[Gllug] Remounting readonly fails

[Tet]

On 4/4/06, Nix <nix at esperi.org.uk> wrote:

> > Sure it isnt something silly like a shell having a directory on /usr
> > as its 'curent working directory'   (hwoever this SHOULD show up in 'fuser').
>
> That's most likely, yes.

Nope, for two reasons:

1. The filesystem had been mounted readonly beforehand. It was
remounted rw, a yum update was run, then the remount readonly failed.
In that brief period of time, it's unlikely that any process on the
system would have a cwd in /usr without me explicitly starting one
that did. Furthermore, the chances of a process being in the state you
described, such that it can hide from fuser are vanishingly small
IMHO.

2. A process with a cwd on a given filesystem doesn't cause a readonly
remount to fail anyway. Only an open file or a writable memory map can
do that.

I once wrote a patch to fuser that showed if maps and open files were
writable, but the maintainer chose to ignore it. I suppose I should
dig it out and compile it up again and see if it sheds any light on
the problem...

Tet
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