From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753103AbdKWPhr (ORCPT ); Thu, 23 Nov 2017 10:37:47 -0500 Received: from mail.kernel.org ([198.145.29.99]:34916 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752946AbdKWPho (ORCPT ); Thu, 23 Nov 2017 10:37:44 -0500 DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8BC1B21924 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=chao@kernel.org From: Chao Yu To: jaegeuk@kernel.org Cc: linux-f2fs-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org, Chao Yu Subject: [PATCH] f2fs: fix lock dependency in between dio_rwsem & i_mmap_sem Date: Thu, 23 Nov 2017 23:26:52 +0800 Message-Id: <20171123152652.16232-1-chao@kernel.org> X-Mailer: git-send-email 2.14.1.145.gb3622a4ee Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Chao Yu test/generic/208 reports a potential deadlock as below: Chain exists of: &mm->mmap_sem --> &fi->i_mmap_sem --> &fi->dio_rwsem[WRITE] Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&fi->dio_rwsem[WRITE]); lock(&fi->i_mmap_sem); lock(&fi->dio_rwsem[WRITE]); lock(&mm->mmap_sem); This patch changes the lock dependency as below in fallocate() to fix this issue: - dio_rwsem - i_mmap_sem Fixes: bb06664a534b ("f2fs: avoid race in between GC and block exchange") Signed-off-by: Chao Yu --- fs/f2fs/file.c | 20 +++++++++----------- 1 file changed, 9 insertions(+), 11 deletions(-) diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c index a292a1a3a692..d08e003e6d6b 100644 --- a/fs/f2fs/file.c +++ b/fs/f2fs/file.c @@ -1185,14 +1185,14 @@ static int f2fs_collapse_range(struct inode *inode, loff_t offset, loff_t len) pg_start = offset >> PAGE_SHIFT; pg_end = (offset + len) >> PAGE_SHIFT; + /* avoid gc operation during block exchange */ + down_write(&F2FS_I(inode)->dio_rwsem[WRITE]); + down_write(&F2FS_I(inode)->i_mmap_sem); /* write out all dirty pages from offset */ ret = filemap_write_and_wait_range(inode->i_mapping, offset, LLONG_MAX); if (ret) - goto out; - - /* avoid gc operation during block exchange */ - down_write(&F2FS_I(inode)->dio_rwsem[WRITE]); + goto out_unlock; truncate_pagecache(inode, offset); @@ -1211,9 +1211,8 @@ static int f2fs_collapse_range(struct inode *inode, loff_t offset, loff_t len) if (!ret) f2fs_i_size_write(inode, new_size); out_unlock: - up_write(&F2FS_I(inode)->dio_rwsem[WRITE]); -out: up_write(&F2FS_I(inode)->i_mmap_sem); + up_write(&F2FS_I(inode)->dio_rwsem[WRITE]); return ret; } @@ -1384,6 +1383,9 @@ static int f2fs_insert_range(struct inode *inode, loff_t offset, loff_t len) f2fs_balance_fs(sbi, true); + /* avoid gc operation during block exchange */ + down_write(&F2FS_I(inode)->dio_rwsem[WRITE]); + down_write(&F2FS_I(inode)->i_mmap_sem); ret = truncate_blocks(inode, i_size_read(inode), true); if (ret) @@ -1394,9 +1396,6 @@ static int f2fs_insert_range(struct inode *inode, loff_t offset, loff_t len) if (ret) goto out; - /* avoid gc operation during block exchange */ - down_write(&F2FS_I(inode)->dio_rwsem[WRITE]); - truncate_pagecache(inode, offset); pg_start = offset >> PAGE_SHIFT; @@ -1424,10 +1423,9 @@ static int f2fs_insert_range(struct inode *inode, loff_t offset, loff_t len) if (!ret) f2fs_i_size_write(inode, new_size); - - up_write(&F2FS_I(inode)->dio_rwsem[WRITE]); out: up_write(&F2FS_I(inode)->i_mmap_sem); + up_write(&F2FS_I(inode)->dio_rwsem[WRITE]); return ret; } -- 2.14.1.145.gb3622a4ee