archive mirror
 help / color / mirror / Atom feed
From: Andrei Borzenkov <>
To: Adam Borowski <>
Cc: Chris Murphy <>,
	Btrfs BTRFS <>
Subject: Re: updatedb does not index /home when /home is Btrfs
Date: Sat, 4 Nov 2017 21:27:00 +0300	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

04.11.2017 10:05, Adam Borowski пишет:
> 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.
>>>> 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

Indeed. I can build the same configuration on non-btrfs and updatedb
would skip non-overlapping mounts just as it would on btrfs. It is just
that it is rather more involved on other filesystems (and as you
mentioned this requires top-level to be mounted at some point), while on
btrfs it is much easier to get (and is default on number of distributions).

So yes, it really appears that updatedb check for duplicated mounts is
wrong in general and needs rethinking.

  reply	other threads:[~2017-11-04 18:27 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-11-04  0:15 Chris Murphy
2017-11-04  4:49 ` Adam Borowski
2017-11-04  6:26   ` Andrei Borzenkov
2017-11-04  7:05     ` Adam Borowski
2017-11-04 18:27       ` Andrei Borzenkov [this message]
2017-11-04 18:55         ` Chris Murphy
2017-11-04 19:37           ` Nicholas D Steeves
2017-11-05  8:01           ` Andrei Borzenkov
2017-11-06 13:51             ` Austin S. Hemmelgarn
2017-11-06 18:35               ` Chris Murphy
2017-11-06 19:44                 ` Austin S. Hemmelgarn
2017-11-05  7:47 ` Fixed subject: updatedb does not index separately mounted btrfs subvolumes Duncan
2017-11-05 14:02   ` Chris Murphy
2017-11-06  0:27   ` Peter Grandi

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \ \ \ \ \ \
    --subject='Re: updatedb does not index /home when /home is Btrfs' \

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).