linux-kernel - Re: [RFC v1 0/6] block: add error handling for *add

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Message-ID: <20200509034312.GH11244@42.do-not-panic.com>
Date:   Sat, 9 May 2020 03:43:12 +0000
From:   Luis Chamberlain <mcgrof@...nel.org>
To:     Bart Van Assche <bvanassche@....org>
Cc:     axboe@...nel.dk, ming.lei@...hat.com, yukuai3@...wei.com,
        linux-block@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [RFC v1 0/6] block: add error handling for *add_disk*()

On Tue, May 05, 2020 at 06:18:22PM -0700, Bart Van Assche wrote:
> On 2020-04-29 00:48, Luis Chamberlain wrote:
> > While working on some blktrace races I noticed that we don't do
> > error handling on *add_disk*() and friends. This is my initial
> > work on that.
> > 
> > This is based on linux-next tag next-20200428, you can also get this
> > on my branch 20200428-block-fixes [0].
> > 
> > Let me know what you think.
> Hi Luis,
> 
> Thank you for having done this work.

My pleasure, I just made one minor change to this series, but that's
all so far. Note that break-blktrace run_0004.sh still yields:

debugfs: Directory 'loop0' with parent 'block' already present!

And so I suspect something else is up, this is even after. That's using
my latest:

https://git.kernel.org/pub/scm/linux/kernel/git/mcgrof/linux-next.git/log/?h=20200508-block-fixes

Some more eyebealls on that would be useful.

> Since triggering error paths can be
> challenging, how about adding fault injection capabilities that make it
> possible to trigger all modified error paths and how about adding
> blktests that trigger these paths? That is the strategy that I followed
> myself recently to fix an error path in blk_mq_realloc_hw_ctxs().

Sure thing, but I get the impression that adding this may make it odd
to or harder to review. Shouldn't this be done after we have *some*
error handling? Right now we shouldn't regress as we never fail, and
that seemss worse.

Let me know, either way, I'll start work on it.

  Luis