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From 09e6d08bc3cb4c80b508d2e72f861fdb1b5612ea Mon Sep 17 00:00:00 2001
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From: John Snow <jsnow@redhat.com>
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Date: Wed, 18 Jul 2018 22:55:10 +0200
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Subject: [PATCH 252/268] nbd/client: Add x-dirty-bitmap to query bitmap from
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 server
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RH-Author: John Snow <jsnow@redhat.com>
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Message-id: <20180718225511.14878-35-jsnow@redhat.com>
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Patchwork-id: 81414
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O-Subject: [RHEL-7.6 qemu-kvm-rhev PATCH 34/35] nbd/client: Add x-dirty-bitmap to query bitmap from server
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Bugzilla: 1207657
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RH-Acked-by: Eric Blake <eblake@redhat.com>
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RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
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RH-Acked-by: Fam Zheng <famz@redhat.com>
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From: Eric Blake <eblake@redhat.com>
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In order to test that the NBD server is properly advertising
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dirty bitmaps, we need a bare minimum client that can request
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and read the context.  Since feature freeze for 3.0 is imminent,
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this is the smallest workable patch, which replaces the qemu
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block status report with the results of the NBD server's dirty
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bitmap (making it very easy to use 'qemu-img map --output=json'
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to learn where the dirty portions are).  Note that the NBD
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protocol defines a dirty section with the same bit but opposite
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sense that normal "base:allocation" uses to report an allocated
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section; so in qemu-img map output, "data":true corresponds to
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clean, "data":false corresponds to dirty.
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A more complete solution that allows dirty bitmaps to be queried
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at the same time as normal block status will be required before
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this addition can lose the x- prefix.  Until then, the fact that
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this replaces normal status with dirty status means actions
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like 'qemu-img convert' will likely misbehave due to treating
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dirty regions of the file as if they are unallocated.
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The next patch adds an iotest to exercise this new code.
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Signed-off-by: Eric Blake <eblake@redhat.com>
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Message-Id: <20180702191458.28741-2-eblake@redhat.com>
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(cherry picked from commit 216ee3657e14013505abe7853cecb632199fb13e)
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Signed-off-by: John Snow <jsnow@redhat.com>
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Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
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---
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 block/nbd-client.c   |  3 +++
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 block/nbd-client.h   |  1 +
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 block/nbd.c          | 10 ++++++++--
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 include/block/nbd.h  |  1 +
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 nbd/client.c         |  4 ++--
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 qapi/block-core.json |  7 ++++++-
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 6 files changed, 21 insertions(+), 5 deletions(-)
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diff --git a/block/nbd-client.c b/block/nbd-client.c
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index e7caf49..98637c0 100644
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--- a/block/nbd-client.c
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+++ b/block/nbd-client.c
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@@ -966,6 +966,7 @@ int nbd_client_init(BlockDriverState *bs,
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                     const char *export,
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                     QCryptoTLSCreds *tlscreds,
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                     const char *hostname,
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+                    const char *x_dirty_bitmap,
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                     Error **errp)
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 {
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     NBDClientSession *client = nbd_get_client_session(bs);
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@@ -978,9 +979,11 @@ int nbd_client_init(BlockDriverState *bs,
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     client->info.request_sizes = true;
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     client->info.structured_reply = true;
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     client->info.base_allocation = true;
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+    client->info.x_dirty_bitmap = g_strdup(x_dirty_bitmap);
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     ret = nbd_receive_negotiate(QIO_CHANNEL(sioc), export,
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                                 tlscreds, hostname,
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                                 &client->ioc, &client->info, errp);
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+    g_free(client->info.x_dirty_bitmap);
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     if (ret < 0) {
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         logout("Failed to negotiate with the NBD server\n");
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         return ret;
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diff --git a/block/nbd-client.h b/block/nbd-client.h
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index 0ece76e..cfc9055 100644
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--- a/block/nbd-client.h
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+++ b/block/nbd-client.h
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@@ -45,6 +45,7 @@ int nbd_client_init(BlockDriverState *bs,
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                     const char *export_name,
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                     QCryptoTLSCreds *tlscreds,
