qemu/posix-aio-compat.c

434 lines
10 KiB
C

/*
* QEMU posix-aio emulation
*
* Copyright IBM, Corp. 2008
*
* Authors:
* Anthony Liguori <aliguori@us.ibm.com>
*
* This work is licensed under the terms of the GNU GPL, version 2. See
* the COPYING file in the top-level directory.
*
*/
#include <sys/ioctl.h>
#include <pthread.h>
#include <unistd.h>
#include <errno.h>
#include <time.h>
#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include "osdep.h"
#include "qemu-common.h"
#include "posix-aio-compat.h"
static pthread_mutex_t lock = PTHREAD_MUTEX_INITIALIZER;
static pthread_cond_t cond = PTHREAD_COND_INITIALIZER;
static pthread_t thread_id;
static pthread_attr_t attr;
static int max_threads = 64;
static int cur_threads = 0;
static int idle_threads = 0;
static TAILQ_HEAD(, qemu_paiocb) request_list;
#ifdef HAVE_PREADV
static int preadv_present = 1;
#else
static int preadv_present = 0;
#endif
static void die2(int err, const char *what)
{
fprintf(stderr, "%s failed: %s\n", what, strerror(err));
abort();
}
static void die(const char *what)
{
die2(errno, what);
}
static void mutex_lock(pthread_mutex_t *mutex)
{
int ret = pthread_mutex_lock(mutex);
if (ret) die2(ret, "pthread_mutex_lock");
}
static void mutex_unlock(pthread_mutex_t *mutex)
{
int ret = pthread_mutex_unlock(mutex);
if (ret) die2(ret, "pthread_mutex_unlock");
}
static int cond_timedwait(pthread_cond_t *cond, pthread_mutex_t *mutex,
struct timespec *ts)
{
int ret = pthread_cond_timedwait(cond, mutex, ts);
if (ret && ret != ETIMEDOUT) die2(ret, "pthread_cond_timedwait");
return ret;
}
static void cond_signal(pthread_cond_t *cond)
{
int ret = pthread_cond_signal(cond);
if (ret) die2(ret, "pthread_cond_signal");
}
static void thread_create(pthread_t *thread, pthread_attr_t *attr,
void *(*start_routine)(void*), void *arg)
{
int ret = pthread_create(thread, attr, start_routine, arg);
if (ret) die2(ret, "pthread_create");
}
static size_t handle_aiocb_ioctl(struct qemu_paiocb *aiocb)
{
int ret;
ret = ioctl(aiocb->aio_fildes, aiocb->aio_ioctl_cmd, aiocb->aio_ioctl_buf);
if (ret == -1)
return -errno;
/*
* This looks weird, but the aio code only consideres a request
* successfull if it has written the number full number of bytes.
*
* Now we overload aio_nbytes as aio_ioctl_cmd for the ioctl command,
* so in fact we return the ioctl command here to make posix_aio_read()
* happy..
*/
return aiocb->aio_nbytes;
}
#ifdef HAVE_PREADV
static ssize_t
qemu_preadv(int fd, const struct iovec *iov, int nr_iov, off_t offset)
{
return preadv(fd, iov, nr_iov, offset);
}
static ssize_t
qemu_pwritev(int fd, const struct iovec *iov, int nr_iov, off_t offset)
{
return pwritev(fd, iov, nr_iov, offset);
}
#else
static ssize_t
qemu_preadv(int fd, const struct iovec *iov, int nr_iov, off_t offset)
{
return -ENOSYS;
}
static ssize_t
qemu_pwritev(int fd, const struct iovec *iov, int nr_iov, off_t offset)
{
return -ENOSYS;
}
#endif
/*
* Check if we need to copy the data in the aiocb into a new
* properly aligned buffer.
