NFSv4/pnfs: Fix layoutget behaviour after invalidation

If the layout gets invalidated, we should wait for any outstanding
layoutget requests for that layout to complete, and we should resend
them only after re-establishing the layout stateid.

Fixes: d29b468d ("pNFS/NFSv4: Improve rejection of out-of-order layouts")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

fs/nfs/pnfs.c

@@ -2014,7 +2014,7 @@ pnfs_update_layout(struct inode *ino,
 	 * If the layout segment list is empty, but there are outstanding
 	 * layoutget calls, then they might be subject to a layoutrecall.
 	 */
-	if (list_empty(&lo->plh_segs) &&
+	if ((list_empty(&lo->plh_segs) || !pnfs_layout_is_valid(lo)) &&
 	    atomic_read(&lo->plh_outstanding) != 0) {
 		spin_unlock(&ino->i_lock);
 		lseg = ERR_PTR(wait_var_event_killable(&lo->plh_outstanding,
@@ -2390,11 +2390,13 @@ pnfs_layout_process(struct nfs4_layoutget *lgp)
 		goto out_forget;
 	}
 
+	if (!pnfs_layout_is_valid(lo) && !pnfs_is_first_layoutget(lo))
+		goto out_forget;
+
 	if (nfs4_stateid_match_other(&lo->plh_stateid, &res->stateid)) {
 		/* existing state ID, make sure the sequence number matches. */
 		if (pnfs_layout_stateid_blocked(lo, &res->stateid)) {
-			if (!pnfs_layout_is_valid(lo) &&
-			    pnfs_is_first_layoutget(lo))
+			if (!pnfs_layout_is_valid(lo))
 				lo->plh_barrier = 0;
 			dprintk("%s forget reply due to sequence\n", __func__);
 			goto out_forget;
@@ -2413,8 +2415,6 @@ pnfs_layout_process(struct nfs4_layoutget *lgp)
 		goto out_forget;
 	} else {
 		/* We have a completely new layout */
-		if (!pnfs_is_first_layoutget(lo))
-			goto out_forget;
 		pnfs_set_layout_stateid(lo, &res->stateid, lgp->cred, true);
 	}