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1 | /* | |
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 | ||
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-io.h" | |
20 | #include "block/block_int.h" | |
21 | #include "sysemu/replay.h" | |
22 | ||
23 | #define NULL_OPT_LATENCY "latency-ns" | |
24 | #define NULL_OPT_ZEROES "read-zeroes" | |
25 | ||
26 | typedef struct { | |
27 | int64_t length; | |
28 | int64_t latency_ns; | |
29 | bool read_zeroes; | |
30 | } BDRVNullState; | |
31 | ||
32 | static QemuOptsList runtime_opts = { | |
33 | .name = "null", | |
34 | .head = QTAILQ_HEAD_INITIALIZER(runtime_opts.head), | |
35 | .desc = { | |
36 | { | |
37 | .name = BLOCK_OPT_SIZE, | |
38 | .type = QEMU_OPT_SIZE, | |
39 | .help = "size of the null block", | |
40 | }, | |
41 | { | |
42 | .name = NULL_OPT_LATENCY, | |
43 | .type = QEMU_OPT_NUMBER, | |
44 | .help = "nanoseconds (approximated) to wait " | |
45 | "before completing request", | |
46 | }, | |
47 | { | |
48 | .name = NULL_OPT_ZEROES, | |
49 | .type = QEMU_OPT_BOOL, | |
50 | .help = "return zeroes when read", | |
51 | }, | |
52 | { /* end of list */ } | |
53 | }, | |
54 | }; | |
55 | ||
56 | static void null_co_parse_filename(const char *filename, QDict *options, | |
57 | Error **errp) | |
58 | { | |
59 | /* This functions only exists so that a null-co:// filename is accepted | |
60 | * with the null-co driver. */ | |
61 | if (strcmp(filename, "null-co://")) { | |
62 | error_setg(errp, "The only allowed filename for this driver is " | |
63 | "'null-co://'"); | |
64 | return; | |
65 | } | |
66 | } | |
67 | ||
68 | static void null_aio_parse_filename(const char *filename, QDict *options, | |
69 | Error **errp) | |
70 | { | |
71 | /* This functions only exists so that a null-aio:// filename is accepted | |
72 | * with the null-aio driver. */ | |
73 | if (strcmp(filename, "null-aio://")) { | |
74 | error_setg(errp, "The only allowed filename for this driver is " | |
75 | "'null-aio://'"); | |
76 | return; | |
77 | } | |
78 | } | |
79 | ||
80 | static int null_file_open(BlockDriverState *bs, QDict *options, int flags, | |
81 | Error **errp) | |
82 | { | |
83 | QemuOpts *opts; | |
84 | BDRVNullState *s = bs->opaque; | |
85 | int ret = 0; | |
86 | ||
87 | opts = qemu_opts_create(&runtime_opts, NULL, 0, &error_abort); | |
88 | qemu_opts_absorb_qdict(opts, options, &error_abort); | |
89 | s->length = | |
90 | qemu_opt_get_size(opts, BLOCK_OPT_SIZE, 1 << 30); | |
91 | s->latency_ns = | |
92 | qemu_opt_get_number(opts, NULL_OPT_LATENCY, 0); | |
93 | if (s->latency_ns < 0) { | |
94 | error_setg(errp, "latency-ns is invalid"); | |
95 | ret = -EINVAL; | |
96 | } | |
97 | s->read_zeroes = qemu_opt_get_bool(opts, NULL_OPT_ZEROES, false); | |
98 | qemu_opts_del(opts); | |
99 | bs->supported_write_flags = BDRV_REQ_FUA; | |
100 | return ret; | |
101 | } | |
102 | ||
103 | static int64_t coroutine_fn null_co_getlength(BlockDriverState *bs) | |
104 | { | |
105 | BDRVNullState *s = bs->opaque; | |
106 | return s->length; | |
107 | } | |
108 | ||
109 | static coroutine_fn int null_co_common(BlockDriverState *bs) | |
110 | { | |
111 | BDRVNullState *s = bs->opaque; | |
112 | ||
113 | if (s->latency_ns) { | |
114 | qemu_co_sleep_ns(QEMU_CLOCK_REALTIME, s->latency_ns); | |
115 | } | |
116 | return 0; | |
117 | } | |
118 | ||
119 | static coroutine_fn int null_co_preadv(BlockDriverState *bs, | |
120 | int64_t offset, int64_t bytes, | |
121 | QEMUIOVector *qiov, | |
122 | BdrvRequestFlags flags) | |
123 | { | |
124 | BDRVNullState *s = bs->opaque; | |
125 | ||
126 | if (s->read_zeroes) { | |
127 | qemu_iovec_memset(qiov, 0, 0, bytes); | |
128 | } | |
129 | ||
130 | return null_co_common(bs); | |
131 | } | |
132 | ||
133 | static coroutine_fn int null_co_pwritev(BlockDriverState *bs, | |
134 | int64_t offset, int64_t bytes, | |
135 | QEMUIOVector *qiov, | |
136 | BdrvRequestFlags flags) | |
137 | { | |
138 | return null_co_common(bs); | |
139 | } | |
140 | ||
141 | static coroutine_fn int null_co_flush(BlockDriverState *bs) | |
142 | { | |
143 | return null_co_common(bs); | |
144 | } | |
145 | ||
146 | typedef struct { | |
147 | BlockAIOCB common; | |
148 | QEMUTimer timer; | |
149 | } NullAIOCB; | |
150 | ||
151 | static const AIOCBInfo null_aiocb_info = { | |
152 | .aiocb_size = sizeof(NullAIOCB), | |
153 | }; | |
154 | ||
155 | static void null_bh_cb(void *opaque) | |
156 | { | |
157 | NullAIOCB *acb = opaque; | |
158 | acb->common.cb(acb->common.opaque, 0); | |
159 | qemu_aio_unref(acb); | |
160 | } | |
161 | ||
162 | static void null_timer_cb(void *opaque) | |
163 | { | |
164 | NullAIOCB *acb = opaque; | |
165 | acb->common.cb(acb->common.opaque, 0); | |
166 | timer_deinit(&acb->timer); | |
167 | qemu_aio_unref(acb); | |
168 | } | |
169 | ||
170 | static inline BlockAIOCB *null_aio_common(BlockDriverState *bs, | |
171 | BlockCompletionFunc *cb, | |
172 | void *opaque) | |
173 | { | |
174 | NullAIOCB *acb; | |
175 | BDRVNullState *s = bs->opaque; | |
176 | ||
177 | acb = qemu_aio_get(&null_aiocb_info, bs, cb, opaque); | |
178 | /* Only emulate latency after vcpu is running. */ | |
179 | if (s->latency_ns) { | |
180 | aio_timer_init(bdrv_get_aio_context(bs), &acb->timer, | |
181 | QEMU_CLOCK_REALTIME, SCALE_NS, | |
182 | null_timer_cb, acb); | |
183 | timer_mod_ns(&acb->timer, | |
184 | qemu_clock_get_ns(QEMU_CLOCK_REALTIME) + s->latency_ns); | |
185 | } else { | |
186 | replay_bh_schedule_oneshot_event(bdrv_get_aio_context(bs), | |
187 | null_bh_cb, acb); | |
188 | } | |
189 | return &acb->common; | |
190 | } | |
191 | ||
192 | static BlockAIOCB *null_aio_preadv(BlockDriverState *bs, | |
193 | int64_t offset, int64_t bytes, | |
194 | QEMUIOVector *qiov, BdrvRequestFlags flags, | |
195 | BlockCompletionFunc *cb, | |
196 | void *opaque) | |
197 | { | |
198 | BDRVNullState *s = bs->opaque; | |
199 | ||
200 | if (s->read_zeroes) { | |
201 | qemu_iovec_memset(qiov, 0, 0, bytes); | |
202 | } | |
203 | ||
204 | return null_aio_common(bs, cb, opaque); | |
205 | } | |
206 | ||
207 | static BlockAIOCB *null_aio_pwritev(BlockDriverState *bs, | |
208 | int64_t offset, int64_t bytes, | |
209 | QEMUIOVector *qiov, BdrvRequestFlags flags, | |
210 | BlockCompletionFunc *cb, | |
211 | void *opaque) | |
212 | { | |
213 | return null_aio_common(bs, cb, opaque); | |
214 | } | |
215 | ||
216 | static BlockAIOCB *null_aio_flush(BlockDriverState *bs, | |
217 | BlockCompletionFunc *cb, | |
218 | void *opaque) | |
219 | { | |
220 | return null_aio_common(bs, cb, opaque); | |
221 | } | |
222 | ||
223 | static int null_reopen_prepare(BDRVReopenState *reopen_state, | |
224 | BlockReopenQueue *queue, Error **errp) | |
225 | { | |
226 | return 0; | |
227 | } | |
228 | ||
229 | static int coroutine_fn null_co_block_status(BlockDriverState *bs, | |
230 | bool want_zero, int64_t offset, | |
231 | int64_t bytes, int64_t *pnum, | |
232 | int64_t *map, | |
233 | BlockDriverState **file) | |
234 | { | |
235 | BDRVNullState *s = bs->opaque; | |
236 | int ret = BDRV_BLOCK_OFFSET_VALID; | |
237 | ||
238 | *pnum = bytes; | |
239 | *map = offset; | |
240 | *file = bs; | |
241 | ||
242 | if (s->read_zeroes) { | |
243 | ret |= BDRV_BLOCK_ZERO; | |
244 | } | |
245 | return ret; | |
246 | } | |
247 | ||
248 | static void null_refresh_filename(BlockDriverState *bs) | |
249 | { | |
250 | const QDictEntry *e; | |
251 | ||
252 | for (e = qdict_first(bs->full_open_options); e; | |
253 | e = qdict_next(bs->full_open_options, e)) | |
254 | { | |
255 | /* These options can be ignored */ | |
256 | if (strcmp(qdict_entry_key(e), "filename") && | |
257 | strcmp(qdict_entry_key(e), "driver") && | |
258 | strcmp(qdict_entry_key(e), NULL_OPT_LATENCY)) | |
259 | { | |
260 | return; | |
261 | } | |
262 | } | |
263 | ||
264 | snprintf(bs->exact_filename, sizeof(bs->exact_filename), "%s://", | |
265 | bs->drv->format_name); | |
266 | } | |
267 | ||
268 | static int64_t coroutine_fn | |
269 | null_co_get_allocated_file_size(BlockDriverState *bs) | |
270 | { | |
271 | return 0; | |
272 | } | |
273 | ||
274 | static const char *const null_strong_runtime_opts[] = { | |
275 | BLOCK_OPT_SIZE, | |
276 | NULL_OPT_ZEROES, | |
277 | ||
278 | NULL | |
279 | }; | |
280 | ||
281 | static BlockDriver bdrv_null_co = { | |
282 | .format_name = "null-co", | |
283 | .protocol_name = "null-co", | |
284 | .instance_size = sizeof(BDRVNullState), | |
285 | ||
286 | .bdrv_file_open = null_file_open, | |
287 | .bdrv_parse_filename = null_co_parse_filename, | |
288 | .bdrv_co_getlength = null_co_getlength, | |
289 | .bdrv_co_get_allocated_file_size = null_co_get_allocated_file_size, | |
290 | ||
291 | .bdrv_co_preadv = null_co_preadv, | |
292 | .bdrv_co_pwritev = null_co_pwritev, | |
293 | .bdrv_co_flush_to_disk = null_co_flush, | |
294 | .bdrv_reopen_prepare = null_reopen_prepare, | |
295 | ||
296 | .bdrv_co_block_status = null_co_block_status, | |
297 | ||
298 | .bdrv_refresh_filename = null_refresh_filename, | |
299 | .strong_runtime_opts = null_strong_runtime_opts, | |
300 | }; | |
301 | ||
302 | static BlockDriver bdrv_null_aio = { | |
303 | .format_name = "null-aio", | |
304 | .protocol_name = "null-aio", | |
305 | .instance_size = sizeof(BDRVNullState), | |
306 | ||
307 | .bdrv_file_open = null_file_open, | |
308 | .bdrv_parse_filename = null_aio_parse_filename, | |
309 | .bdrv_co_getlength = null_co_getlength, | |
310 | .bdrv_co_get_allocated_file_size = null_co_get_allocated_file_size, | |
311 | ||
312 | .bdrv_aio_preadv = null_aio_preadv, | |
313 | .bdrv_aio_pwritev = null_aio_pwritev, | |
314 | .bdrv_aio_flush = null_aio_flush, | |
315 | .bdrv_reopen_prepare = null_reopen_prepare, | |
316 | ||
317 | .bdrv_co_block_status = null_co_block_status, | |
318 | ||
319 | .bdrv_refresh_filename = null_refresh_filename, | |
320 | .strong_runtime_opts = null_strong_runtime_opts, | |
321 | }; | |
322 | ||
323 | static void bdrv_null_init(void) | |
324 | { | |
325 | bdrv_register(&bdrv_null_co); | |
326 | bdrv_register(&bdrv_null_aio); | |
327 | } | |
328 | ||
329 | block_init(bdrv_null_init); |