[Qemu-devel] [PATCH v3 6/9] qmp: add block_job_set_speed command

[Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>]

Add block_job_set_speed, which sets the maximum speed for a background
block operation.

Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
---
 blockdev.c       |   25 +++++++++++++++++++++++++
 hmp-commands.hx  |   14 ++++++++++++++
 hmp.c            |   14 ++++++++++++++
 hmp.h            |    1 +
 qapi-schema.json |   23 +++++++++++++++++++++++
 qmp-commands.hx  |   18 ++++++++++++++++++
 6 files changed, 95 insertions(+), 0 deletions(-)

diff --git a/blockdev.c b/blockdev.c
index 08355cf..b101ba1 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -955,3 +955,28 @@ void qmp_block_stream(const char *device, bool has_base,
 
     trace_qmp_block_stream(bs, bs->job);
 }
+
+static BlockJob *find_block_job(const char *device)
+{
+    BlockDriverState *bs;
+
+    bs = bdrv_find(device);
+    if (!bs || !bs->job) {
+        return NULL;
+    }
+    return bs->job;
+}
+
+void qmp_block_job_set_speed(const char *device, int64_t value, Error **errp)
+{
+    BlockJob *job = find_block_job(device);
+
+    if (!job) {
+        error_set(errp, QERR_DEVICE_NOT_ACTIVE, device);
+        return;
+    }
+
+    if (block_job_set_speed(job, value) < 0) {
+        error_set(errp, QERR_NOT_SUPPORTED);
+    }
+}
diff --git a/hmp-commands.hx b/hmp-commands.hx
index c0de41c..788ec97 100644
--- a/hmp-commands.hx
+++ b/hmp-commands.hx
@@ -85,6 +85,20 @@ Copy data from a backing file into a block device.
 ETEXI
 
     {
+        .name       = "block_job_set_speed",
+        .args_type  = "device:B,value:o",
+        .params     = "device value",
+        .help       = "set maximum speed for a background block operation",
+        .mhandler.cmd = hmp_block_job_set_speed,
+    },
+
+STEXI
+@item block_job_set_stream
+@findex block_job_set_stream
+Set maximum speed for a background block operation.
+ETEXI
+
+    {
         .name       = "eject",
         .args_type  = "force:-f,device:B",
         .params     = "[-f] device",
diff --git a/hmp.c b/hmp.c
index 8b7d7d4..f3edf7c 100644
--- a/hmp.c
+++ b/hmp.c
@@ -545,3 +545,17 @@ void hmp_block_stream(Monitor *mon, const QDict *qdict)
         error_free(error);
     }
 }
+
+void hmp_block_job_set_speed(Monitor *mon, const QDict *qdict)
+{
+    Error *error = NULL;
+    const char *device = qdict_get_str(qdict, "device");
+    int64_t value = qdict_get_int(qdict, "value");
+
+    qmp_block_job_set_speed(device, value, &error);
+
+    if (error) {
+        monitor_printf(mon, "%s\n", error_get_pretty(error));
+        error_free(error);
+    }
+}
diff --git a/hmp.h b/hmp.h
index 3cb6fe5..4c1458e 100644
--- a/hmp.h
+++ b/hmp.h
@@ -38,5 +38,6 @@ void hmp_system_reset(Monitor *mon, const QDict *qdict);
 void hmp_system_powerdown(Monitor *mon, const QDict *qdict);
 void hmp_cpu(Monitor *mon, const QDict *qdict);
 void hmp_block_stream(Monitor *mon, const QDict *qdict);
+void hmp_block_job_set_speed(Monitor *mon, const QDict *qdict);
 
 #endif
diff --git a/qapi-schema.json b/qapi-schema.json
index 65308d2..f6a8252 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -954,3 +954,26 @@
 # Since: 1.1
 ##
 { 'command': 'block_stream', 'data': { 'device': 'str', '*base': 'str' } }
+
+##
+# @block_job_set_speed:
+#
+# Set maximum speed for a background block operation.
+#
+# This command can only be issued when there is an active block job.
+#
+# Throttling can be disabled by setting the speed to 0.
+#
+# Arguments:
+#
+# - device: device name
+# - value:  maximum speed, in bytes per second
+#
+# Errors:
+# NotSupported:    job type does not support speed setting
+# DeviceNotActive: streaming is not active on this device
+#
+# Since: 1.1
+##
+{ 'command': 'block_job_set_speed',
+  'data': { 'device': 'str', 'value': 'int' } }
diff --git a/qmp-commands.hx b/qmp-commands.hx
index 8c1c934..5541ca0 100644
--- a/qmp-commands.hx
+++ b/qmp-commands.hx
@@ -701,6 +701,24 @@ Examples:
 EQMP
 
     {
+        .name       = "block_job_set_speed",
+        .args_type  = "device:B,value:o",
+        .mhandler.cmd_new = qmp_marshal_input_block_job_set_speed,
+    },
+
+SQMP
+block_job_set_speed
+-------------------
+See qapi-schema.json for documentation.
+
+Example:
+
+-> { "execute": "block_job_set_speed",
+    "arguments": { "device": "virtio0", "value": 1024 } }
+
+EQMP
+
+    {
         .name       = "blockdev-snapshot-sync",
         .args_type  = "device:B,snapshot-file:s?,format:s?",
         .params     = "device [new-image-file] [format]",
-- 
1.7.7.3