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13#include "qemu/osdep.h"
14#include "qapi/error.h"
15#include "qapi/qmp/qdict.h"
16#include "qapi/qmp/qstring.h"
17#include "qemu/module.h"
18#include "qemu/option.h"
19#include "block/block_int.h"
20#include "sysemu/replay.h"
21
22#define NULL_OPT_LATENCY "latency-ns"
23#define NULL_OPT_ZEROES "read-zeroes"
24
25typedef struct {
26 int64_t length;
27 int64_t latency_ns;
28 bool read_zeroes;
29} BDRVNullState;
30
31static QemuOptsList runtime_opts = {
32 .name = "null",
33 .head = QTAILQ_HEAD_INITIALIZER(runtime_opts.head),
34 .desc = {
35 {
36 .name = BLOCK_OPT_SIZE,
37 .type = QEMU_OPT_SIZE,
38 .help = "size of the null block",
39 },
40 {
41 .name = NULL_OPT_LATENCY,
42 .type = QEMU_OPT_NUMBER,
43 .help = "nanoseconds (approximated) to wait "
44 "before completing request",
45 },
46 {
47 .name = NULL_OPT_ZEROES,
48 .type = QEMU_OPT_BOOL,
49 .help = "return zeroes when read",
50 },
51 { }
52 },
53};
54
55static void null_co_parse_filename(const char *filename, QDict *options,
56 Error **errp)
57{
58
59
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
71
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
79static int null_file_open(BlockDriverState *bs, QDict *options, int flags,
80 Error **errp)
81{
82 QemuOpts *opts;
83 BDRVNullState *s = bs->opaque;
84 int ret = 0;
85
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);
90 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 }
96 s->read_zeroes = qemu_opt_get_bool(opts, NULL_OPT_ZEROES, false);
97 qemu_opts_del(opts);
98 bs->supported_write_flags = BDRV_REQ_FUA;
99 return ret;
100}
101
102static int64_t null_getlength(BlockDriverState *bs)
103{
104 BDRVNullState *s = bs->opaque;
105 return s->length;
106}
107
108static coroutine_fn int null_co_common(BlockDriverState *bs)
109{
110 BDRVNullState *s = bs->opaque;
111
112 if (s->latency_ns) {
113 qemu_co_sleep_ns(QEMU_CLOCK_REALTIME, s->latency_ns);
114 }
115 return 0;
116}
117
118static coroutine_fn int null_co_preadv(BlockDriverState *bs,
119 int64_t offset, int64_t bytes,
120 QEMUIOVector *qiov,
121 BdrvRequestFlags flags)
122{
123 BDRVNullState *s = bs->opaque;
124
125 if (s->read_zeroes) {
126 qemu_iovec_memset(qiov, 0, 0, bytes);
127 }
128
129 return null_co_common(bs);
130}
131
132static coroutine_fn int null_co_pwritev(BlockDriverState *bs,
133 int64_t offset, int64_t bytes,
134 QEMUIOVector *qiov,
135 BdrvRequestFlags flags)
136{
137 return null_co_common(bs);
138}
139
140static coroutine_fn int null_co_flush(BlockDriverState *bs)
141{
142 return null_co_common(bs);
143}
144
145typedef struct {
146 BlockAIOCB common;
147 QEMUTimer timer;
148} 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);
158 qemu_aio_unref(acb);
159}
160
161static 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
169static inline BlockAIOCB *null_aio_common(BlockDriverState *bs,
170 BlockCompletionFunc *cb,
171 void *opaque)
172{
173 NullAIOCB *acb;
174 BDRVNullState *s = bs->opaque;
175
176 acb = qemu_aio_get(&null_aiocb_info, bs, cb, opaque);
177
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 {
185 replay_bh_schedule_oneshot_event(bdrv_get_aio_context(bs),
