On Wed, Feb 24, 2021 at 10:27:45AM +0800, Anand Jain wrote: > On 23/02/2021 21:53, David Sterba wrote: > > On Mon, Feb 22, 2021 at 10:19:06PM +0100, Goffredo Baroncelli wrote: > > > From: Goffredo Baroncelli <[email protected]> > > > > > > This ioctl is a base for returning / setting information from / to the > > > fields of the btrfs_dev_item object. > > > > Please don't add a new ioctl for properties, they're using the xattr as > > interface alrady. > > > > IMO a feature like this can be in memory only initially[1]. And later > when this feature is stable, add its on-disk.
The "metadata_only" and "data_only" settings need to be persistent for the feature to really work. It is very expensive to recover (need to balance metadata on a spinning disk) if the filesystem allocates a new chunk after mount but before userspace can reestablish the preferences. The whole point of metadata_only and data_only is that we never have to do that. > [1] > https://patchwork.kernel.org/project/linux-btrfs/patch/0ed770d6d5e37fc942f3034d917d2b38477d7d20.1613668002.git.anand.j...@oracle.com/ > > > Thanks, Anand >
