From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from relay.sgi.com (relay1.corp.sgi.com [137.38.102.111]) by oss.sgi.com (Postfix) with ESMTP id 2328A7F4E for ; Mon, 11 Aug 2014 08:29:32 -0500 (CDT) Received: from cuda.sgi.com (cuda3.sgi.com [192.48.176.15]) by relay1.corp.sgi.com (Postfix) with ESMTP id E66018F8059 for ; Mon, 11 Aug 2014 06:29:31 -0700 (PDT) Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) by cuda.sgi.com with ESMTP id LQfHpExHioFPUH9Z (version=TLSv1 cipher=AES256-SHA bits=256 verify=NO) for ; Mon, 11 Aug 2014 06:29:30 -0700 (PDT) Date: Mon, 11 Aug 2014 09:29:19 -0400 From: Brian Foster Subject: Re: [PATCH v2] xfs: don't zero partial page cache pages during O_DIRECT Message-ID: <20140811132919.GB1186@bfoster.bfoster> References: <53E4E03A.7050101@fb.com> <53E61A9C.4020807@fb.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <53E61A9C.4020807@fb.com> List-Id: XFS Filesystem from SGI List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: xfs-bounces@oss.sgi.com Sender: xfs-bounces@oss.sgi.com To: Chris Mason Cc: Eric Sandeen , xfs@oss.sgi.com On Sat, Aug 09, 2014 at 08:57:00AM -0400, Chris Mason wrote: > > xfs is using truncate_pagecache_range to invalidate the page cache > during DIO reads. This is different from the other filesystems who only > invalidate pages during DIO writes. > > truncate_pagecache_range is meant to be used when we are freeing the > underlying data structs from disk, so it will zero any partial ranges in > the page. This means a DIO read can zero out part of the page cache > page, and it is possible the page will stay in cache. > > buffered reads will find an up to date page with zeros instead of the > data actually on disk. > > This patch fixes things by using invalidate_inode_pages2_range instead. > It preserves the page cache invalidation, but won't zero any pages. > > Signed-off-by: Chris Mason > cc: stable@vger.kernel.org > > --- I can't say I grok the risk of removing the invalidation entirely, but this is certainly a more isolated fix: Reviewed-by: Brian Foster > fs/xfs/xfs_file.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c > index 1f66779..023d575 100644 > --- a/fs/xfs/xfs_file.c > +++ b/fs/xfs/xfs_file.c > @@ -295,7 +295,8 @@ xfs_file_read_iter( > xfs_rw_iunlock(ip, XFS_IOLOCK_EXCL); > return ret; > } > - truncate_pagecache_range(VFS_I(ip), pos, -1); > + invalidate_inode_pages2_range(VFS_I(ip)->i_mapping, > + pos >> PAGE_CACHE_SHIFT, -1); > } > xfs_rw_ilock_demote(ip, XFS_IOLOCK_EXCL); > } > -- > 1.8.1 > > _______________________________________________ > xfs mailing list > xfs@oss.sgi.com > http://oss.sgi.com/mailman/listinfo/xfs _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs