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This is an automatically generated e-mail. To reply, visit:
http://git.reviewboard.kde.org/r/106748/
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(Updated Feb. 28, 2013, 5:08 a.m.)
Review request for Nepomuk, KDE Usability, Sebastian Trueg, and Vishesh Handa.
Changes
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Use Kauth to automatically raise the inotify limit.
Description (updated)
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FileWatch: Use KAuth to automatically raise the inotify watch limit if
we run out of watches.
When we run out of watches, use a KAuth action to double the inotify
watch limit (by writing to /proc/sys/fs/inotify/max_user_watches).
At the same time, make the new setting persist across reboots by writing
/etc/sysctl.d/97-kde-nepomuk-filewatch-inotify.conf.
If for some reason raising the limit does not work, print a message to syslog.
==Potential issues==
1. If you don't type the prompt quickly enough, something times out and adding
of watches is not resumed after raising the limit
2. At the moment there is no way to turn this off, except by not using nepomuk
or denying the user the requisite kauth permissions. This is the sort of thing
that people complain about, but I can't really see any reason to want to do
that - you'd be running nepomuk in a "known broken" configuration, which makes
no sense.
3. the action description string is "To avoid missing file changes, raise the
folder watch limit", which could probably be
improved.
4. The method of making the change persist across reboots is to write a file to
/etc/sysctl.d, which is a bit anti-social. (note that if /etc is not writable,
it simply does nothing). /etc/sysctl.d should work on all systemd distros,
debian (including derivatives such as ubuntu) and gentoo.
Part of me wants to make this a separate action, but as I understand it this
would require a second prompt and a second authorization, which would be a bit
annoying. Also, the user's file system isn't going away - if they wanted a
larger limit once, they almost certainly want it again, so there are limited
reasons for not wanting it permanent. But finer grained permissions are a Good
Thing, so I'm not so sure about this.
5. If the user has manually set the watch limit to a too-low number in
sysctl.conf, it could potentially over-ride the file in /etc/sysctl.d, leading
to the prompt appearing on every boot.
Also, I'd just like to mention that I was quite impressed at how easy to KAuth
was to work with.
Diffs (updated)
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services/filewatch/CMakeLists.txt 501d2a1
services/filewatch/kinotify.cpp 60292a9
services/filewatch/nepomukfilewatch.cpp ca5c7d4
services/filewatch/org.kde.nepomuk.filewatch.actions PRE-CREATION
services/filewatch/raiselimit.h PRE-CREATION
services/filewatch/raiselimit.cpp PRE-CREATION
Diff: http://git.reviewboard.kde.org/r/106748/diff/
Testing (updated)
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Set the number of inotify watches to a low value (but not *too* low - it needs
to be high enough to successfully watch the config files). I found 1000 to be a
good value.
> sudo sysctl fs.inotify.max_user_watches=10
Restart the filewatch service, and get a KAuth prompt.
If the watch limit needs to be raised again, no further prompts appear.
Thanks,
Simeon Bird
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