For unknown reason, the ownership of this directory changed. This is a mount point: VM-data is /dev/sda3 which is a btrfs file system.
When I changed it back, I got an error,
chown: changing ownership of 'VM-data': No space left on device
but it seems to have worked.
linux-7gt2:/srv # ls -l total 16 drwxr-xr-x 1 root root 0 Sep 25 2014 ftp drwxr-x--- 1 tftp tftp 0 Apr 28 07:04 tftpboot drwxr-xr-x 1 root root 176 Oct 26 2014 VM-data drwxr-xr-x 1 root root 36 Oct 26 2014 www linux-7gt2:/srv # chown john:users VM-data chown: changing ownership of ‘VM-data’: No space left on device linux-7gt2:/srv # ls -l total 16 drwxr-xr-x 1 root root 0 Sep 25 2014 ftp drwxr-x--- 1 tftp tftp 0 Apr 28 07:04 tftpboot drwxr-xr-x 1 john users 176 Oct 26 2014 VM-data drwxr-xr-x 1 root root 36 Oct 26 2014 www linux-7gt2:/srv #
There is 133GB free on that device, according to fd. "no space" is also the kind of misleading errors I got from a program that was using files in that directory, because it could not write to it. So I wonder if that is the real error or not?
This is the top of a mounted tree, so I wonder if there is something special about how to set ownership and permissions for the file system as a whole that I need to worry about.
It seems to be a glitch in btrfs made it go into read-only mode. Marking it root is probably also part of the defensive lock-down when it detects some error.
I don't know how to check to see if a mount is
rw. I only know what I asked of it, and that differs.
I never saw any indication of errors either. On a desktop OS, can something be turned on to alert the user?