blockdev: Disentangle BlockDriverState and DriveInfo creation

blockdev_init() mixes up BlockDriverState and DriveInfo initialization
Finish the BlockDriverState job before starting to mess with
DriveInfo.  Easier on the eyes.
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
Reviewed-by: NMax Reitz <mreitz@redhat.com>
Reviewed-by: NBenoît Canet <benoit.canet@nodalink.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

blockdev.c

@@ -301,6 +301,7 @@ static DriveInfo *blockdev_init(const char *file, QDict *bs_opts,
     int ro = 0;
     int bdrv_flags = 0;
     int on_read_error, on_write_error;
+    BlockDriverState *bs;
     DriveInfo *dinfo;
     ThrottleConfig cfg;
     int snapshot = 0;
@@ -456,26 +457,27 @@ static DriveInfo *blockdev_init(const char *file, QDict *bs_opts,
     }
 
     /* init */
-    dinfo = g_malloc0(sizeof(*dinfo));
-    dinfo->id = g_strdup(qemu_opts_id(opts));
-    dinfo->bdrv = bdrv_new(dinfo->id, &error);
-    if (error) {
-        error_propagate(errp, error);
-        goto bdrv_new_err;
+    bs = bdrv_new(qemu_opts_id(opts), errp);
+    if (!bs) {
+        goto early_err;
     }
-    dinfo->bdrv->open_flags = snapshot ? BDRV_O_SNAPSHOT : 0;
-    dinfo->bdrv->read_only = ro;
-    dinfo->bdrv->detect_zeroes = detect_zeroes;
-    QTAILQ_INSERT_TAIL(&drives, dinfo, next);
+    bs->open_flags = snapshot ? BDRV_O_SNAPSHOT : 0;
+    bs->read_only = ro;
+    bs->detect_zeroes = detect_zeroes;
 
-    bdrv_set_on_error(dinfo->bdrv, on_read_error, on_write_error);
+    bdrv_set_on_error(bs, on_read_error, on_write_error);
 
     /* disk I/O throttling */
     if (throttle_enabled(&cfg)) {
-        bdrv_io_limits_enable(dinfo->bdrv);
-        bdrv_set_io_limits(dinfo->bdrv, &cfg);
+        bdrv_io_limits_enable(bs);
+        bdrv_set_io_limits(bs, &cfg);
     }
 
+    dinfo = g_malloc0(sizeof(*dinfo));
+    dinfo->id = g_strdup(qemu_opts_id(opts));
+    dinfo->bdrv = bs;
+    QTAILQ_INSERT_TAIL(&drives, dinfo, next);
+
     if (!file || !*file) {
         if (has_driver_specific_opts) {
             file = NULL;
@@ -502,7 +504,8 @@ static DriveInfo *blockdev_init(const char *file, QDict *bs_opts,
     bdrv_flags |= ro ? 0 : BDRV_O_RDWR;
 
     QINCREF(bs_opts);
-    ret = bdrv_open(&dinfo->bdrv, file, NULL, bs_opts, bdrv_flags, drv, &error);
+    ret = bdrv_open(&bs, file, NULL, bs_opts, bdrv_flags, drv, &error);
+    assert(bs == dinfo->bdrv);
 
     if (ret < 0) {
         error_setg(errp, "could not open disk image %s: %s",
@@ -511,8 +514,9 @@ static DriveInfo *blockdev_init(const char *file, QDict *bs_opts,
         goto err;
     }
 
-    if (bdrv_key_required(dinfo->bdrv))
+    if (bdrv_key_required(bs)) {
         autostart = 0;
+    }
 
     QDECREF(bs_opts);
     qemu_opts_del(opts);
@@ -520,9 +524,8 @@ static DriveInfo *blockdev_init(const char *file, QDict *bs_opts,
     return dinfo;
 
 err:
-    bdrv_unref(dinfo->bdrv);
+    bdrv_unref(bs);
     QTAILQ_REMOVE(&drives, dinfo, next);
-bdrv_new_err:
     g_free(dinfo->id);
     g_free(dinfo);
 early_err: