arch/um/os-Linux/aio.c - arm/linux-arm64-legacy - Git at Google

 /*
  * Copyright (C) 2004 Jeff Dike (jdike@addtoit.com)
  * Licensed under the GPL
  */

 #include <stdlib.h>
 #include <unistd.h>
 #include <signal.h>
 #include <string.h>
 #include <errno.h>
 #include <sched.h>
 #include <sys/syscall.h>
 #include "os.h"
 #include "helper.h"
 #include "aio.h"
 #include "init.h"
 #include "user.h"
 #include "mode.h"

 static int aio_req_fd_r = -1;
 static int aio_req_fd_w = -1;

 static int update_aio(struct aio_context *aio, int res)
 {
         if(res < 0)
                 aio->len = res;
         else if((res == 0) && (aio->type == AIO_READ)){
                 /* This is the EOF case - we have hit the end of the file
                  * and it ends in a partial block, so we fill the end of
                  * the block with zeros and claim success.
                  */
                 memset(aio->data, 0, aio->len);
                 aio->len = 0;
         }
         else if(res > 0){
                 aio->len -= res;
                 aio->data += res;
                 aio->offset += res;
                 return aio->len;
         }

         return 0;
 }

 #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, struct aio_context *aio)
 {
         struct iocb iocb, *iocbp = &iocb;
         char c;
         int err;

         iocb = ((struct iocb) { .aio_data 	= (unsigned long) aio,
                                 .aio_reqprio	= 0,
                                 .aio_fildes	= aio->fd,
                                 .aio_buf	= (unsigned long) aio->data,
                                 .aio_nbytes	= aio->len,
                                 .aio_offset	= aio->offset,
                                 .aio_reserved1	= 0,
                                 .aio_reserved2	= 0,
                                 .aio_reserved3	= 0 });

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

         err = io_submit(ctx, 1, &iocbp);
         if(err > 0)
                 err = 0;

  out:
         return err;
 }

 static aio_context_t ctx = 0;

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

         signal(SIGWINCH, SIG_IGN);

         while(1){
                 n = io_getevents(ctx, 1, 1, &event, NULL);
                 if(n < 0){
                         if(errno == EINTR)
                                 continue;
                         printk("aio_thread - io_getevents failed, "
                                "errno = %d\n", errno);
                 }
                 else {
 			aio = (struct aio_context *) event.data;
 			if(update_aio(aio, event.res)){
 				do_aio(ctx, aio);
 				continue;
 			}

                         reply = ((struct aio_thread_reply)
 				{ .data = aio,
 				  .err	= aio->len });
 			err = os_write_file(aio->reply_fd, &reply,
 					    sizeof(reply));
                         if(err != sizeof(reply))
 				printk("aio_thread - write failed, "
 				       "fd = %d, err = %d\n", aio->reply_fd,
 				       -err);
                 }
         }
         return 0;
 }

 #endif

 static int do_not_aio(struct aio_context *aio)
 {
         char c;
         int err;

         switch(aio->type){
         case AIO_READ:
                 err = os_seek_file(aio->fd, aio->offset);
                 if(err)
                         goto out;

                 err = os_read_file(aio->fd, aio->data, aio->len);
                 break;
         case AIO_WRITE:
                 err = os_seek_file(aio->fd, aio->offset);
                 if(err)
                         goto out;

                 err = os_write_file(aio->fd, aio->data, aio->len);
                 break;
         case AIO_MMAP:
                 err = os_seek_file(aio->fd, aio->offset);
                 if(err)
                         goto out;

                 err = os_read_file(aio->fd, &c, sizeof(c));
                 break;
         default:
                 printk("do_not_aio - bad request type : %d\n", aio->type);
                 err = -EINVAL;
                 break;
         }

  out:
         return err;
 }

 static int not_aio_thread(void *arg)
 {
         struct aio_context *aio;
         struct aio_thread_reply reply;
         int err;

         signal(SIGWINCH, SIG_IGN);
         while(1){
                 err = os_read_file(aio_req_fd_r, &aio, sizeof(aio));
                 if(err != sizeof(aio)){
                         if(err < 0)
                                 printk("not_aio_thread - read failed, "
                                        "fd = %d, err = %d\n", aio_req_fd_r,
                                        -err);
                         else {
                                 printk("not_aio_thread - short read, fd = %d, "
                                        "length = %d\n", aio_req_fd_r, err);
                         }
                         continue;
                 }
  again:
                 err = do_not_aio(aio);

                 if(update_aio(aio, err))
                         goto again;

