[Qemu-devel] [PATCH 5/8] block: add drive-mirror command

[Paolo Bonzini]

Signed-off-by: Paolo Bonzini <address@hidden>
---
 blockdev.c       |  102 ++++++++++++++++++++++++++++++++++++++++++++++++++++--
 hmp-commands.hx  |   21 +++++++++++
 hmp.c            |   26 ++++++++++++++
 hmp.h            |    1 +
 qapi-schema.json |   30 ++++++++++++++++
 qmp-commands.hx  |   36 +++++++++++++++++++
 trace-events     |    2 +-
 7 files changed, 214 insertions(+), 4 deletions(-)

diff --git a/blockdev.c b/blockdev.c
index 748e192..ce2f2f6 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -20,6 +20,8 @@
 #include "trace.h"
 #include "arch_init.h"
 
+static void block_job_cb(void *opaque, int ret);
+
 static QTAILQ_HEAD(drivelist, DriveInfo) drives = 
QTAILQ_HEAD_INITIALIZER(drives);
 
 static const char *const if_name[IF_COUNT] = {
@@ -831,6 +833,100 @@ exit:
     return;
 }
 
+void qmp_drive_mirror(const char *device, const char *target,
+                      bool has_format, const char *format, bool full,
+                      bool has_mode, enum NewImageMode mode, Error **errp)
+{
+    BlockDriverState *bs;
+    BlockDriverState *source;
+    BlockDriver *proto_drv;
+    BlockDriver *drv = NULL;
+    int flags;
+    uint64_t size;
+    int ret;
+
+    if (!has_mode) {
+        mode = NEW_IMAGE_MODE_ABSOLUTE_PATHS;
+    }
+    if (!has_format) {
+        format = mode == NEW_IMAGE_MODE_EXISTING ? NULL : "qcow2";
+    }
+    if (format) {
+        drv = bdrv_find_format(format);
+        if (!drv) {
+            error_set(errp, QERR_INVALID_BLOCK_FORMAT, format);
+            return;
+        }
+    }
+
+    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 (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) {
+        full = true;
+    }
+
+    proto_drv = bdrv_find_protocol(target);
+    if (!proto_drv) {
+        error_set(errp, QERR_INVALID_BLOCK_FORMAT, format);
+        return;
+    }
+
+    /* create new image w/backing file */
+    if (full && mode != NEW_IMAGE_MODE_EXISTING) {
+        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:
+            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;
+    }
+
+    /* Grab a reference so hotplug does not delete the BlockDriverState
+     * from underneath us.
+     */
+    drive_get_ref(drive_get_by_blockdev(bs));
+    ret = mirror_start(bs, target, drv, flags,
+                       block_job_cb, bs, full);
+    if (ret < 0) {
+        error_set(errp, QERR_OPEN_FILE_FAILED, target);
+    }
+}
+
+
 
 static void eject_device(BlockDriverState *bs, int force, Error **errp)
 {
@@ -1069,12 +1165,12 @@ static QObject *qobject_from_block_job(BlockJob *job)
                               job->speed);
 }
 
-static void block_stream_cb(void *opaque, int ret)
+static void block_job_cb(void *opaque, int ret)
 {
     BlockDriverState *bs = opaque;
     QObject *obj;
 
-    trace_block_stream_cb(bs, bs->job, ret);
+    trace_block_job_cb(bs, bs->job, ret);
 
     assert(bs->job);
     obj = qobject_from_block_job(bs->job);
@@ -1114,7 +1210,7 @@ void qmp_block_stream(const char *device, bool has_base,
         }
     }
 
-    ret = stream_start(bs, base_bs, base, block_stream_cb, bs);
+    ret = stream_start(bs, base_bs, base, block_job_cb, bs);
     if (ret < 0) {
         switch (ret) {
         case -EBUSY:
diff --git a/hmp-commands.hx b/hmp-commands.hx
index a6f5a84..36f4ef9 100644
--- a/hmp-commands.hx
+++ b/hmp-commands.hx
@@ -901,6 +901,27 @@ 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. New writes are mirrored to 
the\n\t\t\t"
+                      "specified new image file, and the block_stream\n\t\t\t"
+                      "command can then be 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
address@hidden drive_mirror
address@hidden drive_mirror
+Start mirroring a block device's writes to a new destination,
+using the specified target.
+ETEXI
+
+    {
         .name       = "drive_add",
         .args_type  = "pci_addr:s,opts:s",
         .params     = "[[<domain>:]<bus>:]<slot>\n"
diff --git a/hmp.c b/hmp.c
index f3e5163..e7290c9 100644
--- a/hmp.c
+++ b/hmp.c
@@ -688,6 +688,32 @@ 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_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, true, mode, 
&errp);
+    hmp_handle_error(mon, &errp);
+}
+
 void hmp_snapshot_blkdev(Monitor *mon, const QDict *qdict)
 {
     const char *device = qdict_get_str(qdict, "device");
diff --git a/hmp.h b/hmp.h
index 443b812..64bcaa6 100644
--- a/hmp.h
+++ b/hmp.h
@@ -48,6 +48,7 @@ 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);
diff --git a/qapi-schema.json b/qapi-schema.json
index ace55f3..c772bc3 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -1245,6 +1245,36 @@
   'returns': 'str' } 
 
 ##
+# @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: the format of the new destination.
+#
+# @mode: #optional whether and how QEMU should create a new image, default is
+# 'absolute-paths'.
+#
+# @full: whether the whole disk should be copied to the destination, or
+#        only the topmost image.
+#
+# Returns: nothing on success
+#          If @device is not a valid block device, DeviceNotFound
+#          If @target can't be opened, OpenFileFailed
+#          If @format is invalid, InvalidBlockFormat
+#
+# Since 1.1
+##
+{ 'command': 'drive-mirror',
+  'data': { 'device': 'str', 'target': 'str', '*format': 'str',
+            'full': 'bool', '*mode': 'NewImageMode'} }
+
+##
 # @migrate_cancel
 #
 # Cancel the current executing migration process.
diff --git a/qmp-commands.hx b/qmp-commands.hx
index 4d4c749..a51125e 100644
--- a/qmp-commands.hx
+++ b/qmp-commands.hx
@@ -792,6 +792,42 @@ Example:
 EQMP
 
     {
+        .name       = "drive-mirror",
+        .args_type  = "full:-n,device:B,target:s,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 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 qcow2.
+
+Arguments:
+
+- "device": device name to operate on (json-string)
+- "target": name of new image file (json-string)
+- "format": format of new image (json-string)
+- "mode": how an image file should be created into the target
+  file/device (NewImageMode, optional, default 'absolute-paths')
+- "full": whether the whole disk should be copied to the destination,
+  or only the topmost image (json-bool)
+
+Example:
+
+-> { "execute": "drive-mirror", "arguments": { "device": "ide-hd0",
+                                               "target": 
"/some/place/my-image",
+                                               "full": false,
+                                               "format": "qcow2" } }
+<- { "return": {} }
+
+EQMP
+
+    {
         .name       = "balloon",
         .args_type  = "value:M",
         .mhandler.cmd_new = qmp_marshal_input_balloon,
diff --git a/trace-events b/trace-events
index 23aad83..ec268da 100644
--- a/trace-events
+++ b/trace-events
@@ -81,7 +81,7 @@ stream_start(void *bs, void *base, void *s, void *co, void 
*opaque) "bs %p base
 
 # blockdev.c
 qmp_block_job_cancel(void *job) "job %p"
-block_stream_cb(void *bs, void *job, int ret) "bs %p job %p ret %d"
+block_job_cb(void *bs, void *job, int ret) "bs %p job %p ret %d"
 qmp_block_stream(void *bs, void *job) "bs %p job %p"
 
 # hw/virtio-blk.c
-- 
1.7.9.3