On Tue, May 03, 2022 at 08:59:31PM +0200, Steinar H. Gunderson wrote: > On Tue, May 03, 2022 at 07:59:48PM +0200, Julian Andres Klode wrote: > > I fail to see how naming it @root instead of @, or @screwedup for that > > matter makes a difference. > > Try it. :-)
I tried something else... > > > This is a significant regression for users coming from mlocate. They had > > working locate > > No, did they not. The mlocate updatedb code had broken bind mount detection > after the switch from /etc/mtab to /proc/mountinfo, which specifically broke > btrfs subvolumes: > > https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=746943 > > > If you prefer to keep plocate broken with btrfs in Debian, > > Please stop misrepresenting the issue. plocate isn't broken with btrfs, > but you can configure btrfs subvolumes in a way such that plocate > (and basically any other tool that tries to skip bind mounts) will not work > in the default configuration. Removing the /mnt mount of the / root volume makes it work: $ grep btrfs /proc/self/mountinfo 32 1 0:28 /@ / rw,relatime shared:1 - btrfs /dev/mapper/ubuntu--vg-root rw,compress=zstd:3,ssd,space_cache,subvolid=256,subvol=/@ 143 32 0:28 /@apt /var/cache/apt/archives rw,relatime shared:79 - btrfs /dev/mapper/ubuntu--vg-root rw,compress=zstd:3,ssd,space_cache,subvolid=273,subvol=/@apt 146 32 0:28 /@squid /var/cache/squid-deb-proxy rw,relatime shared:81 - btrfs /dev/mapper/ubuntu--vg-root rw,compress=zstd:3,ssd,space_cache,subvolid=274,subvol=/@squid 142 32 0:28 /@log /var/log rw,relatime shared:83 - btrfs /dev/mapper/ubuntu--vg-root rw,compress=zstd:3,ssd,space_cache,subvolid=344,subvol=/@log 2734 32 0:28 /@/snap /snap rw,relatime shared:1 - btrfs /dev/mapper/ubuntu--vg-root rw,compress=zstd:3,ssd,space_cache,subvolid=256,subvol=/@ 4560 32 0:28 /@/var/snap /var/snap rw,relatime shared:1 - btrfs /dev/mapper/ubuntu--vg-root rw,compress=zstd:3,ssd,space_cache,subvolid=256,subvol=/@ 140 32 0:28 / /mnt rw,relatime shared:77 - btrfs /dev/mapper/ubuntu--vg-root rw,compress=zstd:3,ssd,space_cache,subvolid=5,subvol=/ It's not clar to me why that would make a difference but this is all very confusing and needs further investigation. Like it only reads mountinfo and stats / why would the existence of /mnt make a difference to it - did it read "/" on the LHS and took it too mean a bind mount of "/@" because "/@" is mounted at "/"? Clearly subvolumes create confusing paths. That /mnt mountpoint is anormal, but normally apt-btrfs-snapshot mounts to a temporary directory temporarily to create a snapshot (however they get leftover sometimes); whereas snapper uses a different layout where / is the / and snapshots are kept in /.snapshots or something, so it's not affected. -- debian developer - deb.li/jak | jak-linux.org - free software dev ubuntu core developer i speak de, en
