFILE hFile, RTFOFF off,
411	void const pvBuf, size_t cbWrite, void pvUser)
412	{
413	return rtFileAioReqPrepareTransfer(hReq, hFile, LNXKAIO_IOCB_CMD_WRITE,
414	off, (void *)pvBuf, cbWrite, pvUser);
415	}
416
417
418	RTDECL(int) RTFileAioReqPrepareFlush(RTFILEAIOREQ hReq, RTFILE hFile, void *pvUser)
419	{
420	PRTFILEAIOREQINTERNAL pReqInt = hReq;
421	RTFILEAIOREQ_VALID_RETURN(pReqInt);
422	AssertReturn(hFile != NIL_RTFILE, VERR_INVALID_HANDLE);
423	RTFILEAIOREQ_NOT_STATE_RETURN_RC(pReqInt, SUBMITTED, VERR_FILE_AIO_IN_PROGRESS);
424
425	return rtFileAioReqPrepareTransfer(pReqInt, hFile, LNXKAIO_IOCB_CMD_FSYNC,
426	0, NULL, 0, pvUser);
427	}
428
429
430	RTDECL(void *) RTFileAioReqGetUser(RTFILEAIOREQ hReq)
431	{
432	PRTFILEAIOREQINTERNAL pReqInt = hReq;
433	RTFILEAIOREQ_VALID_RETURN_RC(pReqInt, NULL);
434
435	return pReqInt->AioCB.pvUser;
436	}
437
438
439	RTDECL(int) RTFileAioReqCancel(RTFILEAIOREQ hReq)
440	{
441	PRTFILEAIOREQINTERNAL pReqInt = hReq;
442	RTFILEAIOREQ_VALID_RETURN(pReqInt);
443	RTFILEAIOREQ_STATE_RETURN_RC(pReqInt, SUBMITTED, VERR_FILE_AIO_NOT_SUBMITTED);
444
445	LNXKAIOIOEVENT AioEvent;
446	int rc = rtFileAsyncIoLinuxCancel(pReqInt->AioContext, &pReqInt->AioCB, &AioEvent);
447	if (RT_SUCCESS(rc))
448	{
449	/*
450	* Decrement request count because the request will never arrive at the
451	* completion port.
452	*/
453	AssertMsg(VALID_PTR(pReqInt->pCtxInt),
454	("Invalid state. Request was canceled but wasn't submitted\n"));
455
456	ASMAtomicDecS32(&pReqInt->pCtxInt->cRequests);
457	pReqInt->Rc = VERR_FILE_AIO_CANCELED;
458	RTFILEAIOREQ_SET_STATE(pReqInt, COMPLETED);
459	return VINF_SUCCESS;
460	}
461	if (rc == VERR_TRY_AGAIN)
462	return VERR_FILE_AIO_IN_PROGRESS;
463	return rc;
464	}
465
466
467	RTDECL(int) RTFileAioReqGetRC(RTFILEAIOREQ hReq, size_t *pcbTransfered)
468	{
469	PRTFILEAIOREQINTERNAL pReqInt = hReq;
470	RTFILEAIOREQ_VALID_RETURN(pReqInt);
471	AssertPtrNull(pcbTransfered);
472	RTFILEAIOREQ_NOT_STATE_RETURN_RC(pReqInt, SUBMITTED, VERR_FILE_AIO_IN_PROGRESS);
473	RTFILEAIOREQ_NOT_STATE_RETURN_RC(pReqInt, PREPARED, VERR_FILE_AIO_NOT_SUBMITTED);
474
475	if ( pcbTransfered
476	&& RT_SUCCESS(pReqInt->Rc))
477	*pcbTransfered = pReqInt->cbTransfered;
478
479	return pReqInt->Rc;
480	}
481
482
483	RTDECL(int) RTFileAioCtxCreate(PRTFILEAIOCTX phAioCtx, uint32_t cAioReqsMax,
484	uint32_t fFlags)
485	{
486	PRTFILEAIOCTXINTERNAL pCtxInt;
487	AssertPtrReturn(phAioCtx, VERR_INVALID_POINTER);
488	AssertReturn(!(fFlags & ~RTFILEAIOCTX_FLAGS_VALID_MASK), VERR_INVALID_PARAMETER);
489
490	/* The kernel interface needs a maximum. */
491	if (cAioReqsMax == RTFILEAIO_UNLIMITED_REQS)
492	return VERR_OUT_OF_RANGE;
493
494	pCtxInt = (PRTFILEAIOCTXINTERNAL)RTMemAllocZ(sizeof(RTFILEAIOCTXINTERNAL));
495	if (RT_UNLIKELY(!pCtxInt))
496	return VERR_NO_MEMORY;
497
498	/* Init the event handle. */
499	int rc = rtFileAsyncIoLinuxCreate(cAioReqsMax, &pCtxInt->AioContext);
500	if (RT_SUCCESS(rc))
501	{
502	pCtxInt->fWokenUp = false;
503	pCtxInt->fWaiting = false;
504	pCtxInt->hThreadWait = NIL_RTTHREAD;
505	pCtxInt->cRequestsMax = cAioReqsMax;
506	pCtxInt->fFlags = fFlags;
507	pCtxInt->u32Magic = RTFILEAIOCTX_MAGIC;
508	*phAioCtx = (RTFILEAIOCTX)pCtxInt;
509	}
510	else
511	RTMemFree(pCtxInt);
512
513	return rc;
514	}
515
516
517	RTDECL(int) RTFileAioCtxDestroy(RTFILEAIOCTX hAioCtx)
518	{
519	/* Validate the handle and ignore nil. */
520	if (hAioCtx == NIL_RTFILEAIOCTX)
521	return VINF_SUCCESS;
522	PRTFILEAIOCTXINTERNAL pCtxInt = hAioCtx;
523	RTFILEAIOCTX_VALID_RETURN(pCtxInt);
524
525	/* Cannot destroy a busy context. */
526	if (RT_UNLIKELY(pCtxInt->cRequests))
527	return VERR_FILE_AIO_BUSY;
528
529	/* The native bit first, then mark it as dead and free it. */
530	int rc = rtFileAsyncIoLinuxDestroy(pCtxInt->AioContext);
531	if (RT_FAILURE(rc))
532	return rc;
533	ASMAtomicUoWriteU32(&pCtxInt->u32Magic, RTFILEAIOCTX_MAGIC_DEAD);
534	RTMemFree(pCtxInt);
535
536	return VINF_SUCCESS;
537	}
538
539
540	RTDECL(uint32_t) RTFileAioCtxGetMaxReqCount(RTFILEAIOCTX hAioCtx)
541	{
542	/* Nil means global here. */
543	if (hAioCtx == NIL_RTFILEAIOCTX)
544	return RTFILEAIO_UNLIMITED_REQS; /** @todo r=bird: I'm a bit puzzled by this return value since it
545	* is completely useless in RTFileAioCtxCreate. */
546
547	/* Return 0 if the handle is invalid, it's better than garbage I think... */
548	PRTFILEAIOCTXINTERNAL pCtxInt = hAioCtx;
549	RTFILEAIOCTX_VALID_RETURN_RC(pCtxInt, 0);
550
551	return pCtxInt->cRequestsMax;
552	}
553
554	RTDECL(int) RTFileAioCtxAssociateWithFile(RTFILEAIOCTX hAioCtx, RTFILE hFile)
555	{
556	/* Nothing to do. */
557	NOREF(hAioCtx); NOREF(hFile);
558	return VINF_SUCCESS;
559	}
560
561	RTDECL(int) RTFileAioCtxSubmit(RTFILEAIOCTX hAioCtx, PRTFILEAIOREQ pahReqs, size_t cReqs)
562	{
563	int rc = VINF_SUCCESS;
564
565	/*
566	* Parameter validation.
567	*/
568	PRTFILEAIOCTXINTERNAL pCtxInt = hAioCtx;
569	RTFILEAIOCTX_VALID_RETURN(pCtxInt);
570	AssertReturn(cReqs > 0, VERR_INVALID_PARAMETER);
571	AssertPtrReturn(pahReqs, VERR_INVALID_POINTER);
572	uint32_t i = cReqs;
573	PRTFILEAIOREQINTERNAL pReqInt = NULL;
574
575	/*
576	* Validate requests and associate with the context.
577	*/
578	while (i-- > 0)
579	{
580	pReqInt = pahReqs[i];
581	if (RTFILEAIOREQ_IS_NOT_VALID(pReqInt))
582	{
583	/* Undo everything and stop submitting. */
584	size_t iUndo = cReqs;
585	while (iUndo-- > i)
586	{
587	pReqInt = pahReqs[iUndo];
588	RTFILEAIOREQ_SET_STATE(pReqInt, PREPARED);
589	pReqInt->pCtxInt = NULL;
590	}
591	return VERR_INVALID_HANDLE;
592	}
593
594	pReqInt->AioContext = pCtxInt->AioContext;
595	pReqInt->pCtxInt = pCtxInt;
596	RTFILEAIOREQ_SET_STATE(pReqInt, SUBMITTED);
597	}
598
599	do
600	{
601	/*
602	* We cast pahReqs to the Linux iocb structure to avoid copying the requests
603	* into a temporary array. This is possible because the iocb structure is
604	* the first element in the request structure (see PRTFILEAIOCTXINTERNAL).
605	*/
606	int cReqsSubmitted = 0;
607	rc = rtFileAsyncIoLinuxSubmit(pCtxInt->AioContext, cReqs,
608	(PLNXKAIOIOCB *)pahReqs,
609	&cReqsSubmitted);
610	if (RT_FAILURE(rc))
611	{
612	/*
613	* We encountered an error.
614	* This means that the first IoCB
615	* is not correctly initialized
616	* (invalid buffer alignment or bad file descriptor).
617	* Revert every request into the prepared state except
618	* the first one which will switch to completed.
619	* Another reason could be insufficient resources.
620	*/
621	i = cReqs;
622	while (i-- > 0)
623	{
624	/* Already validated. */
625	pReqInt = pahReqs[i];
626	pReqInt->pCtxInt = NULL;
627	pReqInt->AioContext = 0;
628	RTFILEAIOREQ_SET_STATE(pReqInt, PREPARED);
629	}
630
631	if (rc == VERR_TRY_AGAIN)
632	return VERR_FILE_AIO_INSUFFICIENT_RESSOURCES;
633	else
634	{
635	/* The first request failed. */
636	pReqInt = pahReqs[0];
637	RTFILEAIOREQ_SET_STATE(pReqInt, COMPLETED);
638	pReqInt->Rc = rc;
639	pReqInt->cbTransfered = 0;
640	return rc;
641	}
642	}
643
644	/* Advance. */
645	cReqs -= cReqsSubmitted;
646	pahReqs += cReqsSubmitted;
647	ASMAtomicAddS32(&pCtxInt->cRequests, cReqsSubmitted);
648
649	} while (cReqs);
650
651	return rc;
652	}
653
654
655	RTDECL(int) RTFileAioCtxWait(RTFILEAIOCTX hAioCtx, size_t cMinReqs, RTMSINTERVAL cMillies,
656	PRTFILEAIOREQ pahReqs, size_t cReqs, uint32_t *pcReqs)
657	{
658	/*
659	* Validate the parameters, making sure to always set pcReqs.
660	*/
661	AssertPtrReturn(pcReqs, VERR_INVALID_POINTER);
662	pcReqs = 0; / always set */
663	PRTFILEAIOCTXINTERNAL pCtxInt = hAioCtx;
664	RTFILEAIOCTX_VALID_RETURN(pCtxInt);
665	AssertPtrReturn(pahReqs, VERR_INVALID_POINTER);
666	AssertReturn(cReqs != 0, VERR_INVALID_PARAMETER);
667	AssertReturn(cReqs >= cMinReqs, VERR_OUT_OF_RANGE);
668
669	/*
670	* Can't wait if there are not requests around.
671	*/
672	if ( RT_UNLIKELY(ASMAtomicUoReadS32(&pCtxInt->cRequests) == 0)
673	&& !(pCtxInt->fFlags & RTFILEAIOCTX_FLAGS_WAIT_WITHOUT_PENDING_REQUESTS))
674	return VERR_FILE_AIO_NO_REQUEST;
675
676	/*
677	* Convert the timeout if specified.
678	*/
679	struct timespec *pTimeout = NULL;
680	struct timespec Timeout = {0,0};
681	uint64_t StartNanoTS = 0;
682	if (cMillies != RT_INDEFINITE_WAIT)
683	{
684	Timeout.tv_sec = cMillies / 1000;
685	Timeout.tv_nsec = cMillies % 1000 * 1000000;
686	pTimeout = &Timeout;
687	StartNanoTS = RTTimeNanoTS();
688	}
689
690	/* Wait for at least one. */
691	if (!cMinReqs)
692	cMinReqs = 1;
693
694	/* For the wakeup call. */
695	Assert(pCtxInt->hThreadWait == NIL_RTTHREAD);
696	ASMAtomicWriteHandle(&pCtxInt->hThreadWait, RTThreadSelf());
697
698	/*
699	* Loop until we're woken up, hit an error (incl timeout), or
700	* have collected the desired number of requests.
701	*/
702	int rc = VINF_SUCCESS;
703	int cRequestsCompleted = 0;
704	while (!pCtxInt->fWokenUp)
705	{
706	LNXKAIOIOEVENT aPortEvents[AIO_MAXIMUM_REQUESTS_PER_CONTEXT];
707	int cRequestsToWait = RT_MIN(cReqs, AIO_MAXIMUM_REQUESTS_PER_CONTEXT);
708	ASMAtomicXchgBool(&pCtxInt->fWaiting, true);
709	rc = rtFileAsyncIoLinuxGetEvents(pCtxInt->AioContext, cMinReqs, cRequestsToWait, &aPortEvents[0], pTimeout);
710	ASMAtomicXchgBool(&pCtxInt->fWaiting, false);
711	if (RT_FAILURE(rc))
712	break;
713	uint32_t const cDone = rc;
714	rc = VINF_SUCCESS;
715
716	/*
717	* Process received events / requests.
718	*/
719	for (uint32_t i = 0; i < cDone; i++)
720	{
721	/*
722	* The iocb is the first element in our request structure.
723	* So we can safely cast it directly to the handle (see above)
724	*/
725	PRTFILEAIOREQINTERNAL pReqInt = (PRTFILEAIOREQINTERNAL)aPortEvents[i].pIoCB;
726	AssertPtr(pReqInt);
727	Assert(pReqInt->u32Magic == RTFILEAIOREQ_MAGIC);
728
729	/** @todo aeichner: The rc field contains the result code
730	* like you can find in errno for the normal read/write ops.
731	* But there is a second field called rc2. I don't know the
732	* purpose for it yet.
733	*/
734	if (RT_UNLIKELY(aPortEvents[i].rc < 0))
735	pReqInt->Rc = RTErrConvertFromErrno(-aPortEvents[i].rc); /* Convert to positive value. */
736	else
737	{
738	pReqInt->Rc = VINF_SUCCESS;
739	pReqInt->cbTransfered = aPortEvents[i].rc;
740	}
741
742	/* Mark the request as finished. */
743	RTFILEAIOREQ_SET_STATE(pReqInt, COMPLETED);
744
745	pahReqs[cRequestsCompleted++] = (RTFILEAIOREQ)pReqInt;
746	}
747
748	/*
749	* Done Yet? If not advance and try again.
