On Sat, Nov 04, 2017 at 09:26:36AM +0300, Andrei Borzenkov wrote: > 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.
Neither do they refer to in a "normal" bind mount. > 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) losetup -D truncate -s 4G junk losetup -f junk mkfs.ext4 /dev/loop0 mkdir -p foo bar mount /dev/loop0 foo mkdir foo/bar touch foo/fileA foo/bar/fileB mount --bind foo/bar bar umount foo > 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. Well, subvolume mounts are indistinguishable from bind mounts because they _are_ bind mounts. You merely don't need to mount the "master" first. The only way such a "master" mount is special is that, on most filesystems, its root was accessible at least at some point (but it might no longer be, thanks to chroot, pivot_root, etc). Meow! -- ⢀⣴⠾⠻⢶⣦⠀ Laws we want back: Poland, Dz.U. 1921 nr.30 poz.177 (also Dz.U. ⣾⠁⢰⠒⠀⣿⡁ 1920 nr.11 poz.61): Art.2: An official, guilty of accepting a gift ⢿⡄⠘⠷⠚⠋⠀ or another material benefit, or a promise thereof, [in matters ⠈⠳⣄⠀⠀⠀⠀ relevant to duties], shall be punished by death by shooting. -- 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
