On Wed, 22 Apr 2015 11:07:03 -0400 "J. Bruce Fields" <bfields@xxxxxxxxxxxx> wrote: > > Reference of dentry/mnt is like a cache, avoids re-finding of them, > > it is necessary to store them in svc_export. > > > > Neil points out another way of 'fs_pin', I will check that. > > Yes, that'd be interesting. On a very quick look--I don't understand > what it's meant to do at all. But if it does provide a way to get a > callback on umount, that'd certainly be interesting.... Yeah, on a quick look it isn't really obvious at all. But I didn't read the code. I read https://lwn.net/Articles/636730/ which says: In its place is a mechanism by which an object can be added to a vfsmount structure (which represents a mounted filesystem); that object supports only one method: kill(). These "pin" objects hang around until the final reference to the vfsmount goes away, at which point each one's kill() function is called. It thus is a clean mechanism for performing cleanup when a filesystem goes away. This is used to close "BSD process accounting" files on umount, and sound like the perfect interface for flushing things from the sunrpc cache on umount. NeilBrown
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