[Qemu-devel] [PATCH v7 0/3] block: Introduce "null" drivers

[Qemu-devel] [PATCH v7 0/3] block: Introduce "null" drivers

[Fam Zheng]

v7: Add Benoît's rev-by line in patch 2.
    Improved help text in patch 1. (Benoît)

v6: Don't inherit from BlockdevOptionsFile. (Stefan)
    Use .bdrv_co_readv instead of .bdrv_read. (Kevin)
    Sort items in qapi schema definitions in patch 2 & 3.


Fam Zheng (3):
  block: Introduce "null" drivers
  qapi: Sort BlockdevDriver enum data list
  qapi: Sort items in BlockdevOptions definition

 block/Makefile.objs  |   1 +
 block/null.c         | 178 +++++++++++++++++++++++++++++++++++++++++++++++++++
 qapi/block-core.json |  57 +++++++++++------
 3 files changed, 215 insertions(+), 21 deletions(-)
 create mode 100644 block/null.c

-- 
1.9.3

[Qemu-devel] [PATCH v7 1/3] block: Introduce "null" drivers

[Fam Zheng]

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.

Signed-off-by: Fam Zheng <famz@redhat.com>
---
 block/Makefile.objs  |   1 +
 block/null.c         | 178 +++++++++++++++++++++++++++++++++++++++++++++++++++
 qapi/block-core.json |  19 +++++-
 3 files changed, 196 insertions(+), 2 deletions(-)
 create mode 100644 block/null.c

diff --git a/block/Makefile.objs b/block/Makefile.objs
index f45f939..36a844f 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..0037c1f
--- /dev/null
+++ b/block/null.c
@@ -0,0 +1,178 @@
+/*
+ * 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"
+
+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 void null_aio_cancel(BlockDriverAIOCB *blockacb);
+
+static const AIOCBInfo null_aiocb_info = {
+    .aiocb_size = sizeof(NullAIOCB),
+    .cancel     = null_aio_cancel,
+};
+
+static void null_bh_cb(void *opaque)
+{
+    NullAIOCB *acb = opaque;
+    acb->common.cb(acb->common.opaque, 0);
+    qemu_bh_delete(acb->bh);
+    qemu_aio_release(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 void null_aio_cancel(BlockDriverAIOCB *blockacb)
+{
+    NullAIOCB *acb = container_of(blockacb, NullAIOCB, common);
+    qemu_bh_delete(acb->bh);
+    qemu_aio_release(acb);
+}
+
+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 a685d02..bf0cb23 100644
--- a/qapi/block-core.json
+++ b/qapi/block-core.json
@@ -1150,7 +1150,8 @@
   '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
@@ -1203,6 +1204,18 @@
   '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.
@@ -1502,7 +1515,9 @@
       'vhdx':       'BlockdevOptionsGenericFormat',
       'vmdk':       'BlockdevOptionsGenericCOWFormat',
       'vpc':        'BlockdevOptionsGenericFormat',
-      'quorum':     'BlockdevOptionsQuorum'
+      'quorum':     'BlockdevOptionsQuorum',
+      'null-aio':   'BlockdevOptionsNull',
+      'null-co':    'BlockdevOptionsNull'
   } }
 
 ##
-- 
1.9.3

[Qemu-devel] [PATCH v7 2/3] qapi: Sort BlockdevDriver enum data list

[Fam Zheng]

Reviewed-by: Benoît Canet <benoit.canet@nodalink.com>
Signed-off-by: Fam Zheng <famz@redhat.com>
---
 qapi/block-core.json | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/qapi/block-core.json b/qapi/block-core.json
index bf0cb23..35191b4 100644
--- a/qapi/block-core.json
+++ b/qapi/block-core.json
@@ -1147,11 +1147,11 @@
 # Since: 2.0
 ##
 { 'enum': 'BlockdevDriver',
-  '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',
-            'null-aio', 'null-co' ] }
+  'data': [ 'archipelago', 'blkdebug', 'blkverify', 'bochs', 'cloop', 'cow',
+            'dmg', 'file', 'ftp', 'ftps', 'host_cdrom', 'host_device',
+            'host_floppy', 'http', 'https', 'null-aio', 'null-co', 'parallels',
+            'qcow', 'qcow2', 'qed', 'quorum', 'raw', 'tftp', 'vdi', 'vhdx',
+            'vmdk', 'vpc', 'vvfat' ] }
 
 ##
 # @BlockdevOptionsBase
-- 
1.9.3

[Qemu-devel] [PATCH v7 3/3] qapi: Sort items in BlockdevOptions definition

[Fam Zheng]

