#1

When I run the Chromium web browser my root ‘/’ and ‘/home’ Btrfs subvolumes become read only.

I use KDE Plasma and /dev/sda3 is formatted as Btrfs with root and home subvolumes. The problem has occurred since late April or early May and seemed to coincide with Kwin and Plasma changes or problems around that time.

Originally it seemed I needed to do active browsing on Chromium, particularly watching YouTube, for the problem to occur but now it seems consistent that ‘/’ and ‘/home’ become read only soon after starting Chromium.

I am uncertain if the problem occurs solely with Chromium, it may be a symptom not a cause, but I have not seen the problem when running other applications such as Firefox.

I considered if the hard disk may be causing problems but checks with GSmartControl and btrfs scrub do not reveal any problems.

The information I have given is perhaps too fuzzy to identify the cause or a fix, so are there more checks I can do to provide additional useful information?

#2

How read only?
Can you create file with sudo?

like recursively or only at /home ?

Try

$ sudo touch ~/testfile

does it create a file?

fails when chromium runs? What you close it? Does it become rw again?

Btrfs is bizzare to me I have not tried it yet

#3

Since my original post I have set up and logged in to a test account on my Manjaro system and run Chromium and from there logged in to my Google accounts to synchronise my Chromium settings and data. I also browsed around trying to recreate the read only problem but to no avail.

This now implies to me that the problem may lie within a file in
~/.config/chromium/ or
~/.cache/chromium/
in my normal account home directory.

I could simply rename those directories to get rid of the problem, but even though I have backups, some websites have important data associated with them that I would like to preserve. Furthermore identifying the cause of the problem may be valuable information for the community.

No, as expected it produces the error:
Cannot touch '~/testfile': Read-only file system.

The read only problem occurs soon after Chromium completes loading and remains after closing it, as indicated here:

$ mount | grep sda
/dev/sda3 on / type btrfs (ro,relatime,lazytime,space_cache,autodefrag,subvolid=257,subvol=/@)
/dev/sda3 on /home type btrfs (ro,relatime,lazytime,space_cache,autodefrag,subvolid=258,subvol=/@home)

I have used Btrfs for several years, I find the snapshots especially useful.

1 Like
#4

Well I think it’s some sort of self defence feature of the btrf itself.

Like if some btrfs cache getting full, are you sure you are not running out of space on that partition?

#5

I no longer use (I rather just test) btrfs but try

sudo btrfs check --repair /dev/sda3
#6

I just had a very strange thought. What if the browsers private mode settings are somehow being exported to the system (instead of just within the browser). It wouldn’t seem possible, but maybe these symptoms could be related to the privacy mode.

#7

One more… it reminds me of situations where remount readonly kicks in.
Too long to remember exactly… Getting old s@$#s

#8

Plugins/extensions on your original install causing issues?

#9

Thanks for your thoughts and suggestions, they led me to try another simple experiment;

I copied the Chromium directories ~/.config/chromium/ and ~/.cache/chromium/ to the test account that I had set up earlier, logged in to the test account, changed the ownership of the Chromium directories to the test user, then ran Chromium. There were no problems, ‘/’ and ‘/home’ remained read and write and I was able to use Chromium as if logged in to my usual account.

This now suggests another solution would be to start afresh with the KDE plasma desktop in my usual account, once I can find a guide to which files and directories I need to remove (or rename) such that the desktop starts afresh on the next login.

That will not identify the cause of the read only problem but will very likely solve it. I have been having some minor issues with the KDE desktop anyway, probably due to the numerous update cycles it has been through for a very long time now, so I have been considering a fresh KDE desktop may be of benefit.

Any further thoughts and comments are welcome.

#10

This may help you do what you said:

#11

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