Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935035AbbHDPNY (ORCPT ); Tue, 4 Aug 2015 11:13:24 -0400 Received: from mx2.suse.de ([195.135.220.15]:58899 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756336AbbHDOl2 (ORCPT ); Tue, 4 Aug 2015 10:41:28 -0400 X-Amavis-Alert: BAD HEADER SECTION, Duplicate header field: "References" From: Jiri Slaby To: stable@vger.kernel.org Cc: linux-kernel@vger.kernel.org, "Theodore Ts'o" , Jiri Slaby Subject: [PATCH 3.12 039/123] ext4: fix race between truncate and __ext4_journalled_writepage() Date: Tue, 4 Aug 2015 16:39:43 +0200 Message-Id: X-Mailer: git-send-email 2.5.0 In-Reply-To: References: In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4811 Lines: 141 From: Theodore Ts'o 3.12-stable review patch. If anyone has any objections, please let me know. =============== commit bdf96838aea6a265f2ae6cbcfb12a778c84a0b8e upstream. The commit cf108bca465d: "ext4: Invert the locking order of page_lock and transaction start" caused __ext4_journalled_writepage() to drop the page lock before the page was written back, as part of changing the locking order to jbd2_journal_start -> page_lock. However, this introduced a potential race if there was a truncate racing with the data=journalled writeback mode. Fix this by grabbing the page lock after starting the journal handle, and then checking to see if page had gotten truncated out from under us. This fixes a number of different warnings or BUG_ON's when running xfstests generic/086 in data=journalled mode, including: jbd2_journal_dirty_metadata: vdc-8: bad jh for block 115643: transaction (ee3fe7 c0, 164), jh->b_transaction ( (null), 0), jh->b_next_transaction ( (null), 0), jlist 0 - and - kernel BUG at /usr/projects/linux/ext4/fs/jbd2/transaction.c:2200! ... Call Trace: [] ? __ext4_journalled_invalidatepage+0x117/0x117 [] __ext4_journalled_invalidatepage+0x10f/0x117 [] ? __ext4_journalled_invalidatepage+0x117/0x117 [] ? lock_buffer+0x36/0x36 [] ext4_journalled_invalidatepage+0xd/0x22 [] do_invalidatepage+0x22/0x26 [] truncate_inode_page+0x5b/0x85 [] truncate_inode_pages_range+0x156/0x38c [] truncate_inode_pages+0x11/0x15 [] truncate_pagecache+0x55/0x71 [] ext4_setattr+0x4a9/0x560 [] ? current_kernel_time+0x10/0x44 [] notify_change+0x1c7/0x2be [] do_truncate+0x65/0x85 [] ? file_ra_state_init+0x12/0x29 - and - WARNING: CPU: 1 PID: 1331 at /usr/projects/linux/ext4/fs/jbd2/transaction.c:1396 irty_metadata+0x14a/0x1ae() ... Call Trace: [] ? console_unlock+0x3a1/0x3ce [] dump_stack+0x48/0x60 [] warn_slowpath_common+0x89/0xa0 [] ? jbd2_journal_dirty_metadata+0x14a/0x1ae [] warn_slowpath_null+0x14/0x18 [] jbd2_journal_dirty_metadata+0x14a/0x1ae [] __ext4_handle_dirty_metadata+0xd4/0x19d [] write_end_fn+0x40/0x53 [] ext4_walk_page_buffers+0x4e/0x6a [] ext4_writepage+0x354/0x3b8 [] ? mpage_release_unused_pages+0xd4/0xd4 [] ? wait_on_buffer+0x2c/0x2c [] ? ext4_writepage+0x3b8/0x3b8 [] __writepage+0x10/0x2e [] write_cache_pages+0x22d/0x32c [] ? ext4_writepage+0x3b8/0x3b8 [] ext4_writepages+0x102/0x607 [] ? sched_clock_local+0x10/0x10e [] ? __lock_is_held+0x2e/0x44 [] ? lock_is_held+0x43/0x51 [] do_writepages+0x1c/0x29 [] __writeback_single_inode+0xc3/0x545 [] writeback_sb_inodes+0x21f/0x36d ... Signed-off-by: Theodore Ts'o Signed-off-by: Jiri Slaby --- fs/ext4/inode.c | 23 +++++++++++++++++++---- 1 file changed, 19 insertions(+), 4 deletions(-) diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index 70a390bb4733..c51ac796bcd4 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -1744,19 +1744,32 @@ static int __ext4_journalled_writepage(struct page *page, ext4_walk_page_buffers(handle, page_bufs, 0, len, NULL, bget_one); } - /* As soon as we unlock the page, it can go away, but we have - * references to buffers so we are safe */ + /* + * We need to release the page lock before we start the + * journal, so grab a reference so the page won't disappear + * out from under us. + */ + get_page(page); unlock_page(page); handle = ext4_journal_start(inode, EXT4_HT_WRITE_PAGE, ext4_writepage_trans_blocks(inode)); if (IS_ERR(handle)) { ret = PTR_ERR(handle); - goto out; + put_page(page); + goto out_no_pagelock; } - BUG_ON(!ext4_handle_valid(handle)); + lock_page(page); + put_page(page); + if (page->mapping != mapping) { + /* The page got truncated from under us */ + ext4_journal_stop(handle); + ret = 0; + goto out; + } + if (inline_data) { ret = ext4_journal_get_write_access(handle, inode_bh); @@ -1781,6 +1794,8 @@ static int __ext4_journalled_writepage(struct page *page, NULL, bput_one); ext4_set_inode_state(inode, EXT4_STATE_JDATA); out: + unlock_page(page); +out_no_pagelock: brelse(inode_bh); return ret; } -- 2.5.0 -- 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/