qmp: add drive-mirror command

This adds the monitor commands that start the mirroring job.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

blockdev.c

@@ -1181,6 +1181,130 @@ void qmp_block_commit(const char *device,
     drive_get_ref(drive_get_by_blockdev(bs));
 }
 
+void qmp_drive_mirror(const char *device, const char *target,
+                      bool has_format, const char *format,
+                      enum MirrorSyncMode sync,
+                      bool has_mode, enum NewImageMode mode,
+                      bool has_speed, int64_t speed, Error **errp)
+{
+    BlockDriverInfo bdi;
+    BlockDriverState *bs;
+    BlockDriverState *source, *target_bs;
+    BlockDriver *proto_drv;
+    BlockDriver *drv = NULL;
+    Error *local_err = NULL;
+    int flags;
+    uint64_t size;
+    int ret;
+
+    if (!has_speed) {
+        speed = 0;
+    }
+    if (!has_mode) {
+        mode = NEW_IMAGE_MODE_ABSOLUTE_PATHS;
+    }
+
+    bs = bdrv_find(device);
+    if (!bs) {
+        error_set(errp, QERR_DEVICE_NOT_FOUND, device);
+        return;
+    }
+
+    if (!bdrv_is_inserted(bs)) {
+        error_set(errp, QERR_DEVICE_HAS_NO_MEDIUM, device);
+        return;
+    }
+
+    if (!has_format) {
+        format = mode == NEW_IMAGE_MODE_EXISTING ? NULL : bs->drv->format_name;
+    }
+    if (format) {
+        drv = bdrv_find_format(format);
+        if (!drv) {
+            error_set(errp, QERR_INVALID_BLOCK_FORMAT, format);
+            return;
+        }
+    }
+
+    if (bdrv_in_use(bs)) {
+        error_set(errp, QERR_DEVICE_IN_USE, device);
+        return;
+    }
+
+    flags = bs->open_flags | BDRV_O_RDWR;
+    source = bs->backing_hd;
+    if (!source && sync == MIRROR_SYNC_MODE_TOP) {
+        sync = MIRROR_SYNC_MODE_FULL;
+    }
+
+    proto_drv = bdrv_find_protocol(target);
+    if (!proto_drv) {
+        error_set(errp, QERR_INVALID_BLOCK_FORMAT, format);
+        return;
+    }
+
+    if (sync == MIRROR_SYNC_MODE_FULL && mode != NEW_IMAGE_MODE_EXISTING) {
+        /* create new image w/o backing file */
+        assert(format && drv);
+        bdrv_get_geometry(bs, &size);
+        size *= 512;
+        ret = bdrv_img_create(target, format,
+                              NULL, NULL, NULL, size, flags);
+    } else {
+        switch (mode) {
+        case NEW_IMAGE_MODE_EXISTING:
+            ret = 0;
+            break;
+        case NEW_IMAGE_MODE_ABSOLUTE_PATHS:
+            /* create new image with backing file */
+            ret = bdrv_img_create(target, format,
+                                  source->filename,
+                                  source->drv->format_name,
+                                  NULL, -1, flags);
+            break;
+        default:
+            abort();
+        }
+    }
+
+    if (ret) {
+        error_set(errp, QERR_OPEN_FILE_FAILED, target);
+        return;
+    }
+
+    target_bs = bdrv_new("");
+    ret = bdrv_open(target_bs, target, flags | BDRV_O_NO_BACKING, drv);
+
+    if (ret < 0) {
+        bdrv_delete(target_bs);
+        error_set(errp, QERR_OPEN_FILE_FAILED, target);
+        return;
+    }
+
+    /* We need a backing file if we will copy parts of a cluster.  */
+    if (bdrv_get_info(target_bs, &bdi) >= 0 && bdi.cluster_size != 0 &&
+        bdi.cluster_size >= BDRV_SECTORS_PER_DIRTY_CHUNK * 512) {
+        ret = bdrv_open_backing_file(target_bs);
+        if (ret < 0) {
+            bdrv_delete(target_bs);
+            error_set(errp, QERR_OPEN_FILE_FAILED, target);
+            return;
+        }
+    }
+
+    mirror_start(bs, target_bs, speed, sync, block_job_cb, bs, &local_err);
+    if (local_err != NULL) {
+        bdrv_delete(target_bs);
+        error_propagate(errp, local_err);
+        return;
+    }
+
+    /* Grab a reference so hotplug does not delete the BlockDriverState from
+     * underneath us.
+     */
+    drive_get_ref(drive_get_by_blockdev(bs));
+}
+
 static BlockJob *find_block_job(const char *device)
 {
     BlockDriverState *bs;

hmp-commands.hx

@@ -1001,6 +1001,27 @@ STEXI
 @item snapshot_blkdev
 @findex snapshot_blkdev
 Snapshot device, using snapshot file as target if provided
+ETEXI
+
+    {
+        .name       = "drive_mirror",
+        .args_type  = "reuse:-n,full:-f,device:B,target:s,format:s?",
+        .params     = "[-n] [-f] device target [format]",
+        .help       = "initiates live storage\n\t\t\t"
+                      "migration for a device. The device's contents are\n\t\t\t"
+                      "copied to the new image file, including data that\n\t\t\t"
+                      "is written after the command is started.\n\t\t\t"
+                      "The -n flag requests QEMU to reuse the image found\n\t\t\t"
+                      "in new-image-file, instead of recreating it from scratch.\n\t\t\t"
+                      "The -f flag requests QEMU to copy the whole disk,\n\t\t\t"
+                      "so that the result does not need a backing file.\n\t\t\t",
+        .mhandler.cmd = hmp_drive_mirror,
+    },
+STEXI
+@item drive_mirror
+@findex drive_mirror
+Start mirroring a block device's writes to a new destination,
+using the specified target.
 ETEXI
 
     {

hmp.c

@@ -771,6 +771,34 @@ void hmp_block_resize(Monitor *mon, const QDict *qdict)
     hmp_handle_error(mon, &errp);
 }
 
+void hmp_drive_mirror(Monitor *mon, const QDict *qdict)
+{
+    const char *device = qdict_get_str(qdict, "device");
+    const char *filename = qdict_get_str(qdict, "target");
+    const char *format = qdict_get_try_str(qdict, "format");
+    int reuse = qdict_get_try_bool(qdict, "reuse", 0);
+    int full = qdict_get_try_bool(qdict, "full", 0);
+    enum NewImageMode mode;
+    Error *errp = NULL;
+
+    if (!filename) {
+        error_set(&errp, QERR_MISSING_PARAMETER, "target");
+        hmp_handle_error(mon, &errp);
+        return;
+    }
+
+    if (reuse) {
+        mode = NEW_IMAGE_MODE_EXISTING;
+    } else {
+        mode = NEW_IMAGE_MODE_ABSOLUTE_PATHS;
+    }
+
+    qmp_drive_mirror(device, filename, !!format, format,
+                     full ? MIRROR_SYNC_MODE_FULL : MIRROR_SYNC_MODE_TOP,
+                     true, mode, false, 0, &errp);
+    hmp_handle_error(mon, &errp);
+}
+
 void hmp_snapshot_blkdev(Monitor *mon, const QDict *qdict)
 {
     const char *device = qdict_get_str(qdict, "device");

hmp.h

@@ -51,6 +51,7 @@ void hmp_block_passwd(Monitor *mon, const QDict *qdict);
 void hmp_balloon(Monitor *mon, const QDict *qdict);
 void hmp_block_resize(Monitor *mon, const QDict *qdict);
 void hmp_snapshot_blkdev(Monitor *mon, const QDict *qdict);
+void hmp_drive_mirror(Monitor *mon, const QDict *qdict);
 void hmp_migrate_cancel(Monitor *mon, const QDict *qdict);
 void hmp_migrate_set_downtime(Monitor *mon, const QDict *qdict);
 void hmp_migrate_set_speed(Monitor *mon, const QDict *qdict);

qapi-schema.json

@@ -1606,6 +1606,40 @@
   'data': { 'device': 'str', '*base': 'str', 'top': 'str',
             '*speed': 'int' } }
 
+##
+# @drive-mirror
+#
+# Start mirroring a block device's writes to a new destination.
+#
+# @device:  the name of the device whose writes should be mirrored.
+#
+# @target: the target of the new image. If the file exists, or if it
+#          is a device, the existing file/device will be used as the new
+#          destination.  If it does not exist, a new file will be created.
+#
+# @format: #optional the format of the new destination, default is to
+#          probe if @mode is 'existing', else the format of the source
+#
+# @mode: #optional whether and how QEMU should create a new image, default is
+#        'absolute-paths'.
+#
+# @speed:  #optional the maximum speed, in bytes per second
+#
+# @sync: what parts of the disk image should be copied to the destination
+#        (all the disk, only the sectors allocated in the topmost image, or
+#        only new I/O).
+#
+# Returns: nothing on success
+#          If @device is not a valid block device, DeviceNotFound
+#
+# Since 1.3
+##
+{ 'command': 'drive-mirror',
+  'data': { 'device': 'str', 'target': 'str', '*format': 'str',
+            'sync': 'MirrorSyncMode', '*mode': 'NewImageMode',
+            '*speed': 'int' } }
+
+##
 # @migrate_cancel
 #
 # Cancel the current executing migration process.

qmp-commands.hx

@@ -933,6 +933,48 @@ Example:
                                                         "format": "qcow2" } }
 <- { "return": {} }
 
+EQMP
+
+    {
+        .name       = "drive-mirror",
+        .args_type  = "sync:s,device:B,target:s,speed:i?,mode:s?,format:s?",
+        .mhandler.cmd_new = qmp_marshal_input_drive_mirror,
+    },
+
+SQMP
+drive-mirror
+------------
+
+Start mirroring a block device's writes to a new destination. target
+specifies the target of the new image. If the file exists, or if it is
+a device, it will be used as the new destination for writes. If it does not
+exist, a new file will be created. format specifies the format of the
+mirror image, default is to probe if mode='existing', else the format
+of the source.
+
+Arguments:
+
+- "device": device name to operate on (json-string)
+- "target": name of new image file (json-string)
+- "format": format of new image (json-string, optional)
+- "mode": how an image file should be created into the target
+  file/device (NewImageMode, optional, default 'absolute-paths')
+- "speed": maximum speed of the streaming job, in bytes per second
+  (json-int)
+- "sync": what parts of the disk image should be copied to the destination;
+  possibilities include "full" for all the disk, "top" for only the sectors
+  allocated in the topmost image, or "none" to only replicate new I/O
+  (MirrorSyncMode).
+
+
+Example:
+
+-> { "execute": "drive-mirror", "arguments": { "device": "ide-hd0",
+                                               "target": "/some/place/my-image",
+                                               "sync": "full",
+                                               "format": "qcow2" } }
+<- { "return": {} }
+
 EQMP
 
     {