NFSv4: Document the recover_lost_locks kernel parameter

Rename the new 'recover_locks' kernel parameter to 'recover_lost_locks'
and change the default to 'false'. Document why in
Documentation/kernel-parameters.txt

Move the 'recover_lost_locks' kernel parameter to fs/nfs/super.c to
make it easy to backport to kernels prior to 3.6.x, which don't have
a separate NFSv4 module.

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

1 files changed, 12 insertions, 0 deletions

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 15356aca938c..30584b194984 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1847,6 +1847,18 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
                         will be sent.
                         The default is to send the implementation identification
                         information.
+        
+        nfs.recover_lost_locks =
+                        [NFSv4] Attempt to recover locks that were lost due
+                        to a lease timeout on the server. Please note that
+                        doing this risks data corruption, since there are
+                        no guarantees that the file will remain unchanged
+                        after the locks are lost.
+                        If you want to enable the kernel legacy behaviour of
+                        attempting to recover these locks, then set this
+                        parameter to '1'.
+                        The default parameter value of '0' causes the kernel
+                        not to attempt recovery of lost locks.
 
         nfsd.nfs4_disable_idmapping=
                         [NFSv4] When set to the default of '1', the NFSv4