04.11.2017 07:49, Adam Borowski пишет: > On Fri, Nov 03, 2017 at 06:15:53PM -0600, Chris Murphy wrote: >> Ancient bug, still seems to be a bug. >> https://bugzilla.redhat.com/show_bug.cgi?id=906591 >> >> The issue is that updatedb by default will not index bind mounts, but >> by default on Fedora and probably other distros, put /home on a >> subvolume and then mount that subvolume which is in effect a bind >> mount. >> >> There's a lot of early discussion in 2013 about it, but then it's >> dropped off the radar as nobody has any ideas how to fix this in >> mlocate. > > I don't see how this would be a bug in btrfs. The same happens if you > bind-mount /home (or individual homes), which is a valid and non-rare setup. >
It is the problem *on* btrfs because - as opposed to normal bind mount - those mount points do *not* refer to the same content. As was commented in mentioned bug report: mount -o subvol=root /dev/sdb1 /root mount -o subvol=foo /dev/sdb1 /root/foo mount -o subvol bar /dev/sdb1 /bar/bar Both /root/foo and /root/bar, will be skipped even though they are not accessible via any other path (on mounted filesystem) 191 25 0:54 /root /home/bor/tmp/root rw,relatime shared:131 - btrfs /dev/loop0 rw,space_cache,subvolid=258,subvol=/root 285 191 0:54 /foo /home/bor/tmp/root/foo rw,relatime shared:239 - btrfs /dev/loop0 rw,space_cache,subvolid=256,subvol=/foo 325 191 0:54 /bar /home/bor/tmp/root/bar rw,relatime shared:279 - btrfs /dev/loop0 rw,space_cache,subvolid=257,subvol=/bar bor@bor-Latitude-E5450:~/tmp$ sudo updatedb --debug-pruning -l 0 -o ../db -U root ... Matching bind_mount_paths: => adding `/home/bor/tmp/root/foo' => adding `/home/bor/tmp/root/bar' ...done It is a problem *of* btrfs because it does not offer any easy way to distinguish between subvolume mount and bind mount. If you are aware of one, please comment on mentioned bug report. And note that updatedb can be run as non-root as well, so it probably cannot use btrfs specific ioctls to extract information. -- 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
