Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757683AbbEVSUC (ORCPT ); Fri, 22 May 2015 14:20:02 -0400 Received: from mailout3.samsung.com ([203.254.224.33]:10138 "EHLO mailout3.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757185AbbEVSTk (ORCPT ); Fri, 22 May 2015 14:19:40 -0400 X-AuditID: cbfee61a-f79516d000006302-4e-555f7339a7bc From: Ming Lin To: linux-kernel@vger.kernel.org Cc: Christoph Hellwig , Kent Overstreet , Jens Axboe , Dongsu Park , Ming Lin , Christoph Hellwig , Jonathan Corbet , linux-doc@vger.kernel.org Subject: [PATCH v4 11/11] Documentation: update notes in biovecs about arbitrarily sized bios Date: Fri, 22 May 2015 11:18:43 -0700 Message-id: <1432318723-18829-12-git-send-email-mlin@kernel.org> X-Mailer: git-send-email 1.9.1 In-reply-to: <1432318723-18829-1-git-send-email-mlin@kernel.org> References: <1432318723-18829-1-git-send-email-mlin@kernel.org> X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFlrJLMWRmVeSWpSXmKPExsVy+t9jAV3L4vhQg8t9Jhar7/azWTw50M5o sWPGUyaL0xMWMVmsXH2UyeJIU5XFwrYlLBaXd81hszi/7SSrA6fHzll32T02r9DyuHy21GPT qk42j903G9g8FvdNZvV4fPgku8fnTXIBHFFcNimpOZllqUX6dglcGQ//vGAq+MJX0XHzF2MD 42yeLkZODgkBE4lbd44wQdhiEhfurWfrYuTiEBJYxChxav5sJgjnJ6PEulUH2UCq2AQUJA6u 2wDWIQJkb+59xgpSxCwwlUni6pcHzCAJYYF4iec3PrN3MXJwsAioSixblA4S5hVwkGg51soC sU1O4uSxyawgJZxA8d27PEDCQgL2EuvWzWWcwMi7gJFhFaNoakFyQXFSeq6hXnFibnFpXrpe cn7uJkZwAD6T2sG4ssHiEKMAB6MSD6/BwbhQIdbEsuLK3EOMEhzMSiK8un7xoUK8KYmVValF +fFFpTmpxYcYpTlYlMR5T+b7hAoJpCeWpGanphakFsFkmTg4pRoYjyVLK+t+qhDdeHsr49WA XUoNl//daloo1yq/rTZs813XysZr0evFfZd/yPt834SFSXbu7ON58+UNOu0tfx2ZNeWZC1PE 3z0LpadKR8cHPLMu+nd64a+pb+aouYYJzTVbLy7Ve2hHbbQjg+bOry5z5Asb6v+rfpcJZprN xeZt9uyhYu0SZ9klSizFGYmGWsxFxYkAX9YahDwCAAA= Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2109 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/