From patchwork Mon Oct 16 20:10:52 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Matthew Wilcox X-Patchwork-Id: 13424065 Received: from lindbergh.monkeyblade.net (lindbergh.monkeyblade.net [23.128.96.19]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id EE6A638F83 for ; Mon, 16 Oct 2023 20:11:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="Cm2/6gey" Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0ABCF125; Mon, 16 Oct 2023 13:11:24 -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=5zWLpgCpPdJ2OPyT7ybTpYNCwh68G15oM+bmUL5Qut4=; b=Cm2/6geygP8ZUrICSnQ8OvqL6x VIA3Zg5qgrfDLu//yeF2ucQMzFl7gvU4owiaM10L4uVEb9eU/u734bScQAKRaJTsfr6x+9xOYYeFj hLR54mpl1vQKk+XGT2pRrVEzPK9cWhbHcqDNc8XG1zrm3sMq2c4MU/FgkRgdZTRRuxRURoXTXPIGH wtXKayQ3kcdVe38fW2sAB6je4GpBoAKQiCPSNIKUajYpnWsDIHwqfcDxP0vzo29+ikrjYO99Wn7Rf fqDzW3TnjHGr3z+EE8+spbeIFkmdjkOpEKgydANNzprLs5Kajry6ouFuN4oRJZSpu8fnRMzU7Hadx D3CcqJrQ==; Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1qsTvp-0085ac-2Q; Mon, 16 Oct 2023 20:11:17 +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 , Ryusuke Konishi Subject: [PATCH v2 05/27] buffer: Add get_nth_bh() Date: Mon, 16 Oct 2023 21:10:52 +0100 Message-Id: <20231016201114.1928083-6-willy@infradead.org> X-Mailer: git-send-email 2.37.1 In-Reply-To: <20231016201114.1928083-1-willy@infradead.org> References: <20231016201114.1928083-1-willy@infradead.org> Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_BLOCKED, SPF_HELO_NONE,SPF_NONE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net 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..3d85a0cf0ca5 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 __must_check +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