NFS: Fix a use-before-initialised warning in fs/nfs/write.c and fs/nfs/pnfs.c

If the allocation of nfs_write_header fails, the list of nfs_pages that
needs to be cleaned up is still on desc->pg_list...

Reported-by: Bryan Schumaker <bjschuma@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Acked-by: Fred Isaman <iisaman@netapp.com>

fs/nfs/pnfs.c

@@ -1308,7 +1308,7 @@ pnfs_generic_pg_writepages(struct nfs_pageio_descriptor *desc)
 
 	whdr = nfs_writehdr_alloc();
 	if (!whdr) {
-		desc->pg_completion_ops->error_cleanup(&hdr->pages);
+		desc->pg_completion_ops->error_cleanup(&desc->pg_list);
 		put_lseg(desc->pg_lseg);
 		desc->pg_lseg = NULL;
 		return -ENOMEM;

fs/nfs/write.c

@@ -1164,7 +1164,7 @@ static int nfs_generic_pg_writepages(struct nfs_pageio_descriptor *desc)
 
 	whdr = nfs_writehdr_alloc();
 	if (!whdr) {
-		desc->pg_completion_ops->error_cleanup(&hdr->pages);
+		desc->pg_completion_ops->error_cleanup(&desc->pg_list);
 		return -ENOMEM;
 	}
 	hdr = &whdr->header;