block: Split bdrv_new_root() off bdrv_new()

Creating an anonymous BDS can't fail.  Make that obvious.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Benoît Canet <benoit.canet@nodalink.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

block.c

@@ -336,10 +336,11 @@ void bdrv_register(BlockDriver *bdrv)
 }
 
 /* create a new block device (by default it is empty) */
-BlockDriverState *bdrv_new(const char *device_name, Error **errp)
+BlockDriverState *bdrv_new_root(const char *device_name, Error **errp)
 {
     BlockDriverState *bs;
-    int i;
+
+    assert(*device_name);
 
     if (*device_name && !id_wellformed(device_name)) {
         error_setg(errp, "Invalid device name");
@@ -358,12 +359,21 @@ BlockDriverState *bdrv_new(const char *device_name, Error **errp)
         return NULL;
     }
 
+    bs = bdrv_new();
+
+    pstrcpy(bs->device_name, sizeof(bs->device_name), device_name);
+    QTAILQ_INSERT_TAIL(&bdrv_states, bs, device_list);
+
+    return bs;
+}
+
+BlockDriverState *bdrv_new(void)
+{
+    BlockDriverState *bs;
+    int i;
+
     bs = g_new0(BlockDriverState, 1);
     QLIST_INIT(&bs->dirty_bitmaps);
-    pstrcpy(bs->device_name, sizeof(bs->device_name), device_name);
-    if (device_name[0] != '\0') {
-        QTAILQ_INSERT_TAIL(&bdrv_states, bs, device_list);
-    }
     for (i = 0; i < BLOCK_OP_TYPE_MAX; i++) {
         QLIST_INIT(&bs->op_blockers[i]);
     }
@@ -1224,7 +1234,7 @@ int bdrv_open_backing_file(BlockDriverState *bs, QDict *options, Error **errp)
         goto free_exit;
     }
 
-    backing_hd = bdrv_new("", errp);
+    backing_hd = bdrv_new();
 
     if (bs->backing_format[0] != '\0') {
         back_drv = bdrv_find_format(bs->backing_format);
@@ -1353,7 +1363,7 @@ int bdrv_append_temp_snapshot(BlockDriverState *bs, int flags, Error **errp)
     qdict_put(snapshot_options, "file.filename",
               qstring_from_str(tmp_filename));
 
-    bs_snapshot = bdrv_new("", &error_abort);
+    bs_snapshot = bdrv_new();
 
     ret = bdrv_open(&bs_snapshot, NULL, NULL, snapshot_options,
                     flags, bdrv_qcow2, &local_err);
@@ -1424,7 +1434,7 @@ int bdrv_open(BlockDriverState **pbs, const char *filename,
     if (*pbs) {
         bs = *pbs;
     } else {
-        bs = bdrv_new("", &error_abort);
+        bs = bdrv_new();
     }
 
     /* NULL means an empty set of options */

block/iscsi.c

@@ -1519,7 +1519,7 @@ static int iscsi_create(const char *filename, QemuOpts *opts, Error **errp)
     IscsiLun *iscsilun = NULL;
     QDict *bs_options;
 
-    bs = bdrv_new("", &error_abort);
+    bs = bdrv_new();
 
     /* Read out options */
     total_size = DIV_ROUND_UP(qemu_opt_get_size_del(opts, BLOCK_OPT_SIZE, 0),

block/vvfat.c

@@ -2939,7 +2939,7 @@ static int enable_write_target(BDRVVVFATState *s, Error **errp)
     unlink(s->qcow_filename);
 #endif
 
-    bdrv_set_backing_hd(s->bs, bdrv_new("", &error_abort));
+    bdrv_set_backing_hd(s->bs, bdrv_new());
     s->bs->backing_hd->drv = &vvfat_write_target;
     s->bs->backing_hd->opaque = g_new(void *, 1);
     *(void**)s->bs->backing_hd->opaque = s;

blockdev.c

@@ -523,7 +523,7 @@ static DriveInfo *blockdev_init(const char *file, QDict *bs_opts,
     }
 
     /* init */
-    bs = bdrv_new(qemu_opts_id(opts), errp);
+    bs = bdrv_new_root(qemu_opts_id(opts), errp);
     if (!bs) {
         goto early_err;
     }

hw/block/xen_disk.c

@@ -858,7 +858,7 @@ static int blk_connect(struct XenDevice *xendev)
 
         /* setup via xenbus -> create new block driver instance */
         xen_be_printf(&blkdev->xendev, 2, "create new bdrv (xenbus setup)\n");
-        blkdev->bs = bdrv_new(blkdev->dev, NULL);
+        blkdev->bs = bdrv_new_root(blkdev->dev, NULL);
         if (!blkdev->bs) {
             return -1;
         }

include/block/block.h

@@ -204,7 +204,8 @@ BlockDriver *bdrv_find_whitelisted_format(const char *format_name,
 int bdrv_create(BlockDriver *drv, const char* filename,
                 QemuOpts *opts, Error **errp);
 int bdrv_create_file(const char *filename, QemuOpts *opts, Error **errp);
-BlockDriverState *bdrv_new(const char *device_name, Error **errp);
+BlockDriverState *bdrv_new_root(const char *device_name, Error **errp);
+BlockDriverState *bdrv_new(void);
 void bdrv_make_anon(BlockDriverState *bs);
 void bdrv_swap(BlockDriverState *bs_new, BlockDriverState *bs_old);
 void bdrv_append(BlockDriverState *bs_new, BlockDriverState *bs_top);

qemu-img.c

@@ -296,7 +296,7 @@ static BlockDriverState *bdrv_new_open(const char *id,
     Error *local_err = NULL;
     int ret;
 
-    bs = bdrv_new(id, &error_abort);
+    bs = bdrv_new_root(id, &error_abort);
 
     if (fmt) {
         drv = bdrv_find_format(fmt);
@@ -2423,7 +2423,7 @@ static int img_rebase(int argc, char **argv)
     if (!unsafe) {
         char backing_name[1024];
 
-        bs_old_backing = bdrv_new("old_backing", &error_abort);
+        bs_old_backing = bdrv_new_root("old_backing", &error_abort);
         bdrv_get_backing_filename(bs, backing_name, sizeof(backing_name));
         ret = bdrv_open(&bs_old_backing, backing_name, NULL, NULL, src_flags,
                         old_backing_drv, &local_err);
@@ -2434,7 +2434,7 @@ static int img_rebase(int argc, char **argv)
             goto out;
         }
         if (out_baseimg[0]) {
-            bs_new_backing = bdrv_new("new_backing", &error_abort);
+            bs_new_backing = bdrv_new_root("new_backing", &error_abort);
             ret = bdrv_open(&bs_new_backing, out_baseimg, NULL, NULL, src_flags,
                             new_backing_drv, &local_err);
             if (ret) {

qemu-io.c

@@ -58,7 +58,7 @@ static int openfile(char *name, int flags, int growable, QDict *opts)
         return 1;
     }
 
-    qemuio_bs = bdrv_new("hda", &error_abort);
+    qemuio_bs = bdrv_new_root("hda", &error_abort);
 
     if (growable) {
         flags |= BDRV_O_PROTOCOL;

qemu-nbd.c

@@ -691,7 +691,7 @@ int main(int argc, char **argv)
         drv = NULL;
     }
 
-    bs = bdrv_new("hda", &error_abort);
+    bs = bdrv_new_root("hda", &error_abort);
 
     srcpath = argv[optind];
     ret = bdrv_open(&bs, srcpath, NULL, NULL, flags, drv, &local_err);