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From: Christoph Hellwig <hch@lst.de>
To: Sagi Grimberg <sagi@grimberg.me>
Cc: Chao Leng <lengchao@huawei.com>,
	linux-nvme@lists.infradead.org, linux-block@vger.kernel.org,
	kbusch@kernel.org, axboe@fb.com, hch@lst.de
Subject: Re: [PATCH 1/3] nvme-core: improve avoiding false remove namespace
Date: Thu, 20 Aug 2020 10:29:18 +0200	[thread overview]
Message-ID: <20200820082918.GA12926@lst.de> (raw)
In-Reply-To: <ead8ccd0-d89d-b47e-0a6f-22c976a3b3a6@grimberg.me>

On Wed, Aug 19, 2020 at 09:33:22PM -0700, Sagi Grimberg wrote:
> We really need to take a step back here, I really don't like how
> we are growing implicit assumptions on how statuses are interpreted.
>
> Why don't we remove the -ENODEV error propagation back and instead
> take care of it in the specific call-sites where we want to ignore
> errors with proper quirks?

So the one thing I'm not even sure about is if just ignoring the
errors was a good idea to start with.  They obviously are if we just
did a rescan and did run into an error while rescanning a namespace
that didn't change.  But what if it actually did change?

So I think a logic like in this patch kinda makes sense, but I think
we also need to retry and scan again on these kinds of errors.  Btw,
did you ever actually see -ENOMEM in practice?  With the small
allocations that we do it really should not happen normally, so
special casing for it always felt a little strange.

FYI, I've started rebasing various bits of work I've done to start
untangling the mess.  Here is my current WIP, which in this form
is completely untested:

http://git.infradead.org/users/hch/misc.git/shortlog/refs/heads/nvme-scanning-cleanup

WARNING: multiple messages have this Message-ID (diff)
From: Christoph Hellwig <hch@lst.de>
To: Sagi Grimberg <sagi@grimberg.me>
Cc: axboe@fb.com, linux-nvme@lists.infradead.org,
	linux-block@vger.kernel.org, Chao Leng <lengchao@huawei.com>,
	kbusch@kernel.org, hch@lst.de
Subject: Re: [PATCH 1/3] nvme-core: improve avoiding false remove namespace
Date: Thu, 20 Aug 2020 10:29:18 +0200	[thread overview]
Message-ID: <20200820082918.GA12926@lst.de> (raw)
In-Reply-To: <ead8ccd0-d89d-b47e-0a6f-22c976a3b3a6@grimberg.me>

On Wed, Aug 19, 2020 at 09:33:22PM -0700, Sagi Grimberg wrote:
> We really need to take a step back here, I really don't like how
> we are growing implicit assumptions on how statuses are interpreted.
>
> Why don't we remove the -ENODEV error propagation back and instead
> take care of it in the specific call-sites where we want to ignore
> errors with proper quirks?

So the one thing I'm not even sure about is if just ignoring the
errors was a good idea to start with.  They obviously are if we just
did a rescan and did run into an error while rescanning a namespace
that didn't change.  But what if it actually did change?

So I think a logic like in this patch kinda makes sense, but I think
we also need to retry and scan again on these kinds of errors.  Btw,
did you ever actually see -ENOMEM in practice?  With the small
allocations that we do it really should not happen normally, so
special casing for it always felt a little strange.

FYI, I've started rebasing various bits of work I've done to start
untangling the mess.  Here is my current WIP, which in this form
is completely untested:

http://git.infradead.org/users/hch/misc.git/shortlog/refs/heads/nvme-scanning-cleanup

_______________________________________________
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Linux-nvme@lists.infradead.org
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  parent reply	other threads:[~2020-08-20  8:29 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-08-20  3:53 [PATCH 1/3] nvme-core: improve avoiding false remove namespace Chao Leng
2020-08-20  3:53 ` Chao Leng
2020-08-20  4:33 ` Sagi Grimberg
2020-08-20  4:33   ` Sagi Grimberg
2020-08-20  6:22   ` Chao Leng
2020-08-20  6:22     ` Chao Leng
2020-08-20  8:29   ` Christoph Hellwig [this message]
2020-08-20  8:29     ` Christoph Hellwig
2020-08-20 15:44     ` Sagi Grimberg
2020-08-20 15:44       ` Sagi Grimberg
2020-08-21  1:36       ` Chao Leng
2020-08-21  1:36         ` Chao Leng
2020-08-21  6:25       ` Christoph Hellwig
2020-08-21  6:25         ` Christoph Hellwig
2020-08-21 20:23         ` Sagi Grimberg
2020-08-21 20:23           ` Sagi Grimberg

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