NFSv4.1: pnfs_layout_io_set_failed must clear invalid lsegs

If pnfs_layout_io_test_failed() authorises a retry of the failed layoutgets,
we should clear the existing layout segments so that we start afresh. Do
this in pnfs_layout_io_set_failed().
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

fs/nfs/pnfs.c

@@ -265,10 +265,18 @@ static void
 pnfs_layout_io_set_failed(struct pnfs_layout_hdr *lo, u32 iomode)
 {
 	struct inode *inode = lo->plh_inode;
+	struct pnfs_layout_range range = {
+		.iomode = iomode,
+		.offset = 0,
+		.length = NFS4_MAX_UINT64,
+	};
+	LIST_HEAD(head);
 
 	spin_lock(&inode->i_lock);
 	pnfs_layout_set_fail_bit(lo, pnfs_iomode_to_fail_bit(iomode));
+	pnfs_mark_matching_lsegs_invalid(lo, &head, &range);
 	spin_unlock(&inode->i_lock);
+	pnfs_free_lseg_list(&head);
 	dprintk("%s Setting layout IOMODE_%s fail bit\n", __func__,
 			iomode == IOMODE_RW ?  "RW" : "READ");
 }