smb: client: set missing retry flag in cifs_writev_callback()

Set NETFS_SREQ_NEED_RETRY flag to tell netfslib that the subreq needs
to be retried.

Fixes: ee4cdf7 ("netfs: Speed up buffered reading")
Signed-off-by: Paulo Alcantara (Red Hat) <pc@manguebit.org>
Signed-off-by: David Howells <dhowells@redhat.com>
Link: https://lore.kernel.org/20250701163852.2171681-9-dhowells@redhat.com
Tested-by: Steve French <sfrench@samba.org>
Cc: linux-cifs@vger.kernel.org
Cc: netfs@lists.linux.dev
Signed-off-by: Christian Brauner <brauner@kernel.org>

Author: pcacjr

fs/smb/client/cifssmb.c

@@ -1715,6 +1715,7 @@ cifs_writev_callback(struct mid_q_entry *mid)
 		break;
 	case MID_REQUEST_SUBMITTED:
 	case MID_RETRY_NEEDED:
+		__set_bit(NETFS_SREQ_NEED_RETRY, &wdata->subreq.flags);
 		result = -EAGAIN;
 		break;
 	default: