arch/um/os-Linux/aio.c - kernel/bruno - Git at Google

 /*
  * Copyright (C) 2004 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
  * Licensed under the GPL
  */

 #include <unistd.h>
 #include <sched.h>
 #include <signal.h>
 #include <errno.h>
 #include <sys/time.h>
 #include <asm/unistd.h>
 #include <aio.h>
 #include <init.h>
 #include <kern_util.h>
 #include <os.h>

 struct aio_thread_req {
 	enum aio_type type;
 	int io_fd;
 	unsigned long long offset;
 	char *buf;
 	int len;
 	struct aio_context *aio;
 };

 #if defined(HAVE_AIO_ABI)
 #include <linux/aio_abi.h>

 /*
  * If we have the headers, we are going to build with AIO enabled.
  * If we don't have aio in libc, we define the necessary stubs here.
  */

 #if !defined(HAVE_AIO_LIBC)

 static long io_setup(int n, aio_context_t *ctxp)
 {
 	return syscall(__NR_io_setup, n, ctxp);
 }

 static long io_submit(aio_context_t ctx, long nr, struct iocb **iocbpp)
 {
 	return syscall(__NR_io_submit, ctx, nr, iocbpp);
 }

 static long io_getevents(aio_context_t ctx_id, long min_nr, long nr,
 			 struct io_event *events, struct timespec *timeout)
 {
 	return syscall(__NR_io_getevents, ctx_id, min_nr, nr, events, timeout);
 }

 #endif

 /*
  * The AIO_MMAP cases force the mmapped page into memory here
  * rather than in whatever place first touches the data.  I used
  * to do this by touching the page, but that's delicate because
  * gcc is prone to optimizing that away.  So, what's done here
  * is we read from the descriptor from which the page was
  * mapped.  The caller is required to pass an offset which is
  * inside the page that was mapped.  Thus, when the read
  * returns, we know that the page is in the page cache, and
  * that it now backs the mmapped area.
  */

 static int do_aio(aio_context_t ctx, enum aio_type type, int fd, char *buf,
 		  int len, unsigned long long offset, struct aio_context *aio)
 {
 	struct iocb *iocbp = & ((struct iocb) {
 				    .aio_data       = (unsigned long) aio,
 				    .aio_fildes     = fd,
 				    .aio_buf        = (unsigned long) buf,
 				    .aio_nbytes     = len,
 				    .aio_offset     = offset
 			     });
 	char c;

 	switch (type) {
 	case AIO_READ:
 		iocbp->aio_lio_opcode = IOCB_CMD_PREAD;
 		break;
 	case AIO_WRITE:
 		iocbp->aio_lio_opcode = IOCB_CMD_PWRITE;
 		break;
 	case AIO_MMAP:
 		iocbp->aio_lio_opcode = IOCB_CMD_PREAD;
 		iocbp->aio_buf = (unsigned long) &c;
 		iocbp->aio_nbytes = sizeof(c);
 		break;
 	default:
 		printk(UM_KERN_ERR "Bogus op in do_aio - %d\n", type);
 		return -EINVAL;
 	}

 	return (io_submit(ctx, 1, &iocbp) > 0) ? 0 : -errno;
 }

 /* Initialized in an initcall and unchanged thereafter */
 static aio_context_t ctx = 0;

 static int aio_thread(void *arg)
 {
 	struct aio_thread_reply reply;
 	struct io_event event;
 	int err, n, reply_fd;

 	os_fix_helper_signals();
 	while (1) {
 		n = io_getevents(ctx, 1, 1, &event, NULL);
 		if (n < 0) {
 			if (errno == EINTR)
 				continue;
 			printk(UM_KERN_ERR "aio_thread - io_getevents failed, "
 			       "errno = %d\n", errno);
 		}
 		else {
 			reply = ((struct aio_thread_reply)
 				{ .data = (void *) (long) event.data,
 						.err	= event.res });
 			reply_fd = ((struct aio_context *) reply.data)->reply_fd;
 			err = write(reply_fd, &reply, sizeof(reply));
 			if (err != sizeof(reply))
 				printk(UM_KERN_ERR "aio_thread - write failed, "
 				       "fd = %d, err = %d\n", reply_fd, errno);
 		}
 	}
 	return 0;
 }

 #endif

 static int do_not_aio(struct aio_thread_req *req)
 {
 	char c;
 	unsigned long long actual;
 	int n;

 	actual = lseek64(req->io_fd, req->offset, SEEK_SET);
 	if (actual != req->offset)
 		return -errno;

 	switch (req->type) {
 	case AIO_READ:
 		n = read(req->io_fd, req->buf, req->len);
 		break;
 	case AIO_WRITE:
 		n = write(req->io_fd, req->buf, req->len);
 		break;
 	case AIO_MMAP:
 		n = read(req->io_fd, &c, sizeof(c));
 		break;
 	default:
 		printk(UM_KERN_ERR "do_not_aio - bad request type : %d\n",
 		       req->type);
 		return -EINVAL;
 	}

 	if (n < 0)
 		return -errno;
 	return 0;
 }

 /* These are initialized in initcalls and not changed */
 static int aio_req_fd_r = -1;
 static int aio_req_fd_w = -1;
 static int aio_pid = -1;
 static unsigned long aio_stack;

 static int not_aio_thread(void *arg)
 {
 	struct aio_thread_req req;
 	struct aio_thread_reply reply;
 	int err;

 	os_fix_helper_signals();
 	while (1) {
 		err = read(aio_req_fd_r, &req, sizeof(req));
 		if (err != sizeof(req)) {
 			if (err < 0)
 				printk(UM_KERN_ERR "not_aio_thread - "
 				       "read failed, fd = %d, err = %d\n",
 				       aio_req_fd_r,
 				       errno);
 			else {
 				printk(UM_KERN_ERR "not_aio_thread - short "
 				       "read, fd = %d, length = %d\n",
 				       aio_req_fd_r, err);
 			}
 			continue;
 		}
 		err = do_not_aio(&req);
 		reply = ((struct aio_thread_reply) { .data 	= req.aio,
 						     .err	= err });
 		err = write(req.aio->reply_fd, &reply, sizeof(reply));
 		if (err != sizeof(reply))
 			printk(UM_KERN_ERR "not_aio_thread - write failed, "
 			       "fd = %d, err = %d\n", req.aio->reply_fd, errno);
 	}

 	return 0;
 }

 static int init_aio_24(void)
 {
 	int fds[2], err;

 	err = os_pipe(fds, 1, 1);
 	if (err)
 		goto out;

 	aio_req_fd_w = fds[0];
 	aio_req_fd_r = fds[1];

 	err = os_set_fd_block(aio_req_fd_w, 0);
 	if (err)
 		goto out_close_pipe;

 	err = run_helper_thread(not_aio_thread, NULL,
 				CLONE_FILES | CLONE_VM, &aio_stack);
 	if (err < 0)
 		goto out_close_pipe;

 	aio_pid = err;
 	goto out;

 out_close_pipe:
 	close(fds[0]);
 	close(fds[1]);
 	aio_req_fd_w = -1;
 	aio_req_fd_r = -1;
 out:
 #ifndef HAVE_AIO_ABI
 	printk(UM_KERN_INFO "/usr/include/linux/aio_abi.h not present during "
 	       "build\n");
 #endif
 	printk(UM_KERN_INFO "2.6 host AIO support not used - falling back to "
 	       "I/O thread\n");
 	return 0;
 }

 #ifdef HAVE_AIO_ABI
 #define DEFAULT_24_AIO 0
 static int init_aio_26(void)
 {
 	int err;

 	if (io_setup(256, &ctx)) {
 		err = -errno;
 		printk(UM_KERN_ERR "aio_thread failed to initialize context, "
 		       "err = %d\n", errno);
 		return err;
 	}

 	err = run_helper_thread(aio_thread, NULL,
 				CLONE_FILES | CLONE_VM, &aio_stack);
 	if (err < 0)
 		return err;

 	aio_pid = err;

 	printk(UM_KERN_INFO "Using 2.6 host AIO\n");
 	return 0;
 }

 static int submit_aio_26(enum aio_type type, int io_fd, char *buf, int len,
 			 unsigned long long offset, struct aio_context *aio)
 {
 	struct aio_thread_reply reply;
 	int err;

 	err = do_aio(ctx, type, io_fd, buf, len, offset, aio);
 	if (err) {
 		reply = ((struct aio_thread_reply) { .data = aio,
 					 .err  = err });
 		err = write(aio->reply_fd, &reply, sizeof(reply));
 		if (err != sizeof(reply)) {
 			err = -errno;
 			printk(UM_KERN_ERR "submit_aio_26 - write failed, "
 			       "fd = %d, err = %d\n", aio->reply_fd, -err);
 		}
 		else err = 0;
 	}

 	return err;
 }

 #else
 #define DEFAULT_24_AIO 1
 static int init_aio_26(void)
 {
 	return -ENOSYS;
 }

 static int submit_aio_26(enum aio_type type, int io_fd, char *buf, int len,
 			 unsigned long long offset, struct aio_context *aio)
 {
 	return -ENOSYS;
 }
 #endif

 /* Initialized in an initcall and unchanged thereafter */
 static int aio_24 = DEFAULT_24_AIO;

 static int __init set_aio_24(char *name, int *add)
 {
 	aio_24 = 1;
 	return 0;
 }

 __uml_setup("aio=2.4", set_aio_24,
 "aio=2.4\n"
 "    This is used to force UML to use 2.4-style AIO even when 2.6 AIO is\n"
 "    available.  2.4 AIO is a single thread that handles one request at a\n"
 "    time, synchronously.  2.6 AIO is a thread which uses the 2.6 AIO \n"
 "    interface to handle an arbitrary number of pending requests.  2.6 AIO \n"
 "    is not available in tt mode, on 2.4 hosts, or when UML is built with\n"
 "    /usr/include/linux/aio_abi.h not available.  Many distributions don't\n"
 "    include aio_abi.h, so you will need to copy it from a kernel tree to\n"
 "    your /usr/include/linux in order to build an AIO-capable UML\n\n"
 );

 static int init_aio(void)
 {
 	int err;

 	if (!aio_24) {
 		err = init_aio_26();
 		if (err && (errno == ENOSYS)) {
 			printk(UM_KERN_INFO "2.6 AIO not supported on the "
 			       "host - reverting to 2.4 AIO\n");
 			aio_24 = 1;
 		}
 		else return err;
 	}

 	if (aio_24)
 		return init_aio_24();

 	return 0;
 }

 /*
  * The reason for the __initcall/__uml_exitcall asymmetry is that init_aio
  * needs to be called when the kernel is running because it calls run_helper,
  * which needs get_free_page.  exit_aio is a __uml_exitcall because the generic
  * kernel does not run __exitcalls on shutdown, and can't because many of them
  * break when called outside of module unloading.
  */
 __initcall(init_aio);

 static void exit_aio(void)
 {
 	if (aio_pid != -1) {
 		os_kill_process(aio_pid, 1);
 		free_stack(aio_stack, 0);
 	}
 }

 __uml_exitcall(exit_aio);

 static int submit_aio_24(enum aio_type type, int io_fd, char *buf, int len,
 			 unsigned long long offset, struct aio_context *aio)
 {
 	struct aio_thread_req req = { .type 		= type,
 				      .io_fd		= io_fd,
 				      .offset		= offset,
 				      .buf		= buf,
 				      .len		= len,
 				      .aio		= aio,
 	};
 	int err;

 	err = write(aio_req_fd_w, &req, sizeof(req));
 	if (err == sizeof(req))
 		err = 0;
 	else err = -errno;

 	return err;
 }

 int submit_aio(enum aio_type type, int io_fd, char *buf, int len,
 	       unsigned long long offset, int reply_fd,
 	       struct aio_context *aio)
 {
 	aio->reply_fd = reply_fd;
 	if (aio_24)
 		return submit_aio_24(type, io_fd, buf, len, offset, aio);
 	else
 		return submit_aio_26(type, io_fd, buf, len, offset, aio);
 }
	/*
	* Copyright (C) 2004 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
	* Licensed under the GPL
	*/

	#include <unistd.h>
	#include <sched.h>
	#include <signal.h>
	#include <errno.h>
	#include <sys/time.h>
	#include <asm/unistd.h>
	#include <aio.h>
	#include <init.h>
	#include <kern_util.h>
	#include <os.h>

	struct aio_thread_req {
	enum aio_type type;
	int io_fd;
	unsigned long long offset;
	char *buf;
	int len;
	struct aio_context *aio;
	};

	#if defined(HAVE_AIO_ABI)
	#include <linux/aio_abi.h>

	/*
	* If we have the headers, we are going to build with AIO enabled.
	* If we don't have aio in libc, we define the necessary stubs here.
	*/

	#if !defined(HAVE_AIO_LIBC)

	static long io_setup(int n, aio_context_t *ctxp)
	{
	return syscall(__NR_io_setup, n, ctxp);
	}

	static long io_submit(aio_context_t ctx, long nr, struct iocb **iocbpp)
	{
	return syscall(__NR_io_submit, ctx, nr, iocbpp);
	}

	static long io_getevents(aio_context_t ctx_id, long min_nr, long nr,
	struct io_event events, struct timespec timeout)
	{
	return syscall(__NR_io_getevents, ctx_id, min_nr, nr, events, timeout);
	}

	#endif

	/*
	* The AIO_MMAP cases force the mmapped page into memory here
	* rather than in whatever place first touches the data. I used
	* to do this by touching the page, but that's delicate because
	* gcc is prone to optimizing that away. So, what's done here
	* is we read from the descriptor from which the page was
	* mapped. The caller is required to pass an offset which is
	* inside the page that was mapped. Thus, when the read
	* returns, we know that the page is in the page cache, and
	* that it now backs the mmapped area.
	*/

	static int do_aio(aio_context_t ctx, enum aio_type type, int fd, char *buf,
	int len, unsigned long long offset, struct aio_context *aio)
	{
	struct iocb *iocbp = & ((struct iocb) {
	.aio_data = (unsigned long) aio,
	.aio_fildes = fd,
	.aio_buf = (unsigned long) buf,
	.aio_nbytes = len,
	.aio_offset = offset
	});
	char c;

	switch (type) {
	case AIO_READ:
	iocbp->aio_lio_opcode = IOCB_CMD_PREAD;
	break;
	case AIO_WRITE:
	iocbp->aio_lio_opcode = IOCB_CMD_PWRITE;
	break;
	case AIO_MMAP:
	iocbp->aio_lio_opcode = IOCB_CMD_PREAD;
	iocbp->aio_buf = (unsigned long) &c;
	iocbp->aio_nbytes = sizeof(c);
	break;
	default:
	printk(UM_KERN_ERR "Bogus op in do_aio - %d\n", type);
	return -EINVAL;
	}

	return (io_submit(ctx, 1, &iocbp) > 0) ? 0 : -errno;
	}

	/* Initialized in an initcall and unchanged thereafter */
	static aio_context_t ctx = 0;

	static int aio_thread(void *arg)
	{
	struct aio_thread_reply reply;
	struct io_event event;
	int err, n, reply_fd;

	os_fix_helper_signals();
	while (1) {
	n = io_getevents(ctx, 1, 1, &event, NULL);
	if (n < 0) {
	if (errno == EINTR)
	continue;
	printk(UM_KERN_ERR "aio_thread - io_getevents failed, "
	"errno = %d\n", errno);
	}
	else {
	reply = ((struct aio_thread_reply)
	{ .data = (void *) (long) event.data,
	.err = event.res });
	reply_fd = ((struct aio_context *) reply.data)->reply_fd;
	err = write(reply_fd, &reply, sizeof(reply));
	if (err != sizeof(reply))
	printk(UM_KERN_ERR "aio_thread - write failed, "
	"fd = %d, err = %d\n", reply_fd, errno);
	}
	}
	return 0;
	}

	#endif

	static int do_not_aio(struct aio_thread_req *req)
	{
	char c;
	unsigned long long actual;
	int n;

	actual = lseek64(req->io_fd, req->offset, SEEK_SET);
	if (actual != req->offset)
	return -errno;

	switch (req->type) {
	case AIO_READ:
	n = read(req->io_fd, req->buf, req->len);
	break;
	case AIO_WRITE:
	n = write(req->io_fd, req->buf, req->len);
	break;
	case AIO_MMAP:
	n = read(req->io_fd, &c, sizeof(c));
	break;
	default:
	printk(UM_KERN_ERR "do_not_aio - bad request type : %d\n",
	req->type);
	return -EINVAL;
	}

	if (n < 0)
	return -errno;
	return 0;
	}

	/* These are initialized in initcalls and not changed */
	static int aio_req_fd_r = -1;
	static int aio_req_fd_w = -1;
	static int aio_pid = -1;
	static unsigned long aio_stack;

	static int not_aio_thread(void *arg)
	{
	struct aio_thread_req req;
	struct aio_thread_reply reply;
	int err;

	os_fix_helper_signals();
	while (1) {
	err = read(aio_req_fd_r, &req, sizeof(req));
	if (err != sizeof(req)) {
	if (err < 0)
	printk(UM_KERN_ERR "not_aio_thread - "
	"read failed, fd = %d, err = %d\n",
	aio_req_fd_r,
	errno);
	else {
	printk(UM_KERN_ERR "not_aio_thread - short "
	"read, fd = %d, length = %d\n",
	aio_req_fd_r, err);
	}
	continue;
	}
	err = do_not_aio(&req);
	reply = ((struct aio_thread_reply) { .data = req.aio,
	.err = err });
	err = write(req.aio->reply_fd, &reply, sizeof(reply));
	if (err != sizeof(reply))
	printk(UM_KERN_ERR "not_aio_thread - write failed, "
	"fd = %d, err = %d\n", req.aio->reply_fd, errno);
	}

	return 0;
	}

	static int init_aio_24(void)
	{
	int fds[2], err;

	err = os_pipe(fds, 1, 1);
	if (err)
	goto out;

	aio_req_fd_w = fds[0];
	aio_req_fd_r = fds[1];

	err = os_set_fd_block(aio_req_fd_w, 0);
	if (err)
	goto out_close_pipe;

	err = run_helper_thread(not_aio_thread, NULL,
	CLONE_FILES \| CLONE_VM, &aio_stack);
	if (err < 0)
	goto out_close_pipe;

	aio_pid = err;
	goto out;

	out_close_pipe:
	close(fds[0]);
	close(fds[1]);
	aio_req_fd_w = -1;
	aio_req_fd_r = -1;
	out:
	#ifndef HAVE_AIO_ABI
	printk(UM_KERN_INFO "/usr/include/linux/aio_abi.h not present during "
	"build\n");
	#endif
	printk(UM_KERN_INFO "2.6 host AIO support not used - falling back to "
	"I/O thread\n");
	return 0;
	}

