From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:52039) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XMeJ0-0002pH-MK for qemu-devel@nongnu.org; Wed, 27 Aug 2014 10:34:39 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1XMeIu-0001u7-GZ for qemu-devel@nongnu.org; Wed, 27 Aug 2014 10:34:34 -0400 Received: from lputeaux-656-01-25-125.w80-12.abo.wanadoo.fr ([80.12.84.125]:38961 helo=paradis.irqsave.net) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XMeIu-0001u1-0o for qemu-devel@nongnu.org; Wed, 27 Aug 2014 10:34:28 -0400 Date: Wed, 27 Aug 2014 16:33:40 +0200 From: =?iso-8859-1?Q?Beno=EEt?= Canet Message-ID: <20140827143340.GG31176@irqsave.net> References: <1409120576-5726-1-git-send-email-famz@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <1409120576-5726-1-git-send-email-famz@redhat.com> Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [PATCH] block: Introduce "null" driver List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Fam Zheng Cc: Kevin Wolf , qemu-devel@nongnu.org, Stefan Hajnoczi The Wednesday 27 Aug 2014 =E0 14:22:56 (+0800), Fam Zheng wrote : > This is an analogue to Linux null_blk. It can be used for testing block > device emulation and general block layer functionalities such as > coroutines and throttling, where disk IO is not necessary or wanted. >=20 > Signed-off-by: Fam Zheng > --- > block/Makefile.objs | 1 + > block/null.c | 172 ++++++++++++++++++++++++++++++++++++++++++++= ++++++++ > 2 files changed, 173 insertions(+) > create mode 100644 block/null.c >=20 > diff --git a/block/Makefile.objs b/block/Makefile.objs > index 858d2b3..087e281 100644 > --- a/block/Makefile.objs > +++ b/block/Makefile.objs > @@ -9,6 +9,7 @@ block-obj-y +=3D snapshot.o qapi.o > block-obj-$(CONFIG_WIN32) +=3D raw-win32.o win32-aio.o > block-obj-$(CONFIG_POSIX) +=3D raw-posix.o > block-obj-$(CONFIG_LINUX_AIO) +=3D linux-aio.o > +block-obj-y +=3D null.o > =20 > ifeq ($(CONFIG_POSIX),y) > block-obj-y +=3D nbd.o nbd-client.o sheepdog.o > diff --git a/block/null.c b/block/null.c > new file mode 100644 > index 0000000..d93a24d > --- /dev/null > +++ b/block/null.c > @@ -0,0 +1,172 @@ > +/* > + * 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 =3D { > + .name =3D "null", > + .head =3D QTAILQ_HEAD_INITIALIZER(runtime_opts.head), > + .desc =3D { > + { > + .name =3D "filename", > + .type =3D QEMU_OPT_STRING, > + .help =3D "", > + }, > + { /* end of list */ } > + }, > +}; > + > +static int null_file_open(BlockDriverState *bs, QDict *options, int fl= ags, > + Error **errp) > +{ > + QemuOpts *opts; > + > + opts =3D qemu_opts_create(&runtime_opts, NULL, 0, &error_abort); > + qemu_opts_absorb_qdict(opts, options, &error_abort); > + qemu_opts_del(opts); > + return 0; > +} > + > +static void null_close(BlockDriverState *bs) > +{ > +} > + > +static int64_t null_getlength(BlockDriverState *bs) > +{ > + /* Size is not very relevant, let's report 1G for now */ > + return 1 << 30; > +} > + > +#ifdef NULL_COROUTINE Aren't you afraid that the conditional compilation will let parts of the = code bitrot ? Best regards