750	*/
751	if (cDone >= cMinReqs)
752	break;
753	cMinReqs -= cDone;
754	cReqs -= cDone;
755
756	if (cMillies != RT_INDEFINITE_WAIT)
757	{
758	/* The API doesn't return ETIMEDOUT, so we have to fix that ourselves. */
759	uint64_t NanoTS = RTTimeNanoTS();
760	uint64_t cMilliesElapsed = (NanoTS - StartNanoTS) / 1000000;
761	if (cMilliesElapsed >= cMillies)
762	{
763	rc = VERR_TIMEOUT;
764	break;
765	}
766
767	/* The syscall supposedly updates it, but we're paranoid. :-) */
768	Timeout.tv_sec = (cMillies - (RTMSINTERVAL)cMilliesElapsed) / 1000;
769	Timeout.tv_nsec = (cMillies - (RTMSINTERVAL)cMilliesElapsed) % 1000 * 1000000;
770	}
771	}
772
773	/*
774	* Update the context state and set the return value.
775	*/
776	*pcReqs = cRequestsCompleted;
777	ASMAtomicSubS32(&pCtxInt->cRequests, cRequestsCompleted);
778	Assert(pCtxInt->hThreadWait == RTThreadSelf());
779	ASMAtomicWriteHandle(&pCtxInt->hThreadWait, NIL_RTTHREAD);
780
781	/*
782	* Clear the wakeup flag and set rc.
783	*/
784	if ( pCtxInt->fWokenUp
785	&& RT_SUCCESS(rc))
786	{
787	ASMAtomicXchgBool(&pCtxInt->fWokenUp, false);
788	rc = VERR_INTERRUPTED;
789	}
790
791	return rc;
792	}
793
794
795	RTDECL(int) RTFileAioCtxWakeup(RTFILEAIOCTX hAioCtx)
796	{
797	PRTFILEAIOCTXINTERNAL pCtxInt = hAioCtx;
798	RTFILEAIOCTX_VALID_RETURN(pCtxInt);
799
800	/** @todo r=bird: Define the protocol for how to resume work after calling
801	* this function. */
802
803	bool fWokenUp = ASMAtomicXchgBool(&pCtxInt->fWokenUp, true);
804
805	/*
806	* Read the thread handle before the status flag.
807	* If we read the handle after the flag we might
808	* end up with an invalid handle because the thread
809	* waiting in RTFileAioCtxWakeup() might get scheduled
810	* before we read the flag and returns.
811	* We can ensure that the handle is valid if fWaiting is true
812	* when reading the handle before the status flag.
813	*/
814	RTTHREAD hThread;
815	ASMAtomicReadHandle(&pCtxInt->hThreadWait, &hThread);
816	bool fWaiting = ASMAtomicReadBool(&pCtxInt->fWaiting);
817	if ( !fWokenUp
818	&& fWaiting)
819	{
820	/*
821	* If a thread waits the handle must be valid.
822	* It is possible that the thread returns from
823	* rtFileAsyncIoLinuxGetEvents() before the signal
824	* is send.
825	* This is no problem because we already set fWokenUp
826	* to true which will let the thread return VERR_INTERRUPTED
827	* and the next call to RTFileAioCtxWait() will not
828	* return VERR_INTERRUPTED because signals are not saved
829	* and will simply vanish if the destination thread can't
830	* receive it.
831	*/
832	Assert(hThread != NIL_RTTHREAD);
833	RTThreadPoke(hThread);
834	}
835
836	return VINF_SUCCESS;
837	}
838

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source: vbox/trunk/src/VBox/Runtime/r3/linux/fileaio-linux.cpp@ 78359

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