On Fri, May 26, 2017 at 08:44:41PM +0000, Sargun Dhillon wrote: > This patch introduces two new ioctls to create, and remove qgroups. These > offer a somewhat more intuitive set of operations with the opportunity > to add flags that gate to unintentional manipulation of qgroups. > > The create qgroup ioctl has a a new semantic which level-0 qgroups cannot > be created unless a matching subvolume ID is created. > > The delete qgroup ioctl has the new semantic that it will not let you > delete a currently utilized (referenced by a subvolume) level-0 > qgroup unless you pass the BTRFS_QGROUP_NO_SUBVOL_CHECK flag.
I'm fine with the qgroup ioctl revisions, if only to address the lack of the flags or reserved fields. The updated semantics also justify a new ioctl number. On the implementation side, options are to do one ioctl per action or do the "swiss army knife" style (multiple actions under on ioctl number). Adding a special data structure for each ioctl is not necessary, as you can see, btrfs_ioctl_qgroup_create_args_v2 and btrfs_ioctl_qgroup_remove_args_v2 are the same. Although we could extend them in different ways in the future, this could also happen if it were just one structure and flags are set to denote meaning of whatever new struct members would be added. I'd go for something similar as the subvolume creation/deletion ioctls, to have separate ioctl numbers assigned but use the same structure. Similar to the mount options, new ioctls need some time to settle, but merging this patchset in 4.13 seems still doable. -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
