Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933766AbaGVWmr (ORCPT ); Tue, 22 Jul 2014 18:42:47 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:44672 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933086AbaGVWZn (ORCPT ); Tue, 22 Jul 2014 18:25:43 -0400 From: Kamal Mostafa To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Jan Kara , "Theodore Ts'o" , Kamal Mostafa Subject: [PATCH 3.8 032/116] ext4: fix zeroing of page during writeback Date: Tue, 22 Jul 2014 15:20:43 -0700 Message-Id: <1406067727-19683-33-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1406067727-19683-1-git-send-email-kamal@canonical.com> References: <1406067727-19683-1-git-send-email-kamal@canonical.com> X-Extended-Stable: 3.8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.8.13.27 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Jan Kara commit eeece469dedadf3918bad50ad80f4616a0064e90 upstream. Tail of a page straddling inode size must be zeroed when being written out due to POSIX requirement that modifications of mmaped page beyond inode size must not be written to the file. ext4_bio_write_page() did this only for blocks fully beyond inode size but didn't properly zero blocks partially beyond inode size. Fix this. The problem has been uncovered by mmap_11-4 test in openposix test suite (part of LTP). Reported-by: Xiaoguang Wang Fixes: 5a0dc7365c240 Fixes: bd2d0210cf22f Signed-off-by: Jan Kara Signed-off-by: Theodore Ts'o Signed-off-by: Kamal Mostafa --- fs/ext4/page-io.c | 24 ++++++++++++------------ 1 file changed, 12 insertions(+), 12 deletions(-) diff --git a/fs/ext4/page-io.c b/fs/ext4/page-io.c index 311d1db..a30ef89 100644 --- a/fs/ext4/page-io.c +++ b/fs/ext4/page-io.c @@ -446,24 +446,24 @@ int ext4_bio_write_page(struct ext4_io_submit *io, set_page_writeback(page); ClearPageError(page); + /* + * 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." + */ + if (len < PAGE_CACHE_SIZE) + zero_user_segment(page, len, PAGE_CACHE_SIZE); + for (bh = head = page_buffers(page), block_start = 0; bh != head || !block_start; block_start = block_end, bh = bh->b_this_page) { 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; -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/