From patchwork Wed Sep 20 22:22:27 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Howells X-Patchwork-Id: 13393535 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9ECAFCD37AB for ; Wed, 20 Sep 2023 22:24:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229720AbjITWYd (ORCPT ); Wed, 20 Sep 2023 18:24:33 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57010 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229652AbjITWYY (ORCPT ); Wed, 20 Sep 2023 18:24:24 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C2DBE125 for ; Wed, 20 Sep 2023 15:23:02 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1695248582; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=QdaDFgQ/IdiUz+wPFCKvBKKks+ni1Kcs8Sp2gYxHcOI=; b=JRiNz4IurgkaGdPhEAzMudSzsvStb9BTmmn5+SEmROte1USPyRBFPcpcU7CeP6BUaAXNn8 dqC+wvpLM0ZZb+u/vuRuh9Ii+dzHtwOJbHaIZDFwAp9tnprE0jocZ9TiC5EjwfsM5TCFS2 mhad9Z2bd9JhU1/3V1v383QVU3LJdqI= Received: from mimecast-mx02.redhat.com (mx-ext.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-169-pcHmzeEEOaC540eqzQ0x5A-1; Wed, 20 Sep 2023 18:22:56 -0400 X-MC-Unique: pcHmzeEEOaC540eqzQ0x5A-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.rdu2.redhat.com [10.11.54.6]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id EEE4328EC113; Wed, 20 Sep 2023 22:22:55 +0000 (UTC) Received: from warthog.procyon.org.com (unknown [10.42.28.216]) by smtp.corp.redhat.com (Postfix) with ESMTP id 55F5F2156A27; Wed, 20 Sep 2023 22:22:54 +0000 (UTC) From: David Howells To: Jens Axboe Cc: David Howells , Al Viro , Linus Torvalds , Christoph Hellwig , Christian Brauner , David Laight , Matthew Wilcox , Jeff Layton , linux-fsdevel@vger.kernel.org, linux-block@vger.kernel.org, linux-mm@kvack.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v5 07/11] iov_iter: Add a kernel-type iterator-only iteration function Date: Wed, 20 Sep 2023 23:22:27 +0100 Message-ID: <20230920222231.686275-8-dhowells@redhat.com> In-Reply-To: <20230920222231.686275-1-dhowells@redhat.com> References: <20230920222231.686275-1-dhowells@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.6 Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org Add an iteration function that can only iterate over kernel internal-type iterators (ie. BVEC, KVEC, XARRAY) and not user-backed iterators (ie. UBUF and IOVEC). This allows for smaller iterators to be built when it is known the caller won't have a user-backed iterator. Signed-off-by: David Howells cc: Alexander Viro cc: Jens Axboe cc: Christoph Hellwig cc: Christian Brauner cc: Matthew Wilcox cc: Linus Torvalds cc: David Laight cc: linux-block@vger.kernel.org cc: linux-fsdevel@vger.kernel.org cc: linux-mm@kvack.org --- include/linux/iov_iter.h | 31 +++++++++++++++++++++++++++++++ 1 file changed, 31 insertions(+) diff --git a/include/linux/iov_iter.h b/include/linux/iov_iter.h index 270454a6703d..a94d605d7386 100644 --- a/include/linux/iov_iter.h +++ b/include/linux/iov_iter.h @@ -271,4 +271,35 @@ size_t iterate_and_advance(struct iov_iter *iter, size_t len, void *priv, return iterate_and_advance2(iter, len, priv, NULL, ustep, step); } +/** + * iterate_and_advance_kernel - Iterate over a kernel iterator + * @iter: The iterator to iterate over. + * @len: The amount to iterate over. + * @priv: Data for the step functions. + * @step: Processing function; given kernel addresses. + * + * Like iterate_and_advance2(), but rejected UBUF and IOVEC iterators and does + * not take a user-step function. + */ +static __always_inline +size_t iterate_and_advance_kernel(struct iov_iter *iter, size_t len, void *priv, + void *priv2, iov_step_f step) +{ + if (unlikely(iter->count < len)) + len = iter->count; + if (unlikely(!len)) + return 0; + + if (iov_iter_is_bvec(iter)) + return iterate_bvec(iter, len, priv, priv2, step); + if (iov_iter_is_kvec(iter)) + return iterate_kvec(iter, len, priv, priv2, step); + if (iov_iter_is_xarray(iter)) + return iterate_xarray(iter, len, priv, priv2, step); + if (iov_iter_is_discard(iter)) + return iterate_discard(iter, len, priv, priv2, step); + WARN_ON_ONCE(1); + return 0; +} + #endif /* _LINUX_IOV_ITER_H */