From patchwork Thu May 11 19:17:02 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Goldwyn Rodrigues X-Patchwork-Id: 761301 Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 3wP2vk550Kz9s84 for ; Fri, 12 May 2017 05:18:42 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934495AbdEKTRd (ORCPT ); Thu, 11 May 2017 15:17:33 -0400 Received: from mx2.suse.de ([195.135.220.15]:41790 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S933002AbdEKTRa (ORCPT ); Thu, 11 May 2017 15:17:30 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay1.suse.de (charybdis-ext.suse.de [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 8E3CCAD98; Thu, 11 May 2017 19:17:28 +0000 (UTC) From: Goldwyn Rodrigues To: linux-fsdevel@vger.kernel.org Cc: jack@suse.com, hch@infradead.org, linux-block@vger.kernel.org, linux-btrfs@vger.kernel.org, linux-ext4@vger.kernel.org, linux-xfs@vger.kernel.org, sagi@grimberg.me, avi@scylladb.com, axboe@kernel.dk, linux-api@vger.kernel.org, Goldwyn Rodrigues Subject: [PATCH 02/10] fs: Introduce filemap_range_has_page() Date: Thu, 11 May 2017 14:17:02 -0500 Message-Id: <20170511191710.31959-3-rgoldwyn@suse.de> X-Mailer: git-send-email 2.12.0 In-Reply-To: <20170511191710.31959-1-rgoldwyn@suse.de> References: <20170511191710.31959-1-rgoldwyn@suse.de> Sender: linux-ext4-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org From: Goldwyn Rodrigues filemap_range_has_page() return true if the file's mapping has a page within the range mentioned. This function will be used to check if a write() call will cause a writeback of previous writes. Signed-off-by: Goldwyn Rodrigues Reviewed-by: Christoph Hellwig --- include/linux/fs.h | 2 ++ mm/filemap.c | 33 +++++++++++++++++++++++++++++++++ 2 files changed, 35 insertions(+) diff --git a/include/linux/fs.h b/include/linux/fs.h index 869c9a6fe58d..2e6fc6a23f91 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -2513,6 +2513,8 @@ extern int filemap_fdatawait(struct address_space *); extern void filemap_fdatawait_keep_errors(struct address_space *); extern int filemap_fdatawait_range(struct address_space *, loff_t lstart, loff_t lend); +extern int filemap_range_has_page(struct address_space *, loff_t lstart, + loff_t lend); extern int filemap_write_and_wait(struct address_space *mapping); extern int filemap_write_and_wait_range(struct address_space *mapping, loff_t lstart, loff_t lend); diff --git a/mm/filemap.c b/mm/filemap.c index 1694623a6289..fae5a361befb 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -376,6 +376,39 @@ int filemap_flush(struct address_space *mapping) } EXPORT_SYMBOL(filemap_flush); +/** + * filemap_range_has_page - check if a page exists in range. + * @mapping: address space structure to wait for + * @start_byte: offset in bytes where the range starts + * @end_byte: offset in bytes where the range ends (inclusive) + * + * Find at least one page in the range supplied, usually used to check if + * direct writing in this range will trigger a writeback. + */ +int filemap_range_has_page(struct address_space *mapping, + loff_t start_byte, loff_t end_byte) +{ + pgoff_t index = start_byte >> PAGE_SHIFT; + pgoff_t end = end_byte >> PAGE_SHIFT; + struct pagevec pvec; + int ret; + + if (end_byte < start_byte) + return 0; + + if (mapping->nrpages == 0) + return 0; + + pagevec_init(&pvec, 0); + ret = pagevec_lookup(&pvec, mapping, index, 1); + if (!ret) + return 0; + ret = (pvec.pages[0]->index <= end); + pagevec_release(&pvec); + return ret; +} +EXPORT_SYMBOL(filemap_range_has_page); + static int __filemap_fdatawait_range(struct address_space *mapping, loff_t start_byte, loff_t end_byte) {