NFS: Ensure O_DIRECT reports an error if the bytes read/written is 0

If the attempt to resend the I/O results in no bytes being read/written,
we must ensure that we report the error.
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Fixes: 0a00b77b ("nfs: mirroring support for direct io")
Cc: stable@vger.kernel.org # v3.20+

fs/nfs/direct.c

@@ -401,15 +401,21 @@ static void nfs_direct_read_completion(struct nfs_pgio_header *hdr)
 	unsigned long bytes = 0;
 	struct nfs_direct_req *dreq = hdr->dreq;
 
-	if (test_bit(NFS_IOHDR_REDO, &hdr->flags))
-		goto out_put;
-
 	spin_lock(&dreq->lock);
-	if (test_bit(NFS_IOHDR_ERROR, &hdr->flags) && (hdr->good_bytes == 0))
+	if (test_bit(NFS_IOHDR_ERROR, &hdr->flags))
 		dreq->error = hdr->error;
-	else
+
+	if (test_bit(NFS_IOHDR_REDO, &hdr->flags)) {
+		spin_unlock(&dreq->lock);
+		goto out_put;
+	}
+
+	if (hdr->good_bytes != 0)
 		nfs_direct_good_bytes(dreq, hdr);
 
+	if (test_bit(NFS_IOHDR_EOF, &hdr->flags))
+		dreq->error = 0;
+
 	spin_unlock(&dreq->lock);
 
 	while (!list_empty(&hdr->pages)) {
@@ -782,16 +788,19 @@ static void nfs_direct_write_completion(struct nfs_pgio_header *hdr)
 	bool request_commit = false;
 	struct nfs_page *req = nfs_list_entry(hdr->pages.next);
 
-	if (test_bit(NFS_IOHDR_REDO, &hdr->flags))
-		goto out_put;
-
 	nfs_init_cinfo_from_dreq(&cinfo, dreq);
 
 	spin_lock(&dreq->lock);
 
 	if (test_bit(NFS_IOHDR_ERROR, &hdr->flags))
 		dreq->error = hdr->error;
-	if (dreq->error == 0) {
+
+	if (test_bit(NFS_IOHDR_REDO, &hdr->flags)) {
+		spin_unlock(&dreq->lock);
+		goto out_put;
+	}
+
+	if (hdr->good_bytes != 0) {
 		nfs_direct_good_bytes(dreq, hdr);
 		if (nfs_write_need_commit(hdr)) {
 			if (dreq->flags == NFS_ODIRECT_RESCHED_WRITES)

fs/nfs/pagelist.c

@@ -1266,6 +1266,7 @@ int nfs_pageio_resend(struct nfs_pageio_descriptor *desc,
 	if (!list_empty(&pages)) {
 		int err = desc->pg_error < 0 ? desc->pg_error : -EIO;
 		hdr->completion_ops->error_cleanup(&pages, err);
+		nfs_set_pgio_error(hdr, err, hdr->io_start);
 		return err;
 	}
 	return 0;