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/option.h"
18 #include "block/block_int.h"
20 #define NULL_OPT_LATENCY "latency-ns"
21 #define NULL_OPT_ZEROES "read-zeroes"
29 static QemuOptsList runtime_opts = {
31 .head = QTAILQ_HEAD_INITIALIZER(runtime_opts.head),
34 .name = BLOCK_OPT_SIZE,
35 .type = QEMU_OPT_SIZE,
36 .help = "size of the null block",
39 .name = NULL_OPT_LATENCY,
40 .type = QEMU_OPT_NUMBER,
41 .help = "nanoseconds (approximated) to wait "
42 "before completing request",
45 .name = NULL_OPT_ZEROES,
46 .type = QEMU_OPT_BOOL,
47 .help = "return zeroes when read",
53 static void null_co_parse_filename(const char *filename, QDict *options,
56 /* This functions only exists so that a null-co:// filename is accepted
57 * with the null-co driver. */
58 if (strcmp(filename, "null-co://")) {
59 error_setg(errp, "The only allowed filename for this driver is "
65 static void null_aio_parse_filename(const char *filename, QDict *options,
68 /* This functions only exists so that a null-aio:// filename is accepted
69 * with the null-aio driver. */
70 if (strcmp(filename, "null-aio://")) {
71 error_setg(errp, "The only allowed filename for this driver is "
77 static int null_file_open(BlockDriverState *bs, QDict *options, int flags,
81 BDRVNullState *s = bs->opaque;
84 opts = qemu_opts_create(&runtime_opts, NULL, 0, &error_abort);
85 qemu_opts_absorb_qdict(opts, options, &error_abort);
87 qemu_opt_get_size(opts, BLOCK_OPT_SIZE, 1 << 30);
89 qemu_opt_get_number(opts, NULL_OPT_LATENCY, 0);
90 if (s->latency_ns < 0) {
91 error_setg(errp, "latency-ns is invalid");
94 s->read_zeroes = qemu_opt_get_bool(opts, NULL_OPT_ZEROES, false);
96 bs->supported_write_flags = BDRV_REQ_FUA;
100 static int64_t null_getlength(BlockDriverState *bs)
102 BDRVNullState *s = bs->opaque;
106 static coroutine_fn int null_co_common(BlockDriverState *bs)
108 BDRVNullState *s = bs->opaque;
111 qemu_co_sleep_ns(QEMU_CLOCK_REALTIME, s->latency_ns);
116 static coroutine_fn int null_co_preadv(BlockDriverState *bs,
117 uint64_t offset, uint64_t bytes,
118 QEMUIOVector *qiov, int flags)
120 BDRVNullState *s = bs->opaque;
122 if (s->read_zeroes) {
123 qemu_iovec_memset(qiov, 0, 0, bytes);
126 return null_co_common(bs);
129 static coroutine_fn int null_co_pwritev(BlockDriverState *bs,
130 uint64_t offset, uint64_t bytes,
131 QEMUIOVector *qiov, int flags)
133 return null_co_common(bs);
136 static coroutine_fn int null_co_flush(BlockDriverState *bs)
138 return null_co_common(bs);
146 static const AIOCBInfo null_aiocb_info = {
147 .aiocb_size = sizeof(NullAIOCB),
150 static void null_bh_cb(void *opaque)
152 NullAIOCB *acb = opaque;
153 acb->common.cb(acb->common.opaque, 0);
157 static void null_timer_cb(void *opaque)
159 NullAIOCB *acb = opaque;
160 acb->common.cb(acb->common.opaque, 0);
161 timer_deinit(&acb->timer);
165 static inline BlockAIOCB *null_aio_common(BlockDriverState *bs,
166 BlockCompletionFunc *cb,
170 BDRVNullState *s = bs->opaque;
