[Qemu-devel] [PATCH 2/3] Introduce do_snapshot_blkdev() and monitor command to handle it.

[Jes.Sorensen@redhat.com]

From: Jes Sorensen <Jes.Sorensen@redhat.com>

The monitor command is:
snapshot_blkdev <device> [snapshot-file] [format]

Default format is qcow2. For now snapshots without a snapshot-file, eg
internal snapshots, are not supported.

Signed-off-by: Jes Sorensen <Jes.Sorensen@redhat.com>
---
 blockdev.c      |   61 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 blockdev.h      |    1 +
 hmp-commands.hx |   19 +++++++++++++++++
 3 files changed, 81 insertions(+), 0 deletions(-)

diff --git a/blockdev.c b/blockdev.c
index f6ac439..1ea24d7 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -514,6 +514,67 @@ void do_commit(Monitor *mon, const QDict *qdict)
     }
 }
 
+int do_snapshot_blkdev(Monitor *mon, const QDict *qdict, QObject **ret_data)
+{
+    const char *device = qdict_get_str(qdict, "device");
+    const char *filename = qdict_get_try_str(qdict, "snapshot_file");
+    const char *format = qdict_get_try_str(qdict, "format");
+    const char format_qcow2[] = "qcow2";
+    BlockDriverState *bs;
+    BlockDriver *drv, *proto_drv;
+    int ret = 0;
+    int flags;
+
+    bs = bdrv_find(device);
+    if (!bs) {
+        qerror_report(QERR_DEVICE_NOT_FOUND, device);
+        ret = -1;
+        goto out;
+    }
+
+    if (!format) {
+        format = format_qcow2;
+    }
+
+    drv = bdrv_find_format(format);
+    if (!drv) {
+        qerror_report(QERR_INVALID_BLOCK_FORMAT, format);
+        ret = -1;
+        goto out;
+    }
+
+    proto_drv = bdrv_find_protocol(filename);
+    if (!proto_drv) {
+        qerror_report(QERR_INVALID_BLOCK_FORMAT, format);
+        ret = -1;
+        goto out;
+    }
+
+    ret = bdrv_img_create(filename, format, bs->filename,
+                          bs->drv->format_name, NULL, -1, bs->open_flags);
+    if (ret) {
+        goto out;
+    }
+
+    qemu_aio_flush();
+    bdrv_flush(bs);
+
+    flags = bs->open_flags;
+    bdrv_close(bs);
+    ret = bdrv_open(bs, filename, flags, drv);
+    /*
+     * If reopening the image file we just created fails, we really
+     * are in trouble :(
+     */
+    assert(ret == 0);
+out:
+    if (ret) {
+        ret = 1;
+    }
+
+    return ret;
+}
+
 static int eject_device(Monitor *mon, BlockDriverState *bs, int force)
 {
     if (!force) {
diff --git a/blockdev.h b/blockdev.h
index 4cb8ca9..4536b5c 100644
--- a/blockdev.h
+++ b/blockdev.h
@@ -52,5 +52,6 @@ int do_block_set_passwd(Monitor *mon, const QDict *qdict, QObject **ret_data);
 int do_change_block(Monitor *mon, const char *device,
                     const char *filename, const char *fmt);
 int do_drive_del(Monitor *mon, const QDict *qdict, QObject **ret_data);
+int do_snapshot_blkdev(Monitor *mon, const QDict *qdict, QObject **ret_data);
 
 #endif
diff --git a/hmp-commands.hx b/hmp-commands.hx
index 23024ba..97e744e 100644
--- a/hmp-commands.hx
+++ b/hmp-commands.hx
@@ -801,6 +801,25 @@ STEXI
 Set maximum tolerated downtime (in seconds) for migration.
 ETEXI
 
+    {
+        .name       = "snapshot_blkdev",
+        .args_type  = "device:s,snapshot_file:s?,format:s?",
+        .params     = "device [snapshot-file] [format]",
+        .help       = "initiates a live snapshot\n\t\t\t"
+                      "of device. If a snapshot file is specified, the\n\t\t\t"
+                      "snapshot file will become the new root image. If\n\t\t\t"
+                      "format is specified, the snapshot file will be\n\t\t\t"
+                      "created in that format. Otherwise the snapshot\n\t\t\t"
+                      "will be internal! (currently unsupported)",
+        .mhandler.cmd_new = do_snapshot_blkdev,
+    },
+
+STEXI
+@item snapshot_blkdev
+@findex snapshot_blkdev
+Snapshot device, using snapshot file as target if provided
+ETEXI
+
 #if defined(TARGET_I386)
     {
         .name       = "drive_add",
-- 
1.7.3.2