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=-2.2 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no 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 B7C2CC432C2 for ; Tue, 24 Sep 2019 09:50:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8E8A820872 for ; Tue, 24 Sep 2019 09:50:53 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=mbobrowski-org.20150623.gappssmtp.com header.i=@mbobrowski-org.20150623.gappssmtp.com header.b="xmqgf7fI" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2395409AbfIXJuw (ORCPT ); Tue, 24 Sep 2019 05:50:52 -0400 Received: from mail-pg1-f196.google.com ([209.85.215.196]:35516 "EHLO mail-pg1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2392592AbfIXJuw (ORCPT ); Tue, 24 Sep 2019 05:50:52 -0400 Received: by mail-pg1-f196.google.com with SMTP id a24so1032154pgj.2 for ; Tue, 24 Sep 2019 02:50:51 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=mbobrowski-org.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=KP3ygMAQcqcQDcZ3quRP4RvDD/ax05m9chGvKN8GjEQ=; b=xmqgf7fILmOdgiQ9igMqtMEnqctaqr/9aMHQ0wp7vIdNvUKJVnxoaozQFyzLJyw1tC uwcCaSZQfISmursWWKqtlUZ6o7ZmN7y9vixTVfvPfXLKCMvSLAVKc108vGf/lTQwNNvG QRI0X4bsg4kwsbQdWhpViXa9soQBVpLOPHK1TIwJqbmhAxqS8Bsu41qTkpIpiS9PrGv5 KCo/2liK3fZIjG97bK1VELtR/90yzELlKDwO1lBNDC/0bzP7JPKtMuSOFTYxxXXU7ifI z7LMmBk/dMslzXnDZQ9XqdBuIZHesjCAvH1kj2lHRt8bLjKMaeh8RpbTNs2CRUdaxYRH HjpQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=KP3ygMAQcqcQDcZ3quRP4RvDD/ax05m9chGvKN8GjEQ=; b=KLRhH8SKvCyX+1EkpHU9QIBVG61QPEURly5wu3hJ2bm/nPyYm105KZ4wKtsmYZjK2l m+NazRvJHvD2Pp6yQ+41EcvY/SOLSR7DbjfaxR+SVzIIEObBWpM+u4ttO7XrKyAiNhNU EFJBaRIDzgmrUQ5YhZFoxubxJoSZWFe1x0c2gIfzcR4rSOjUeaTZPGbjUzbTF0nopa4z wkZhMCQ0mG5oKgsc40+6KGUyofMCKR0zKL6eLGGa2Va97E92EGNWZlAQXPMKyF+91YK0 9jDbSUmdDkw4LWk7b0X443unRqVSKgHSEhCZOw663PSJ7r0ZesloDIr/5bpee/mri85g s7cQ== X-Gm-Message-State: APjAAAXD1rWhIQ3p4gTO45urv/xuYeCsJIspNZizF6DqT4nMnR8ga7st eAIoS5HWKRH7TLiV1TSqj+cb X-Google-Smtp-Source: APXvYqwya17V2dVgrStvbblc/AFj+boI86h/Bo1/1YRsbCxn+e4U1i0ffv7gJVc9fmQGnnMt12euNA== X-Received: by 2002:a62:7883:: with SMTP id t125mr2426174pfc.204.1569318651092; Tue, 24 Sep 2019 02:50:51 -0700 (PDT) Received: from bobrowski ([110.232.114.101]) by smtp.gmail.com with ESMTPSA id q13sm4952434pjq.0.2019.09.24.02.50.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 24 Sep 2019 02:50:50 -0700 (PDT) Date: Tue, 24 Sep 2019 19:50:44 +1000 From: Matthew Bobrowski To: Jan Kara Cc: tytso@mit.edu, adilger.kernel@dilger.ca, linux-ext4@vger.kernel.org, linux-fsdevel@vger.kernel.org, david@fromorbit.com, hch@infradead.org, darrick.wong@oracle.com Subject: Re: [PATCH v3 2/6] ext4: move inode extension/truncate code out from ext4_iomap_end() Message-ID: <20190924095044.GB17526@bobrowski> References: <784214745d589dd2bdcde2d69a69e837e6980592.1568282664.git.mbobrowski@mbobrowski.org> <20190923162115.GG20367@quack2.