qemu/block/null.c
Vladimir Sementsov-Ogievskiy e75abedab7 block: use int64_t instead of uint64_t in driver write handlers
We are generally moving to int64_t for both offset and bytes parameters
on all io paths.

Main motivation is realization of 64-bit write_zeroes operation for
fast zeroing large disk chunks, up to the whole disk.

We chose signed type, to be consistent with off_t (which is signed) and
with possibility for signed return type (where negative value means
error).

So, convert driver write handlers parameters which are already 64bit to
signed type.

While being here, convert also flags parameter to be BdrvRequestFlags.

Now let's consider all callers. Simple

  git grep '\->bdrv_\(aio\|co\)_pwritev\(_part\)\?'

shows that's there three callers of driver function:

 bdrv_driver_pwritev() and bdrv_driver_pwritev_compressed() in
 block/io.c, both pass int64_t, checked by bdrv_check_qiov_request() to
 be non-negative.

 qcow2_save_vmstate() does bdrv_check_qiov_request().

Still, the functions may be called directly, not only by drv->...
Let's check:

git grep '\.bdrv_\(aio\|co\)_pwritev\(_part\)\?\s*=' | \
awk '{print $4}' | sed 's/,//' | sed 's/&//' | sort | uniq | \
while read func; do git grep "$func(" | \
grep -v "$func(BlockDriverState"; done

shows several callers:

qcow2:
  qcow2_co_truncate() write at most up to @offset, which is checked in
    generic qcow2_co_truncate() by bdrv_check_request().
  qcow2_co_pwritev_compressed_task() pass the request (or part of the
    request) that already went through normal write path, so it should
    be OK

qcow:
  qcow_co_pwritev_compressed() pass int64_t, it's updated by this patch

quorum:
  quorum_co_pwrite_zeroes() pass int64_t and int - OK

throttle:
  throttle_co_pwritev_compressed() pass int64_t, it's updated by this
  patch

vmdk:
  vmdk_co_pwritev_compressed() pass int64_t, it's updated by this
  patch

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20210903102807.27127-5-vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
2021-09-29 13:46:31 -05:00

328 lines
9.2 KiB
C

/*
* 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 "qapi/qmp/qdict.h"
#include "qapi/qmp/qstring.h"
#include "qemu/module.h"
#include "qemu/option.h"
#include "block/block_int.h"
#include "sysemu/replay.h"
#define NULL_OPT_LATENCY "latency-ns"
#define NULL_OPT_ZEROES "read-zeroes"
typedef struct {
int64_t length;
int64_t latency_ns;
bool read_zeroes;
} BDRVNullState;
static QemuOptsList runtime_opts = {
.name = "null",
.head = QTAILQ_HEAD_INITIALIZER(runtime_opts.head),
.desc = {
{
.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",
},
{
.name = NULL_OPT_ZEROES,
.type = QEMU_OPT_BOOL,
.help = "return zeroes when read",
},
{ /* end of list */ }
},
};
static void null_co_parse_filename(const char *filename, QDict *options,
Error **errp)
{
/* This functions only exists so that a null-co:// filename is accepted
* with the null-co driver. */
if (strcmp(filename, "null-co://")) {
error_setg(errp, "The only allowed filename for this driver is "
"'null-co://'");
return;
}
}
static void null_aio_parse_filename(const char *filename, QDict *options,
Error **errp)
{
/* This functions only exists so that a null-aio:// filename is accepted
* with the null-aio driver. */
if (strcmp(filename, "null-aio://")) {
error_setg(errp, "The only allowed filename for this driver is "
"'null-aio://'");
return;
}
}
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;
}
s->read_zeroes = qemu_opt_get_bool(opts, NULL_OPT_ZEROES, false);
qemu_opts_del(opts);
bs->supported_write_flags = BDRV_REQ_FUA;
return ret;
}
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) {
qemu_co_sleep_ns(QEMU_CLOCK_REALTIME, s->latency_ns);
}
return 0;
}
static coroutine_fn int null_co_preadv(BlockDriverState *bs,
int64_t offset, int64_t bytes,
QEMUIOVector *qiov,
BdrvRequestFlags flags)
{
BDRVNullState *s = bs->opaque;
if (s->read_zeroes) {
qemu_iovec_memset(qiov, 0, 0, bytes);
}
return null_co_common(bs);
}
static coroutine_fn int null_co_pwritev(BlockDriverState *bs,
int64_t offset, int64_t bytes,
QEMUIOVector *qiov,
BdrvRequestFlags flags)
{
return null_co_common(bs);
}
static coroutine_fn int null_co_flush(BlockDriverState *bs)
{
return null_co_common(bs);
}
typedef struct {
BlockAIOCB common;
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_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 {
replay_bh_schedule_oneshot_event(bdrv_get_aio_context(bs),
null_bh_cb, acb);
}
return &acb->common;
}
static BlockAIOCB *null_aio_preadv(BlockDriverState *bs,
int64_t offset, int64_t bytes,
QEMUIOVector *qiov, BdrvRequestFlags flags,
BlockCompletionFunc *cb,
void *opaque)
{
BDRVNullState *s = bs->opaque;
if (s->read_zeroes) {
qemu_iovec_memset(qiov, 0, 0, bytes);
}
return null_aio_common(bs, cb, opaque);
}
static BlockAIOCB *null_aio_pwritev(BlockDriverState *bs,
int64_t offset, int64_t bytes,
QEMUIOVector *qiov, BdrvRequestFlags flags,
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 int coroutine_fn null_co_block_status(BlockDriverState *bs,
bool want_zero, int64_t offset,
int64_t bytes, int64_t *pnum,
int64_t *map,
BlockDriverState **file)
{
BDRVNullState *s = bs->opaque;
int ret = BDRV_BLOCK_OFFSET_VALID;
*pnum = bytes;
*map = offset;
*file = bs;
if (s->read_zeroes) {
ret |= BDRV_BLOCK_ZERO;
}
return ret;
}
static void null_refresh_filename(BlockDriverState *bs)
{
const QDictEntry *e;
for (e = qdict_first(bs->full_open_options); e;
e = qdict_next(bs->full_open_options, e))
{
/* These options can be ignored */
if (strcmp(qdict_entry_key(e), "filename") &&
strcmp(qdict_entry_key(e), "driver") &&
strcmp(qdict_entry_key(e), NULL_OPT_LATENCY))
{
return;
}
}
snprintf(bs->exact_filename, sizeof(bs->exact_filename), "%s://",
bs->drv->format_name);
}
static int64_t null_allocated_file_size(BlockDriverState *bs)
{
return 0;
}
static const char *const null_strong_runtime_opts[] = {
BLOCK_OPT_SIZE,
NULL_OPT_ZEROES,
NULL
};
static BlockDriver bdrv_null_co = {
.format_name = "null-co",
.protocol_name = "null-co",
.instance_size = sizeof(BDRVNullState),
.bdrv_file_open = null_file_open,
.bdrv_parse_filename = null_co_parse_filename,
.bdrv_getlength = null_getlength,
.bdrv_get_allocated_file_size = null_allocated_file_size,
.bdrv_co_preadv = null_co_preadv,
.bdrv_co_pwritev = null_co_pwritev,
.bdrv_co_flush_to_disk = null_co_flush,
.bdrv_reopen_prepare = null_reopen_prepare,
.bdrv_co_block_status = null_co_block_status,
.bdrv_refresh_filename = null_refresh_filename,
.strong_runtime_opts = null_strong_runtime_opts,
};
static BlockDriver bdrv_null_aio = {
.format_name = "null-aio",
.protocol_name = "null-aio",
.instance_size = sizeof(BDRVNullState),
.bdrv_file_open = null_file_open,
.bdrv_parse_filename = null_aio_parse_filename,
.bdrv_getlength = null_getlength,
.bdrv_get_allocated_file_size = null_allocated_file_size,
.bdrv_aio_preadv = null_aio_preadv,
.bdrv_aio_pwritev = null_aio_pwritev,
.bdrv_aio_flush = null_aio_flush,
.bdrv_reopen_prepare = null_reopen_prepare,
.bdrv_co_block_status = null_co_block_status,
.bdrv_refresh_filename = null_refresh_filename,
.strong_runtime_opts = null_strong_runtime_opts,
};
static void bdrv_null_init(void)
{
bdrv_register(&bdrv_null_co);
bdrv_register(&bdrv_null_aio);
}
block_init(bdrv_null_init);