From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e28smtp09.in.ibm.com ([122.248.162.9]:56585 "EHLO e28smtp09.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755681AbbJ1IKs (ORCPT ); Wed, 28 Oct 2015 04:10:48 -0400 Received: from /spool/local by e28smtp09.in.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Wed, 28 Oct 2015 13:40:45 +0530 Received: from d28relay04.in.ibm.com (d28relay04.in.ibm.com [9.184.220.61]) by d28dlp03.in.ibm.com (Postfix) with ESMTP id A00E01258061 for ; Wed, 28 Oct 2015 13:40:37 +0530 (IST) Received: from d28av02.in.ibm.com (d28av02.in.ibm.com [9.184.220.64]) by d28relay04.in.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id t9S8AeC451183638 for ; Wed, 28 Oct 2015 13:40:40 +0530 Received: from d28av02.in.ibm.com (localhost [127.0.0.1]) by d28av02.in.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id t9S8Ab0g003611 for ; Wed, 28 Oct 2015 13:40:40 +0530 From: Chandan Rajendra To: linux-btrfs@vger.kernel.org Cc: Chandan Rajendra , clm@fb.com, jbacik@fb.com, bo.li.liu@oracle.com, dsterba@suse.cz, quwenruo@cn.fujitsu.com, chandan@mykolab.com Subject: [PATCH V8 12/13] Btrfs: prepare_pages: Retry adding a page to the page cache Date: Wed, 28 Oct 2015 13:40:26 +0530 Message-Id: <1446019827-685-13-git-send-email-chandan@linux.vnet.ibm.com> In-Reply-To: <1446019827-685-1-git-send-email-chandan@linux.vnet.ibm.com> References: <1446019827-685-1-git-send-email-chandan@linux.vnet.ibm.com> Sender: linux-btrfs-owner@vger.kernel.org List-ID: When reading the page from the disk, we can race with Direct I/O which can get the page lock (before prepare_uptodate_page() gets it) and can go ahead and invalidate the page. Hence if the page is not found in the inode's address space, retry the operation of getting a page. Reported-by: Jakub Palider Reviewed-by: Josef Bacik Signed-off-by: Chandan Rajendra --- fs/btrfs/file.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c index 5a7551c..0e54a53 100644 --- a/fs/btrfs/file.c +++ b/fs/btrfs/file.c @@ -1316,6 +1316,7 @@ static noinline int prepare_pages(struct inode *inode, struct page **pages, int faili; for (i = 0; i < num_pages; i++) { +again: pages[i] = find_or_create_page(inode->i_mapping, index + i, mask | __GFP_WRITE); if (!pages[i]) { @@ -1330,6 +1331,21 @@ static noinline int prepare_pages(struct inode *inode, struct page **pages, if (i == num_pages - 1) err = prepare_uptodate_page(pages[i], pos + write_bytes, false); + + /* + * When reading the page from the disk, we can race + * with direct i/o which can get the page lock (before + * prepare_uptodate_page() gets it) and can go ahead + * and invalidate the page. Hence if the page is found + * to be not belonging to the inode's address space, + * retry the operation of getting a page. + */ + if (unlikely(pages[i]->mapping != inode->i_mapping)) { + unlock_page(pages[i]); + page_cache_release(pages[i]); + goto again; + } + if (err) { page_cache_release(pages[i]); faili = i - 1; -- 2.1.0