embedded terminal doesn't update

[Jean-Baptiste Lallement]

Ubuntu Desktop 20120316

The content of the embedded terminal doesn't update during installation. The content is
Mar 16 09:48:37 ubuntu ubiquity[21172]: Ubiquity 2.9.29
Mar 16 09:48:38 ubuntu ubiquity[21172]: log-output -t ubiquity laptop-detect

and never refreshes.

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: ubiquity 2.9.29
ProcVersionSignature: Ubuntu 3.2.0-18.29-generic 3.2.9
Uname: Linux 3.2.0-18-generic x86_64
ApportVersion: 1.94.1-0ubuntu2
Architecture: amd64
CasperVersion: 1.311
Date: Fri Mar 16 11:15:54 2012
InstallCmdLine: noprompt cdrom-detect/try-usb=true persistent file=/cdrom/preseed/ubuntu.seed boot=casper initrd=/casper/initrd.lz quiet splash -- maybe-ubiquity
LiveMediaBuild: Ubuntu 12.04 LTS "Precise Pangolin" - Alpha amd64 (20120316)
ProcEnviron:
 TERM=xterm
 LANG=fr_FR.UTF-8
 SHELL=/bin/bash
SourcePackage: ubiquity
UpgradeStatus: No upgrade log present (probably fresh install)

[Brian Murray (brian-murray)]

Apparently, the fix for bug 830946 wasn't enough.

[Stéphane Graber (stgraber)]

I'm wondering if the lack of refresh isn't the overlayfs bug?

[Stéphane Graber (stgraber)]

yeah, it's. It's calling tail and tail will never update because of overlayfs, problem solved :)
Well, rather, problem identified.

[Mike Mestnik (cheako)]

Tail should work even without inotify, actually there is nothing that should not be so fragile that the lack of any one add-on, or dare I say optional, feature should cause a problem.

Tail worked long b4 inotify, it needs to detect malfunctions in inotify and fall back to legacy code. Actually what's wrong with select(2) for tail?

[Mike Mestnik (cheako)]

...did I make a double negative there. I think you can get at what I'm saying.

[Stéphane Graber (stgraber)]

tail works perfectly without inotify but like a large number of software will use inotify if present.

The bug we're tracking in bug 882147 is the fact that overlayfs advertises inotify support and allows software to call the inotify API but without actually sending the events.

So the userspace side is doing the right thing as there's no way for it to know that inotify isn't working (what it's receiving is identical to a file that's simply not changing), the problem lands on the kernel side and that's what we're focusing on now.

[Mike Mestnik (cheako)]

This doesn't account for situations where a filesystem would partially support inotify. It's vary common in some places for a technology to be usable some of most of the time, while not being usable in some situations.

For example inotify might be impossible to implement while flock is in use on a file.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.