[Qemu-devel] [PATCH] Add the drive-reopen command

[Federico Simoncelli]

Signed-off-by: Federico Simoncelli <address@hidden>
---
 blockdev.c       |   40 +++++++++++++++++++++++++++-------------
 hmp-commands.hx  |   16 ++++++++++++++++
 hmp.c            |   11 +++++++++++
 hmp.h            |    1 +
 qapi-schema.json |   22 ++++++++++++++++++++++
 5 files changed, 77 insertions(+), 13 deletions(-)

diff --git a/blockdev.c b/blockdev.c
index 058b6d5..56da5c9 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -646,9 +646,8 @@ void do_commit(Monitor *mon, const QDict *qdict)
     }
 }
 
-void qmp_blockdev_snapshot_sync(const char *device, const char *snapshot_file,
-                                bool has_format, const char *format,
-                                Error **errp)
+static void change_blockdev_image(const char *device, const char 
*new_image_file,
+                                  const char *format, bool create, Error 
**errp)
 {
     BlockDriverState *bs;
     BlockDriver *drv, *old_drv, *proto_drv;
@@ -671,7 +670,7 @@ void qmp_blockdev_snapshot_sync(const char *device, const 
char *snapshot_file,
     old_drv = bs->drv;
     flags = bs->open_flags;
 
-    if (!has_format) {
+    if (!format) {
         format = "qcow2";
     }
 
@@ -681,24 +680,26 @@ void qmp_blockdev_snapshot_sync(const char *device, const 
char *snapshot_file,
         return;
     }
 
-    proto_drv = bdrv_find_protocol(snapshot_file);
+    proto_drv = bdrv_find_protocol(new_image_file);
     if (!proto_drv) {
         error_set(errp, QERR_INVALID_BLOCK_FORMAT, format);
         return;
     }
 
-    ret = bdrv_img_create(snapshot_file, format, bs->filename,
-                          bs->drv->format_name, NULL, -1, flags);
-    if (ret) {
-        error_set(errp, QERR_UNDEFINED_ERROR);
-        return;
+    if (create) {
+        ret = bdrv_img_create(new_image_file, format, bs->filename,
+                              bs->drv->format_name, NULL, -1, flags);
+        if (ret) {
+            error_set(errp, QERR_UNDEFINED_ERROR);
+            return;
+        }
     }
 
     bdrv_drain_all();
     bdrv_flush(bs);
 
     bdrv_close(bs);
-    ret = bdrv_open(bs, snapshot_file, flags, drv);
+    ret = bdrv_open(bs, new_image_file, flags, drv);
     /*
      * If reopening the image file we just created fails, fall back
      * and try to re-open the original image. If that fails too, we
@@ -709,11 +710,25 @@ void qmp_blockdev_snapshot_sync(const char *device, const 
char *snapshot_file,
         if (ret != 0) {
             error_set(errp, QERR_OPEN_FILE_FAILED, old_filename);
         } else {
-            error_set(errp, QERR_OPEN_FILE_FAILED, snapshot_file);
+            error_set(errp, QERR_OPEN_FILE_FAILED, new_image_file);
         }
     }
 }
 
+void qmp_drive_reopen(const char *device, const char *new_image_file,
+                      bool has_format, const char *format, Error **errp)
+{
+    change_blockdev_image(device, new_image_file,
+                          has_format ? format : NULL, false, errp);
+}
+
+void qmp_blockdev_snapshot_sync(const char *device, const char *snapshot_file,
+                                bool has_format, const char *format,
+                                Error **errp)
+{
+    change_blockdev_image(device, snapshot_file,
+                          has_format ? format : NULL, true, errp);
+}
 
 /* New and old BlockDriverState structs for group snapshots */
 typedef struct BlkTransactionStates {
@@ -877,7 +892,6 @@ exit:
     return;
 }
 
-
 static void eject_device(BlockDriverState *bs, int force, Error **errp)
 {
     if (bdrv_in_use(bs)) {
diff --git a/hmp-commands.hx b/hmp-commands.hx
index 64b3656..9e08123 100644
--- a/hmp-commands.hx
+++ b/hmp-commands.hx
@@ -900,6 +900,22 @@ Snapshot device, using snapshot file as target if provided
 ETEXI
 
     {
+        .name       = "drive-reopen",
+        .args_type  = "device:B,new-image-file:s,format:s?",
+        .params     = "device new-image-file [format]",
+        .help       = "Assigns a new image file to a device.\n\t\t\t"
+                      "The image will be opened using the format\n\t\t\t"
+                      "specified or 'qcow2' by default.\n\t\t\t",
+        .mhandler.cmd = hmp_drive_reopen,
+    },
+
+STEXI
address@hidden drive-reopen
address@hidden drive-reopen
+Assigns a new image file to a device.
+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 3a54455..ab069ad 100644
--- a/hmp.c
+++ b/hmp.c
@@ -706,6 +706,17 @@ void hmp_snapshot_blkdev(Monitor *mon, const QDict *qdict)
     hmp_handle_error(mon, &errp);
 }
 
+void hmp_drive_reopen(Monitor *mon, const QDict *qdict)
+{
+    const char *device = qdict_get_str(qdict, "device");
+    const char *filename = qdict_get_str(qdict, "new-image-file");
+    const char *format = qdict_get_try_str(qdict, "format");
+    Error *errp = NULL;
+
+    qmp_drive_reopen(device, filename, !!format, format, &errp);
+    hmp_handle_error(mon, &errp);
+}
+
 void hmp_migrate_cancel(Monitor *mon, const QDict *qdict)
 {
     qmp_migrate_cancel(NULL);
diff --git a/hmp.h b/hmp.h
index 5409464..e96926d 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_reopen(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 fd5973d..b33875d 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -1214,6 +1214,28 @@
   'data': { 'device': 'str', 'snapshot-file': 'str', '*format': 'str' } }
 
 ##
+# @drive-reopen
+#
+# Assigns a new image file to a device.
+#
+# @device: the name of the device for which we are changing the image file.
+#
+# @new-image-file: the target of the new image. If the file doesn't exists the
+#                  command will fail.
+#
+# @format: #optional the format of the new image, default is 'qcow2'.
+#
+# Returns: nothing on success
+#          If @device is not a valid block device, DeviceNotFound
+#          If @new-image-file can't be opened, OpenFileFailed
+#          If @format is invalid, InvalidBlockFormat
+#
+# Since 1.1
+##
+{ 'command': 'drive-reopen',
+  'data': { 'device': 'str', 'new-image-file': 'str', '*format': 'str' } }
+
+##
 # @human-monitor-command:
 #
 # Execute a command on the human monitor and return the output.
-- 
1.7.1