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.
next prev parent 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
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