I reviewed this once again: 1. persistent /dev/bcache<i> - not possible or needed due to how kernel enumeration works 2. our userspace handles /dev/by-dname/<symlink> properly so we just need CACHED_UUID given to us during coldplug in some way to properly create /dev/bcache/by-uuid/<link> symlinks and consequently by-dname symlinks.
3. bcache, like almost all block device drivers, gets "struct device_type disk_type" by using alloc_disk from genhd.c which gives us standard contents for the uevent file. Partitions are a notable exception and use "struct device_type part_type" which has a .uevent field (http://elixir.free-electrons.com/linux/v4.14.2/source/block /partition-generic.c#L223) that allows customization of uevent file contents in a bus-, class- and type-specific manner (http://elixir.free- electrons.com/linux/v4.14.2/source/drivers/base/core.c#L903). cat /sys/class/block/nvme0n1/uevent MAJOR=259 MINOR=0 DEVNAME=nvme0n1 DEVTYPE=disk as opposed to the following with partitions cat /sys/class/block/nvme0n1p1/uevent MAJOR=259 MINOR=1 DEVNAME=nvme0n1p1 DEVTYPE=partition PARTN=1 PARTNAME=Basic data partition While we could have a new block device type of "bcache" with a custom uevent content that had CACHED_UUID of a superblock this would be a userspace breakage which is hardly upstreamable. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1729145 Title: /dev/bcache/by-uuid links not created after reboot To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1729145/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
