From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.7 required=3.0 tests=FORGED_MUA_MOZILLA, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D4595ECE58D for ; Wed, 9 Oct 2019 06:40:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B637F20B7C for ; Wed, 9 Oct 2019 06:40:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726698AbfJIGkB (ORCPT ); Wed, 9 Oct 2019 02:40:01 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:22834 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725776AbfJIGkA (ORCPT ); Wed, 9 Oct 2019 02:40:00 -0400 Received: from pps.filterd (m0187473.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.27/8.16.0.27) with SMTP id x996bUql167856 for ; Wed, 9 Oct 2019 02:39:59 -0400 Received: from e06smtp01.uk.ibm.com (e06smtp01.uk.ibm.com [195.75.94.97]) by mx0a-001b2d01.pphosted.com with ESMTP id 2vgyqbt4dk-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Wed, 09 Oct 2019 02:39:59 -0400 Received: from localhost by e06smtp01.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Wed, 9 Oct 2019 07:39:53 +0100 Received: from d06av24.portsmouth.uk.ibm.com (d06av24.portsmouth.uk.ibm.com [9.149.105.60]) by b06cxnps4076.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x996dq9U52625408 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 9 Oct 2019 06:39:52 GMT Received: from d06av24.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 1FF674203F; Wed, 9 Oct 2019 06:39:52 +0000 (GMT) Received: from d06av24.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 604C042047; Wed, 9 Oct 2019 06:39:50 +0000 (GMT) Received: from [9.199.159.72] (unknown [9.199.159.72]) by d06av24.portsmouth.uk.ibm.com (Postfix) with ESMTP; Wed, 9 Oct 2019 06:39:50 +0000 (GMT) Subject: Re: [PATCH v4 4/8] ext4: introduce direct I/O read path using iomap infrastructure To: Matthew Bobrowski , tytso@mit.edu, jack@suse.cz, adilger.kernel@dilger.ca Cc: linux-ext4@vger.kernel.org, linux-fsdevel@vger.kernel.org, hch@infradead.org, david@fromorbit.com, darrick.wong@oracle.com References: From: Ritesh Harjani Date: Wed, 9 Oct 2019 12:09:49 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.2 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 x-cbid: 19100906-4275-0000-0000-0000037059F0 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19100906-4276-0000-0000-000038835CE2 Message-Id: <20191009063950.604C042047@d06av24.portsmouth.uk.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-10-09_03:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1908290000 definitions=main-1910090060 Sender: linux-ext4-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org On 10/3/19 5:04 PM, Matthew Bobrowski wrote: > This patch introduces a new direct I/O read path that makes use of the > iomap infrastructure. > > The new function ext4_dio_read_iter() is responsible for calling into > the iomap infrastructure via iomap_dio_rw(). If the read operation > being performed on the inode does not pass the preliminary checks > performed within ext4_dio_supported(), then we simply fallback to > buffered I/O in order to fulfil the request. > > Existing direct I/O read buffer_head code has been removed as it's now > redundant. > > Signed-off-by: Matthew Bobrowski > --- > fs/ext4/file.c | 58 +++++++++++++++++++++++++++++++++++++++++++++---- > fs/ext4/inode.c | 32 +-------------------------- > 2 files changed, 55 insertions(+), 35 deletions(-) > > diff --git a/fs/ext4/file.c b/fs/ext4/file.c > index ab75aee3e687..69ac042fb74b 100644 > --- a/fs/ext4/file.c > +++ b/fs/ext4/file.c > @@ -34,6 +34,53 @@ > #include "xattr.h" > #include "acl.h" > > +static bool ext4_dio_supported(struct inode *inode) > +{ > + if (IS_ENABLED(CONFIG_FS_ENCRYPTION) && IS_ENCRYPTED(inode)) > + return false; > + if (fsverity_active(inode)) > + return false; > + if (ext4_should_journal_data(inode)) > + return false; > + if (ext4_has_inline_data(inode)) > + return false; > + return true; > +} > + > +static ssize_t ext4_dio_read_iter(struct kiocb *iocb, struct iov_iter *to) > +{ > + ssize_t ret; > + struct inode *inode = file_inode(iocb->ki_filp); > + > + /* > + * Get exclusion from truncate and other inode operations. > + */ > + if (!inode_trylock_shared(inode)) { > + if (iocb->ki_flags & IOCB_NOWAIT) > + return -EAGAIN; > + inode_lock_shared(inode); > + } Same comments here. Let's follow as per the discussion here https://patchwork.kernel.org/patch/11141577/ > + > + if (!ext4_dio_supported(inode)) { > + inode_unlock_shared(inode); > + /* > + * Fallback to buffered I/O if the operation being > + * performed on the inode is not supported by direct > + * I/O. The IOCB_DIRECT flag needs to be cleared here > + * in order to ensure that the direct I/O path withiin > + * generic_file_read_iter() is not taken. > + */ > + iocb->ki_flags &= ~IOCB_DIRECT; > + return generic_file_read_iter(iocb, to); > + } > + > + ret = iomap_dio_rw(iocb, to, &ext4_iomap_ops, NULL); > + inode_unlock_shared(inode); > + > + file_accessed(iocb->ki_filp); > + return ret; > +} > + > #ifdef CONFIG_FS_DAX > static ssize_t ext4_dax_read_iter(struct kiocb *iocb, struct iov_iter *to) > { > @@ -64,16 +111,19 @@ static ssize_t ext4_dax_read_iter(struct kiocb *iocb, struct iov_iter *to) > > static ssize_t ext4_file_read_iter(struct kiocb *iocb, struct iov_iter *to) > { > - if (unlikely(ext4_forced_shutdown(EXT4_SB(file_inode(iocb->ki_filp)->i_sb)))) > + struct inode *inode = file_inode(iocb->ki_filp); > + > + if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb)))) > return -EIO; > > if (!iov_iter_count(to)) > return 0; /* skip atime */ > > -#ifdef CONFIG_FS_DAX > - if (IS_DAX(file_inode(iocb->ki_filp))) > + if (IS_DAX(inode)) > return ext4_dax_read_iter(iocb, to); > -#endif > + > + if (iocb->ki_flags & IOCB_DIRECT) > + return ext4_dio_read_iter(iocb, to); > return generic_file_read_iter(iocb, to); > } > > diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c > index 1dace576b8bd..159ffb92f82d 100644 > --- a/fs/ext4/inode.c > +++ b/fs/ext4/inode.c > @@ -863,9 +863,6 @@ int ext4_dio_get_block(struct inode *inode, sector_t iblock, > { > /* We don't expect handle for direct IO */ > WARN_ON_ONCE(ext4_journal_current_handle()); > - > - if (!create) > - return _ext4_get_block(inode, iblock, bh, 0); > return ext4_get_block_trans(inode, iblock, bh, EXT4_GET_BLOCKS_CREATE); > } > > @@ -3855,30 +3852,6 @@ static ssize_t ext4_direct_IO_write(struct kiocb *iocb, struct iov_iter *iter) > return ret; > } > > -static ssize_t ext4_direct_IO_read(struct kiocb *iocb, struct iov_iter *iter) > -{ > - struct address_space *mapping = iocb->ki_filp->f_mapping; > - struct inode *inode = mapping->host; > - size_t count = iov_iter_count(iter); > - ssize_t ret; > - > - /* > - * Shared inode_lock is enough for us - it protects against concurrent > - * writes & truncates and since we take care of writing back page cache, > - * we are protected against page writeback as well. > - */ > - inode_lock_shared(inode); > - ret = filemap_write_and_wait_range(mapping, iocb->ki_pos, > - iocb->ki_pos + count - 1); > - if (ret) > - goto out_unlock; > - ret = __blockdev_direct_IO(iocb, inode, inode->i_sb->s_bdev, > - iter, ext4_dio_get_block, NULL, NULL, 0); > -out_unlock: > - inode_unlock_shared(inode); > - return ret; > -} > - > static ssize_t ext4_direct_IO(struct kiocb *iocb, struct iov_iter *iter) > { > struct file *file = iocb->ki_filp; > @@ -3905,10 +3878,7 @@ static ssize_t ext4_direct_IO(struct kiocb *iocb, struct iov_iter *iter) > return 0; > > trace_ext4_direct_IO_enter(inode, offset, count, iov_iter_rw(iter)); > - if (iov_iter_rw(iter) == READ) > - ret = ext4_direct_IO_read(iocb, iter); > - else > - ret = ext4_direct_IO_write(iocb, iter); > + ret = ext4_direct_IO_write(iocb, iter); > trace_ext4_direct_IO_exit(inode, offset, count, iov_iter_rw(iter), ret); > return ret; > } >