From: Mike Snitzer <snitzer@redhat.com> To: Christoph Hellwig <hch@lst.de> Cc: linux-nvme@lists.infradead.org, Hannes Reinecke <hare@suse.de>, Keith Busch <keith.busch@intel.com>, Sagi Grimberg <sagi@grimberg.me>, axboe@kernel.dk, Martin Wilck <mwilck@suse.com>, lijie <lijie34@huawei.com>, xose.vazquez@gmail.com, chengjike.cheng@huawei.com, shenhong09@huawei.com, dm-devel@redhat.com, wangzhoumengjian@huawei.com, christophe.varoqui@opensvc.com, bmarzins@redhat.com, sschremm@netapp.com, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: nvme: allow ANA support to be independent of native multipathing Date: Fri, 16 Nov 2018 09:12:29 -0500 [thread overview] Message-ID: <20181116141229.GC28870@redhat.com> (raw) In-Reply-To: <20181116091458.GA17267@lst.de> On Fri, Nov 16 2018 at 4:14am -0500, Christoph Hellwig <hch@lst.de> wrote: > On Thu, Nov 15, 2018 at 12:46:05PM -0500, Mike Snitzer wrote: > > Whether or not ANA is present is a choice of the target implementation; > > the host (and whether it supports multipathing) has _zero_ influence on > > this. If the target declares a path as 'inaccessible' the path _is_ > > inaccessible to the host. As such, ANA support should be functional > > even if native multipathing is not. > > > > Introduce ability to always re-read ANA log page as required due to ANA > > error and make current ANA state available via sysfs -- even if native > > multipathing is disabled on the host (e.g. nvme_core.multipath=N). > > The first part I could see, but I still want to make it conditional > in some way as nvme is going into deeply embedded setups, and I don't > want to carry the weight of the ANA code around for everyone. So disabling CONFIG_NVME_MULTIPATH isn't adequate? You see a need for enabling CONFIG_NVME_MULTIPATH but disallowing consideration of ANA state management for these embedded cases? That doesn't make much sense in that ANA won't be enabled on the target, and if it is then shouldn't the NVMe host enable ANA support? > The second I fundamentally disagree with. And even if you found agreement > it would have to be in a separate patch as it is a separate feature. In a later mail you clarified that by "second" you meant the sysfs export. nvme_ns_id_attrs_are_visible() calls nvme_ctrl_use_ana() to know whether to export the ana state via sysfs. Makes no sense to enable ANA to work, independent of native multipathing, and then even though ANA is active disallow exporting the associated ANA state. We need consistency.. if the sysfs file exists it means ANA state is being managed. All I can figure is that what you're suggesting is born out of disallowing uses you fundamentally disagree with (e.g. multipath-tools reading the ANA state from this sysfs file). Mike
WARNING: multiple messages have this Message-ID (diff)
From: snitzer@redhat.com (Mike Snitzer) Subject: nvme: allow ANA support to be independent of native multipathing Date: Fri, 16 Nov 2018 09:12:29 -0500 [thread overview] Message-ID: <20181116141229.GC28870@redhat.com> (raw) In-Reply-To: <20181116091458.GA17267@lst.de> On Fri, Nov 16 2018 at 4:14am -0500, Christoph Hellwig <hch@lst.de> wrote: > On Thu, Nov 15, 2018@12:46:05PM -0500, Mike Snitzer wrote: > > Whether or not ANA is present is a choice of the target implementation; > > the host (and whether it supports multipathing) has _zero_ influence on > > this. If the target declares a path as 'inaccessible' the path _is_ > > inaccessible to the host. As such, ANA support should be functional > > even if native multipathing is not. > > > > Introduce ability to always re-read ANA log page as required due to ANA > > error and make current ANA state available via sysfs -- even if native > > multipathing is disabled on the host (e.g. nvme_core.multipath=N). > > The first part I could see, but I still want to make it conditional > in some way as nvme is going into deeply embedded setups, and I don't > want to carry the weight of the ANA code around for everyone. So disabling CONFIG_NVME_MULTIPATH isn't adequate? You see a need for enabling CONFIG_NVME_MULTIPATH but disallowing consideration of ANA state management for these embedded cases? That doesn't make much sense in that ANA won't be enabled on the target, and if it is then shouldn't the NVMe host enable ANA support? > The second I fundamentally disagree with. And even if you found agreement > it would have to be in a separate patch as it is a separate feature. In a later mail you clarified that by "second" you meant the sysfs export. nvme_ns_id_attrs_are_visible() calls nvme_ctrl_use_ana() to know whether to export the ana state via sysfs. Makes no sense to enable ANA to work, independent of native multipathing, and then even though ANA is active disallow exporting the associated ANA state. We need consistency.. if the sysfs file exists it means ANA state is being managed. All I can figure is that what you're suggesting is born out of disallowing uses you fundamentally disagree with (e.g. multipath-tools reading the ANA state from this sysfs file). Mike
next prev parent reply other threads:[~2018-11-16 14:12 UTC|newest] Thread overview: 63+ messages / expand[flat|nested] mbox.gz Atom feed top 2018-11-08 6:09 [PATCH] multipath-tools: add ANA support for NVMe device lijie 2018-11-12 16:23 ` Martin Wilck 2018-11-12 21:53 ` Mike Snitzer 2018-11-12 21:53 ` Mike Snitzer 2018-11-13 6:59 ` Martin Wilck 2018-11-13 6:59 ` Martin Wilck 2018-11-13 16:18 ` Keith Busch 2018-11-13 16:18 ` Keith Busch 2018-11-13 18:00 ` Mike Snitzer 2018-11-13 18:00 ` Mike Snitzer 2018-11-14 5:38 ` Mike Snitzer 2018-11-14 5:38 ` Mike Snitzer 2018-11-14 7:49 ` Hannes Reinecke 2018-11-14 7:49 ` Hannes Reinecke 2018-11-14 10:36 ` [dm-devel] " Martin Wilck 2018-11-14 10:36 ` Martin Wilck 2018-11-14 17:47 ` Mike Snitzer 2018-11-14 17:47 ` Mike Snitzer 2018-11-14 18:51 ` Hannes Reinecke 2018-11-14 18:51 ` Hannes Reinecke 2018-11-14 19:26 ` Mike Snitzer 2018-11-14 19:26 ` Mike Snitzer 2018-11-15 17:46 ` [PATCH] nvme: allow ANA support to be independent of native multipathing Mike Snitzer 2018-11-15 17:46 ` Mike Snitzer 2018-11-16 7:25 ` Hannes Reinecke 2018-11-16 7:25 ` Hannes Reinecke 2018-11-16 14:01 ` Mike Snitzer 2018-11-16 14:01 ` Mike Snitzer 2018-11-16 9:14 ` [PATCH] " Christoph Hellwig 2018-11-16 9:14 ` Christoph Hellwig 2018-11-16 9:40 ` Hannes Reinecke 2018-11-16 9:40 ` Hannes Reinecke 2018-11-16 9:49 ` Christoph Hellwig 2018-11-16 9:49 ` Christoph Hellwig 2018-11-16 10:06 ` Hannes Reinecke 2018-11-16 10:06 ` Hannes Reinecke 2018-11-16 10:17 ` Christoph Hellwig 2018-11-16 10:17 ` Christoph Hellwig 2018-11-16 19:28 ` Mike Snitzer 2018-11-16 19:28 ` Mike Snitzer 2018-11-16 19:34 ` Laurence Oberman 2018-11-16 19:34 ` Laurence Oberman 2018-11-19 9:39 ` Christoph Hellwig 2018-11-19 9:39 ` Christoph Hellwig 2018-11-19 14:56 ` Mike Snitzer 2018-11-19 14:56 ` Mike Snitzer 2018-11-19 14:56 ` Mike Snitzer 2018-11-20 9:42 ` Christoph Hellwig 2018-11-20 9:42 ` Christoph Hellwig 2018-11-20 13:37 ` Mike Snitzer 2018-11-20 13:37 ` Mike Snitzer 2018-11-20 16:23 ` Christoph Hellwig 2018-11-20 16:23 ` Christoph Hellwig 2018-11-16 14:12 ` Mike Snitzer [this message] 2018-11-16 14:12 ` Mike Snitzer 2018-11-16 18:59 ` [PATCH v2] " Mike Snitzer 2018-11-16 18:59 ` Mike Snitzer 2018-11-14 7:24 ` multipath-tools: add ANA support for NVMe device Hannes Reinecke 2018-11-14 7:24 ` Hannes Reinecke 2018-11-14 15:35 ` Christoph Hellwig 2018-11-14 15:35 ` Christoph Hellwig 2018-11-14 16:16 ` Mike Snitzer 2018-11-14 16:16 ` Mike Snitzer
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