                 reply = ((struct aio_thread_reply) { .data 	= aio,
                                                      .err	= aio->len });
                 err = os_write_file(aio->reply_fd, &reply, sizeof(reply));
                 if(err != sizeof(reply))
                         printk("not_aio_thread - write failed, fd = %d, "
                                "err = %d\n", aio_req_fd_r, -err);
         }
 }

 static int submit_aio_24(struct aio_context *aio)
 {
         int err;

         err = os_write_file(aio_req_fd_w, &aio, sizeof(aio));
         if(err == sizeof(aio))
                 err = 0;

         return err;
 }

 static int aio_pid = -1;
 static int (*submit_proc)(struct aio_context *aio);

 static int init_aio_24(void)
 {
         unsigned long stack;
         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 = run_helper_thread(not_aio_thread, NULL,
                                 CLONE_FILES | CLONE_VM | SIGCHLD, &stack, 0);
         if(err < 0)
                 goto out_close_pipe;

         aio_pid = err;
         goto out;

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

 	submit_proc = submit_aio_24;

         return 0;
 }

 #ifdef HAVE_AIO_ABI
 #define DEFAULT_24_AIO 0
 static int submit_aio_26(struct aio_context *aio)
 {
 	struct aio_thread_reply reply;
 	int err;

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

 	return err;
 }

 static int init_aio_26(void)
 {
         unsigned long stack;
         int err;

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

         err = run_helper_thread(aio_thread, NULL,
                                 CLONE_FILES | CLONE_VM | SIGCHLD, &stack, 0);
         if(err < 0)
                 return -errno;

         aio_pid = err;

 	printk("Using 2.6 host AIO\n");

 	submit_proc = submit_aio_26;

         return 0;
 }

 #else
 #define DEFAULT_24_AIO 1
 static int submit_aio_26(struct aio_context *aio)
 {
         return -ENOSYS;
 }

 static int init_aio_26(void)
 {
 	submit_proc = submit_aio_26;
         return -ENOSYS;
 }
 #endif

 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;

         CHOOSE_MODE(({
                 if(!aio_24){
                         printk("Disabling 2.6 AIO in tt mode\n");
                         aio_24 = 1;
                 } }), (void) 0);

         if(!aio_24){
                 err = init_aio_26();
                 if(err && (errno == ENOSYS)){
                         printk("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);
 }

 __uml_exitcall(exit_aio);

 int submit_aio(struct aio_context *aio)
 {
 	return (*submit_proc)(aio);
 }
	/*
	* Copyright (C) 2004 Jeff Dike (jdike@addtoit.com)
	* Licensed under the GPL
	*/

	#include <stdlib.h>
	#include <unistd.h>
	#include <signal.h>
	#include <string.h>
	#include <errno.h>
	#include <sched.h>
	#include <sys/syscall.h>
	#include "os.h"
	#include "helper.h"
	#include "aio.h"
	#include "init.h"
	#include "user.h"
	#include "mode.h"

	static int aio_req_fd_r = -1;
	static int aio_req_fd_w = -1;

	static int update_aio(struct aio_context *aio, int res)
	{
	if(res < 0)
	aio->len = res;
	else if((res == 0) && (aio->type == AIO_READ)){
	/* This is the EOF case - we have hit the end of the file
	* and it ends in a partial block, so we fill the end of
	* the block with zeros and claim success.
	*/
	memset(aio->data, 0, aio->len);
	aio->len = 0;
	}
	else if(res > 0){
	aio->len -= res;
	aio->data += res;
	aio->offset += res;
	return aio->len;
	}

	return 0;
	}

	#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, struct aio_context *aio)
	{
	struct iocb iocb, *iocbp = &iocb;
	char c;
	int err;

	iocb = ((struct iocb) { .aio_data = (unsigned long) aio,
	.aio_reqprio = 0,
	.aio_fildes = aio->fd,
	.aio_buf = (unsigned long) aio->data,
	.aio_nbytes = aio->len,
	.aio_offset = aio->offset,
	.aio_reserved1 = 0,
	.aio_reserved2 = 0,
	.aio_reserved3 = 0 });

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

	err = io_submit(ctx, 1, &iocbp);
	if(err > 0)
	err = 0;

	out:
	return err;
	}

	static aio_context_t ctx = 0;