Beno=EEt > +static coroutine_fn int null_co_read(BlockDriverState *bs, int64_t sec= tor_num, > + uint8_t *buf, int nb_sectors) > +{ > + return 0; > +} > + > +static coroutine_fn int null_co_write(BlockDriverState *bs, int64_t se= ctor_num, > + const uint8_t *buf, int nb_secto= rs) > +{ > + return 0; > +} > + > +static coroutine_fn int null_co_flush(BlockDriverState *bs) > +{ > + return 0; > +} > +#else > + > +typedef struct { > + BlockDriverAIOCB common; > + QEMUBH *bh; > +} NullAIOCB; > + > +typedef struct BlkdebugSuspendedReq { > + Coroutine *co; > + char *tag; > + QLIST_ENTRY(BlkdebugSuspendedReq) next; > +} BlkdebugSuspendedReq; > + > +static void null_aio_cancel(BlockDriverAIOCB *blockacb); > + > +static const AIOCBInfo null_aiocb_info =3D { > + .aiocb_size =3D sizeof(NullAIOCB), > + .cancel =3D null_aio_cancel, > +}; > + > +static void null_bh_cb(void *opaque) > +{ > + NullAIOCB *acb =3D opaque; > + acb->common.cb(acb->common.opaque, 0); > + qemu_bh_delete(acb->bh); > + qemu_aio_release(acb); > +} > + > +static BlockDriverAIOCB *null_aio_readv(BlockDriverState *bs, > + int64_t sector_num, QEMUIOVect= or *qiov, > + int nb_sectors, > + BlockDriverCompletionFunc *cb, > + void *opaque) > +{ > + NullAIOCB *acb; > + > + acb =3D qemu_aio_get(&null_aiocb_info, bs, cb, opaque); > + acb->bh =3D aio_bh_new(bdrv_get_aio_context(bs), null_bh_cb, acb); > + qemu_bh_schedule(acb->bh); > + return &acb->common; > +} > + > +static BlockDriverAIOCB *null_aio_writev(BlockDriverState *bs, > + int64_t sector_num, QEMUIOVec= tor *qiov, > + int nb_sectors, > + BlockDriverCompletionFunc *cb= , > + void *opaque) > +{ > + NullAIOCB *acb; > + > + acb =3D qemu_aio_get(&null_aiocb_info, bs, cb, opaque); > + acb->bh =3D aio_bh_new(bdrv_get_aio_context(bs), null_bh_cb, acb); > + qemu_bh_schedule(acb->bh); > + return &acb->common; > +} > + > +static BlockDriverAIOCB *null_aio_flush(BlockDriverState *bs, > + BlockDriverCompletionFunc *cb, > + void *opaque) > +{ > + NullAIOCB *acb; > + > + acb =3D qemu_aio_get(&null_aiocb_info, bs, cb, opaque); > + acb->bh =3D aio_bh_new(bdrv_get_aio_context(bs), null_bh_cb, acb); > + qemu_bh_schedule(acb->bh); > + return &acb->common; > +} > + > +static void null_aio_cancel(BlockDriverAIOCB *blockacb) > +{ > + NullAIOCB *acb =3D container_of(blockacb, NullAIOCB, common); > + qemu_bh_delete(acb->bh); > + qemu_aio_release(acb); > +} > + > +#endif > + > +static BlockDriver bdrv_null =3D { > + .format_name =3D "null", > + .protocol_name =3D "null", > + .instance_size =3D sizeof(BDRVNullState), > + > + .bdrv_file_open =3D null_file_open, > + .bdrv_close =3D null_close, > + .bdrv_getlength =3D null_getlength, > + > +#ifdef NULL_COROUTINE > + .bdrv_read =3D null_co_read, > + .bdrv_write =3D null_co_write, > + .bdrv_co_flush_to_disk =3D null_co_flush, > +#else > + .bdrv_aio_readv =3D null_aio_readv, > + .bdrv_aio_writev =3D null_aio_writev, > + .bdrv_aio_flush =3D null_aio_flush, > +#endif > +}; > + > +static void bdrv_null_init(void) > +{ > + bdrv_register(&bdrv_null); > +} > + > +block_init(bdrv_null_init); > --=20 > 2.1.0 >=20 >=20