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                     const char *hostname,
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+                    const char *x_dirty_bitmap,
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                     Error **errp);
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 void nbd_client_close(BlockDriverState *bs);
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diff --git a/block/nbd.c b/block/nbd.c
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index 10912c3..f29c10f 100644
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--- a/block/nbd.c
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+++ b/block/nbd.c
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@@ -378,6 +378,12 @@ static QemuOptsList nbd_runtime_opts = {
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             .type = QEMU_OPT_STRING,
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             .help = "ID of the TLS credentials to use",
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         },
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+        {
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+            .name = "x-dirty-bitmap",
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+            .type = QEMU_OPT_STRING,
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+            .help = "experimental: expose named dirty bitmap in place of "
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+                    "block status",
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+        },
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         { /* end of list */ }
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     },
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 };
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@@ -438,8 +444,8 @@ static int nbd_open(BlockDriverState *bs, QDict *options, int flags,
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     }
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     /* NBD handshake */
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-    ret = nbd_client_init(bs, sioc, s->export,
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-                          tlscreds, hostname, errp);
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+    ret = nbd_client_init(bs, sioc, s->export, tlscreds, hostname,
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+                          qemu_opt_get(opts, "x-dirty-bitmap"), errp);
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  error:
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     if (sioc) {
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         object_unref(OBJECT(sioc));
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diff --git a/include/block/nbd.h b/include/block/nbd.h
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index daaeae6..4638c83 100644
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--- a/include/block/nbd.h
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+++ b/include/block/nbd.h
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@@ -259,6 +259,7 @@ static inline bool nbd_reply_type_is_error(int type)
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 struct NBDExportInfo {
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     /* Set by client before nbd_receive_negotiate() */
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     bool request_sizes;
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+    char *x_dirty_bitmap;
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     /* In-out fields, set by client before nbd_receive_negotiate() and
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      * updated by server results during nbd_receive_negotiate() */
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diff --git a/nbd/client.c b/nbd/client.c
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index b9e175d..25603f2 100644
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--- a/nbd/client.c
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+++ b/nbd/client.c
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@@ -1,5 +1,5 @@
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 /*
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- *  Copyright (C) 2016-2017 Red Hat, Inc.
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+ *  Copyright (C) 2016-2018 Red Hat, Inc.
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  *  Copyright (C) 2005  Anthony Liguori <anthony@codemonkey.ws>
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  *
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  *  Network Block Device Client Side
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@@ -825,7 +825,7 @@ int nbd_receive_negotiate(QIOChannel *ioc, const char *name,
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             if (info->structured_reply && base_allocation) {
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                 result = nbd_negotiate_simple_meta_context(
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-                        ioc, name, "base:allocation",
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+                        ioc, name, info->x_dirty_bitmap ?: "base:allocation",
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                         &info->meta_base_allocation_id, errp);
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                 if (result < 0) {
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                     goto fail;
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diff --git a/qapi/block-core.json b/qapi/block-core.json
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index b2de7af..a6399af 100644
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--- a/qapi/block-core.json
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+++ b/qapi/block-core.json
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@@ -3457,12 +3457,17 @@
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 #
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 # @tls-creds:   TLS credentials ID
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 #
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+# @x-dirty-bitmap: A "qemu:dirty-bitmap:NAME" string to query in place of
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+#                  traditional "base:allocation" block status (see
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+#                  NBD_OPT_LIST_META_CONTEXT in the NBD protocol) (since 3.0)
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+#
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 # Since: 2.9
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 ##
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 { 'struct': 'BlockdevOptionsNbd',
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   'data': { 'server': 'SocketAddress',
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             '*export': 'str',
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-            '*tls-creds': 'str' } }
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+            '*tls-creds': 'str',
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+            '*x-dirty-bitmap': 'str' } }
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 ##
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 # @BlockdevOptionsRaw:
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-- 
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1.8.3.1
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