5 * Fam Zheng <famz@redhat.com>
7 * Copyright (C) 2014 Red Hat, Inc.
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.
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"
23 #define NULL_OPT_LATENCY "latency-ns"
24 #define NULL_OPT_ZEROES "read-zeroes"
32 static QemuOptsList runtime_opts = {
34 .head = QTAILQ_HEAD_INITIALIZER(runtime_opts.head),
37 .name = BLOCK_OPT_SIZE,
38 .type = QEMU_OPT_SIZE,
39 .help = "size of the null block",
42 .name = NULL_OPT_LATENCY,
43 .type = QEMU_OPT_NUMBER,
44 .help = "nanoseconds (approximated) to wait "
45 "before completing request",
48 .name = NULL_OPT_ZEROES,
49 .type = QEMU_OPT_BOOL,
50 .help = "return zeroes when read",
56 static void null_co_parse_filename(const char *filename, QDict *options,
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 "
68 static void null_aio_parse_filename(const char *filename, QDict *options,
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 "
80 static int null_file_open(BlockDriverState *bs, QDict *options, int flags,
84 BDRVNullState *s = bs->opaque;
87 opts = qemu_opts_create(&runtime_opts, NULL, 0, &error_abort);
88 qemu_opts_absorb_qdict(opts, options, &error_abort);
90 qemu_opt_get_size(opts, BLOCK_OPT_SIZE, 1 << 30);
92 qemu_opt_get_number(opts, NULL_OPT_LATENCY, 0);
93 if (s->latency_ns < 0) {
94 error_setg(errp, "latency-ns is invalid");
97 s->read_zeroes = qemu_opt_get_bool(opts, NULL_OPT_ZEROES, false);
99 bs->supported_write_flags = BDRV_REQ_FUA;
103 static int64_t coroutine_fn null_co_getlength(BlockDriverState *bs)
105 BDRVNullState *s = bs->opaque;
109 static coroutine_fn int null_co_common(BlockDriverState *bs)
111 BDRVNullState *s = bs->opaque;
114 qemu_co_sleep_ns(QEMU_CLOCK_REALTIME, s->latency_ns);
119 static coroutine_fn int null_co_preadv(BlockDriverState *bs,
120 int64_t offset, int64_t bytes,
122 BdrvRequestFlags flags)
124 BDRVNullState *s = bs->opaque;
126 if (s->read_zeroes) {
127 qemu_iovec_memset(qiov, 0, 0, bytes);
130 return null_co_common(bs);
133 static coroutine_fn int null_co_pwritev(BlockDriverState *bs,
134 int64_t offset, int64_t bytes,
136 BdrvRequestFlags flags)
138 return null_co_common(bs);
141 static coroutine_fn int null_co_flush(BlockDriverState *bs)
143 return null_co_common(bs);
151 static const AIOCBInfo null_aiocb_info = {
152 .aiocb_size = sizeof(NullAIOCB),
155 static void null_bh_cb(void *opaque)
157 NullAIOCB *acb = opaque;
158 acb->common.cb(acb->common.opaque, 0);
162 static void null_timer_cb(void *opaque)
164 NullAIOCB *acb = opaque;
165 acb->common.cb(acb->common.opaque, 0);
166 timer_deinit(&acb->timer);
170 static inline BlockAIOCB *null_aio_common(BlockDriverState *bs,
171 BlockCompletionFunc *cb,
175 BDRVNullState *s = bs->opaque;
177 acb = qemu_aio_get(&null_aiocb_info, bs, cb, opaque);
178 /* Only emulate latency after vcpu is running. */
180 aio_timer_init(bdrv_get_aio_context(bs), &acb->timer,
181 QEMU_CLOCK_REALTIME, SCALE_NS,
183 timer_mod_ns(&acb->timer,
184 qemu_clock_get_ns(QEMU_CLOCK_REALTIME) + s->latency_ns);
186 replay_bh_schedule_oneshot_event(bdrv_get_aio_context(bs),
192 static BlockAIOCB *null_aio_preadv(BlockDriverState *bs,
193 int64_t offset, int64_t bytes,
194 QEMUIOVector *qiov, BdrvRequestFlags flags,
195 BlockCompletionFunc *cb,
198 BDRVNullState *s = bs->opaque;
200 if (s->read_zeroes) {
201 qemu_iovec_memset(qiov, 0, 0, bytes);
204 return null_aio_common(bs, cb, opaque);
207 static BlockAIOCB *null_aio_pwritev(BlockDriverState *bs,
208 int64_t offset, int64_t bytes,
209 QEMUIOVector *qiov, BdrvRequestFlags flags,
210 BlockCompletionFunc *cb,
213 return null_aio_common(bs, cb, opaque);
216 static BlockAIOCB *null_aio_flush(BlockDriverState *bs,
217 BlockCompletionFunc *cb,
220 return null_aio_common(bs, cb, opaque);
223 static int null_reopen_prepare(BDRVReopenState *reopen_state,
224 BlockReopenQueue *queue, Error **errp)
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,
233 BlockDriverState **file)
235 BDRVNullState *s = bs->opaque;
236 int ret = BDRV_BLOCK_OFFSET_VALID;
242 if (s->read_zeroes) {
243 ret |= BDRV_BLOCK_ZERO;
248 static void null_refresh_filename(BlockDriverState *bs)
252 for (e = qdict_first(bs->full_open_options); e;
253 e = qdict_next(bs->full_open_options, e))
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))
264 snprintf(bs->exact_filename, sizeof(bs->exact_filename), "%s://",
265 bs->drv->format_name);
268 static int64_t coroutine_fn
269 null_co_get_allocated_file_size(BlockDriverState *bs)
274 static const char *const null_strong_runtime_opts[] = {
281 static BlockDriver bdrv_null_co = {
282 .format_name = "null-co",
283 .protocol_name = "null-co",
284 .instance_size = sizeof(BDRVNullState),
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,
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,
296 .bdrv_co_block_status = null_co_block_status,
298 .bdrv_refresh_filename = null_refresh_filename,
299 .strong_runtime_opts = null_strong_runtime_opts,
302 static BlockDriver bdrv_null_aio = {
303 .format_name = "null-aio",
304 .protocol_name = "null-aio",
305 .instance_size = sizeof(BDRVNullState),
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,
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,
317 .bdrv_co_block_status = null_co_block_status,
319 .bdrv_refresh_filename = null_refresh_filename,
320 .strong_runtime_opts = null_strong_runtime_opts,
323 static void bdrv_null_init(void)
325 bdrv_register(&bdrv_null_co);
326 bdrv_register(&bdrv_null_aio);
329 block_init(bdrv_null_init);