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190923162115.GG20367@quack2.suse.cz> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Mon, Sep 23, 2019 at 06:21:15PM +0200, Jan Kara wrote: > On Thu 12-09-19 21:04:00, Matthew Bobrowski wrote: > > @@ -233,12 +234,90 @@ static ssize_t ext4_write_checks(struct kiocb *iocb, struct iov_iter *from) > > return iov_iter_count(from); > > } > > > > +static int ext4_handle_inode_extension(struct inode *inode, loff_t offset, > > + ssize_t len, size_t count) > > Traditionally, we call one of the length arguments 'copied' or 'written' to > denote actual amount of data processed and the original length is called > 'len' or 'length' in iomap code. Can you please rename the arguments to > follow this convention? Sure, I will go with 'written'. > > +/* > > + * The inode may have been placed onto the orphan list or has had > > + * blocks allocated beyond EOF as a result of an extension. We need to > > + * ensure that any necessary cleanup routines are performed if the > > + * error path has been taken for a write. > > + */ > > +static int ext4_handle_failed_inode_extension(struct inode *inode, loff_t size) > > +{ > > + handle_t *handle; > > + > > + if (size > i_size_read(inode)) > > + ext4_truncate_failed_write(inode); > > + > > + if (!list_empty(&EXT4_I(inode)->i_orphan)) { > > + handle = ext4_journal_start(inode, EXT4_HT_INODE, 2); > > + if (IS_ERR(handle)) { > > + if (inode->i_nlink) > > + ext4_orphan_del(NULL, inode); > > + return PTR_ERR(handle); > > + } > > + if (inode->i_nlink) > > + ext4_orphan_del(handle, inode); > > + ext4_journal_stop(handle); > > + } > > + return 0; > > +} > > + > > After some thought, I'd just drop this function and fold the functionality > into ext4_handle_inode_extension() by making it accept negative 'len' > argument indicating error. The code just happens to be the simplest in that > case (see below). > > > @@ -255,7 +334,18 @@ ext4_dax_write_iter(struct kiocb *iocb, struct iov_iter *from) > > if (ret) > > goto out; > > > > + offset = iocb->ki_pos; > > ret = dax_iomap_rw(iocb, from, &ext4_iomap_ops); > > + if (ret > 0 && iocb->ki_pos > i_size_read(inode)) > > + error = ext4_handle_inode_extension(inode, offset, ret, > > + iov_iter_count(from)); > > You need to sample iov_iter_count(from) before calling dax_iomap_rw(). At > this point iov_iter_count(from) is just what's left in the iter after > writing what we could. > > Also I don't think the condition iocb->ki_pos > i_size_read(inode) is > correct here. Because it may happen that offset + count > i_size so we > allocate some blocks beyond i_size but then we manage to copy only less so > offset + ret == iocb->ki_pos <= i_size and you will not call > ext4_handle_inode_extension() to truncate allocated blocks beyond i_size. Yeah, this makes sense. I will implement it this way. Once again, appreciate your suggestions. > So I'd just call ext4_handle_inode_extension() unconditionally like: > > error = ext4_handle_inode_extension(inode, offset, ret, len); > > and have a quick check at the beginning of that function to avoid starting > transaction when there isn't anything to do. Something like: > > /* > * DIO and DAX writes get exclusion from truncate (i_rwsem) and > * page writeback (i_rwsem and flushing all dirty pages). > */ > WARN_ON_ONCE(i_size_read(inode) != EXT4_I(inode)->i_disksize); > if (offset + count <= i_size_read(inode)) > return 0; > if (len < 0) > goto truncate; > > ... do the heavylifting with transaction start, inode size update, > and orphan handling... > > if (truncate) { > truncate: > ext4_truncate_failed_write(inode); > orphan_del: > /* > * If the truncate operation failed early the inode > * may still be on the orphan list. In that case, we > * need try remove the inode from the linked list in > * memory. > */ > if (inode->i_nlink) > ext4_orphan_del(NULL, inode); > } ----