From e819ab22777fd455d5b130afe48c808d35ef7e93 Mon Sep 17 00:00:00 2001 From: Fam Zheng Date: Thu, 11 Sep 2014 14:09:56 +0800 Subject: block: Introduce "null" drivers MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit This is an analogue to Linux null_blk. It can be used for testing or benchmarking block device emulation and general block layer functionalities such as coroutines and throttling, where disk IO is not necessary or wanted. Use null-aio:// for AIO version, and null-co:// for coroutine version. [Resolved conflict with Fam's async bdrv_aio_cancel() series: 1. Drop .bdrv_aio_cancel() since it is now done by block.c 2. Rename qemu_aio_release() to qemu_aio_unref() --Stefan] Signed-off-by: Fam Zheng Reviewed-by: Benoît Canet Reviewed-by: Eric Blake Message-id: 1410415798-20673-2-git-send-email-famz@redhat.com Signed-off-by: Stefan Hajnoczi --- block/Makefile.objs | 1 + block/null.c | 168 +++++++++++++++++++++++++++++++++++++++++++++++++++ qapi/block-core.json | 19 +++++- 3 files changed, 186 insertions(+), 2 deletions(-) create mode 100644 block/null.c diff --git a/block/Makefile.objs b/block/Makefile.objs index c9c8bbb..d6e23a2 100644 --- a/block/Makefile.objs +++ b/block/Makefile.objs @@ -9,6 +9,7 @@ block-obj-y += snapshot.o qapi.o block-obj-$(CONFIG_WIN32) += raw-win32.o win32-aio.o block-obj-$(CONFIG_POSIX) += raw-posix.o block-obj-$(CONFIG_LINUX_AIO) += linux-aio.o +block-obj-y += null.o block-obj-y += nbd.o nbd-client.o sheepdog.o block-obj-$(CONFIG_LIBISCSI) += iscsi.o diff --git a/block/null.c b/block/null.c new file mode 100644 index 0000000..8284419 --- /dev/null +++ b/block/null.c @@ -0,0 +1,168 @@ +/* + * Null block driver + * + * Authors: + * Fam Zheng + * + * 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" + +typedef struct { + int64_t length; +} 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", + }, + { /* end of list */ } + }, +}; + +static int null_file_open(BlockDriverState *bs, QDict *options, int flags, + Error **errp) +{ + QemuOpts *opts; + BDRVNullState *s = bs->opaque; + + 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); + qemu_opts_del(opts); + return 0; +} + +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_readv(BlockDriverState *bs, + int64_t sector_num, int nb_sectors, + QEMUIOVector *qiov) +{ + return 0; +} + +static coroutine_fn int null_co_writev(BlockDriverState *bs, + int64_t sector_num, int nb_sectors, + QEMUIOVector *qiov) +{ + return 0; +} + +static coroutine_fn int null_co_flush(BlockDriverState *bs) +{ + return 0; +} + +typedef struct { + BlockDriverAIOCB common; + QEMUBH *bh; +} 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 inline BlockDriverAIOCB *null_aio_common(BlockDriverState *bs, + BlockDriverCompletionFunc *cb, + void *opaque) +{ + NullAIOCB *acb; + + acb = qemu_aio_get(&null_aiocb_info, bs, cb, opaque); + acb->bh = aio_bh_new(bdrv_get_aio_context(bs), null_bh_cb, acb); + qemu_bh_schedule(acb->bh); + return &acb->common; +} + +static BlockDriverAIOCB *null_aio_readv(BlockDriverState *bs, + int64_t sector_num, QEMUIOVector *qiov, + int nb_sectors, + BlockDriverCompletionFunc *cb, + void *opaque) +{ + return null_aio_common(bs, cb, opaque); +} + +static BlockDriverAIOCB *null_aio_writev(BlockDriverState *bs, + int64_t sector_num, QEMUIOVector *qiov, + int nb_sectors, + BlockDriverCompletionFunc *cb, + void *opaque) +{ + return null_aio_common(bs, cb, opaque); +} + +static BlockDriverAIOCB *null_aio_flush(BlockDriverState *bs, + BlockDriverCompletionFunc *cb, + void *opaque) +{ + return null_aio_common(bs, cb, opaque); +} + +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, +}; + +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, +}; + +static void bdrv_null_init(void) +{ + bdrv_register(&bdrv_null_co); + bdrv_register(&bdrv_null_aio); +} + +block_init(bdrv_null_init); diff --git a/qapi/block-core.json b/qapi/block-core.json index 95dcd81..a886b5d 100644 --- a/qapi/block-core.json +++ b/qapi/block-core.json @@ -1151,7 +1151,8 @@ 'data': [ 'archipelago', 'file', 'host_device', 'host_cdrom', 'host_floppy', 'http', 'https', 'ftp', 'ftps', 'tftp', 'vvfat', 'blkdebug', 'blkverify', 'bochs', 'cloop', 'cow', 'dmg', 'parallels', 'qcow', - 'qcow2', 'qed', 'raw', 'vdi', 'vhdx', 'vmdk', 'vpc', 'quorum' ] } + 'qcow2', 'qed', 'raw', 'vdi', 'vhdx', 'vmdk', 'vpc', 'quorum', + 'null-aio', 'null-co' ] } ## # @BlockdevOptionsBase @@ -1204,6 +1205,18 @@ 'data': { 'filename': 'str' } } ## +# @BlockdevOptionsNull +# +# Driver specific block device options for the null backend. +# +# @size: #optional size of the device in bytes. +# +# Since: 2.2 +## +{ 'type': 'BlockdevOptionsNull', + 'data': { '*size': 'int' } } + +## # @BlockdevOptionsVVFAT # # Driver specific block device options for the vvfat protocol. @@ -1503,7 +1516,9 @@ 'vhdx': 'BlockdevOptionsGenericFormat', 'vmdk': 'BlockdevOptionsGenericCOWFormat', 'vpc': 'BlockdevOptionsGenericFormat', - 'quorum': 'BlockdevOptionsQuorum' + 'quorum': 'BlockdevOptionsQuorum', + 'null-aio': 'BlockdevOptionsNull', + 'null-co': 'BlockdevOptionsNull' } } ## -- cgit v1.1