172 acb = qemu_aio_get(&null_aiocb_info, bs, cb, opaque);
173 /* Only emulate latency after vcpu is running. */
175 aio_timer_init(bdrv_get_aio_context(bs), &acb->timer,
176 QEMU_CLOCK_REALTIME, SCALE_NS,
178 timer_mod_ns(&acb->timer,
179 qemu_clock_get_ns(QEMU_CLOCK_REALTIME) + s->latency_ns);
181 aio_bh_schedule_oneshot(bdrv_get_aio_context(bs), null_bh_cb, acb);
186 static BlockAIOCB *null_aio_preadv(BlockDriverState *bs,
187 uint64_t offset, uint64_t bytes,
188 QEMUIOVector *qiov, int flags,
189 BlockCompletionFunc *cb,
192 BDRVNullState *s = bs->opaque;
194 if (s->read_zeroes) {
195 qemu_iovec_memset(qiov, 0, 0, bytes);
198 return null_aio_common(bs, cb, opaque);
201 static BlockAIOCB *null_aio_pwritev(BlockDriverState *bs,
202 uint64_t offset, uint64_t bytes,
203 QEMUIOVector *qiov, int flags,
204 BlockCompletionFunc *cb,
207 return null_aio_common(bs, cb, opaque);
210 static BlockAIOCB *null_aio_flush(BlockDriverState *bs,
211 BlockCompletionFunc *cb,
214 return null_aio_common(bs, cb, opaque);
217 static int null_reopen_prepare(BDRVReopenState *reopen_state,
218 BlockReopenQueue *queue, Error **errp)
223 static int coroutine_fn null_co_block_status(BlockDriverState *bs,
224 bool want_zero, int64_t offset,
225 int64_t bytes, int64_t *pnum,
227 BlockDriverState **file)
229 BDRVNullState *s = bs->opaque;
230 int ret = BDRV_BLOCK_OFFSET_VALID;
236 if (s->read_zeroes) {
237 ret |= BDRV_BLOCK_ZERO;
242 static void null_refresh_filename(BlockDriverState *bs, QDict *opts)
244 qdict_del(opts, "filename");
246 if (!qdict_size(opts)) {
247 snprintf(bs->exact_filename, sizeof(bs->exact_filename), "%s://",
248 bs->drv->format_name);
251 qdict_put_str(opts, "driver", bs->drv->format_name);
252 bs->full_open_options = qobject_ref(opts);
255 static BlockDriver bdrv_null_co = {
256 .format_name = "null-co",
257 .protocol_name = "null-co",
258 .instance_size = sizeof(BDRVNullState),
260 .bdrv_file_open = null_file_open,
261 .bdrv_parse_filename = null_co_parse_filename,
262 .bdrv_getlength = null_getlength,
264 .bdrv_co_preadv = null_co_preadv,
265 .bdrv_co_pwritev = null_co_pwritev,
266 .bdrv_co_flush_to_disk = null_co_flush,
267 .bdrv_reopen_prepare = null_reopen_prepare,
269 .bdrv_co_block_status = null_co_block_status,
271 .bdrv_refresh_filename = null_refresh_filename,
274 static BlockDriver bdrv_null_aio = {
275 .format_name = "null-aio",
276 .protocol_name = "null-aio",
277 .instance_size = sizeof(BDRVNullState),
279 .bdrv_file_open = null_file_open,
280 .bdrv_parse_filename = null_aio_parse_filename,
281 .bdrv_getlength = null_getlength,
283 .bdrv_aio_preadv = null_aio_preadv,
284 .bdrv_aio_pwritev = null_aio_pwritev,
285 .bdrv_aio_flush = null_aio_flush,
286 .bdrv_reopen_prepare = null_reopen_prepare,
288 .bdrv_co_block_status = null_co_block_status,
290 .bdrv_refresh_filename = null_refresh_filename,
293 static void bdrv_null_init(void)
295 bdrv_register(&bdrv_null_co);
296 bdrv_register(&bdrv_null_aio);
299 block_init(bdrv_null_init);