--- /dev/null
+/*
+ * 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 "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);
Code Review / kvmfornfv.git / blobdiff