linux-kernel - Re: [PATCH v6 5/6] pmem: refactor pmem_clear

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Date:   Tue, 22 Mar 2022 01:53:03 -0700
From:   Christoph Hellwig <hch@...radead.org>
To:     Jane Chu <jane.chu@...cle.com>
Cc:     david@...morbit.com, djwong@...nel.org, dan.j.williams@...el.com,
        hch@...radead.org, vishal.l.verma@...el.com, dave.jiang@...el.com,
        agk@...hat.com, snitzer@...hat.com, dm-devel@...hat.com,
        ira.weiny@...el.com, willy@...radead.org, vgoyal@...hat.com,
        linux-fsdevel@...r.kernel.org, nvdimm@...ts.linux.dev,
        linux-kernel@...r.kernel.org, linux-xfs@...r.kernel.org
Subject: Re: [PATCH v6 5/6] pmem: refactor pmem_clear_poison()

> -static void hwpoison_clear(struct pmem_device *pmem,
> -		phys_addr_t phys, unsigned int len)
> +static phys_addr_t to_phys(struct pmem_device *pmem, phys_addr_t offset)
>  {
> +	return pmem->phys_addr + offset;
> +}
> +
> +static sector_t to_sect(struct pmem_device *pmem, phys_addr_t offset)
> +{
> +	return (offset - pmem->data_offset) / 512;
> +}
> +
> +static phys_addr_t to_offset(struct pmem_device *pmem, sector_t sector)
> +{
> +	return sector * 512 + pmem->data_offset;
> +}

The multiplicate / divison using 512 could use shifts using
SECTOR_SHIFT.

> +
> +static void clear_hwpoison(struct pmem_device *pmem, phys_addr_t offset,
> +		unsigned int len)

> +static void clear_bb(struct pmem_device *pmem, sector_t sector, long blks)

All these functions lack a pmem_ prefix.

> +static blk_status_t __pmem_clear_poison(struct pmem_device *pmem,
> +		phys_addr_t offset, unsigned int len,
> +		unsigned int *blks)
> +{
> +	phys_addr_t phys = to_phys(pmem, offset);
>  	long cleared;
> +	blk_status_t rc;
>  
> +	cleared = nvdimm_clear_poison(to_dev(pmem), phys, len);
> +	*blks = cleared / 512;
> +	rc = (cleared < len) ? BLK_STS_IOERR : BLK_STS_OK;
> +	if (cleared <= 0 || *blks == 0)
> +		return rc;

This look odd.  I think just returing the cleared byte value would
make much more sense:

static long __pmem_clear_poison(struct pmem_device *pmem,
		phys_addr_t offset, unsigned int len)
{
	long cleared = nvdimm_clear_poison(to_dev(pmem), phys, len);

	if (cleared > 0) {
		clear_hwpoison(pmem, offset, cleared);
		arch_invalidate_pmem(pmem->virt_addr + offset, len);
	}

	return cleared;
}