Hello,

On Fri 09-03-12 14:40:22, Andor Daam wrote:

Is it ever possible for a superblock for a mounted filesystem to be
free'd without a previous call to unmount the filesystem?

  No, I don't think so (well, except for cases where we do not manage to
fully setup the superblock). But be aware that mount/umount need not be
really the entry points you are looking for since filesystem can be mounted
several times. Rather deactivate_locked_supers() is the place you are
looking for...

I need to be certain that the function cleancache_invalidate_fs, which is
at the moment called by deactivate_locked_super (fs/super.c) [1], is
called before every free on a superblock of cleancache-enabled
filesystems.  Is this already the case or are there situations in which
this does not happen?

It would be interesting to know this, as we are planning to have
cleancache save pointers to superblocks of every mounted
cleancache-enabled filesystem [2] and it would be fatal if a
superblock is free'd without cleancache being notified.

								Honza
-- 
Jan Kara [off-list ref]
SUSE Labs, CR