Signed-off-by: Fam Zheng <famz@redhat.com>
---
 qapi/block-core.json | 38 +++++++++++++++++++-------------------
 1 file changed, 19 insertions(+), 19 deletions(-)

diff --git a/qapi/block-core.json b/qapi/block-core.json
index 35191b4..5adef27 100644
--- a/qapi/block-core.json
+++ b/qapi/block-core.json
@@ -1483,41 +1483,41 @@
   'discriminator': 'driver',
   'data': {
       'archipelago':'BlockdevOptionsArchipelago',
+      'blkdebug':   'BlockdevOptionsBlkdebug',
+      'blkverify':  'BlockdevOptionsBlkverify',
+      'bochs':      'BlockdevOptionsGenericFormat',
+      'cloop':      'BlockdevOptionsGenericFormat',
+      'cow':        'BlockdevOptionsGenericCOWFormat',
+      'dmg':        'BlockdevOptionsGenericFormat',
       'file':       'BlockdevOptionsFile',
-      'host_device':'BlockdevOptionsFile',
+      'ftp':        'BlockdevOptionsFile',
+      'ftps':       'BlockdevOptionsFile',
+# TODO gluster: Wait for structured options
       'host_cdrom': 'BlockdevOptionsFile',
+      'host_device':'BlockdevOptionsFile',
       'host_floppy':'BlockdevOptionsFile',
       'http':       'BlockdevOptionsFile',
       'https':      'BlockdevOptionsFile',
-      'ftp':        'BlockdevOptionsFile',
-      'ftps':       'BlockdevOptionsFile',
-      'tftp':       'BlockdevOptionsFile',
-# TODO gluster: Wait for structured options
 # TODO iscsi: Wait for structured options
 # TODO nbd: Should take InetSocketAddress for 'host'?
 # TODO nfs: Wait for structured options
-# TODO rbd: Wait for structured options
-# TODO sheepdog: Wait for structured options
-# TODO ssh: Should take InetSocketAddress for 'host'?
-      'vvfat':      'BlockdevOptionsVVFAT',
-      'blkdebug':   'BlockdevOptionsBlkdebug',
-      'blkverify':  'BlockdevOptionsBlkverify',
-      'bochs':      'BlockdevOptionsGenericFormat',
-      'cloop':      'BlockdevOptionsGenericFormat',
-      'cow':        'BlockdevOptionsGenericCOWFormat',
-      'dmg':        'BlockdevOptionsGenericFormat',
+      'null-aio':   'BlockdevOptionsNull',
+      'null-co':    'BlockdevOptionsNull',
       'parallels':  'BlockdevOptionsGenericFormat',
-      'qcow':       'BlockdevOptionsGenericCOWFormat',
       'qcow2':      'BlockdevOptionsQcow2',
+      'qcow':       'BlockdevOptionsGenericCOWFormat',
       'qed':        'BlockdevOptionsGenericCOWFormat',
+      'quorum':     'BlockdevOptionsQuorum',
       'raw':        'BlockdevOptionsGenericFormat',
+# TODO rbd: Wait for structured options
+# TODO sheepdog: Wait for structured options
+# TODO ssh: Should take InetSocketAddress for 'host'?
+      'tftp':       'BlockdevOptionsFile',
       'vdi':        'BlockdevOptionsGenericFormat',
       'vhdx':       'BlockdevOptionsGenericFormat',
       'vmdk':       'BlockdevOptionsGenericCOWFormat',
       'vpc':        'BlockdevOptionsGenericFormat',
-      'quorum':     'BlockdevOptionsQuorum',
-      'null-aio':   'BlockdevOptionsNull',
-      'null-co':    'BlockdevOptionsNull'
+      'vvfat':      'BlockdevOptionsVVFAT'
   } }
 
 ##
-- 
1.9.3

Re: [Qemu-devel] [PATCH v7 0/3] block: Introduce "null" drivers

[Benoît Canet]

The Thursday 11 Sep 2014 à 14:09:55 (+0800), Fam Zheng wrote :
> v7: Add Benoît's rev-by line in patch 2.
>     Improved help text in patch 1. (Benoît)
> 
> v6: Don't inherit from BlockdevOptionsFile. (Stefan)
>     Use .bdrv_co_readv instead of .bdrv_read. (Kevin)
>     Sort items in qapi schema definitions in patch 2 & 3.
> 
> 
> Fam Zheng (3):
>   block: Introduce "null" drivers
>   qapi: Sort BlockdevDriver enum data list
>   qapi: Sort items in BlockdevOptions definition
> 
>  block/Makefile.objs  |   1 +
>  block/null.c         | 178 +++++++++++++++++++++++++++++++++++++++++++++++++++
>  qapi/block-core.json |  57 +++++++++++------
>  3 files changed, 215 insertions(+), 21 deletions(-)
>  create mode 100644 block/null.c
> 
> -- 
> 1.9.3
> 

I don't think I will be able to break it further.

Reviewed-by: Benoît Canet <benoit.canet@nodalink.com>

Re: [Qemu-devel] [PATCH v7 0/3] block: Introduce "null" drivers

[Eric Blake]

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On 09/11/2014 12:09 AM, Fam Zheng wrote:
> v7: Add Benoît's rev-by line in patch 2.
>     Improved help text in patch 1. (Benoît)
> 
> v6: Don't inherit from BlockdevOptionsFile. (Stefan)
>     Use .bdrv_co_readv instead of .bdrv_read. (Kevin)
>     Sort items in qapi schema definitions in patch 2 & 3.
> 
> 
> Fam Zheng (3):
>   block: Introduce "null" drivers
>   qapi: Sort BlockdevDriver enum data list
>   qapi: Sort items in BlockdevOptions definition

Series: Reviewed-by: Eric Blake <eblake@redhat.com>

> 
>  block/Makefile.objs  |   1 +
>  block/null.c         | 178 +++++++++++++++++++++++++++++++++++++++++++++++++++
>  qapi/block-core.json |  57 +++++++++++------
>  3 files changed, 215 insertions(+), 21 deletions(-)
>  create mode 100644 block/null.c
> 

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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Re: [Qemu-devel] [PATCH v7 0/3] block: Introduce "null" drivers

[Stefan Hajnoczi]

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On Mon, Sep 15, 2014 at 11:47:02AM -0600, Eric Blake wrote:
> On 09/11/2014 12:09 AM, Fam Zheng wrote:
> > v7: Add Benoît's rev-by line in patch 2.
> >     Improved help text in patch 1. (Benoît)
> > 
> > v6: Don't inherit from BlockdevOptionsFile. (Stefan)
> >     Use .bdrv_co_readv instead of .bdrv_read. (Kevin)
> >     Sort items in qapi schema definitions in patch 2 & 3.
> > 
> > 
> > Fam Zheng (3):
> >   block: Introduce "null" drivers
> >   qapi: Sort BlockdevDriver enum data list
> >   qapi: Sort items in BlockdevOptions definition
> 
> Series: Reviewed-by: Eric Blake <eblake@redhat.com>

In order for Reviewed-by to get picked up by my scripts, it needs to be
in the first column.  This prevents false positives like quoted commit
messages from polluting the Reviewed-by tags.

In the future, please reply to the cover letter with Reviewed-by in the
first column.  It is not necessary to say "Series:".

Thanks,
Stefan

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Re: [Qemu-devel] [PATCH v7 0/3] block: Introduce "null" drivers

[Eric Blake]

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On 09/16/2014 04:30 AM, Stefan Hajnoczi wrote:
> On Mon, Sep 15, 2014 at 11:47:02AM -0600, Eric Blake wrote:
>> On 09/11/2014 12:09 AM, Fam Zheng wrote:
>>> v7: Add Benoît's rev-by line in patch 2.
>>>     Improved help text in patch 1. (Benoît)
>>>
>>> v6: Don't inherit from BlockdevOptionsFile. (Stefan)
>>>     Use .bdrv_co_readv instead of .bdrv_read. (Kevin)
>>>     Sort items in qapi schema definitions in patch 2 & 3.
>>>
>>>
>>> Fam Zheng (3):
>>>   block: Introduce "null" drivers
>>>   qapi: Sort BlockdevDriver enum data list
>>>   qapi: Sort items in BlockdevOptions definition
>>
>> Series: Reviewed-by: Eric Blake <eblake@redhat.com>
> 
> In order for Reviewed-by to get picked up by my scripts, it needs to be
> in the first column.  This prevents false positives like quoted commit
> messages from polluting the Reviewed-by tags.
> 
> In the future, please reply to the cover letter with Reviewed-by in the
> first column.  It is not necessary to say "Series:".

Sure, will do.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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Re: [Qemu-devel] [PATCH v7 0/3] block: Introduce "null" drivers

[Stefan Hajnoczi]

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On Thu, Sep 11, 2014 at 02:09:55PM +0800, Fam Zheng wrote:
> v7: Add Benoît's rev-by line in patch 2.
>     Improved help text in patch 1. (Benoît)
> 
> v6: Don't inherit from BlockdevOptionsFile. (Stefan)
>     Use .bdrv_co_readv instead of .bdrv_read. (Kevin)
>     Sort items in qapi schema definitions in patch 2 & 3.
> 
> 
> Fam Zheng (3):
>   block: Introduce "null" drivers
>   qapi: Sort BlockdevDriver enum data list
>   qapi: Sort items in BlockdevOptions definition
> 
>  block/Makefile.objs  |   1 +
>  block/null.c         | 178 +++++++++++++++++++++++++++++++++++++++++++++++++++
>  qapi/block-core.json |  57 +++++++++++------
>  3 files changed, 215 insertions(+), 21 deletions(-)
>  create mode 100644 block/null.c
> 
> -- 
> 1.9.3
> 
> 

Thanks, applied to my block tree:
https://github.com/stefanha/qemu/commits/block

Stefan

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