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: ee4cdf7ba857 ("netfs: Speed up buffered reading")
Signed-off-by: Paulo Alcantara (Red Hat) <[e-mail]>
Signed-off-by: David Howells <[e-mail]>
Link: https://lore.kernel.org/[e-mail]
Tested-by: Steve French <[e-mail]>
Cc: [e-mail]
Cc: [e-mail]
Signed-off-by: Christian Brauner <[e-mail]>

fs/smb/client/cifssmb.c

···
 		break;
 	case MID_REQUEST_SUBMITTED:
 	case MID_RETRY_NEEDED:
+		__set_bit(NETFS_SREQ_NEED_RETRY, &wdata->subreq.flags);
 		result = -EAGAIN;
 		break;
 	default: