Skip to content

HTTPS clone URL

Subversion checkout URL

You can clone with HTTPS or Subversion.

Download ZIP
tag: 20130110
Fetching contributors…

Cannot retrieve contributors at this time

656 lines (544 sloc) 16.162 kb
/*
* 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 <sys/types.h>
#include <pthread.h>
#include <unistd.h>
#include <errno.h>
#include <time.h>
#include <signal.h>
#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include "qemu-queue.h"
#include "osdep.h"
#include "sysemu.h"
#include "qemu-common.h"
#include "trace.h"
#include "block_int.h"
#include "compatfd.h"
#include "block/raw-posix-aio.h"
struct qemu_paiocb {
BlockDriverAIOCB common;
int aio_fildes;
union {
struct iovec *aio_iov;
void *aio_ioctl_buf;
};
int aio_niov;
size_t aio_nbytes;
#define aio_ioctl_cmd aio_nbytes /* for QEMU_AIO_IOCTL */
int ev_signo;
off_t aio_offset;
QTAILQ_ENTRY(qemu_paiocb) node;
int aio_type;
ssize_t ret;
int active;
struct qemu_paiocb *next;
int async_context_id;
};
typedef struct PosixAioState {
int fd;
struct qemu_paiocb *first_aio;
} PosixAioState;
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 QTAILQ_HEAD(, qemu_paiocb) request_list;
#ifdef CONFIG_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 ssize_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
* successful 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;
}
static ssize_t handle_aiocb_flush(struct qemu_paiocb *aiocb)
{
int ret;
ret = qemu_fdatasync(aiocb->aio_fildes);
if (ret == -1)
return -errno;
return 0;
}
#ifdef CONFIG_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
static ssize_t handle_aiocb_rw_vector(struct qemu_paiocb *aiocb)
{
size_t offset = 0;
ssize_t len;
do {
if (aiocb->aio_type & QEMU_AIO_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 ssize_t handle_aiocb_rw_linear(struct qemu_paiocb *aiocb, char *buf)
{
ssize_t offset = 0;
ssize_t len;
while (offset < aiocb->aio_nbytes) {
if (aiocb->aio_type & QEMU_AIO_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 ssize_t handle_aiocb_rw(struct qemu_paiocb *aiocb)
{
ssize_t nbytes;
char *buf;
if (!(aiocb->aio_type & QEMU_AIO_MISALIGNED)) {
/*
* 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_blockalign(aiocb->common.bs, aiocb->aio_nbytes);
if (aiocb->aio_type & QEMU_AIO_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_AIO_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;
pid = getpid();
while (1) {
struct qemu_paiocb *aiocb;
ssize_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 (QTAILQ_EMPTY(&request_list) &&
!(ret == ETIMEDOUT)) {
ret = cond_timedwait(&cond, &lock, &ts);
}
if (QTAILQ_EMPTY(&request_list))
break;
aiocb = QTAILQ_FIRST(&request_list);
QTAILQ_REMOVE(&request_list, aiocb, node);
aiocb->active = 1;
idle_threads--;
mutex_unlock(&lock);
switch (aiocb->aio_type & QEMU_AIO_TYPE_MASK) {
case QEMU_AIO_READ:
case QEMU_AIO_WRITE:
ret = handle_aiocb_rw(aiocb);
break;
case QEMU_AIO_FLUSH:
ret = handle_aiocb_flush(aiocb);
break;
case QEMU_AIO_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)
{
sigset_t set, oldset;
cur_threads++;
idle_threads++;
/* block all signals */
if (sigfillset(&set)) die("sigfillset");
if (sigprocmask(SIG_SETMASK, &set, &oldset)) die("sigprocmask");
thread_create(&thread_id, &attr, aio_thread, NULL);
if (sigprocmask(SIG_SETMASK, &oldset, NULL)) die("sigprocmask restore");
}
static void qemu_paio_submit(struct qemu_paiocb *aiocb)
{
aiocb->ret = -EINPROGRESS;
aiocb->active = 0;
mutex_lock(&lock);
if (idle_threads == 0 && cur_threads < max_threads)
spawn_thread();
QTAILQ_INSERT_TAIL(&request_list, aiocb, node);
mutex_unlock(&lock);
cond_signal(&cond);
}
static ssize_t qemu_paio_return(struct qemu_paiocb *aiocb)
{
ssize_t ret;
mutex_lock(&lock);
ret = aiocb->ret;
mutex_unlock(&lock);
return ret;
}
static 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;
}
static int posix_aio_process_queue(void *opaque)
{
PosixAioState *s = opaque;
struct qemu_paiocb *acb, **pacb;
int ret;
int result = 0;
int async_context_id = get_async_context_id();
for(;;) {
pacb = &s->first_aio;
for(;;) {
acb = *pacb;
if (!acb)
return result;
/* we're only interested in requests in the right context */
if (acb->async_context_id != async_context_id) {
