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=-15.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable 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 AEF73C64E75 for ; Wed, 25 Nov 2020 12:29:57 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 158A9206E5 for ; Wed, 25 Nov 2020 12:29:56 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 158A9206E5 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.cz Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 2DCD66B0071; Wed, 25 Nov 2020 07:29:56 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 265B36B0072; Wed, 25 Nov 2020 07:29:56 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 154DF6B0075; Wed, 25 Nov 2020 07:29:56 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0213.hostedemail.com [216.40.44.213]) by kanga.kvack.org (Postfix) with ESMTP id F06656B0071 for ; Wed, 25 Nov 2020 07:29:55 -0500 (EST) Received: from smtpin25.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id B4399181AEF32 for ; Wed, 25 Nov 2020 12:29:55 +0000 (UTC) X-FDA: 77522872350.25.verse87_3f00c3b27376 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin25.hostedemail.com (Postfix) with ESMTP id 8ACF61804E3A0 for ; Wed, 25 Nov 2020 12:29:55 +0000 (UTC) X-HE-Tag: verse87_3f00c3b27376 X-Filterd-Recvd-Size: 4657 Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by imf03.hostedemail.com (Postfix) with ESMTP for ; Wed, 25 Nov 2020 12:29:54 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id BF41AACBD; Wed, 25 Nov 2020 12:29:53 +0000 (UTC) Received: by quack2.suse.cz (Postfix, from userid 1000) id 416E21E130F; Wed, 25 Nov 2020 13:29:53 +0100 (CET) Date: Wed, 25 Nov 2020 13:29:53 +0100 From: Jan Kara To: Christoph Hellwig Cc: Jens Axboe , Tejun Heo , Josef Bacik , Konrad Rzeszutek Wilk , Coly Li , Mike Snitzer , Greg Kroah-Hartman , Jan Kara , Johannes Thumshirn , dm-devel@redhat.com, Richard Weinberger , Jan Kara , linux-block@vger.kernel.org, xen-devel@lists.xenproject.org, linux-bcache@vger.kernel.org, linux-mtd@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH 04/45] fs: simplify freeze_bdev/thaw_bdev Message-ID: <20201125122953.GH16944@quack2.suse.cz> References: <20201124132751.3747337-1-hch@lst.de> <20201124132751.3747337-5-hch@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201124132751.3747337-5-hch@lst.de> User-Agent: Mutt/1.10.1 (2018-07-13) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue 24-11-20 14:27:10, Christoph Hellwig wrote: > Store the frozen superblock in struct block_device to avoid the awkward > interface that can return a sb only used a cookie, an ERR_PTR or NULL. > > Signed-off-by: Christoph Hellwig Some comments below... > diff --git a/fs/block_dev.c b/fs/block_dev.c > index d8664f5c1ff669..60492620d51866 100644 > --- a/fs/block_dev.c > +++ b/fs/block_dev.c > @@ -548,55 +548,47 @@ EXPORT_SYMBOL(fsync_bdev); > * count down in thaw_bdev(). When it becomes 0, thaw_bdev() will unfreeze > * actually. > */ > -struct super_block *freeze_bdev(struct block_device *bdev) > +int freeze_bdev(struct block_device *bdev) > { > struct super_block *sb; > int error = 0; > > mutex_lock(&bdev->bd_fsfreeze_mutex); > - if (++bdev->bd_fsfreeze_count > 1) { > - /* > - * We don't even need to grab a reference - the first call > - * to freeze_bdev grab an active reference and only the last > - * thaw_bdev drops it. > - */ > - sb = get_super(bdev); > - if (sb) > - drop_super(sb); > - mutex_unlock(&bdev->bd_fsfreeze_mutex); > - return sb; > - } > + if (++bdev->bd_fsfreeze_count > 1) > + goto done; > > sb = get_active_super(bdev); > if (!sb) > - goto out; > + goto sync; > if (sb->s_op->freeze_super) > error = sb->s_op->freeze_super(sb); > else > error = freeze_super(sb); > + deactivate_super(sb); > + > if (error) { > - deactivate_super(sb); > bdev->bd_fsfreeze_count--; > - mutex_unlock(&bdev->bd_fsfreeze_mutex); > - return ERR_PTR(error); > + goto done; > } > - deactivate_super(sb); > - out: > + bdev->bd_fsfreeze_sb = sb; > + > +sync: > sync_blockdev(bdev); > +done: > mutex_unlock(&bdev->bd_fsfreeze_mutex); > - return sb; /* thaw_bdev releases s->s_umount */ > + return error; /* thaw_bdev releases s->s_umount */ The comment about thaw_bdev() seems to be stale? At least I don't see what it's speaking about... > } > EXPORT_SYMBOL(freeze_bdev); > > /** > * thaw_bdev -- unlock filesystem > * @bdev: blockdevice to unlock > - * @sb: associated superblock > * > * Unlocks the filesystem and marks it writeable again after freeze_bdev(). > */ > -int thaw_bdev(struct block_device *bdev, struct super_block *sb) > +int thaw_bdev(struct block_device *bdev) > { > + struct super_block *sb; > int error = -EINVAL; > > mutex_lock(&bdev->bd_fsfreeze_mutex); > @@ -607,6 +599,7 @@ int thaw_bdev(struct block_device *bdev, struct super_block *sb) > if (--bdev->bd_fsfreeze_count > 0) > goto out; > > + sb = bdev->bd_fsfreeze_sb; > if (!sb) > goto out; > > @@ -618,7 +611,7 @@ int thaw_bdev(struct block_device *bdev, struct super_block *sb) > bdev->bd_fsfreeze_count++; > out: > mutex_unlock(&bdev->bd_fsfreeze_mutex); > - return error; > + return 0; But we now won't return -EINVAL if this gets called e.g. with bd_fsfreeze_count == 0, right? Honza -- Jan Kara SUSE Labs, CR