From 1c8349a17137b93f0a83f276c764a6df1b9a116e Mon Sep 17 00:00:00 2001 From: Namjae Jeon Date: Mon, 12 May 2014 08:12:25 -0400 Subject: ext4: fix data integrity sync in ordered mode When we perform a data integrity sync we tag all the dirty pages with PAGECACHE_TAG_TOWRITE at start of ext4_da_writepages. Later we check for this tag in write_cache_pages_da and creates a struct mpage_da_data containing contiguously indexed pages tagged with this tag and sync these pages with a call to mpage_da_map_and_submit. This process is done in while loop until all the PAGECACHE_TAG_TOWRITE pages are synced. We also do journal start and stop in each iteration. journal_stop could initiate journal commit which would call ext4_writepage which in turn will call ext4_bio_write_page even for delayed OR unwritten buffers. When ext4_bio_write_page is called for such buffers, even though it does not sync them but it clears the PAGECACHE_TAG_TOWRITE of the corresponding page and hence these pages are also not synced by the currently running data integrity sync. We will end up with dirty pages although sync is completed. This could cause a potential data loss when the sync call is followed by a truncate_pagecache call, which is exactly the case in collapse_range. (It will cause generic/127 failure in xfstests) To avoid this issue, we can use set_page_writeback_keepwrite instead of set_page_writeback, which doesn't clear TOWRITE tag. Cc: stable@vger.kernel.org Signed-off-by: Namjae Jeon Signed-off-by: Ashish Sangwan Signed-off-by: "Theodore Ts'o" Reviewed-by: Jan Kara --- fs/ext4/page-io.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) (limited to 'fs/ext4/page-io.c') diff --git a/fs/ext4/page-io.c b/fs/ext4/page-io.c index c18d95b50540..4cb2743cb2e3 100644 --- a/fs/ext4/page-io.c +++ b/fs/ext4/page-io.c @@ -401,7 +401,8 @@ submit_and_retry: int ext4_bio_write_page(struct ext4_io_submit *io, struct page *page, int len, - struct writeback_control *wbc) + struct writeback_control *wbc, + bool keep_towrite) { struct inode *inode = page->mapping->host; unsigned block_start, blocksize; @@ -414,7 +415,10 @@ int ext4_bio_write_page(struct ext4_io_submit *io, BUG_ON(!PageLocked(page)); BUG_ON(PageWriteback(page)); - set_page_writeback(page); + if (keep_towrite) + set_page_writeback_keepwrite(page); + else + set_page_writeback(page); ClearPageError(page); /* -- cgit v1.2.1 From eeece469dedadf3918bad50ad80f4616a0064e90 Mon Sep 17 00:00:00 2001 From: Jan Kara Date: Tue, 27 May 2014 12:48:55 -0400 Subject: ext4: fix zeroing of page during writeback 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 CC: stable@vger.kernel.org Signed-off-by: Jan Kara Signed-off-by: Theodore Ts'o --- fs/ext4/page-io.c | 24 +++++++++++------------- 1 file changed, 11 insertions(+), 13 deletions(-) (limited to 'fs/ext4/page-io.c') diff --git a/fs/ext4/page-io.c b/fs/ext4/page-io.c index 4cb2743cb2e3..b6a3804a9855 100644 --- a/fs/ext4/page-io.c +++ b/fs/ext4/page-io.c @@ -421,6 +421,17 @@ 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); /* * In the first loop we prepare and mark buffers to submit. We have to * mark all buffers in the page before submitting so that @@ -432,19 +443,6 @@ int ext4_bio_write_page(struct ext4_io_submit *io, do { block_start = bh_offset(bh); 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_start + blocksize); clear_buffer_dirty(bh); set_buffer_uptodate(bh); continue; -- cgit v1.2.1