tree 0b20f42bb8cdef9bba26c7ca0e4afe883e5c9c25
parent f26a3988917913b3d11b2bd741601a2c64ab9204
author Trond Myklebust <Trond.Myklebust@netapp.com> 1210002341 -0400
committer Trond Myklebust <Trond.Myklebust@netapp.com> 1210956201 -0700

NFS: Ensure that 'noac' and/or 'actimeo=0' turn off attribute caching

Both the 'noac' and 'actimeo=0' mount options should ensure that attributes
are not cached, however a bug in nfs_attribute_timeout() means that
currently, the attributes may in fact get cached for up to one jiffy. This
has been seen to cause corruption in some applications.

The reason for the bug is that the time_in_range() test returns 'true' as
long as the current time lies between nfsi->read_cache_jiffies and
nfsi->read_cache_jiffies + nfsi->attrtimeo. In other words, if jiffies
equals nfsi->read_cache_jiffies, then we still cache the attribute data.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>