From: Christoph Hellwig <hch@infradead.org>
To: Vivek Goyal <vgoyal@redhat.com>
Cc: linux-fsdevel@vger.kernel.org, linux-nvdimm@lists.01.org,
hch@infradead.org, dm-devel@redhat.com
Subject: Re: [PATCH 1/5] dax, pmem: Add a dax operation zero_page_range
Date: Wed, 5 Feb 2020 10:30:50 -0800 [thread overview]
Message-ID: <20200205183050.GA26711@infradead.org> (raw)
In-Reply-To: <20200203200029.4592-2-vgoyal@redhat.com>
> + /*
> + * There are no users as of now. Once users are there, fix dm code
> + * to be able to split a long range across targets.
> + */
This comment confused me. I think this wants to say something like:
/*
* There are now callers that want to zero across a page boundary as of
* now. Once there are users this check can be removed after the
* device mapper code has been updated to split ranges across targets.
*/
> +static int pmem_dax_zero_page_range(struct dax_device *dax_dev, pgoff_t pgoff,
> + unsigned int offset, size_t len)
> +{
> + int rc = 0;
> + phys_addr_t phys_pos = pgoff * PAGE_SIZE + offset;
Any reason not to pass a phys_addr_t in the calling convention for the
method and maybe also for dax_zero_page_range itself?
> + sector_start = ALIGN(phys_pos, 512)/512;
> + sector_end = ALIGN_DOWN(phys_pos + bytes, 512)/512;
Missing whitespaces. Also this could use DIV_ROUND_UP and
DIV_ROUND_DOWN.
> + if (sector_end > sector_start)
> + nr_sectors = sector_end - sector_start;
> +
> + if (nr_sectors &&
> + unlikely(is_bad_pmem(&pmem->bb, sector_start,
> + nr_sectors * 512)))
> + bad_pmem = true;
How could nr_sectors be zero?
> + write_pmem(pmem_addr, page, 0, bytes);
> + if (unlikely(bad_pmem)) {
> + /*
> + * Pass block aligned offset and length. That seems
> + * to work as of now. Other finer grained alignment
> + * cases can be addressed later if need be.
> + */
> + rc = pmem_clear_poison(pmem, ALIGN(pmem_off, 512),
> + nr_sectors * 512);
> + write_pmem(pmem_addr, page, 0, bytes);
> + }
This code largerly duplicates the write side of pmem_do_bvec. I
think it might make sense to split pmem_do_bvec into a read and a write
side as a prep patch, and then reuse the write side here.
> +int generic_dax_zero_page_range(struct dax_device *dax_dev, pgoff_t pgoff,
> + unsigned int offset, size_t len);
This should probably go into a separare are of the header and have
comment about being a section for generic helpers for drivers.
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next prev parent reply other threads:[~2020-02-05 18:30 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-03 20:00 [RFC PATCH 0/5][V2] dax,pmem: Provide a dax operation to zero range of memory Vivek Goyal
2020-02-03 20:00 ` [PATCH 1/5] dax, pmem: Add a dax operation zero_page_range Vivek Goyal
2020-02-05 18:30 ` Christoph Hellwig [this message]
2020-02-05 20:02 ` Vivek Goyal
2020-02-06 0:40 ` Dan Williams
2020-02-06 7:41 ` Christoph Hellwig
2020-02-07 16:57 ` Dan Williams
2020-02-07 17:01 ` Vivek Goyal
2020-02-07 17:06 ` Dan Williams
2020-02-06 14:34 ` Vivek Goyal
2020-02-07 16:58 ` Dan Williams
2020-02-03 20:00 ` [PATCH 2/5] s390,dax: Add dax zero_page_range operation to dcssblk driver Vivek Goyal
2020-02-05 18:32 ` Christoph Hellwig
2020-02-05 20:04 ` Vivek Goyal
2020-02-03 20:00 ` [PATCH 3/5] dm,dax: Add dax zero_page_range operation Vivek Goyal
2020-02-05 18:33 ` Christoph Hellwig
2020-02-07 16:34 ` Vivek Goyal
2020-02-03 20:00 ` [PATCH 4/5] dax,iomap: Start using dax native zero_page_range() Vivek Goyal
2020-02-05 18:33 ` Christoph Hellwig
2020-02-05 20:10 ` Vivek Goyal
2020-02-07 15:31 ` Vivek Goyal
2020-02-03 20:00 ` [PATCH 5/5] dax,iomap: Add helper dax_iomap_zero() to zero a range Vivek Goyal
2020-02-04 5:17 ` kbuild test robot
2020-02-05 18:36 ` Christoph Hellwig
2020-02-05 20:15 ` Vivek Goyal
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