*/
static int aiocb_needs_copy(struct qemu_paiocb *aiocb)
{
if (aiocb->aio_flags & QEMU_AIO_SECTOR_ALIGNED) {
int i;
for (i = 0; i < aiocb->aio_niov; i++)
if ((uintptr_t) aiocb->aio_iov[i].iov_base % 512)
return 1;
}
return 0;
}
static size_t handle_aiocb_rw_vector(struct qemu_paiocb *aiocb)
{
size_t offset = 0;
ssize_t len;
do {
if (aiocb->aio_type == QEMU_PAIO_WRITE)
len = qemu_pwritev(aiocb->aio_fildes,
aiocb->aio_iov,
aiocb->aio_niov,
aiocb->aio_offset + offset);
else
len = qemu_preadv(aiocb->aio_fildes,
aiocb->aio_iov,
aiocb->aio_niov,
aiocb->aio_offset + offset);
} while (len == -1 && errno == EINTR);
if (len == -1)
return -errno;
return len;
}
static size_t handle_aiocb_rw_linear(struct qemu_paiocb *aiocb, char *buf)
{
size_t offset = 0;
size_t len;
while (offset < aiocb->aio_nbytes) {
if (aiocb->aio_type == QEMU_PAIO_WRITE)
len = pwrite(aiocb->aio_fildes,
(const char *)buf + offset,
aiocb->aio_nbytes - offset,
aiocb->aio_offset + offset);
else
len = pread(aiocb->aio_fildes,
buf + offset,
aiocb->aio_nbytes - offset,
aiocb->aio_offset + offset);
if (len == -1 && errno == EINTR)
continue;
else if (len == -1) {
offset = -errno;
break;
} else if (len == 0)
break;
offset += len;
}
return offset;
}
static size_t handle_aiocb_rw(struct qemu_paiocb *aiocb)
{
size_t nbytes;
char *buf;
if (!aiocb_needs_copy(aiocb)) {
/*
* If there is just a single buffer, and it is properly aligned
* we can just use plain pread/pwrite without any problems.
*/
if (aiocb->aio_niov == 1)
return handle_aiocb_rw_linear(aiocb, aiocb->aio_iov->iov_base);
/*
* We have more than one iovec, and all are properly aligned.
*
* Try preadv/pwritev first and fall back to linearizing the
* buffer if it's not supported.
*/
if (preadv_present) {
nbytes = handle_aiocb_rw_vector(aiocb);
if (nbytes == aiocb->aio_nbytes)
return nbytes;
if (nbytes < 0 && nbytes != -ENOSYS)
return nbytes;
preadv_present = 0;
}
/*
* XXX(hch): short read/write. no easy way to handle the reminder
* using these interfaces. For now retry using plain
* pread/pwrite?
*/
}
/*
* Ok, we have to do it the hard way, copy all segments into
* a single aligned buffer.
*/
buf = qemu_memalign(512, aiocb->aio_nbytes);
if (aiocb->aio_type == QEMU_PAIO_WRITE) {
char *p = buf;
int i;
for (i = 0; i < aiocb->aio_niov; ++i) {
memcpy(p, aiocb->aio_iov[i].iov_base, aiocb->aio_iov[i].iov_len);
p += aiocb->aio_iov[i].iov_len;
}
}
nbytes = handle_aiocb_rw_linear(aiocb, buf);
if (aiocb->aio_type != QEMU_PAIO_WRITE) {
char *p = buf;
size_t count = aiocb->aio_nbytes, copy;
int i;
for (i = 0; i < aiocb->aio_niov && count; ++i) {
copy = count;
if (copy > aiocb->aio_iov[i].iov_len)
copy = aiocb->aio_iov[i].iov_len;
memcpy(aiocb->aio_iov[i].iov_base, p, copy);
p += copy;
count -= copy;
}
}
qemu_vfree(buf);
return nbytes;
