NFS: Don't wait for congestion in nfs_update_request()

It is redundant, and will interfere with the call to
balance_dirty_pages_ratelimited_nr in generic_file_write().
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

fs/nfs/write.c

@@ -594,34 +594,6 @@ static inline int nfs_scan_commit(struct inode *inode, struct list_head *dst, un
 }
 #endif
 
-static int nfs_wait_on_write_congestion(struct address_space *mapping)
-{
-	struct inode *inode = mapping->host;
-	struct backing_dev_info *bdi = mapping->backing_dev_info;
-	int ret = 0;
-
-	might_sleep();
-
-	if (!bdi_write_congested(bdi))
-		return 0;
-
-	nfs_inc_stats(inode, NFSIOS_CONGESTIONWAIT);
-
-	do {
-		struct rpc_clnt *clnt = NFS_CLIENT(inode);
-		sigset_t oldset;
-
-		rpc_clnt_sigmask(clnt, &oldset);
-		ret = congestion_wait_interruptible(WRITE, HZ/10);
-		rpc_clnt_sigunmask(clnt, &oldset);
-		if (ret == -ERESTARTSYS)
-			break;
-		ret = 0;
-	} while (bdi_write_congested(bdi));
-
-	return ret;
-}
-
 /*
  * Try to update any existing write request, or create one if there is none.
  * In order to match, the request's credentials must match those of
@@ -640,8 +612,6 @@ static struct nfs_page * nfs_update_request(struct nfs_open_context* ctx,
 
 	end = offset + bytes;
 
-	if (nfs_wait_on_write_congestion(mapping))
-		return ERR_PTR(-ERESTARTSYS);
 	for (;;) {
 		/* Loop over all inode entries and see if we find
 		 * A request for the page we wish to update