linux-kernel - Re: [PATCH v9 1/8] fsdax: Output address in dax_iomap

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Date:   Thu, 16 Sep 2021 09:36:25 +0800
From:   Shiyang Ruan <ruansy.fnst@...itsu.com>
To:     "Darrick J. Wong" <djwong@...nel.org>
CC:     <hch@....de>, <linux-xfs@...r.kernel.org>,
        <dan.j.williams@...el.com>, <david@...morbit.com>,
        <linux-fsdevel@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <nvdimm@...ts.linux.dev>, <rgoldwyn@...e.de>,
        <viro@...iv.linux.org.uk>, <willy@...radead.org>,
        Ritesh Harjani <riteshh@...ux.ibm.com>
Subject: Re: [PATCH v9 1/8] fsdax: Output address in dax_iomap_pfn() and
 rename it



On 2021/9/16 8:09, Darrick J. Wong wrote:
> On Wed, Sep 15, 2021 at 06:44:54PM +0800, Shiyang Ruan wrote:
>> Add address output in dax_iomap_pfn() in order to perform a memcpy() in
>> CoW case.  Since this function both output address and pfn, rename it to
>> dax_iomap_direct_access().
>>
>> Signed-off-by: Shiyang Ruan <ruansy.fnst@...itsu.com>
>> Reviewed-by: Christoph Hellwig <hch@....de>
>> Reviewed-by: Ritesh Harjani <riteshh@...ux.ibm.com>
>> Reviewed-by: Dan Williams <dan.j.williams@...el.com>
> 
> Could've sworn I reviewed this a few revisions ago...

Oh, sorry, Maybe I missed that.

> Reviewed-by: Darrick J. Wong <djwong@...nel.org>

Thanks!

--
Ruan

> 
> --D
> 
>> ---
>>   fs/dax.c | 16 ++++++++++++----
>>   1 file changed, 12 insertions(+), 4 deletions(-)
>>
>> diff --git a/fs/dax.c b/fs/dax.c
>> index 4e3e5a283a91..8b482a58acae 100644
>> --- a/fs/dax.c
>> +++ b/fs/dax.c
>> @@ -1010,8 +1010,8 @@ static sector_t dax_iomap_sector(const struct iomap *iomap, loff_t pos)
>>   	return (iomap->addr + (pos & PAGE_MASK) - iomap->offset) >> 9;
>>   }
>>   
>> -static int dax_iomap_pfn(const struct iomap *iomap, loff_t pos, size_t size,
>> -			 pfn_t *pfnp)
>> +static int dax_iomap_direct_access(const struct iomap *iomap, loff_t pos,
>> +		size_t size, void **kaddr, pfn_t *pfnp)
>>   {
>>   	const sector_t sector = dax_iomap_sector(iomap, pos);
>>   	pgoff_t pgoff;
>> @@ -1023,11 +1023,13 @@ static int dax_iomap_pfn(const struct iomap *iomap, loff_t pos, size_t size,
>>   		return rc;
>>   	id = dax_read_lock();
>>   	length = dax_direct_access(iomap->dax_dev, pgoff, PHYS_PFN(size),
>> -				   NULL, pfnp);
>> +				   kaddr, pfnp);
>>   	if (length < 0) {
>>   		rc = length;
>>   		goto out;
>>   	}
>> +	if (!pfnp)
>> +		goto out_check_addr;
>>   	rc = -EINVAL;
>>   	if (PFN_PHYS(length) < size)
>>   		goto out;
>> @@ -1037,6 +1039,12 @@ static int dax_iomap_pfn(const struct iomap *iomap, loff_t pos, size_t size,
>>   	if (length > 1 && !pfn_t_devmap(*pfnp))
>>   		goto out;
>>   	rc = 0;
>> +
>> +out_check_addr:
>> +	if (!kaddr)
>> +		goto out;
>> +	if (!*kaddr)
>> +		rc = -EFAULT;
>>   out:
>>   	dax_read_unlock(id);
>>   	return rc;
>> @@ -1401,7 +1409,7 @@ static vm_fault_t dax_fault_iter(struct vm_fault *vmf,
>>   		return pmd ? VM_FAULT_FALLBACK : VM_FAULT_SIGBUS;
>>   	}
>>   
>> -	err = dax_iomap_pfn(&iter->iomap, pos, size, &pfn);
>> +	err = dax_iomap_direct_access(&iter->iomap, pos, size, NULL, &pfn);
>>   	if (err)
>>   		return pmd ? VM_FAULT_FALLBACK : dax_fault_return(err);
>>   
>> -- 
>> 2.33.0
>>
>>
>>