186 null_bh_cb, acb);
187 }
188 return &acb->common;
189}
190
191static BlockAIOCB *null_aio_preadv(BlockDriverState *bs,
192 int64_t offset, int64_t bytes,
193 QEMUIOVector *qiov, BdrvRequestFlags flags,
194 BlockCompletionFunc *cb,
195 void *opaque)
196{
197 BDRVNullState *s = bs->opaque;
198
199 if (s->read_zeroes) {
200 qemu_iovec_memset(qiov, 0, 0, bytes);
201 }
202
203 return null_aio_common(bs, cb, opaque);
204}
205
206static BlockAIOCB *null_aio_pwritev(BlockDriverState *bs,
207 int64_t offset, int64_t bytes,
208 QEMUIOVector *qiov, BdrvRequestFlags flags,
209 BlockCompletionFunc *cb,
210 void *opaque)
211{
212 return null_aio_common(bs, cb, opaque);
213}
214
215static BlockAIOCB *null_aio_flush(BlockDriverState *bs,
216 BlockCompletionFunc *cb,
217 void *opaque)
218{
219 return null_aio_common(bs, cb, opaque);
220}
221
222static int null_reopen_prepare(BDRVReopenState *reopen_state,
223 BlockReopenQueue *queue, Error **errp)
224{
225 return 0;
226}
227
228static 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)
233{
234 BDRVNullState *s = bs->opaque;
235 int ret = BDRV_BLOCK_OFFSET_VALID;
236
237 *pnum = bytes;
238 *map = offset;
239 *file = bs;
240
241 if (s->read_zeroes) {
242 ret |= BDRV_BLOCK_ZERO;
243 }
244 return ret;
245}
246
247static void null_refresh_filename(BlockDriverState *bs)
248{
249 const QDictEntry *e;
250
251 for (e = qdict_first(bs->full_open_options); e;
252 e = qdict_next(bs->full_open_options, e))
253 {
254
255 if (strcmp(qdict_entry_key(e), "filename") &&
256 strcmp(qdict_entry_key(e), "driver") &&
257 strcmp(qdict_entry_key(e), NULL_OPT_LATENCY))
258 {
259 return;
260 }
261 }
262
263 snprintf(bs->exact_filename, sizeof(bs->exact_filename), "%s://",
264 bs->drv->format_name);
265}
266
267static int64_t null_allocated_file_size(BlockDriverState *bs)
268{
269 return 0;
270}
271
272static const char *const null_strong_runtime_opts[] = {
273 BLOCK_OPT_SIZE,
274 NULL_OPT_ZEROES,
275
276 NULL
277};
278
279static 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,
285 .bdrv_parse_filename = null_co_parse_filename,
286 .bdrv_getlength = null_getlength,
287 .bdrv_get_allocated_file_size = null_allocated_file_size,
288
289 .bdrv_co_preadv = null_co_preadv,
290 .bdrv_co_pwritev = null_co_pwritev,
291 .bdrv_co_flush_to_disk = null_co_flush,
292 .bdrv_reopen_prepare = null_reopen_prepare,
293
294 .bdrv_co_block_status = null_co_block_status,
295
296 .bdrv_refresh_filename = null_refresh_filename,
297 .strong_runtime_opts = null_strong_runtime_opts,
298};
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,
306 .bdrv_parse_filename = null_aio_parse_filename,
307 .bdrv_getlength = null_getlength,
308 .bdrv_get_allocated_file_size = null_allocated_file_size,
309
310 .bdrv_aio_preadv = null_aio_preadv,
311 .bdrv_aio_pwritev = null_aio_pwritev,
312 .bdrv_aio_flush = null_aio_flush,
313 .bdrv_reopen_prepare = null_reopen_prepare,
314
315 .bdrv_co_block_status = null_co_block_status,
316
317 .bdrv_refresh_filename = null_refresh_filename,
318 .strong_runtime_opts = null_strong_runtime_opts,
319};
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);
328
