linux-kernel - Re: [PATCH 5/6] dax,pmem: Add data recovery feature to pmem_copy_to/from

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Date:   Fri, 22 Oct 2021 00:58:04 +0000
From:   Jane Chu <jane.chu@...cle.com>
To:     Christoph Hellwig <hch@...radead.org>
CC:     "david@...morbit.com" <david@...morbit.com>,
        "djwong@...nel.org" <djwong@...nel.org>,
        "dan.j.williams@...el.com" <dan.j.williams@...el.com>,
        "vishal.l.verma@...el.com" <vishal.l.verma@...el.com>,
        "dave.jiang@...el.com" <dave.jiang@...el.com>,
        "agk@...hat.com" <agk@...hat.com>,
        "snitzer@...hat.com" <snitzer@...hat.com>,
        "dm-devel@...hat.com" <dm-devel@...hat.com>,
        "ira.weiny@...el.com" <ira.weiny@...el.com>,
        "willy@...radead.org" <willy@...radead.org>,
        "vgoyal@...hat.com" <vgoyal@...hat.com>,
        "linux-fsdevel@...r.kernel.org" <linux-fsdevel@...r.kernel.org>,
        "nvdimm@...ts.linux.dev" <nvdimm@...ts.linux.dev>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-xfs@...r.kernel.org" <linux-xfs@...r.kernel.org>
Subject: Re: [PATCH 5/6] dax,pmem: Add data recovery feature to
 pmem_copy_to/from_iter()

On 10/21/2021 4:28 AM, Christoph Hellwig wrote:
>> +	if (flags & DAXDEV_F_RECOVERY) {
>> +		lead_off = (unsigned long)addr & ~PAGE_MASK;
>> +		len = PFN_PHYS(PFN_UP(lead_off + bytes));
>> +		if (is_bad_pmem(&pmem->bb, PFN_PHYS(pgoff) / 512, len)) {
>> +			if (lead_off || !(PAGE_ALIGNED(bytes))) {
>> +				dev_warn(dev, "Found poison, but addr(%p) and/or bytes(%#lx) not page aligned\n",
>> +					addr, bytes);
>> +				return (size_t) -EIO;
>> +			}
>> +			pmem_off = PFN_PHYS(pgoff) + pmem->data_offset;
>> +			if (pmem_clear_poison(pmem, pmem_off, bytes) !=
>> +					BLK_STS_OK)
>> +				return (size_t) -EIO;
>> +		}
> 
> Shouldn't this just go down in a separe ->clear_poison operation
> to make the whole thing a little easier to follow?
> 

Do you mean to lift or refactor the above to a helper function so as
to improve the readability of the code?  I can do that, just to confirm.
On the same note, would you prefer to refactor the read path as well?

thanks!
-jane