nvdimm.lists.linux.dev archive mirror
 help / color / mirror / Atom feed
From: Christoph Hellwig <hch@lst.de>
To: Shiyang Ruan <ruansy.fnst@fujitsu.com>
Cc: linux-kernel@vger.kernel.org, linux-xfs@vger.kernel.org,
	nvdimm@lists.linux.dev, linux-mm@kvack.org,
	linux-fsdevel@vger.kernel.org, dm-devel@redhat.com,
	darrick.wong@oracle.com, dan.j.williams@intel.com,
	david@fromorbit.com, hch@lst.de, agk@redhat.com,
	snitzer@redhat.com, rgoldwyn@suse.de
Subject: Re: [PATCH v5 2/9] dax: Introduce holder for dax_device
Date: Mon, 19 Jul 2021 17:17:44 +0200	[thread overview]
Message-ID: <20210719151744.GA22718@lst.de> (raw)
In-Reply-To: <20210628000218.387833-3-ruansy.fnst@fujitsu.com>

On Mon, Jun 28, 2021 at 08:02:11AM +0800, Shiyang Ruan wrote:
> +int dax_holder_notify_failure(struct dax_device *dax_dev, loff_t offset,
> +			      size_t size, void *data)
> +{
> +	int rc = -ENXIO;
> +	if (!dax_dev)
> +		return rc;
> +
> +	if (dax_dev->holder_data) {
> +		rc = dax_dev->holder_ops->notify_failure(dax_dev, offset,
> +							 size, data);
> +		if (rc == -ENODEV)
> +			rc = -ENXIO;
> +	} else
> +		rc = -EOPNOTSUPP;

The style looks a little odd.  Why not:

	if (!dax_dev)
		return -ENXIO
	if (!dax_dev->holder_data)
		return -EOPNOTSUPP;
	return dax_dev->holder_ops->notify_failure(dax_dev, offset, size, data);

and let everyone deal with the same errno codes?

Also why do we even need the dax_dev NULL check?

> +void dax_set_holder(struct dax_device *dax_dev, void *holder,
> +		const struct dax_holder_operations *ops)
> +{
> +	if (!dax_dev)
> +		return;

I don't think we really need that check here.

> +void *dax_get_holder(struct dax_device *dax_dev)
> +{
> +	void *holder_data;
> +
> +	if (!dax_dev)
> +		return NULL;

Same here.

> +
> +	down_read(&dax_dev->holder_rwsem);
> +	holder_data = dax_dev->holder_data;
> +	up_read(&dax_dev->holder_rwsem);
> +
> +	return holder_data;

That lock won't protect anything.  I think we simply must have
synchronization to prevent unregistration while the ->notify_failure
call is in progress.

  reply	other threads:[~2021-07-19 15:28 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-28  0:02 [PATCH v5 0/9] fsdax: introduce fs query to support reflink Shiyang Ruan
2021-06-28  0:02 ` [PATCH v5 1/9] pagemap: Introduce ->memory_failure() Shiyang Ruan
2021-06-28  0:02 ` [PATCH v5 2/9] dax: Introduce holder for dax_device Shiyang Ruan
2021-07-19 15:17   ` Christoph Hellwig [this message]
2021-07-20 10:37     ` ruansy.fnst
2021-06-28  0:02 ` [PATCH v5 3/9] mm: factor helpers for memory_failure_dev_pagemap Shiyang Ruan
2021-06-28  0:02 ` [PATCH v5 4/9] pmem,mm: Implement ->memory_failure in pmem driver Shiyang Ruan
2021-06-28  0:02 ` [PATCH v5 5/9] mm: Introduce mf_dax_kill_procs() for fsdax case Shiyang Ruan
2021-06-28  3:23   ` kernel test robot
2021-06-28 11:49   ` Matthew Wilcox
2021-06-29  7:49     ` ruansy.fnst
2021-06-29 11:46       ` Matthew Wilcox
2021-07-16  6:32         ` ruansy.fnst
2021-06-28  0:02 ` [PATCH v5 6/9] xfs: Implement ->corrupted_range() for XFS Shiyang Ruan
2021-06-28  2:02   ` kernel test robot
2021-06-28  3:05   ` kernel test robot
2021-06-28  0:02 ` [PATCH v5 7/9] dm: Introduce ->rmap() to find bdev offset Shiyang Ruan
2021-06-28  0:02 ` [PATCH v5 8/9] md: Implement dax_holder_operations Shiyang Ruan
2021-06-28  0:02 ` [PATCH v5 9/9] fs/dax: Remove useless functions Shiyang Ruan
2021-07-19 15:18   ` Christoph Hellwig

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20210719151744.GA22718@lst.de \
    --to=hch@lst.de \
    --cc=agk@redhat.com \
    --cc=dan.j.williams@intel.com \
    --cc=darrick.wong@oracle.com \
    --cc=david@fromorbit.com \
    --cc=dm-devel@redhat.com \
    --cc=linux-fsdevel@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=linux-xfs@vger.kernel.org \
    --cc=nvdimm@lists.linux.dev \
    --cc=rgoldwyn@suse.de \
    --cc=ruansy.fnst@fujitsu.com \
    --cc=snitzer@redhat.com \
    --subject='Re: [PATCH v5 2/9] dax: Introduce holder for dax_device' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
on how to clone and mirror all data and code used for this inbox