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Fam Zhenge819ab22014-09-11 14:09:56 +08001/*
2 * Null block driver
3 *
4 * Authors:
5 * Fam Zheng <famz@redhat.com>
6 *
7 * Copyright (C) 2014 Red Hat, Inc.
8 *
9 * This work is licensed under the terms of the GNU GPL, version 2 or later.
10 * See the COPYING file in the top-level directory.
11 */
12
Peter Maydell80c71a22016-01-18 18:01:42 +000013#include "qemu/osdep.h"
Markus Armbrusterda34e652016-03-14 09:01:28 +010014#include "qapi/error.h"
Max Reitz67882b12016-06-10 20:57:48 +020015#include "qapi/qmp/qdict.h"
16#include "qapi/qmp/qstring.h"
Markus Armbruster0b8fa322019-05-23 16:35:07 +020017#include "qemu/module.h"
Markus Armbruster922a01a2018-02-01 12:18:46 +010018#include "qemu/option.h"
Fam Zhenge819ab22014-09-11 14:09:56 +080019#include "block/block_int.h"
Pavel Dovgalyuke4ec5ad2019-09-17 14:58:19 +030020#include "sysemu/replay.h"
Fam Zhenge819ab22014-09-11 14:09:56 +080021
Fam Zhenge5e51dd2015-04-01 09:45:38 +080022#define NULL_OPT_LATENCY "latency-ns"
Max Reitzcd219eb2016-03-24 23:33:58 +010023#define NULL_OPT_ZEROES "read-zeroes"
Fam Zhenge5e51dd2015-04-01 09:45:38 +080024
Fam Zhenge819ab22014-09-11 14:09:56 +080025typedef struct {
26 int64_t length;
Fam Zhenge5e51dd2015-04-01 09:45:38 +080027 int64_t latency_ns;
Max Reitzcd219eb2016-03-24 23:33:58 +010028 bool read_zeroes;
Fam Zhenge819ab22014-09-11 14:09:56 +080029} BDRVNullState;
30
31static QemuOptsList runtime_opts = {
32 .name = "null",
33 .head = QTAILQ_HEAD_INITIALIZER(runtime_opts.head),
34 .desc = {
35 {
Fam Zhenge819ab22014-09-11 14:09:56 +080036 .name = BLOCK_OPT_SIZE,
37 .type = QEMU_OPT_SIZE,
38 .help = "size of the null block",
39 },
Fam Zhenge5e51dd2015-04-01 09:45:38 +080040 {
41 .name = NULL_OPT_LATENCY,
42 .type = QEMU_OPT_NUMBER,
43 .help = "nanoseconds (approximated) to wait "
44 "before completing request",
45 },
Max Reitzcd219eb2016-03-24 23:33:58 +010046 {
47 .name = NULL_OPT_ZEROES,
48 .type = QEMU_OPT_BOOL,
49 .help = "return zeroes when read",
50 },
Fam Zhenge819ab22014-09-11 14:09:56 +080051 { /* end of list */ }
52 },
53};
54
Kevin Wolf809eb702017-08-04 12:44:22 +020055static void null_co_parse_filename(const char *filename, QDict *options,
56 Error **errp)
57{
58 /* This functions only exists so that a null-co:// filename is accepted
59 * with the null-co driver. */
60 if (strcmp(filename, "null-co://")) {
61 error_setg(errp, "The only allowed filename for this driver is "
62 "'null-co://'");
63 return;
64 }
65}
66
67static void null_aio_parse_filename(const char *filename, QDict *options,
68 Error **errp)
69{
70 /* This functions only exists so that a null-aio:// filename is accepted
71 * with the null-aio driver. */
72 if (strcmp(filename, "null-aio://")) {
73 error_setg(errp, "The only allowed filename for this driver is "
74 "'null-aio://'");
75 return;
76 }
77}
78
Fam Zhenge819ab22014-09-11 14:09:56 +080079static int null_file_open(BlockDriverState *bs, QDict *options, int flags,
80 Error **errp)
81{
82 QemuOpts *opts;
83 BDRVNullState *s = bs->opaque;
Fam Zhenge5e51dd2015-04-01 09:45:38 +080084 int ret = 0;
Fam Zhenge819ab22014-09-11 14:09:56 +080085
86 opts = qemu_opts_create(&runtime_opts, NULL, 0, &error_abort);
87 qemu_opts_absorb_qdict(opts, options, &error_abort);
88 s->length =
89 qemu_opt_get_size(opts, BLOCK_OPT_SIZE, 1 << 30);
Fam Zhenge5e51dd2015-04-01 09:45:38 +080090 s->latency_ns =
91 qemu_opt_get_number(opts, NULL_OPT_LATENCY, 0);
92 if (s->latency_ns < 0) {
93 error_setg(errp, "latency-ns is invalid");
94 ret = -EINVAL;
95 }
Max Reitzcd219eb2016-03-24 23:33:58 +010096 s->read_zeroes = qemu_opt_get_bool(opts, NULL_OPT_ZEROES, false);
Fam Zhenge819ab22014-09-11 14:09:56 +080097 qemu_opts_del(opts);
Eric Blakeb3241e92018-04-24 14:25:03 -050098 bs->supported_write_flags = BDRV_REQ_FUA;
Fam Zhenge5e51dd2015-04-01 09:45:38 +080099 return ret;
Fam Zhenge819ab22014-09-11 14:09:56 +0800100}
101
Fam Zhenge819ab22014-09-11 14:09:56 +0800102static int64_t null_getlength(BlockDriverState *bs)
103{
104 BDRVNullState *s = bs->opaque;
105 return s->length;
106}
107
Fam Zhenge5e51dd2015-04-01 09:45:38 +0800108static coroutine_fn int null_co_common(BlockDriverState *bs)
109{
110 BDRVNullState *s = bs->opaque;
111
112 if (s->latency_ns) {
Stefan Hajnoczi78f1d3d2017-11-09 10:26:52 +0000113 qemu_co_sleep_ns(QEMU_CLOCK_REALTIME, s->latency_ns);
Fam Zhenge5e51dd2015-04-01 09:45:38 +0800114 }
115 return 0;
116}
117
Eric Blakeb3241e92018-04-24 14:25:03 -0500118static coroutine_fn int null_co_preadv(BlockDriverState *bs,
Vladimir Sementsov-Ogievskiyf7ef38d2021-09-03 13:27:59 +0300119 int64_t offset, int64_t bytes,
120 QEMUIOVector *qiov,
121 BdrvRequestFlags flags)
Fam Zhenge819ab22014-09-11 14:09:56 +0800122{
Max Reitzcd219eb2016-03-24 23:33:58 +0100123 BDRVNullState *s = bs->opaque;
124
125 if (s->read_zeroes) {
Eric Blakeb3241e92018-04-24 14:25:03 -0500126 qemu_iovec_memset(qiov, 0, 0, bytes);
Max Reitzcd219eb2016-03-24 23:33:58 +0100127 }
128
Fam Zhenge5e51dd2015-04-01 09:45:38 +0800129 return null_co_common(bs);
Fam Zhenge819ab22014-09-11 14:09:56 +0800130}
131
Eric Blakeb3241e92018-04-24 14:25:03 -0500132static coroutine_fn int null_co_pwritev(BlockDriverState *bs,
Vladimir Sementsov-Ogievskiye75abed2021-09-03 13:28:00 +0300133 int64_t offset, int64_t bytes,
134 QEMUIOVector *qiov,
135 BdrvRequestFlags flags)
Fam Zhenge819ab22014-09-11 14:09:56 +0800136{
Fam Zhenge5e51dd2015-04-01 09:45:38 +0800137 return null_co_common(bs);
Fam Zhenge819ab22014-09-11 14:09:56 +0800138}
139
140static coroutine_fn int null_co_flush(BlockDriverState *bs)
141{
Fam Zhenge5e51dd2015-04-01 09:45:38 +0800142 return null_co_common(bs);
Fam Zhenge819ab22014-09-11 14:09:56 +0800143}
144
145typedef struct {
Markus Armbruster7c84b1b2014-10-07 13:59:14 +0200146 BlockAIOCB common;
Fam Zhenge5e51dd2015-04-01 09:45:38 +0800147 QEMUTimer timer;
Fam Zhenge819ab22014-09-11 14:09:56 +0800148} NullAIOCB;
149
150static const AIOCBInfo null_aiocb_info = {
151 .aiocb_size = sizeof(NullAIOCB),
152};
153
154static void null_bh_cb(void *opaque)
155{
156 NullAIOCB *acb = opaque;
157 acb->common.cb(acb->common.opaque, 0);
Fam Zhenge819ab22014-09-11 14:09:56 +0800158 qemu_aio_unref(acb);
159}
160
Fam Zhenge5e51dd2015-04-01 09:45:38 +0800161static void null_timer_cb(void *opaque)
162{
163 NullAIOCB *acb = opaque;
164 acb->common.cb(acb->common.opaque, 0);
165 timer_deinit(&acb->timer);
166 qemu_aio_unref(acb);
167}
168
Markus Armbruster7c84b1b2014-10-07 13:59:14 +0200169static inline BlockAIOCB *null_aio_common(BlockDriverState *bs,
Markus Armbruster097310b2014-10-07 13:59:15 +0200170 BlockCompletionFunc *cb,
Markus Armbruster7c84b1b2014-10-07 13:59:14 +0200171 void *opaque)
Fam Zhenge819ab22014-09-11 14:09:56 +0800172{
173 NullAIOCB *acb;
Fam Zhenge5e51dd2015-04-01 09:45:38 +0800174 BDRVNullState *s = bs->opaque;
Fam Zhenge819ab22014-09-11 14:09:56 +0800175
176 acb = qemu_aio_get(&null_aiocb_info, bs, cb, opaque);
Fam Zhenge5e51dd2015-04-01 09:45:38 +0800177 /* Only emulate latency after vcpu is running. */
178 if (s->latency_ns) {
179 aio_timer_init(bdrv_get_aio_context(bs), &acb->timer,
180 QEMU_CLOCK_REALTIME, SCALE_NS,
181 null_timer_cb, acb);
182 timer_mod_ns(&acb->timer,
183 qemu_clock_get_ns(QEMU_CLOCK_REALTIME) + s->latency_ns);
184 } else {
Pavel Dovgalyuke4ec5ad2019-09-17 14:58:19 +0300185 replay_bh_schedule_oneshot_event(bdrv_get_aio_context(bs),
186 null_bh_cb, acb);
Fam Zhenge5e51dd2015-04-01 09:45:38 +0800187 }
Fam Zhenge819ab22014-09-11 14:09:56 +0800188 return &acb->common;
189}
190
Eric Blakeb3241e92018-04-24 14:25:03 -0500191static BlockAIOCB *null_aio_preadv(BlockDriverState *bs,
Vladimir Sementsov-Ogievskiyf7ef38d2021-09-03 13:27:59 +0300192 int64_t offset, int64_t bytes,
193 QEMUIOVector *qiov, BdrvRequestFlags flags,
Eric Blakeb3241e92018-04-24 14:25:03 -0500194 BlockCompletionFunc *cb,
195 void *opaque)
Fam Zhenge819ab22014-09-11 14:09:56 +0800196{
Max Reitzcd219eb2016-03-24 23:33:58 +0100197 BDRVNullState *s = bs->opaque;
198
199 if (s->read_zeroes) {
Eric Blakeb3241e92018-04-24 14:25:03 -0500200 qemu_iovec_memset(qiov, 0, 0, bytes);
Max Reitzcd219eb2016-03-24 23:33:58 +0100201 }
202
Fam Zhenge819ab22014-09-11 14:09:56 +0800203 return null_aio_common(bs, cb, opaque);
204}
205
