While debugging something else, I notice that every time
I did a ls on a nfs mounted directory a wto ACCESS rpc was
*always* happening (with a  2.4.21 kernel). Taking a closer
look it turns out the access cache  was dropping previous
access bits. Here is the scenario...

nfs_permission is called with mode = MAY_EXEC
the cached value is Zero so an ACCESS rpc is done.
after the rpc, the cached value is _set_ to MAY_EXEC

then nfs_permission is called with mode = MAY_READ
the cached value is MAY_EXEC, so an ACCESS rpc is done.
after the rpc, the cache value is _set_ to MAY_READ

again, nfs_permission is called with mode = MAY_EXEC
this time the cached value is MAY_READ so _again_ an RPC is done
after the rpc, the cached value is _set_ to MAY_EXEC

Its a vicious cycle...

So this patch changes the setting of the masked value
to the or-ing of the masked value. This cause the
previous bits to be remembered thus cutting down on
the number of otw rpcs...


SteveD.