qmp: add block_job_set_speed command

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>
Acked-by: Luiz Capitulino <lcapitulino@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

6 files changed, 79 insertions, 0 deletions

diff --git a/blockdev.c b/blockdev.c
index 06f179ef87..4c8fcdd31e 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -964,3 +964,28 @@ 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 5f09594756..813705ee35 100644
--- a/hmp-commands.hx
+++ b/hmp-commands.hx
@@ -84,6 +84,20 @@ 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 cde8d7a5cb..bf3d9df88f 100644
--- a/hmp.c
+++ b/hmp.c
@@ -794,3 +794,14 @@ void hmp_block_stream(Monitor *mon, const QDict *qdict)
 
     hmp_handle_error(mon, &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);
+
+    hmp_handle_error(mon, &error);
+}
diff --git a/hmp.h b/hmp.h
index 9234f28db6..edd902077e 100644
--- a/hmp.h
+++ b/hmp.h
@@ -55,5 +55,6 @@ void hmp_eject(Monitor *mon, const QDict *qdict);
 void hmp_change(Monitor *mon, const QDict *qdict);
 void hmp_block_set_io_throttle(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 9a1d9a936b..d9f66c67f1 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -1465,3 +1465,25 @@
 # 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.
+#
+# @device: the device name
+#
+# @value:  the maximum speed, in bytes per second
+#
+# Returns: Nothing on success
+#          If the job type does not support throttling, NotSupported
+#          If streaming is not active on this device, DeviceNotActive
+#
+# Since: 1.1
+##
+{ 'command': 'block_job_set_speed',
+  'data': { 'device': 'str', 'value': 'int' } }
diff --git a/qmp-commands.hx b/qmp-commands.hx
index 0dfc80e26f..e4615ca795 100644
--- a/qmp-commands.hx
+++ b/qmp-commands.hx
@@ -655,6 +655,12 @@ EQMP
     },
 
     {
+        .name       = "block_job_set_speed",
+        .args_type  = "device:B,value:o",
+        .mhandler.cmd_new = qmp_marshal_input_block_job_set_speed,
+    },
+
+    {
         .name       = "blockdev-snapshot-sync",
         .args_type  = "device:B,snapshot-file:s,format:s?",
         .mhandler.cmd_new = qmp_marshal_input_blockdev_snapshot_sync,