From patchwork Tue Jun 20 12:05:41 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Goldwyn Rodrigues X-Patchwork-Id: 9799327 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id E80EC601BC for ; Tue, 20 Jun 2017 12:06:00 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id D94FF201BC for ; Tue, 20 Jun 2017 12:06:00 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id CDCAC205A4; Tue, 20 Jun 2017 12:06:00 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 6DD93201BC for ; Tue, 20 Jun 2017 12:06:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751078AbdFTMGA (ORCPT ); Tue, 20 Jun 2017 08:06:00 -0400 Received: from mx2.suse.de ([195.135.220.15]:57348 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751056AbdFTMF7 (ORCPT ); Tue, 20 Jun 2017 08:05:59 -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 47B2AAB46; Tue, 20 Jun 2017 12:05:58 +0000 (UTC) From: Goldwyn Rodrigues To: axboe@kernel.dk Cc: viro@ZenIV.linux.org.uk, hch@lst.de, jack@suse.cz, akpm@linux-foundation.org, linux-block@vger.kernel.org, Goldwyn Rodrigues Subject: [PATCH 02/10] fs: Introduce filemap_range_has_page() Date: Tue, 20 Jun 2017 07:05:41 -0500 Message-Id: <20170620120549.23147-3-rgoldwyn@suse.de> X-Mailer: git-send-email 2.12.0 In-Reply-To: <20170620120549.23147-1-rgoldwyn@suse.de> References: <20170620120549.23147-1-rgoldwyn@suse.de> Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP 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. Reviewed-by: Christoph Hellwig Reviewed-by: Jan Kara Signed-off-by: Goldwyn Rodrigues --- include/linux/fs.h | 2 ++ mm/filemap.c | 32 ++++++++++++++++++++++++++++++++ 2 files changed, 34 insertions(+) diff --git a/include/linux/fs.h b/include/linux/fs.h index 96a1a1fa54a9..0d34f5b5a6b0 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -2518,6 +2518,8 @@ 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 bool 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 6f1be573a5e6..9b39a2390b9e 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -376,6 +376,38 @@ 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 within which to check + * @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. + */ +bool 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; + bool ret; + + if (end_byte < start_byte) + return false; + + if (mapping->nrpages == 0) + return false; + + pagevec_init(&pvec, 0); + if (!pagevec_lookup(&pvec, mapping, index, 1)) + return false; + 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) {