From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933309AbcECAdR (ORCPT ); Mon, 2 May 2016 20:33:17 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:60339 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933281AbcECA0u (ORCPT ); Mon, 2 May 2016 20:26:50 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Jan Kara , Theodore Tso Subject: [PATCH 4.4 147/163] ext4: move unlocked dio protection from ext4_alloc_file_blocks() Date: Mon, 2 May 2016 17:12:55 -0700 Message-Id: <20160503000513.304640681@linuxfoundation.org> X-Mailer: git-send-email 2.8.2 In-Reply-To: <20160503000508.556845508@linuxfoundation.org> References: <20160503000508.556845508@linuxfoundation.org> User-Agent: quilt/0.64 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jan Kara commit 17048e8a083fec7ad841d88ef0812707fbc7e39f upstream. Currently ext4_alloc_file_blocks() was handling protection against unlocked DIO. However we now need to sometimes call it under i_mmap_sem and sometimes not and DIO protection ranks above it (although strictly speaking this cannot currently create any deadlocks). Also ext4_zero_range() was actually getting & releasing unlocked DIO protection twice in some cases. Luckily it didn't introduce any real bug but it was a land mine waiting to be stepped on. So move DIO protection out from ext4_alloc_file_blocks() into the two callsites. Signed-off-by: Jan Kara Signed-off-by: Theodore Ts'o Signed-off-by: Greg Kroah-Hartman --- fs/ext4/extents.c | 21 ++++++++++----------- 1 file changed, 10 insertions(+), 11 deletions(-) --- a/fs/ext4/extents.c +++ b/fs/ext4/extents.c @@ -4685,10 +4685,6 @@ static int ext4_alloc_file_blocks(struct if (len <= EXT_UNWRITTEN_MAX_LEN) flags |= EXT4_GET_BLOCKS_NO_NORMALIZE; - /* Wait all existing dio workers, newcomers will block on i_mutex */ - ext4_inode_block_unlocked_dio(inode); - inode_dio_wait(inode); - /* * credits to insert 1 extent into extent tree */ @@ -4752,8 +4748,6 @@ retry: goto retry; } - ext4_inode_resume_unlocked_dio(inode); - return ret > 0 ? ret2 : ret; } @@ -4827,6 +4821,10 @@ static long ext4_zero_range(struct file if (mode & FALLOC_FL_KEEP_SIZE) flags |= EXT4_GET_BLOCKS_KEEP_SIZE; + /* Wait all existing dio workers, newcomers will block on i_mutex */ + ext4_inode_block_unlocked_dio(inode); + inode_dio_wait(inode); + /* Preallocate the range including the unaligned edges */ if (partial_begin || partial_end) { ret = ext4_alloc_file_blocks(file, @@ -4835,7 +4833,7 @@ static long ext4_zero_range(struct file round_down(offset, 1 << blkbits)) >> blkbits, new_size, flags, mode); if (ret) - goto out_mutex; + goto out_dio; } @@ -4844,10 +4842,6 @@ static long ext4_zero_range(struct file flags |= (EXT4_GET_BLOCKS_CONVERT_UNWRITTEN | EXT4_EX_NOCACHE); - /* Wait all existing dio workers, newcomers will block on i_mutex */ - ext4_inode_block_unlocked_dio(inode); - inode_dio_wait(inode); - /* * Prevent page faults from reinstantiating pages we have * released from page cache. @@ -4992,8 +4986,13 @@ long ext4_fallocate(struct file *file, i goto out; } + /* Wait all existing dio workers, newcomers will block on i_mutex */ + ext4_inode_block_unlocked_dio(inode); + inode_dio_wait(inode); + ret = ext4_alloc_file_blocks(file, lblk, max_blocks, new_size, flags, mode); + ext4_inode_resume_unlocked_dio(inode); if (ret) goto out;