pNFS: Don't send COMMITs to the DSes if the server invalidated our layout

If the layout was invalidated, then assume we should requeue all the
pending writes for the DS in question.

Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>

fs/nfs/pnfs_nfs.c

@@ -217,6 +217,13 @@ pnfs_generic_alloc_ds_commits(struct nfs_commit_info *cinfo,
 	for (i = 0; i < fl_cinfo->nbuckets; i++, bucket++) {
 		if (list_empty(&bucket->committing))
 			continue;
+		/*
+		 * If the layout segment is invalid, then let
+		 * pnfs_generic_retry_commit() clean up the bucket.
+		 */
+		if (!pnfs_is_valid_lseg(bucket->clseg) &&
+		    !test_bit(NFS_LSEG_LAYOUTRETURN, &bucket->clseg->pls_flags))
+			continue;
 		data = nfs_commitdata_alloc(false);
 		if (!data)
 			break;