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 <[email protected]>

Index: qemu/block.c
===================================================================

block.c +11 -11

@@ -428,10 +428,16 @@ int bdrv_open2(BlockDriverState *bs, con
             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);
 

@@ -452,23 +458,17 @@ int bdrv_open2(BlockDriverState *bs, con
             (flags & (BDRV_O_CACHE_MASK|BDRV_O_NATIVE_AIO));
     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 == -EACCES || ret == -EPERM) && !(flags & BDRV_O_FILE)) {
         ret = drv->bdrv_open(bs, filename, open_flags & ~BDRV_O_RDWR);
         bs->read_only = 1;
     }
+
     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;
     }

To keep the behaviour as previously you'd need to set at least bs->drv in the unlink_and_fail case, too. I have no clue why it's important to set it to NULL when bs isn't going to be used anyway (probably it is, but I don't know where), but Fabrice committed this in 6b21b973 as a fix. Unfortunately, the commit message looks like most of Fabrice's commit messages, so it's of no use for me...

Quoted 6 lines

To keep the behaviour as previously you'd need to set at least bs->drv in the unlink_and_fail case, too. I have no clue why it's important to set it to NULL when bs isn't going to be used anyway (probably it is, but I don't know where), but Fabrice committed this in 6b21b973 as a fix. Unfortunately, the commit message looks like most of Fabrice's commit messages, so it's of no use for me...

The unlink_and_fail label can only be reached from places where we haven't set bs->drv yet, so it should be fine.