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/*
* Null block driver
*
* Authors:
* Fam Zheng <famz@redhat.com>
*
* Copyright (C) 2014 Red Hat, Inc.
*
* This work is licensed under the terms of the GNU GPL, version 2 or later.
* See the COPYING file in the top-level directory.
*/
#include "qemu/osdep.h"
#include "qapi/error.h"
#include "block/block_int.h"
#define NULL_OPT_LATENCY "latency-ns"
typedef struct {
int64_t length;
int64_t latency_ns;
} BDRVNullState;
static QemuOptsList runtime_opts = {
.name = "null",
.head = QTAILQ_HEAD_INITIALIZER(runtime_opts.head),
.desc = {
{
.name = "filename",
.type = QEMU_OPT_STRING,
.help = "",
},
{
.name = BLOCK_OPT_SIZE,
.type = QEMU_OPT_SIZE,
.help = "size of the null block",
},
{
.name = NULL_OPT_LATENCY,
.type = QEMU_OPT_NUMBER,
.help = "nanoseconds (approximated) to wait "
"before completing request",
},
{ /* end of list */ }
},
};
static int null_file_open(BlockDriverState *bs, QDict *options, int flags,
Error **errp)
{
QemuOpts *opts;
BDRVNullState *s = bs->opaque;
int ret = 0;
opts = qemu_opts_create(&runtime_opts, NULL, 0, &error_abort);
qemu_opts_absorb_qdict(opts, options, &error_abort);
s->length =
qemu_opt_get_size(opts, BLOCK_OPT_SIZE, 1 << 30);
s->latency_ns =
qemu_opt_get_number(opts, NULL_OPT_LATENCY, 0);
if (s->latency_ns < 0) {
error_setg(errp, "latency-ns is invalid");
ret = -EINVAL;
}
qemu_opts_del(opts);
return ret;
}
static void null_close(BlockDriverState *bs)
{
}
static int64_t null_getlength(BlockDriverState *bs)
{
BDRVNullState *s = bs->opaque;
return s->length;
}
static coroutine_fn int null_co_common(BlockDriverState *bs)
{
BDRVNullState *s = bs->opaque;
if (s->latency_ns) {
co_aio_sleep_ns(bdrv_get_aio_context(bs), QEMU_CLOCK_REALTIME,
s->latency_ns);
}
return 0;
}
static coroutine_fn int null_co_readv(BlockDriverState *bs,
int64_t sector_num, int nb_sectors,
QEMUIOVector *qiov)
{
return null_co_common(bs);
}
static coroutine_fn int null_co_writev(BlockDriverState *bs,
int64_t sector_num, int nb_sectors,
QEMUIOVector *qiov)
{
return null_co_common(bs);
}
static coroutine_fn int null_co_flush(BlockDriverState *bs)
{
return null_co_common(bs);
}
typedef struct {
BlockAIOCB common;
QEMUBH *bh;
QEMUTimer timer;
} NullAIOCB;
static const AIOCBInfo null_aiocb_info = {
.aiocb_size = sizeof(NullAIOCB),
};
static void null_bh_cb(void *opaque)
{
NullAIOCB *acb = opaque;
acb->common.cb(acb->common.opaque, 0);
qemu_bh_delete(acb->bh);
qemu_aio_unref(acb);
}
static void null_timer_cb(void *opaque)
{
NullAIOCB *acb = opaque;
acb->common.cb(acb->common.opaque, 0);
timer_deinit(&acb->timer);
qemu_aio_unref(acb);
}
static inline BlockAIOCB *null_aio_common(BlockDriverState *bs,
BlockCompletionFunc *cb,
void *opaque)
{
NullAIOCB *acb;
BDRVNullState *s = bs->opaque;
acb = qemu_aio_get(&null_aiocb_info, bs, cb, opaque);
/* Only emulate latency after vcpu is running. */
if (s->latency_ns) {
aio_timer_init(bdrv_get_aio_context(bs), &acb->timer,
QEMU_CLOCK_REALTIME, SCALE_NS,
null_timer_cb, acb);
timer_mod_ns(&acb->timer,
qemu_clock_get_ns(QEMU_CLOCK_REALTIME) + s->latency_ns);
} else {
acb->bh = aio_bh_new(bdrv_get_aio_context(bs), null_bh_cb, acb);
qemu_bh_schedule(acb->bh);
}
return &acb->common;
}
static BlockAIOCB *null_aio_readv(BlockDriverState *bs,
int64_t sector_num, QEMUIOVector *qiov,
int nb_sectors,
BlockCompletionFunc *cb,
void *opaque)
{
return null_aio_common(bs, cb, opaque);
}
static BlockAIOCB *null_aio_writev(BlockDriverState *bs,
int64_t sector_num, QEMUIOVector *qiov,
int nb_sectors,
BlockCompletionFunc *cb,
void *opaque)
{
return null_aio_common(bs, cb, opaque);
}
static BlockAIOCB *null_aio_flush(BlockDriverState *bs,
BlockCompletionFunc *cb,
void *opaque)
{
return null_aio_common(bs, cb, opaque);
}
static int null_reopen_prepare(BDRVReopenState *reopen_state,
BlockReopenQueue *queue, Error **errp)
{
return 0;
}
static BlockDriver bdrv_null_co = {
.format_name = "null-co",
.protocol_name = "null-co",
.instance_size = sizeof(BDRVNullState),
.bdrv_file_open = null_file_open,
.bdrv_close = null_close,
.bdrv_getlength = null_getlength,
.bdrv_co_readv = null_co_readv,
.bdrv_co_writev = null_co_writev,
.bdrv_co_flush_to_disk = null_co_flush,
.bdrv_reopen_prepare = null_reopen_prepare,
};
static BlockDriver bdrv_null_aio = {
.format_name = "null-aio",
.protocol_name = "null-aio",
.instance_size = sizeof(BDRVNullState),
.bdrv_file_open = null_file_open,
.bdrv_close = null_close,
.bdrv_getlength = null_getlength,
.bdrv_aio_readv = null_aio_readv,
.bdrv_aio_writev = null_aio_writev,
.bdrv_aio_flush = null_aio_flush,
.bdrv_reopen_prepare = null_reopen_prepare,
};
static void bdrv_null_init(void)
{
bdrv_register(&bdrv_null_co);
bdrv_register(&bdrv_null_aio);
}
block_init(bdrv_null_init);
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