NFSv4: Allow entries in the idmap cache to expire

 If someone changes the uid/gid mapping in userland, then we do eventually
 want those changes to be propagated to the kernel. Currently the kernel
 assumes that it may cache entries forever.

 Add an expiration time + garbage collector for idmap entries.

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

1 files changed, 4 insertions, 0 deletions

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 309c9cec6e7c..a482fde09bbb 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -914,6 +914,10 @@ running once the system is up.
                         [NFS] set the TCP port on which the NFSv4 callback
                         channel should listen.
 
+        nfs.idmap_cache_timeout=
+                        [NFS] set the maximum lifetime for idmapper cache
+                        entries.
+
         nmi_watchdog=   [KNL,BUGS=IA-32] Debugging features for SMP kernels
 
         no387           [BUGS=IA-32] Tells the kernel to use the 387 maths