From 09e6d08bc3cb4c80b508d2e72f861fdb1b5612ea Mon Sep 17 00:00:00 2001

From: John Snow <jsnow@redhat.com>

Date: Wed, 18 Jul 2018 22:55:10 +0200

Subject: [PATCH 252/268] nbd/client: Add x-dirty-bitmap to query bitmap from

 server

RH-Author: John Snow <jsnow@redhat.com>

Message-id: <20180718225511.14878-35-jsnow@redhat.com>

Patchwork-id: 81414

O-Subject: [RHEL-7.6 qemu-kvm-rhev PATCH 34/35] nbd/client: Add x-dirty-bitmap to query bitmap from server

Bugzilla: 1207657

RH-Acked-by: Eric Blake <eblake@redhat.com>

RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>

RH-Acked-by: Fam Zheng <famz@redhat.com>

From: Eric Blake <eblake@redhat.com>

In order to test that the NBD server is properly advertising

dirty bitmaps, we need a bare minimum client that can request

and read the context.  Since feature freeze for 3.0 is imminent,

this is the smallest workable patch, which replaces the qemu

block status report with the results of the NBD server's dirty

bitmap (making it very easy to use 'qemu-img map --output=json'

to learn where the dirty portions are).  Note that the NBD

protocol defines a dirty section with the same bit but opposite

sense that normal "base:allocation" uses to report an allocated

section; so in qemu-img map output, "data":true corresponds to

clean, "data":false corresponds to dirty.

A more complete solution that allows dirty bitmaps to be queried

at the same time as normal block status will be required before

this addition can lose the x- prefix.  Until then, the fact that

this replaces normal status with dirty status means actions

like 'qemu-img convert' will likely misbehave due to treating

dirty regions of the file as if they are unallocated.

The next patch adds an iotest to exercise this new code.

Signed-off-by: Eric Blake <eblake@redhat.com>

Message-Id: <20180702191458.28741-2-eblake@redhat.com>

(cherry picked from commit 216ee3657e14013505abe7853cecb632199fb13e)

Signed-off-by: John Snow <jsnow@redhat.com>

Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>

---

 block/nbd-client.c   |  3 +++

 block/nbd-client.h   |  1 +

 block/nbd.c          | 10 ++++++++--

 include/block/nbd.h  |  1 +

 nbd/client.c         |  4 ++--

 qapi/block-core.json |  7 ++++++-

 6 files changed, 21 insertions(+), 5 deletions(-)

diff --git a/block/nbd-client.c b/block/nbd-client.c

index e7caf49..98637c0 100644

--- a/block/nbd-client.c

+++ b/block/nbd-client.c

@@ -966,6 +966,7 @@ int nbd_client_init(BlockDriverState *bs,

                     const char *export,

                     QCryptoTLSCreds *tlscreds,

                     const char *hostname,

+                    const char *x_dirty_bitmap,

                     Error **errp)

 {

     NBDClientSession *client = nbd_get_client_session(bs);

@@ -978,9 +979,11 @@ int nbd_client_init(BlockDriverState *bs,

     client->info.request_sizes = true;

     client->info.structured_reply = true;

     client->info.base_allocation = true;

+    client->info.x_dirty_bitmap = g_strdup(x_dirty_bitmap);

     ret = nbd_receive_negotiate(QIO_CHANNEL(sioc), export,

                                 tlscreds, hostname,

                                 &client->ioc, &client->info, errp);

+    g_free(client->info.x_dirty_bitmap);

     if (ret < 0) {

         logout("Failed to negotiate with the NBD server\n");

         return ret;

diff --git a/block/nbd-client.h b/block/nbd-client.h

index 0ece76e..cfc9055 100644

--- a/block/nbd-client.h

+++ b/block/nbd-client.h

@@ -45,6 +45,7 @@ int nbd_client_init(BlockDriverState *bs,

                     const char *export_name,

                     QCryptoTLSCreds *tlscreds,

                     const char *hostname,

+                    const char *x_dirty_bitmap,

                     Error **errp);

 void nbd_client_close(BlockDriverState *bs);

diff --git a/block/nbd.c b/block/nbd.c

index 10912c3..f29c10f 100644

--- a/block/nbd.c

+++ b/block/nbd.c

@@ -378,6 +378,12 @@ static QemuOptsList nbd_runtime_opts = {

             .type = QEMU_OPT_STRING,

             .help = "ID of the TLS credentials to use",

         },

+        {

+            .name = "x-dirty-bitmap",

+            .type = QEMU_OPT_STRING,

+            .help = "experimental: expose named dirty bitmap in place of "

+                    "block status",

+        },

         { /* end of list */ }

     },

 };

@@ -438,8 +444,8 @@ static int nbd_open(BlockDriverState *bs, QDict *options, int flags,

     }

     /* NBD handshake */

-    ret = nbd_client_init(bs, sioc, s->export,

-                          tlscreds, hostname, errp);

+    ret = nbd_client_init(bs, sioc, s->export, tlscreds, hostname,

+                          qemu_opt_get(opts, "x-dirty-bitmap"), errp);

  error:

     if (sioc) {

         object_unref(OBJECT(sioc));

diff --git a/include/block/nbd.h b/include/block/nbd.h

index daaeae6..4638c83 100644

--- a/include/block/nbd.h

+++ b/include/block/nbd.h

@@ -259,6 +259,7 @@ static inline bool nbd_reply_type_is_error(int type)

 struct NBDExportInfo {

     /* Set by client before nbd_receive_negotiate() */

     bool request_sizes;

+    char *x_dirty_bitmap;

     /* In-out fields, set by client before nbd_receive_negotiate() and

      * updated by server results during nbd_receive_negotiate() */

diff --git a/nbd/client.c b/nbd/client.c

index b9e175d..25603f2 100644

--- a/nbd/client.c

+++ b/nbd/client.c

@@ -1,5 +1,5 @@

 /*

- *  Copyright (C) 2016-2017 Red Hat, Inc.

+ *  Copyright (C) 2016-2018 Red Hat, Inc.

  *  Copyright (C) 2005  Anthony Liguori <anthony@codemonkey.ws>

  *

  *  Network Block Device Client Side

@@ -825,7 +825,7 @@ int nbd_receive_negotiate(QIOChannel *ioc, const char *name,

             if (info->structured_reply && base_allocation) {

                 result = nbd_negotiate_simple_meta_context(

-                        ioc, name, "base:allocation",

+                        ioc, name, info->x_dirty_bitmap ?: "base:allocation",

                         &info->meta_base_allocation_id, errp);

                 if (result < 0) {

                     goto fail;

diff --git a/qapi/block-core.json b/qapi/block-core.json

index b2de7af..a6399af 100644

--- a/qapi/block-core.json

+++ b/qapi/block-core.json

@@ -3457,12 +3457,17 @@

 #

 # @tls-creds:   TLS credentials ID

 #

+# @x-dirty-bitmap: A "qemu:dirty-bitmap:NAME" string to query in place of

+#                  traditional "base:allocation" block status (see

+#                  NBD_OPT_LIST_META_CONTEXT in the NBD protocol) (since 3.0)

+#

 # Since: 2.9

 ##

 { 'struct': 'BlockdevOptionsNbd',

   'data': { 'server': 'SocketAddress',

             '*export': 'str',

-            '*tls-creds': 'str' } }

+            '*tls-creds': 'str',

+            '*x-dirty-bitmap': 'str' } }

 ##

 # @BlockdevOptionsRaw:

-- 

1.8.3.1