pacb = &acb->next;
continue;
}
ret = qemu_paio_error(acb);
if (ret == ECANCELED) {
/* remove the request */
*pacb = acb->next;
qemu_aio_release(acb);
result = 1;
} else if (ret != EINPROGRESS) {
/* end of aio */
if (ret == 0) {
ret = qemu_paio_return(acb);
if (ret == acb->aio_nbytes)
ret = 0;
else
ret = -EINVAL;
} else {
ret = -ret;
}
/* remove the request */
*pacb = acb->next;
/* call the callback */
acb->common.cb(acb->common.opaque, ret);
qemu_aio_release(acb);
result = 1;
break;
} else {
pacb = &acb->next;
}
}
}
return result;
}
static void posix_aio_read(void *opaque)
{
PosixAioState *s = opaque;
union {
struct qemu_signalfd_siginfo siginfo;
char buf[128];
} sig;
size_t offset;
/* try to read from signalfd, don't freak out if we can't read anything */
offset = 0;
while (offset < 128) {
ssize_t len;
len = read(s->fd, sig.buf + offset, 128 - offset);
if (len == -1 && errno == EINTR)
continue;
if (len == -1 && errno == EAGAIN) {
/* there is no natural reason for this to happen,
* so we'll spin hard until we get everything just
* to be on the safe side. */
if (offset > 0)
continue;
}
offset += len;
}
posix_aio_process_queue(s);
}
static int posix_aio_flush(void *opaque)
{
PosixAioState *s = opaque;
return !!s->first_aio;
}
static PosixAioState *posix_aio_state;
static void paio_remove(struct qemu_paiocb *acb)
{
struct qemu_paiocb **pacb;
/* remove the callback from the queue */
pacb = &posix_aio_state->first_aio;
for(;;) {
if (*pacb == NULL) {
fprintf(stderr, "paio_remove: aio request not found!\n");
break;
} else if (*pacb == acb) {
*pacb = acb->next;
qemu_aio_release(acb);
break;
}
pacb = &(*pacb)->next;
}
}
static void paio_cancel(BlockDriverAIOCB *blockacb)
{
struct qemu_paiocb *acb = (struct qemu_paiocb *)blockacb;
int active = 0;
mutex_lock(&lock);
if (!acb->active) {
QTAILQ_REMOVE(&request_list, acb, node);
acb->ret = -ECANCELED;
} else if (acb->ret == -EINPROGRESS) {
active = 1;
}
mutex_unlock(&lock);
if (active) {
/* fail safe: if the aio could not be canceled, we wait for
it */
while (qemu_paio_error(acb) == EINPROGRESS)
;
}
paio_remove(acb);
}
static AIOPool raw_aio_pool = {
.aiocb_size = sizeof(struct qemu_paiocb),
.cancel = paio_cancel,
};
BlockDriverAIOCB *paio_submit(BlockDriverState *bs, int fd,
int64_t sector_num, QEMUIOVector *qiov, int nb_sectors,
BlockDriverCompletionFunc *cb, void *opaque, int type)
{
struct qemu_paiocb *acb;
acb = qemu_aio_get(&raw_aio_pool, bs, cb, opaque);
if (!acb)
return NULL;
acb->aio_type = type;
acb->aio_fildes = fd;
acb->ev_signo = SIGUSR2;
acb->async_context_id = get_async_context_id();
if (qiov) {
acb->aio_iov = qiov->iov;
acb->aio_niov = qiov->niov;
}
acb->aio_nbytes = nb_sectors * 512;
acb->aio_offset = sector_num * 512;
acb->next = posix_aio_state->first_aio;
posix_aio_state->first_aio = acb;
trace_paio_submit(acb, opaque, sector_num, nb_sectors, type);
qemu_paio_submit(acb);
return &acb->common;
}
BlockDriverAIOCB *paio_ioctl(BlockDriverState *bs, int fd,
unsigned long int req, void *buf,
BlockDriverCompletionFunc *cb, void *opaque)
{
struct qemu_paiocb *acb;
acb = qemu_aio_get(&raw_aio_pool, bs, cb, opaque);
if (!acb)
return NULL;
acb->aio_type = QEMU_AIO_IOCTL;
acb->aio_fildes = fd;
acb->ev_signo = SIGUSR2;
acb->async_context_id = get_async_context_id();
acb->aio_offset = 0;
acb->aio_ioctl_buf = buf;
acb->aio_ioctl_cmd = req;
acb->next = posix_aio_state->first_aio;
posix_aio_state->first_aio = acb;
qemu_paio_submit(acb);
return &acb->common;
}
int paio_init(void)
{
sigset_t mask;
PosixAioState *s;
int ret;
if (posix_aio_state)
return 0;
s = qemu_malloc(sizeof(PosixAioState));
/* Make sure to block AIO signal */
sigemptyset(&mask);
sigaddset(&mask, SIGUSR2);
sigprocmask(SIG_BLOCK, &mask, NULL);
s->first_aio = NULL;
s->fd = qemu_signalfd(&mask);
if (s->fd == -1) {
fprintf(stderr, "failed to create signalfd\n");
return -1;
}
fcntl(s->fd, F_SETFL, O_NONBLOCK);
qemu_aio_set_fd_handler(s->fd, posix_aio_read, NULL, posix_aio_flush,
posix_aio_process_queue, s);
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");
QTAILQ_INIT(&request_list);
posix_aio_state = s;
return 0;
}
Jump to Line
Something went wrong with that request. Please try again.