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qemu/posix-aio-compat.c
Paolo Bonzini 47e6b251a5 block: switch posix-aio-compat to threadpool 
This is not meant for portability, but to remove code duplication.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2012-10-31 10:38:12 +01:00

330 lines
8.5 KiB
C
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/*
* 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.
*
* Contributions after 2012-01-13 are licensed under the terms of the
* GNU GPL, version 2 or (at your option) any later version.
*/
#include <sys/ioctl.h>
#include <sys/types.h>
#include <pthread.h>
#include <unistd.h>
#include <errno.h>
#include <time.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 "thread-pool.h"
#include "block_int.h"
#include "iov.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 */
off_t aio_offset;
int aio_type;
};
#ifdef CONFIG_PREADV
static int preadv_present = 1;
#else
static int preadv_present = 0;
#endif
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 considers a request
* successful if it has written the 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)
{
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);
else
len = qemu_preadv(aiocb->aio_fildes,
aiocb->aio_iov,
aiocb->aio_niov,
aiocb->aio_offset);
} while (len == -1 && errno == EINTR);
if (len == -1)
return -errno;
return len;
}
/*
* Read/writes the data to/from a given linear buffer.
*
* Returns the number of bytes handles or -errno in case of an error. Short
* reads are only returned if the end of the file is reached.
*/
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 int aio_worker(void *arg)
{
struct qemu_paiocb *aiocb = arg;
ssize_t ret = 0;
switch (aiocb->aio_type & QEMU_AIO_TYPE_MASK) {
case QEMU_AIO_READ:
ret = handle_aiocb_rw(aiocb);
if (ret >= 0 && ret < aiocb->aio_nbytes && aiocb->common.bs->growable) {
/* A short read means that we have reached EOF. Pad the buffer
* with zeros for bytes after EOF. */
iov_memset(aiocb->aio_iov, aiocb->aio_niov, ret,
0, aiocb->aio_nbytes - ret);
ret = aiocb->aio_nbytes;
}
if (ret == aiocb->aio_nbytes) {
ret = 0;
} else if (ret >= 0 && ret < aiocb->aio_nbytes) {
ret = -EINVAL;
}
break;
case QEMU_AIO_WRITE:
ret = handle_aiocb_rw(aiocb);
if (ret == aiocb->aio_nbytes) {
ret = 0;
} else if (ret >= 0 && ret < aiocb->aio_nbytes) {
ret = -EINVAL;
}
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;
}
qemu_aio_release(aiocb);
return ret;
}
static AIOPool raw_aio_pool = {
.aiocb_size = sizeof(struct qemu_paiocb),
};
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);
acb->aio_type = type;
acb->aio_fildes = fd;
if (qiov) {
acb->aio_iov = qiov->iov;
acb->aio_niov = qiov->niov;
}
acb->aio_nbytes = nb_sectors * 512;
acb->aio_offset = sector_num * 512;
trace_paio_submit(acb, opaque, sector_num, nb_sectors, type);
return thread_pool_submit_aio(aio_worker, acb, cb, opaque);
}
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);
acb->aio_type = QEMU_AIO_IOCTL;
acb->aio_fildes = fd;
acb->aio_offset = 0;
acb->aio_ioctl_buf = buf;
acb->aio_ioctl_cmd = req;
return thread_pool_submit_aio(aio_worker, acb, cb, opaque);
}
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