aboutsummaryrefslogtreecommitdiff
path: root/block/null.c
blob: d90165dea7c40a6ef419c1d04277ea6edeebd78e (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
/*
 * 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 "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);