sync in-cache fs data after remount ro on error?

[Andreas Dilger]

On Oct 19, 2007  12:57 -0400, Ed L Cashin wrote:
> For example, I can temporarily shut down the network interfaces that
> make an AoE target accessible (simulating, e.g., somebody accidentally
> unplugging a network switch).  When the I/O fails, the filesystem is
> automatically mounted read-only, which is great.
> 
> But if valuable data has been committed to the in-cache filesystem but
> not the on-disk filesystem, it would ideally be possible to remount
> the filesystem read-write once the device is online again (from
> running aoe-revalidate), so that the new data could be sync'ed out to
> disk.

No, there isn't any way to do this, because the filesystem has no way to
know which previous writes have succeeded and which have failed, so any
further writes from cache have a danger of corrupting the filesystem.

Cheers, Andreas
--
Andreas Dilger
Sr. Software Engineer, Lustre Group
Sun Microsystems of Canada, Inc.