pnfs-obj: Proper delay for NFS4ERR_RECALLCONFLICT in layout_get_done

Sorry forgot to CC Stable Tree <[email protected]>

Greg hi

In Linux v3.9 there is a conflict around this area exactly do to change:
[30005121] NFSv4.1: LAYOUTGET EDELAY loops timeout to the MDS

If there are stables below 3.9 please tell me I will send you a patch for these.

Thanks
Boaz

Subject: [PATCH] pnfs-obj: Proper delay for NFS4ERR_RECALLCONFLICT in layout_get_done

An NFS4ERR_RECALLCONFLICT is returned by server from a GET_LAYOUT only when a Server Sent a RECALL do to that GET_LAYOUT, or the RECALL and GET_LAYOUT crossed on the wire.
In any way this means we want to wait at most until in-flight IO is finished and the RECALL can be satisfied.

So a proper wait here is more like 1/10 of a second, not 15 seconds like we have now. (We use NFS4_POLL_RETRY_MIN here)

Current code totally craps out performance of very large files on most pnfs-objects layouts, because of how the map changes when the file has grown and spills into the next raid group.

CC Stable Tree <[email protected]>

Signed-off-by Boaz Harrosh <[email protected]>

An NFS4ERR_RECALLCONFLICT is returned by server from a GET_LAYOUT only when a Server Sent a RECALL do to that GET_LAYOUT, or the RECALL and GET_LAYOUT crossed on the wire.
In any way this means we want to wait at most until in-flight IO is finished and the RECALL can be satisfied.

So a proper wait here is more like 1/10 of a second, not 15 seconds like we have now. (We use NFS4_POLL_RETRY_MIN here)

Current code totally craps out performance of very large files on most pnfs-objects layouts, because of how the map changes when the file has grown and spills into the next raid group.

CC Stable Tree <[email protected]>

Signed-off-by Boaz Harrosh <[email protected]>

---
 fs/nfs/nfs4proc.c | 22 +++++++++++++++++++---
 1 file changed, 19 insertions(+), 3 deletions(-)

fs/nfs/nfs4proc.c +19 -3

index d53d678..3264fca 100644
@@ -7058,7 +7058,7 @@ static void nfs4_layoutget_done(struct rpc_task *task, void *calldata)
 	struct nfs4_state *state = NULL;
 	unsigned long timeo, giveup;
 
-	dprintk("--> %s\n", __func__);
+	dprintk("--> %s tk_status => %d\n", __func__, task->tk_status);
 
 	if (!nfs41_sequence_done(task, &lgp->res.seq_res))
 		goto out;

@@ -7067,11 +7067,27 @@ static void nfs4_layoutget_done(struct rpc_task *task, void *calldata)
 	case 0:
 		goto out;
 	case -NFS4ERR_LAYOUTTRYLATER:
+	/* NFS4ERR_RECALLCONFLICT is always a minimal delay (conflict with
+	 * self)
+	 * TODO: NFS4ERR_LAYOUTTRYLATER is a conflict with another client
+	 * (or clients). What we should do is randomize a short delay like on a
+	 * network broadcast burst, and raise the random max every failure.
+	 * For now leave it stateless and do this polling.
+	 */
 	case -NFS4ERR_RECALLCONFLICT:
 		timeo = rpc_get_timeout(task->tk_client);
 		giveup = lgp->args.timestamp + timeo;
-		if (time_after(giveup, jiffies))
-			task->tk_status = -NFS4ERR_DELAY;
+		if (time_after(giveup, jiffies)) {
+			/* Do a minimum delay, We are actually waiting for our
+			 * own IO to finish (In most cases)
+			 */
+			dprintk("%s: NFS4ERR_RECALLCONFLICT waiting\n",
+				__func__);
+			rpc_delay(task, NFS4_POLL_RETRY_MIN);
+			task->tk_status = 0;
+			rpc_restart_call_prepare(task);
+			goto out; /* Do not call nfs4_async_handle_error() */
+		}
 		break;
 	case -NFS4ERR_EXPIRED:
 	case -NFS4ERR_BAD_STATEID: