From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 76C44155749 for ; Wed, 15 May 2024 15:42:17 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1715787739; cv=none; b=gZySfurlfOmq0kElTeqOiU9sizlZaz0MO6ZocldY8K3Md7aHCF8uT8S2+qTdPz6fpSs1S7QBS/qYa7YEVNHNNEJ/RW8Tb/OP/U6CH17SFMYbR+82jwTv2/wFfK0ES8mDdXUuvQKE8/Cl1lFSMXTW6oiUWy25kHWyT1gH6Bj+ee8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1715787739; c=relaxed/simple; bh=/deTcq+w80Cb17xbYuE3uBl4Y02GhqRR0ENPYtWyjOI=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=a4wxt9GyeW2UAgxLOxr4ywHS5/WjnIQ5wOLcPnnL80UANfjSg2Nclx6/7kTYxL52mkRH+844kGs5jMDXsWVCcHOlCKBBSO0fy6joGx1SWHuCQ4HEvcAQV7pMXNiOxJYxtInSWkFcoKJGQ/Q4r8SDqoop5kHuNDkpDHwhdqphd9s= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=R/pnp8Ze; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="R/pnp8Ze" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1715787736; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=KDC9yVDJQXh1VBgH8zcKx1ck2Zow97M73RPc1/GvQ4U=; b=R/pnp8Zeyq+adzat/cco2i0vqQCWeWgF7cEtNGqjDiyqi+sbKFk/KnHpyazxSll6eXyAYP bvMijIaOgOU8bAlFEugwiR6M9RhXK1qrmcHMMNinol3pJ8hJzKk5NuX9utWOLsc+35IK56 2ESQ7vj470wrB1AWZu3JjcsvDja+SjI= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-524-ewEautHJMya3PrE8ptHmoQ-1; Wed, 15 May 2024 11:42:05 -0400 X-MC-Unique: ewEautHJMya3PrE8ptHmoQ-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.rdu2.redhat.com [10.11.54.5]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 7218E80118E; Wed, 15 May 2024 15:42:04 +0000 (UTC) Received: from bmarzins-01.fast.eng.rdu2.dc.redhat.com (bmarzins-01.fast.eng.rdu2.dc.redhat.com [10.6.23.12]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 6641028E2; Wed, 15 May 2024 15:42:04 +0000 (UTC) Received: from bmarzins-01.fast.eng.rdu2.dc.redhat.com (localhost [127.0.0.1]) by bmarzins-01.fast.eng.rdu2.dc.redhat.com (8.17.2/8.17.1) with ESMTPS id 44FFg4f3119750 (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384 bits=256 verify=NOT); Wed, 15 May 2024 11:42:04 -0400 Received: (from bmarzins@localhost) by bmarzins-01.fast.eng.rdu2.dc.redhat.com (8.17.2/8.17.2/Submit) id 44FFg4q7119749; Wed, 15 May 2024 11:42:04 -0400 Date: Wed, 15 May 2024 11:42:04 -0400 From: Benjamin Marzinski To: Yang Yang Cc: Alasdair Kergon , Mike Snitzer , Mikulas Patocka , dm-devel@lists.linux.dev, linux-kernel@vger.kernel.org Subject: Re: [PATCH 3/5] dm: support retrieving struct dm_target from struct dm_dev Message-ID: References: <20240514090445.2847-1-yang.yang@vivo.com> <20240514090445.2847-4-yang.yang@vivo.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240514090445.2847-4-yang.yang@vivo.com> X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.5 On Tue, May 14, 2024 at 05:04:42PM +0800, Yang Yang wrote: > Add a list to the struct dm_dev structure to store the associated > targets, while also allowing differentiation between different target > types. I still think this is more complex than it needs to be. If devices that support flush_pass_around can guarantee that: 1. They will send a flush bio to all of their table devices 2. They are fine with another target sending the flush bio to their table devices Then I don't see why we need the table devices to keep track of all the different target types that are using them. Am I missing something here? If we don't need to worry about sending a flush bio to a target of each type that is using a table device, then all we need to do is call __send_empty_flush_bios() for enough targets to cover all the table devices. This seems a lot easier to track. We just need another flag in dm_target, something like sends_pass_around_flush. When a target calls dm_get_device(), if it adds a new table device to t->devices, then it's the first target in this table to use that device. If flush_pass_around is set for this target, then it also sets sends_pass_around_flush. In __send_empty_flush() if the table has flush_pass_around set, when you iterate through the devices, you only call __send_empty_flush_bios() for the ones with sends_pass_around_flush set. Or am I overlooking something? -Ben > > Signed-off-by: Yang Yang > --- > drivers/md/dm-table.c | 36 +++++++++++++++++++++++++++++++++++ > include/linux/device-mapper.h | 3 +++ > 2 files changed, 39 insertions(+) > > diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c > index bd68af10afed..f6554590b7af 100644 > --- a/drivers/md/dm-table.c > +++ b/drivers/md/dm-table.c > @@ -741,6 +741,8 @@ int dm_table_add_target(struct dm_table *t, const char *type, > if (ti->flush_pass_around == 0) > t->flush_pass_around = 0; > > + INIT_LIST_HEAD(&ti->list); > + > return 0; > > bad: > @@ -2134,6 +2136,25 @@ void dm_table_postsuspend_targets(struct dm_table *t) > suspend_targets(t, POSTSUSPEND); > } > > +static int dm_link_dev_to_target(struct dm_target *ti, struct dm_dev *dev, > + sector_t start, sector_t len, void *data) > +{ > + struct list_head *targets = &dev->targets; > + struct dm_target *pti; > + > + if (!list_empty(targets)) { > + list_for_each_entry(pti, targets, list) { > + if (pti->type == ti->type) > + return 0; > + } > + } > + > + if (list_empty(&ti->list)) > + list_add_tail(&ti->list, targets); > + > + return 0; > +} > + > int dm_table_resume_targets(struct dm_table *t) > { > unsigned int i; > @@ -2162,6 +2183,21 @@ int dm_table_resume_targets(struct dm_table *t) > ti->type->resume(ti); > } > > + if (t->flush_pass_around) { > + struct list_head *devices = &t->devices; > + struct dm_dev_internal *dd; > + > + list_for_each_entry(dd, devices, list) > + INIT_LIST_HEAD(&dd->dm_dev->targets); > + > + for (i = 0; i < t->num_targets; i++) { > + struct dm_target *ti = dm_table_get_target(t, i); > + > + if (ti->type->iterate_devices) > + ti->type->iterate_devices(ti, dm_link_dev_to_target, NULL); > + } > + } > + > return 0; > } > > diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h > index 0893ff8c01b6..19e03f9b2589 100644 > --- a/include/linux/device-mapper.h > +++ b/include/linux/device-mapper.h > @@ -169,6 +169,7 @@ struct dm_dev { > struct dax_device *dax_dev; > blk_mode_t mode; > char name[16]; > + struct list_head targets; > }; > > /* > @@ -298,6 +299,8 @@ struct dm_target { > struct dm_table *table; > struct target_type *type; > > + struct list_head list; > + > /* target limits */ > sector_t begin; > sector_t len; > -- > 2.34.1 >