From patchwork Tue Sep 19 04:51:13 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Matthew Wilcox X-Patchwork-Id: 13390767 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 AA7D5CD3439 for ; Tue, 19 Sep 2023 04:52:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231737AbjISEwm (ORCPT ); Tue, 19 Sep 2023 00:52:42 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41978 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231586AbjISEvx (ORCPT ); Tue, 19 Sep 2023 00:51:53 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A743F122; Mon, 18 Sep 2023 21:51:43 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=Content-Transfer-Encoding:MIME-Version: References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From:Sender:Reply-To: Content-Type:Content-ID:Content-Description; bh=nArwds4hDHBhHYufta7EFXQvOR30NKKhjUtIyvFznt4=; b=RTTNLwriDilS/kAKdKH3GwxU+Z 7jktCZAGBgGUmuWIt+5Pse+UewyOWiwO3uXEu8zXRi4MU3iF27q0hSUVvxkGsxkrXyyodbljvAcTp 0LMy4wLm7Of+4x8zyZiuxQCq/rSIpgFdS8Wi2Vjs0saHDOwl9OPAP5MHyEcN0pkK3zuOeVDeN+J6f 9LIzJ1L7U+P7GbH6ABVZJvsvhPtasrFVv307p1uIJDRigSb7QqthAk0YeppXMZvCx6gCNKIr5soCQ TPdbgB84XvpOr5H3RR/9eBDj9R540Bb/LAdli8aC/6jB6QiZLjbt7Mg6a/GJxGfSxBpI87NOJLLrD VfuCNkWA==; Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1qiSi2-00FFkN-Ba; Tue, 19 Sep 2023 04:51:38 +0000 From: "Matthew Wilcox (Oracle)" To: Andrew Morton Cc: "Matthew Wilcox (Oracle)" , linux-fsdevel@vger.kernel.org, gfs2@lists.linux.dev, linux-nilfs@vger.kernel.org, linux-ntfs-dev@lists.sourceforge.net, ntfs3@lists.linux.dev, ocfs2-devel@lists.linux.dev, reiserfs-devel@vger.kernel.org, linux-ext4@vger.kernel.org, Pankaj Raghav Subject: [PATCH 04/26] buffer: Add get_nth_bh() Date: Tue, 19 Sep 2023 05:51:13 +0100 Message-Id: <20230919045135.3635437-5-willy@infradead.org> X-Mailer: git-send-email 2.37.1 In-Reply-To: <20230919045135.3635437-1-willy@infradead.org> References: <20230919045135.3635437-1-willy@infradead.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org Extract this useful helper from nilfs_page_get_nth_block() Signed-off-by: Matthew Wilcox (Oracle) Acked-by: Ryusuke Konishi --- fs/nilfs2/page.h | 7 +------ include/linux/buffer_head.h | 22 ++++++++++++++++++++++ 2 files changed, 23 insertions(+), 6 deletions(-) diff --git a/fs/nilfs2/page.h b/fs/nilfs2/page.h index 21ddcdd4d63e..344d71942d36 100644 --- a/fs/nilfs2/page.h +++ b/fs/nilfs2/page.h @@ -55,12 +55,7 @@ unsigned long nilfs_find_uncommitted_extent(struct inode *inode, static inline struct buffer_head * nilfs_page_get_nth_block(struct page *page, unsigned int count) { - struct buffer_head *bh = page_buffers(page); - - while (count-- > 0) - bh = bh->b_this_page; - get_bh(bh); - return bh; + return get_nth_bh(page_buffers(page), count); } #endif /* _NILFS_PAGE_H */ diff --git a/include/linux/buffer_head.h b/include/linux/buffer_head.h index 1001244a8941..9fc615ee17fd 100644 --- a/include/linux/buffer_head.h +++ b/include/linux/buffer_head.h @@ -457,6 +457,28 @@ __bread(struct block_device *bdev, sector_t block, unsigned size) return __bread_gfp(bdev, block, size, __GFP_MOVABLE); } +/** + * get_nth_bh - Get a reference on the n'th buffer after this one. + * @bh: The buffer to start counting from. + * @count: How many buffers to skip. + * + * This is primarily useful for finding the nth buffer in a folio; in + * that case you pass the head buffer and the byte offset in the folio + * divided by the block size. It can be used for other purposes, but + * it will wrap at the end of the folio rather than returning NULL or + * proceeding to the next folio for you. + * + * Return: The requested buffer with an elevated refcount. + */ +static inline struct buffer_head *get_nth_bh(struct buffer_head *bh, + unsigned int count) +{ + while (count--) + bh = bh->b_this_page; + get_bh(bh); + return bh; +} + bool block_dirty_folio(struct address_space *mapping, struct folio *folio); #ifdef CONFIG_BUFFER_HEAD