Re: [RFC] FSFS filesystem options (long, sorry)

On Mon, Mar 05, 2007 at 02:38:48PM -0500, Greg Hudson wrote:
> On Mon, 2007-03-05 at 19:29 +0000, Malcolm Rowe wrote:
> > I don't see any way to lock existing readers out while we tweak
> > db/format though - FSFS annoyingly doesn't support exclusive locking.
> > So we might need that to be an offline operation.
>
> There's deliberately no way to lock out readers. This is so that
> readers don't have to have permissions to get a repository lock. The
> repository needs to be consistent from a reader's perspective at all
> times, by design.
>

I understand. I guess that means that bumping the db/format file needs
to be an offline operation then, so we can guarantee that old readers
have stopped reading.

So lets say we do implement this transparent upgrade path - how does the
repository admin mark the repo as 'safe to upgrade'? Should we just say
"manually take the repo offline and run this tool (which does 'echo N >
db/format')"?

Regards,
Malcolm