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

	signal(SIGWINCH, SIG_IGN);

	while(1){
	n = io_getevents(ctx, 1, 1, &event, NULL);
	if(n < 0){
	if(errno == EINTR)
	continue;
	printk("aio_thread - io_getevents failed, "
	"errno = %d\n", errno);
	}
	else {
	aio = (struct aio_context *) event.data;
	if(update_aio(aio, event.res)){
	do_aio(ctx, aio);
	continue;
	}

	reply = ((struct aio_thread_reply)
	{ .data = aio,
	.err = aio->len });
	err = os_write_file(aio->reply_fd, &reply,
	sizeof(reply));
	if(err != sizeof(reply))
	printk("aio_thread - write failed, "
	"fd = %d, err = %d\n", aio->reply_fd,
	-err);
	}
	}
	return 0;
	}

	#endif

	static int do_not_aio(struct aio_context *aio)
	{
	char c;
	int err;

	switch(aio->type){
	case AIO_READ:
	err = os_seek_file(aio->fd, aio->offset);
	if(err)
	goto out;

	err = os_read_file(aio->fd, aio->data, aio->len);
	break;
	case AIO_WRITE:
	err = os_seek_file(aio->fd, aio->offset);
	if(err)
	goto out;

	err = os_write_file(aio->fd, aio->data, aio->len);
	break;
	case AIO_MMAP:
	err = os_seek_file(aio->fd, aio->offset);
	if(err)
	goto out;

	err = os_read_file(aio->fd, &c, sizeof(c));
	break;
	default:
	printk("do_not_aio - bad request type : %d\n", aio->type);
	err = -EINVAL;
	break;
	}

	out:
	return err;
	}

	static int not_aio_thread(void *arg)
	{
	struct aio_context *aio;
	struct aio_thread_reply reply;
	int err;

	signal(SIGWINCH, SIG_IGN);
	while(1){
	err = os_read_file(aio_req_fd_r, &aio, sizeof(aio));
	if(err != sizeof(aio)){
	if(err < 0)
	printk("not_aio_thread - read failed, "
	"fd = %d, err = %d\n", aio_req_fd_r,
	-err);
	else {
	printk("not_aio_thread - short read, fd = %d, "
	"length = %d\n", aio_req_fd_r, err);
	}
	continue;
	}
	again:
	err = do_not_aio(aio);

	if(update_aio(aio, err))
	goto again;

	reply = ((struct aio_thread_reply) { .data = aio,
	.err = aio->len });
	err = os_write_file(aio->reply_fd, &reply, sizeof(reply));
	if(err != sizeof(reply))
	printk("not_aio_thread - write failed, fd = %d, "
	"err = %d\n", aio_req_fd_r, -err);
	}
	}

	static int submit_aio_24(struct aio_context *aio)
	{
	int err;

	err = os_write_file(aio_req_fd_w, &aio, sizeof(aio));
	if(err == sizeof(aio))
	err = 0;

	return err;
	}

	static int aio_pid = -1;
	static int (submit_proc)(struct aio_context aio);

	static int init_aio_24(void)
	{
	unsigned long stack;
	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 = run_helper_thread(not_aio_thread, NULL,
	CLONE_FILES \| CLONE_VM \| SIGCHLD, &stack, 0);
	if(err < 0)
	goto out_close_pipe;

	aio_pid = err;
	goto out;

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

	submit_proc = submit_aio_24;

	return 0;
	}

	#ifdef HAVE_AIO_ABI
	#define DEFAULT_24_AIO 0
	static int submit_aio_26(struct aio_context *aio)
	{
	struct aio_thread_reply reply;
	int err;

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

	return err;
	}

	static int init_aio_26(void)
	{
	unsigned long stack;
	int err;

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

	err = run_helper_thread(aio_thread, NULL,
	CLONE_FILES \| CLONE_VM \| SIGCHLD, &stack, 0);
	if(err < 0)
	return -errno;

	aio_pid = err;

	printk("Using 2.6 host AIO\n");

	submit_proc = submit_aio_26;

	return 0;
	}

	#else
	#define DEFAULT_24_AIO 1
	static int submit_aio_26(struct aio_context *aio)
	{
	return -ENOSYS;
	}

	static int init_aio_26(void)
	{
	submit_proc = submit_aio_26;
	return -ENOSYS;
	}
	#endif

	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;

	CHOOSE_MODE(({
	if(!aio_24){
	printk("Disabling 2.6 AIO in tt mode\n");
	aio_24 = 1;
	} }), (void) 0);

	if(!aio_24){
	err = init_aio_26();
	if(err && (errno == ENOSYS)){
	printk("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);
	}

	__uml_exitcall(exit_aio);

	int submit_aio(struct aio_context *aio)
	{
	return (*submit_proc)(aio);
	}