From: Yongqiang Yang Subject: [PATCH 2/2] ext4: let ext4_bio_write_page handle EOF correctly Date: Wed, 7 Dec 2011 13:21:27 +0800 Message-ID: <1323235287-29806-2-git-send-email-xiaoqiangnk@gmail.com> References: <1323235287-29806-1-git-send-email-xiaoqiangnk@gmail.com> Cc: achender@linux.vnet.ibm.com, hughd@google.com, tytso@mit.edu, Yongqiang Yang To: linux-ext4@vger.kernel.org Return-path: Received: from mail-gy0-f174.google.com ([209.85.160.174]:43508 "EHLO mail-gy0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753078Ab1LGIX4 (ORCPT ); Wed, 7 Dec 2011 03:23:56 -0500 Received: by ghbz2 with SMTP id z2so248849ghb.19 for ; Wed, 07 Dec 2011 00:23:56 -0800 (PST) In-Reply-To: <1323235287-29806-1-git-send-email-xiaoqiangnk@gmail.com> Sender: linux-ext4-owner@vger.kernel.org List-ID: We need to zero out part of a page which beyond EOF before setting uptodate, otherwise, mapread or write will see non-zero data beyond EOF. Signed-off-by: Yongqiang Yang --- fs/ext4/page-io.c | 12 ++++++++++++ 1 files changed, 12 insertions(+), 0 deletions(-) diff --git a/fs/ext4/page-io.c b/fs/ext4/page-io.c index 235b79d..9e145b8 100644 --- a/fs/ext4/page-io.c +++ b/fs/ext4/page-io.c @@ -385,6 +385,18 @@ int ext4_bio_write_page(struct ext4_io_submit *io, block_end = block_start + blocksize; if (block_start >= len) { + /* + * Comments copied from block_write_full_page_endio: + * + * The page straddles i_size. It must be zeroed out on + * each and every writepage invocation because it may + * be mmapped. "A file is mapped in multiples of the + * page size. For a file that is not a multiple of + * the page size, the remaining memory is zeroed when + * mapped, and writes to that region are not written + * out to the file." + */ + zero_user_segment(page, block_start, block_end); clear_buffer_dirty(bh); set_buffer_uptodate(bh); continue; -- 1.7.5.1