[PATCH V3] Make inode64 a remountable option

[Christoph Hellwig]

On Fri, Aug 17, 2012 at 11:49:50AM -0300, Carlos Maiolino wrote:
> I don't think there is any lock protection around m_flags, I did a search on the
> code and couldn't find anything protecting it. At a first glance though, I don't
> think there is a need to protect it once this flag is managed only during super
> operations - mount/umount/remount -
> Also, I *think* the sb->s_umount rw_semaphore is enough for protection, once it
> protects the whole mount/umount operation, but I'm 100% sure of it.

Seems like rw_semaphore takes care of it, and we already have a trace
when setting XFS_MOUNT_FS_SHUTDOWN.  I guess it's fine as is for now,
but I'd love to have comment explaining why it's safe.