diff options
Diffstat (limited to 'src/block/null.c')
| -rw-r--r-- | src/block/null.c | 222 |
1 files changed, 222 insertions, 0 deletions
diff --git a/src/block/null.c b/src/block/null.c new file mode 100644 index 0000000..7d08323 --- /dev/null +++ b/src/block/null.c @@ -0,0 +1,222 @@ +/* + * Null block driver + * + * Authors: + * Fam Zheng <famz@redhat.com> + * + * Copyright (C) 2014 Red Hat, Inc. + * + * This work is licensed under the terms of the GNU GPL, version 2 or later. + * See the COPYING file in the top-level directory. + */ + +#include "block/block_int.h" + +#define NULL_OPT_LATENCY "latency-ns" + +typedef struct { + int64_t length; + int64_t latency_ns; +} BDRVNullState; + +static QemuOptsList runtime_opts = { + .name = "null", + .head = QTAILQ_HEAD_INITIALIZER(runtime_opts.head), + .desc = { + { + .name = "filename", + .type = QEMU_OPT_STRING, + .help = "", + }, + { + .name = BLOCK_OPT_SIZE, + .type = QEMU_OPT_SIZE, + .help = "size of the null block", + }, + { + .name = NULL_OPT_LATENCY, + .type = QEMU_OPT_NUMBER, + .help = "nanoseconds (approximated) to wait " + "before completing request", + }, + { /* end of list */ } + }, +}; + +static int null_file_open(BlockDriverState *bs, QDict *options, int flags, + Error **errp) +{ + QemuOpts *opts; + BDRVNullState *s = bs->opaque; + int ret = 0; + + opts = qemu_opts_create(&runtime_opts, NULL, 0, &error_abort); + qemu_opts_absorb_qdict(opts, options, &error_abort); + s->length = + qemu_opt_get_size(opts, BLOCK_OPT_SIZE, 1 << 30); + s->latency_ns = + qemu_opt_get_number(opts, NULL_OPT_LATENCY, 0); + if (s->latency_ns < 0) { + error_setg(errp, "latency-ns is invalid"); + ret = -EINVAL; + } + qemu_opts_del(opts); + return ret; +} + +static void null_close(BlockDriverState *bs) +{ +} + +static int64_t null_getlength(BlockDriverState *bs) +{ + BDRVNullState *s = bs->opaque; + return s->length; +} + +static coroutine_fn int null_co_common(BlockDriverState *bs) +{ + BDRVNullState *s = bs->opaque; + + if (s->latency_ns) { + co_aio_sleep_ns(bdrv_get_aio_context(bs), QEMU_CLOCK_REALTIME, + s->latency_ns); + } + return 0; +} + +static coroutine_fn int null_co_readv(BlockDriverState *bs, + int64_t sector_num, int nb_sectors, + QEMUIOVector *qiov) +{ + return null_co_common(bs); +} + +static coroutine_fn int null_co_writev(BlockDriverState *bs, + int64_t sector_num, int nb_sectors, + QEMUIOVector *qiov) +{ + return null_co_common(bs); +} + +static coroutine_fn int null_co_flush(BlockDriverState *bs) +{ + return null_co_common(bs); +} + +typedef struct { + BlockAIOCB common; + QEMUBH *bh; + QEMUTimer timer; +} NullAIOCB; + +static const AIOCBInfo null_aiocb_info = { + .aiocb_size = sizeof(NullAIOCB), +}; + +static void null_bh_cb(void *opaque) +{ + NullAIOCB *acb = opaque; + acb->common.cb(acb->common.opaque, 0); + qemu_bh_delete(acb->bh); + qemu_aio_unref(acb); +} + +static void null_timer_cb(void *opaque) +{ + NullAIOCB *acb = opaque; + acb->common.cb(acb->common.opaque, 0); + timer_deinit(&acb->timer); + qemu_aio_unref(acb); +} + +static inline BlockAIOCB *null_aio_common(BlockDriverState *bs, + BlockCompletionFunc *cb, + void *opaque) +{ + NullAIOCB *acb; + BDRVNullState *s = bs->opaque; + + acb = qemu_aio_get(&null_aiocb_info, bs, cb, opaque); + /* Only emulate latency after vcpu is running. */ + if (s->latency_ns) { + aio_timer_init(bdrv_get_aio_context(bs), &acb->timer, + QEMU_CLOCK_REALTIME, SCALE_NS, + null_timer_cb, acb); + timer_mod_ns(&acb->timer, + qemu_clock_get_ns(QEMU_CLOCK_REALTIME) + s->latency_ns); + } else { + acb->bh = aio_bh_new(bdrv_get_aio_context(bs), null_bh_cb, acb); + qemu_bh_schedule(acb->bh); + } + return &acb->common; +} + +static BlockAIOCB *null_aio_readv(BlockDriverState *bs, + int64_t sector_num, QEMUIOVector *qiov, + int nb_sectors, + BlockCompletionFunc *cb, + void *opaque) +{ + return null_aio_common(bs, cb, opaque); +} + +static BlockAIOCB *null_aio_writev(BlockDriverState *bs, + int64_t sector_num, QEMUIOVector *qiov, + int nb_sectors, + BlockCompletionFunc *cb, + void *opaque) +{ + return null_aio_common(bs, cb, opaque); +} + +static BlockAIOCB *null_aio_flush(BlockDriverState *bs, + BlockCompletionFunc *cb, + void *opaque) +{ + return null_aio_common(bs, cb, opaque); +} + +static int null_reopen_prepare(BDRVReopenState *reopen_state, + BlockReopenQueue *queue, Error **errp) +{ + return 0; +} + +static BlockDriver bdrv_null_co = { + .format_name = "null-co", + .protocol_name = "null-co", + .instance_size = sizeof(BDRVNullState), + + .bdrv_file_open = null_file_open, + .bdrv_close = null_close, + .bdrv_getlength = null_getlength, + + .bdrv_co_readv = null_co_readv, + .bdrv_co_writev = null_co_writev, + .bdrv_co_flush_to_disk = null_co_flush, + .bdrv_reopen_prepare = null_reopen_prepare, +}; + +static BlockDriver bdrv_null_aio = { + .format_name = "null-aio", + .protocol_name = "null-aio", + .instance_size = sizeof(BDRVNullState), + + .bdrv_file_open = null_file_open, + .bdrv_close = null_close, + .bdrv_getlength = null_getlength, + + .bdrv_aio_readv = null_aio_readv, + .bdrv_aio_writev = null_aio_writev, + .bdrv_aio_flush = null_aio_flush, + .bdrv_reopen_prepare = null_reopen_prepare, +}; + +static void bdrv_null_init(void) +{ + bdrv_register(&bdrv_null_co); + bdrv_register(&bdrv_null_aio); +} + +block_init(bdrv_null_init); |