	#ifdef HAVE_AIO_ABI
	#define DEFAULT_24_AIO 0
	static int init_aio_26(void)
	{
	int err;

	if (io_setup(256, &ctx)) {
	err = -errno;
	printk(UM_KERN_ERR "aio_thread failed to initialize context, "
	"err = %d\n", errno);
	return err;
	}

	err = run_helper_thread(aio_thread, NULL,
	CLONE_FILES \| CLONE_VM, &aio_stack);
	if (err < 0)
	return err;

	aio_pid = err;

	printk(UM_KERN_INFO "Using 2.6 host AIO\n");
	return 0;
	}

	static int submit_aio_26(enum aio_type type, int io_fd, char *buf, int len,
	unsigned long long offset, struct aio_context *aio)
	{
	struct aio_thread_reply reply;
	int err;

	err = do_aio(ctx, type, io_fd, buf, len, offset, aio);
	if (err) {
	reply = ((struct aio_thread_reply) { .data = aio,
	.err = err });
	err = write(aio->reply_fd, &reply, sizeof(reply));
	if (err != sizeof(reply)) {
	err = -errno;
	printk(UM_KERN_ERR "submit_aio_26 - write failed, "
	"fd = %d, err = %d\n", aio->reply_fd, -err);
	}
	else err = 0;
	}

	return err;
	}

	#else
	#define DEFAULT_24_AIO 1
	static int init_aio_26(void)
	{
	return -ENOSYS;
	}

	static int submit_aio_26(enum aio_type type, int io_fd, char *buf, int len,
	unsigned long long offset, struct aio_context *aio)
	{
	return -ENOSYS;
	}
	#endif

	/* Initialized in an initcall and unchanged thereafter */
	static int aio_24 = DEFAULT_24_AIO;

	static int __init set_aio_24(char name, int add)
	{
	aio_24 = 1;
	return 0;
	}

	__uml_setup("aio=2.4", set_aio_24,
	"aio=2.4\n"
	" This is used to force UML to use 2.4-style AIO even when 2.6 AIO is\n"
	" available. 2.4 AIO is a single thread that handles one request at a\n"
	" time, synchronously. 2.6 AIO is a thread which uses the 2.6 AIO \n"
	" interface to handle an arbitrary number of pending requests. 2.6 AIO \n"
	" is not available in tt mode, on 2.4 hosts, or when UML is built with\n"
	" /usr/include/linux/aio_abi.h not available. Many distributions don't\n"
	" include aio_abi.h, so you will need to copy it from a kernel tree to\n"
	" your /usr/include/linux in order to build an AIO-capable UML\n\n"
	);

	static int init_aio(void)
	{
	int err;

	if (!aio_24) {
	err = init_aio_26();
	if (err && (errno == ENOSYS)) {
	printk(UM_KERN_INFO "2.6 AIO not supported on the "
	"host - reverting to 2.4 AIO\n");
	aio_24 = 1;
	}
	else return err;
	}

	if (aio_24)
	return init_aio_24();

	return 0;
	}

	/*
	* The reason for the __initcall/__uml_exitcall asymmetry is that init_aio
	* needs to be called when the kernel is running because it calls run_helper,
	* which needs get_free_page. exit_aio is a __uml_exitcall because the generic
	* kernel does not run __exitcalls on shutdown, and can't because many of them
	* break when called outside of module unloading.
	*/
	__initcall(init_aio);

	static void exit_aio(void)
	{
	if (aio_pid != -1) {
	os_kill_process(aio_pid, 1);
	free_stack(aio_stack, 0);
	}
	}

	__uml_exitcall(exit_aio);

	static int submit_aio_24(enum aio_type type, int io_fd, char *buf, int len,
	unsigned long long offset, struct aio_context *aio)
	{
	struct aio_thread_req req = { .type = type,
	.io_fd = io_fd,
	.offset = offset,
	.buf = buf,
	.len = len,
	.aio = aio,
	};
	int err;

	err = write(aio_req_fd_w, &req, sizeof(req));
	if (err == sizeof(req))
	err = 0;
	else err = -errno;

	return err;
	}

	int submit_aio(enum aio_type type, int io_fd, char *buf, int len,
	unsigned long long offset, int reply_fd,
	struct aio_context *aio)
	{
	aio->reply_fd = reply_fd;
	if (aio_24)
	return submit_aio_24(type, io_fd, buf, len, offset, aio);
	else
	return submit_aio_26(type, io_fd, buf, len, offset, aio);
	}