Re: [PATCH v6 1/8] Btrfs: introduce a tree for items that map UUIDs to something

[Josef Bacik <jbacik@fusionio.com>]

On Wed, Jun 26, 2013 at 11:47:29PM +0200, Stefan Behrens wrote:
> On 06/26/2013 21:55, Zach Brown wrote:
> >>+	if (!uuid_root) {
> >>+		WARN_ON_ONCE(1);
> >>+		ret = -ENOENT;
> >>+		goto out;
> >>+	}
> >
> >WARN_ON_ONCE specifically returns the condition so that you can write:
> >
> >	if (WARN_ON_ONCE(!uuid_root)) {
> >		ret = -ENOENT;
> >		goto out;
> >	}
> >
> >>+	while (item_size) {
> >>+		u64 data;
> >>+
> >>+		read_extent_buffer(eb, &data, offset, sizeof(data));
> >>+		data = le64_to_cpu(data);
> >>+		if (data == subid) {
> >>+			ret = 0;
> >>+			break;
> >>+		}
> >>+		offset += sizeof(data);
> >>+		item_size -= sizeof(data);
> >>+	}
> >
> >fs/btrfs/uuid-tree.c:81 col 24 warning: cast to restricted __le64
> >
> >There are a few more instances of this.  The good news is that fixing
> >the sparse warning makes the code better, too.
> >
> >		__le64 data;
> >
> >		read_extent_buffer(eb, &data, offset, sizeof(data));
> >		if (le64_to_cpu(data) == subid) {
> >
> >Plese make sure the rest of the series doesn't add sparse warnings for
> >Josef to get email about a few seconds after he merges.
> >
> >>+int btrfs_insert_uuid_subvol_item(struct btrfs_trans_handle *trans,
> >>+				  struct btrfs_root *uuid_root, u8 *uuid,
> >>+				  u64 subvol_id)
> >>+{
> >>+	int ret;
> >>+
> >>+	ret = btrfs_uuid_tree_lookup(uuid_root, uuid,
> >>+				     BTRFS_UUID_KEY_SUBVOL, subvol_id);
> >>+	if (ret == -ENOENT)
> >>+		ret = btrfs_uuid_tree_add(trans, uuid_root, uuid,
> >>+					  BTRFS_UUID_KEY_SUBVOL, subvol_id);
> >>+	return ret;
> >>+}
> >
> >
> >>+int btrfs_insert_uuid_received_subvol_item(struct btrfs_trans_handle *trans,
> >>+					   struct btrfs_root *uuid_root,
> >>+					   u8 *uuid, u64 subvol_id)
> >>+{
> >>+	int ret;
> >>+
> >>+	ret = btrfs_uuid_tree_lookup(uuid_root, uuid,
> >>+				     BTRFS_UUID_KEY_RECEIVED_SUBVOL, subvol_id);
> >>+	if (ret == -ENOENT)
> >>+		ret = btrfs_uuid_tree_add(trans, uuid_root, uuid,
> >>+					  BTRFS_UUID_KEY_RECEIVED_SUBVOL,
> >>+					  subvol_id);
> >>+	return ret;
> >>+}
> >
> >Just have callers pass in the key type so we get slightly less enormous
> >function names and less cut-and-paste code.
> 
> Thanks for your comments, but this salami review procedure is not very
> efficient. Everything that you comment on now and before is there since V1.
> 
> Please tell me when you are done with the full review. And please also stop
> the bikeshedding.
> 

This is the way reviews work, people have limited time and pop in and look at
things as closely as possible.  For something this big you are going to go
through a bunch of iterations, and that is good.  I'd rather you be annoyed than
users because something broke, or me when I have to come back and fix stuff and
spend forever trying to figure out the code.

Our goal is to move towards better stability overall, that means more reviews,
more patch iterations and requirements for tests to verify new code.  We are
never going to stabilize if we don't start making firm decisions on our code
quality practices.  Thanks,

Josef