}
static void *aio_thread(void *unused)
{
pid_t pid;
sigset_t set;
pid = getpid();
/* block all signals */
if (sigfillset(&set)) die("sigfillset");
if (sigprocmask(SIG_BLOCK, &set, NULL)) die("sigprocmask");
while (1) {
struct qemu_paiocb *aiocb;
size_t ret = 0;
qemu_timeval tv;
struct timespec ts;
qemu_gettimeofday(&tv);
ts.tv_sec = tv.tv_sec + 10;
ts.tv_nsec = 0;
mutex_lock(&lock);
while (TAILQ_EMPTY(&request_list) &&
!(ret == ETIMEDOUT)) {
ret = cond_timedwait(&cond, &lock, &ts);
}
if (TAILQ_EMPTY(&request_list))
break;
aiocb = TAILQ_FIRST(&request_list);
TAILQ_REMOVE(&request_list, aiocb, node);
aiocb->active = 1;
idle_threads--;
mutex_unlock(&lock);
switch (aiocb->aio_type) {
case QEMU_PAIO_READ:
case QEMU_PAIO_WRITE:
ret = handle_aiocb_rw(aiocb);
break;
case QEMU_PAIO_IOCTL:
ret = handle_aiocb_ioctl(aiocb);
break;
default:
fprintf(stderr, "invalid aio request (0x%x)\n", aiocb->aio_type);
ret = -EINVAL;
break;
}
mutex_lock(&lock);
aiocb->ret = ret;
idle_threads++;
mutex_unlock(&lock);
if (kill(pid, aiocb->ev_signo)) die("kill failed");
}
idle_threads--;
cur_threads--;
mutex_unlock(&lock);
return NULL;
}
static void spawn_thread(void)
{
cur_threads++;
idle_threads++;
thread_create(&thread_id, &attr, aio_thread, NULL);
}
int qemu_paio_init(struct qemu_paioinit *aioinit)
{
int ret;
ret = pthread_attr_init(&attr);
if (ret) die2(ret, "pthread_attr_init");
ret = pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
if (ret) die2(ret, "pthread_attr_setdetachstate");
TAILQ_INIT(&request_list);
return 0;
}
static int qemu_paio_submit(struct qemu_paiocb *aiocb, int type)
{
aiocb->aio_type = type;
aiocb->ret = -EINPROGRESS;
aiocb->active = 0;
mutex_lock(&lock);
if (idle_threads == 0 && cur_threads < max_threads)
spawn_thread();
TAILQ_INSERT_TAIL(&request_list, aiocb, node);
mutex_unlock(&lock);
cond_signal(&cond);
return 0;
}
int qemu_paio_read(struct qemu_paiocb *aiocb)
{
return qemu_paio_submit(aiocb, QEMU_PAIO_READ);
}
int qemu_paio_write(struct qemu_paiocb *aiocb)
{
return qemu_paio_submit(aiocb, QEMU_PAIO_WRITE);
}
int qemu_paio_ioctl(struct qemu_paiocb *aiocb)
{
return qemu_paio_submit(aiocb, QEMU_PAIO_IOCTL);
}
ssize_t qemu_paio_return(struct qemu_paiocb *aiocb)
{
ssize_t ret;
mutex_lock(&lock);
ret = aiocb->ret;
mutex_unlock(&lock);
return ret;
}
int qemu_paio_error(struct qemu_paiocb *aiocb)
{
ssize_t ret = qemu_paio_return(aiocb);
if (ret < 0)
ret = -ret;
else
ret = 0;
return ret;
}
int qemu_paio_cancel(int fd, struct qemu_paiocb *aiocb)
{
int ret;
mutex_lock(&lock);
if (!aiocb->active) {
TAILQ_REMOVE(&request_list, aiocb, node);
aiocb->ret = -ECANCELED;
ret = QEMU_PAIO_CANCELED;
} else if (aiocb->ret == -EINPROGRESS)
ret = QEMU_PAIO_NOTCANCELED;
else
ret = QEMU_PAIO_ALLDONE;
mutex_unlock(&lock);
return ret;
}