Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754501AbbGFHsK (ORCPT ); Mon, 6 Jul 2015 03:48:10 -0400 Received: from mail.kernel.org ([198.145.29.136]:44584 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754204AbbGFHqR (ORCPT ); Mon, 6 Jul 2015 03:46:17 -0400 From: Ming Lin To: linux-kernel@vger.kernel.org Cc: Christoph Hellwig , Jens Axboe , Kent Overstreet , Dongsu Park , Mike Snitzer , Ming Lin , Christoph Hellwig , Jonathan Corbet , linux-doc@vger.kernel.org, Ming Lin Subject: [PATCH v5 11/11] Documentation: update notes in biovecs about arbitrarily sized bios Date: Mon, 6 Jul 2015 00:44:50 -0700 Message-Id: <1436168690-32102-11-git-send-email-mlin@kernel.org> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1436168690-32102-1-git-send-email-mlin@kernel.org> References: <1436168690-32102-1-git-send-email-mlin@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2116 Lines: 49 From: Dongsu Park Update block/biovecs.txt so that it includes a note on what kind of effects arbitrarily sized bios would bring to the block layer. Also fix a trivial typo, bio_iter_iovec. Cc: Christoph Hellwig Cc: Kent Overstreet Cc: Jonathan Corbet Cc: linux-doc@vger.kernel.org Signed-off-by: Dongsu Park Signed-off-by: Ming Lin --- Documentation/block/biovecs.txt | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/Documentation/block/biovecs.txt b/Documentation/block/biovecs.txt index 74a32ad..2568958 100644 --- a/Documentation/block/biovecs.txt +++ b/Documentation/block/biovecs.txt @@ -24,7 +24,7 @@ particular, presenting the illusion of partially completed biovecs so that normal code doesn't have to deal with bi_bvec_done. * Driver code should no longer refer to biovecs directly; we now have - bio_iovec() and bio_iovec_iter() macros that return literal struct biovecs, + bio_iovec() and bio_iter_iovec() macros that return literal struct biovecs, constructed from the raw biovecs but taking into account bi_bvec_done and bi_size. @@ -109,3 +109,11 @@ Other implications: over all the biovecs in the new bio - which is silly as it's not needed. So, don't use bi_vcnt anymore. + + * The current interface allows the block layer to split bios as needed, so we + could eliminate a lot of complexity particularly in stacked drivers. Code + that creates bios can then create whatever size bios are convenient, and + more importantly stacked drivers don't have to deal with both their own bio + size limitations and the limitations of the underlying devices. Thus + there's no need to define ->merge_bvec_fn() callbacks for individual block + drivers. -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/