pNFS/flexfiles: When checking for available DSes, conditionally check for MDS io

Whenever we check to see if we have the needed number of DSes for the
action, we may also have to check to see whether IO is allowed to go to
the MDS or not.

[jlayton: fix merge conflict due to lack of localio patches here]
Signed-off-by: Tom Haynes <loghyr@primarydata.com>
Signed-off-by: Jeff Layton <jeff.layton@primarydata.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

fs/nfs/flexfilelayout/flexfilelayout.c

@@ -1102,8 +1102,7 @@ static int ff_layout_async_handle_error_v4(struct rpc_task *task,
 		rpc_wake_up(&tbl->slot_tbl_waitq);
 		/* fall through */
 	default:
-		if (ff_layout_no_fallback_to_mds(lseg) ||
-		    ff_layout_has_available_ds(lseg))
+		if (ff_layout_avoid_mds_available_ds(lseg))
 			return -NFS4ERR_RESET_TO_PNFS;
 reset:
 		dprintk("%s Retry through MDS. Error %d\n", __func__,
@@ -1765,7 +1764,7 @@ ff_layout_read_pagelist(struct nfs_pgio_header *hdr)
 	return PNFS_ATTEMPTED;
 
 out_failed:
-	if (ff_layout_has_available_ds(lseg))
+	if (ff_layout_avoid_mds_available_ds(lseg))
 		return PNFS_TRY_AGAIN;
 	return PNFS_NOT_ATTEMPTED;
 }

fs/nfs/flexfilelayout/flexfilelayout.h

@@ -191,4 +191,5 @@ nfs4_ff_find_or_create_ds_client(struct pnfs_layout_segment *lseg,
 struct rpc_cred *ff_layout_get_ds_cred(struct pnfs_layout_segment *lseg,
 				       u32 ds_idx, struct rpc_cred *mdscred);
 bool ff_layout_has_available_ds(struct pnfs_layout_segment *lseg);
+bool ff_layout_avoid_mds_available_ds(struct pnfs_layout_segment *lseg);
 #endif /* FS_NFS_NFS4FLEXFILELAYOUT_H */

fs/nfs/flexfilelayout/flexfilelayoutdev.c

@@ -541,6 +541,12 @@ bool ff_layout_has_available_ds(struct pnfs_layout_segment *lseg)
 	return ff_rw_layout_has_available_ds(lseg);
 }
 
+bool ff_layout_avoid_mds_available_ds(struct pnfs_layout_segment *lseg)
+{
+	return ff_layout_no_fallback_to_mds(lseg) ||
+	       ff_layout_has_available_ds(lseg);
+}
+
 module_param(dataserver_retrans, uint, 0644);
 MODULE_PARM_DESC(dataserver_retrans, "The  number of times the NFSv4.1 client "
 			"retries a request before it attempts further "