Eric Blakeb3241e92018-04-24 14:25:03 -0500206static BlockAIOCB *null_aio_pwritev(BlockDriverState *bs,
Vladimir Sementsov-Ogievskiye75abed2021-09-03 13:28:00 +0300207 int64_t offset, int64_t bytes,
208 QEMUIOVector *qiov, BdrvRequestFlags flags,
Eric Blakeb3241e92018-04-24 14:25:03 -0500209 BlockCompletionFunc *cb,
210 void *opaque)
Fam Zhenge819ab22014-09-11 14:09:56 +0800211{
212 return null_aio_common(bs, cb, opaque);
213}
214
Markus Armbruster7c84b1b2014-10-07 13:59:14 +0200215static BlockAIOCB *null_aio_flush(BlockDriverState *bs,
Markus Armbruster097310b2014-10-07 13:59:15 +0200216 BlockCompletionFunc *cb,
Markus Armbruster7c84b1b2014-10-07 13:59:14 +0200217 void *opaque)
Fam Zhenge819ab22014-09-11 14:09:56 +0800218{
219 return null_aio_common(bs, cb, opaque);
220}
221
Fam Zheng1c2b49a2015-04-01 09:45:39 +0800222static int null_reopen_prepare(BDRVReopenState *reopen_state,
223 BlockReopenQueue *queue, Error **errp)
224{
225 return 0;
226}
227
Eric Blake05c33f12018-02-13 14:26:49 -0600228static int coroutine_fn null_co_block_status(BlockDriverState *bs,
229 bool want_zero, int64_t offset,
230 int64_t bytes, int64_t *pnum,
231 int64_t *map,
232 BlockDriverState **file)
Max Reitza9063922016-03-24 23:33:59 +0100233{
234 BDRVNullState *s = bs->opaque;
Eric Blake05c33f12018-02-13 14:26:49 -0600235 int ret = BDRV_BLOCK_OFFSET_VALID;
Max Reitza9063922016-03-24 23:33:59 +0100236
Eric Blake05c33f12018-02-13 14:26:49 -0600237 *pnum = bytes;
238 *map = offset;
Max Reitza9063922016-03-24 23:33:59 +0100239 *file = bs;
240
241 if (s->read_zeroes) {
Eric Blake05c33f12018-02-13 14:26:49 -0600242 ret |= BDRV_BLOCK_ZERO;
Max Reitza9063922016-03-24 23:33:59 +0100243 }
Eric Blake05c33f12018-02-13 14:26:49 -0600244 return ret;
Max Reitza9063922016-03-24 23:33:59 +0100245}
246
Max Reitz998b3a12019-02-01 20:29:28 +0100247static void null_refresh_filename(BlockDriverState *bs)
Max Reitz67882b12016-06-10 20:57:48 +0200248{
Max Reitz998b3a12019-02-01 20:29:28 +0100249 const QDictEntry *e;
Max Reitz67882b12016-06-10 20:57:48 +0200250
Max Reitz998b3a12019-02-01 20:29:28 +0100251 for (e = qdict_first(bs->full_open_options); e;
252 e = qdict_next(bs->full_open_options, e))
253 {
254 /* These options can be ignored */
255 if (strcmp(qdict_entry_key(e), "filename") &&
Max Reitz1e47cb72019-02-01 20:29:33 +0100256 strcmp(qdict_entry_key(e), "driver") &&
257 strcmp(qdict_entry_key(e), NULL_OPT_LATENCY))
Max Reitz998b3a12019-02-01 20:29:28 +0100258 {
259 return;
260 }
Max Reitz67882b12016-06-10 20:57:48 +0200261 }
262
Max Reitz998b3a12019-02-01 20:29:28 +0100263 snprintf(bs->exact_filename, sizeof(bs->exact_filename), "%s://",
264 bs->drv->format_name);
Max Reitz67882b12016-06-10 20:57:48 +0200265}
266
Max Reitz07cd7b62020-06-22 13:58:45 +0200267static int64_t null_allocated_file_size(BlockDriverState *bs)
268{
269 return 0;
270}
271
Max Reitz26542672019-02-01 20:29:25 +0100272static const char *const null_strong_runtime_opts[] = {
273 BLOCK_OPT_SIZE,
274 NULL_OPT_ZEROES,
275
276 NULL
277};
278
Fam Zhenge819ab22014-09-11 14:09:56 +0800279static BlockDriver bdrv_null_co = {
280 .format_name = "null-co",
281 .protocol_name = "null-co",
282 .instance_size = sizeof(BDRVNullState),
283
284 .bdrv_file_open = null_file_open,
Kevin Wolf809eb702017-08-04 12:44:22 +0200285 .bdrv_parse_filename = null_co_parse_filename,
Fam Zhenge819ab22014-09-11 14:09:56 +0800286 .bdrv_getlength = null_getlength,
Max Reitz07cd7b62020-06-22 13:58:45 +0200287 .bdrv_get_allocated_file_size = null_allocated_file_size,
Fam Zhenge819ab22014-09-11 14:09:56 +0800288
Eric Blakeb3241e92018-04-24 14:25:03 -0500289 .bdrv_co_preadv = null_co_preadv,
290 .bdrv_co_pwritev = null_co_pwritev,
Fam Zhenge819ab22014-09-11 14:09:56 +0800291 .bdrv_co_flush_to_disk = null_co_flush,
Fam Zheng1c2b49a2015-04-01 09:45:39 +0800292 .bdrv_reopen_prepare = null_reopen_prepare,
Max Reitza9063922016-03-24 23:33:59 +0100293
Eric Blake05c33f12018-02-13 14:26:49 -0600294 .bdrv_co_block_status = null_co_block_status,
Max Reitz67882b12016-06-10 20:57:48 +0200295
296 .bdrv_refresh_filename = null_refresh_filename,
Max Reitz26542672019-02-01 20:29:25 +0100297 .strong_runtime_opts = null_strong_runtime_opts,
Fam Zhenge819ab22014-09-11 14:09:56 +0800298};
299
300static BlockDriver bdrv_null_aio = {
301 .format_name = "null-aio",
302 .protocol_name = "null-aio",
303 .instance_size = sizeof(BDRVNullState),
304
305 .bdrv_file_open = null_file_open,
Kevin Wolf809eb702017-08-04 12:44:22 +0200306 .bdrv_parse_filename = null_aio_parse_filename,
Fam Zhenge819ab22014-09-11 14:09:56 +0800307 .bdrv_getlength = null_getlength,
Max Reitz07cd7b62020-06-22 13:58:45 +0200308 .bdrv_get_allocated_file_size = null_allocated_file_size,
Fam Zhenge819ab22014-09-11 14:09:56 +0800309
Eric Blakeb3241e92018-04-24 14:25:03 -0500310 .bdrv_aio_preadv = null_aio_preadv,
311 .bdrv_aio_pwritev = null_aio_pwritev,
Fam Zhenge819ab22014-09-11 14:09:56 +0800312 .bdrv_aio_flush = null_aio_flush,
Fam Zheng1c2b49a2015-04-01 09:45:39 +0800313 .bdrv_reopen_prepare = null_reopen_prepare,
Max Reitza9063922016-03-24 23:33:59 +0100314
Eric Blake05c33f12018-02-13 14:26:49 -0600315 .bdrv_co_block_status = null_co_block_status,
Max Reitz67882b12016-06-10 20:57:48 +0200316
317 .bdrv_refresh_filename = null_refresh_filename,
Max Reitz26542672019-02-01 20:29:25 +0100318 .strong_runtime_opts = null_strong_runtime_opts,
Fam Zhenge819ab22014-09-11 14:09:56 +0800319};
320
321static void bdrv_null_init(void)
322{
323 bdrv_register(&bdrv_null_co);
324 bdrv_register(&bdrv_null_aio);
325}
326
327block_init(bdrv_null_init);