NFSv4.1: Clear lseg pointer in ->doio function

Now that we have access to the pointer, clear it immediately after
the put, instead of in caller.

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

fs/nfs/read.c

@@ -311,6 +311,7 @@ static int nfs_pagein_multi(struct nfs_pageio_descriptor *desc)
 		nbytes -= rsize;
 	} while (nbytes != 0);
 	put_lseg(lseg);
+	desc->pg_lseg = NULL;
 
 	return ret;
 
@@ -357,6 +358,7 @@ static int nfs_pagein_one(struct nfs_pageio_descriptor *desc)
 				0, lseg);
 out:
 	put_lseg(lseg);
+	desc->pg_lseg = NULL;
 	return ret;
 }