On Wed, Aug 9, 2017 at 8:55 AM, David Howells [off-list ref] wrote:
You may also want to flush any outstanding dirty data and wait for in-progress
operations.
Sorry for the delayed response but I've been thinking about it as this
is a tricky one (for me at least).
Even currently, each file system needs a way to deal with flushing
cached data to storage in the situation where creds might have expired
in between when the kernel returned control back to the user but
before all of buffered writes are flushed. NFS4.1 has wording in the
spec for using machine credentials in that case.
At the VFS layer, there no what to tell which dirty data belongs to
which user. Flushing all data under the superblock seems like a bad
idea?