block: clean up bdrv_open2 structure a bit

Check the whitelist as early as possible instead of continuing the
setup, and move all the error handling code to the end of the
function.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

diff --git a/block.c b/block.c
index 3721d939541cab02ade18e77774cd5d592b0d143..5f29020152691ea35607246d2ea2b21aeb2f23ab 100644 (file)
--- a/block.c
+++ b/block.c
@@ -428,10 +428,16 @@ int bdrv_open2(BlockDriverState *bs, const char *filename, int flags,
             drv = find_image_format(filename);
         }
     }
+
     if (!drv) {
         ret = -ENOENT;
         goto unlink_and_fail;
     }
+    if (use_bdrv_whitelist && !bdrv_is_whitelisted(drv)) {
+        ret = -ENOTSUP;
+        goto unlink_and_fail;
+    }
+
     bs->drv = drv;
     bs->opaque = qemu_mallocz(drv->instance_size);
 
@@ -453,20 +459,12 @@ int bdrv_open2(BlockDriverState *bs, const char *filename, int flags,
     } else {
         open_flags = flags & ~(BDRV_O_FILE | BDRV_O_SNAPSHOT);
     }
-    if (use_bdrv_whitelist && !bdrv_is_whitelisted(drv)) {
-        ret = -ENOTSUP;
-    } else {
-        ret = drv->bdrv_open(bs, filename, open_flags);
-    }
+
+    ret = drv->bdrv_open(bs, filename, open_flags);
     if (ret < 0) {
-        qemu_free(bs->opaque);
-        bs->opaque = NULL;
-        bs->drv = NULL;
-    unlink_and_fail:
-        if (bs->is_temporary)
-            unlink(filename);
-        return ret;
+        goto free_and_fail;
     }
+
     if (drv->bdrv_getlength) {
         bs->total_sectors = bdrv_getlength(bs) >> BDRV_SECTOR_BITS;
     }
@@ -499,6 +497,15 @@ int bdrv_open2(BlockDriverState *bs, const char *filename, int flags,
             bs->change_cb(bs->change_opaque);
     }
     return 0;
+
+free_and_fail:
+    qemu_free(bs->opaque);
+    bs->opaque = NULL;
+    bs->drv = NULL;
+unlink_and_fail:
+    if (bs->is_temporary)
+        unlink(filename);
+    return ret;
 }
 
 void bdrv_close(BlockDriverState *bs)