linux-kernel - Re: [PATCH 3/7] fsdax: Copy data before write

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Date:   Tue, 9 Feb 2021 09:53:10 +0800
From:   Ruan Shiyang <ruansy.fnst@...fujitsu.com>
To:     Christoph Hellwig <hch@....de>
CC:     <linux-kernel@...r.kernel.org>, <linux-xfs@...r.kernel.org>,
        <linux-nvdimm@...ts.01.org>, <linux-fsdevel@...r.kernel.org>,
        <darrick.wong@...cle.com>, <dan.j.williams@...el.com>,
        <willy@...radead.org>, <jack@...e.cz>, <viro@...iv.linux.org.uk>,
        <linux-btrfs@...r.kernel.org>, <ocfs2-devel@....oracle.com>,
        <david@...morbit.com>, <rgoldwyn@...e.de>
Subject: Re: [PATCH 3/7] fsdax: Copy data before write



On 2021/2/8 下午11:14, Christoph Hellwig wrote:
>>   	switch (iomap.type) {
>>   	case IOMAP_MAPPED:
>> +cow:
>>   		if (iomap.flags & IOMAP_F_NEW) {
>>   			count_vm_event(PGMAJFAULT);
>>   			count_memcg_event_mm(vma->vm_mm, PGMAJFAULT);
>>   			major = VM_FAULT_MAJOR;
>>   		}
>>   		error = dax_iomap_direct_access(&iomap, pos, PAGE_SIZE,
>> -						NULL, &pfn);
>> +						&kaddr, &pfn);
> 
> Any chance you could look into factoring out this code into a helper
> to avoid the goto magic, which is a little too convoluted?
> 
>>   	switch (iomap.type) {
>>   	case IOMAP_MAPPED:
>> +cow:
>>   		error = dax_iomap_direct_access(&iomap, pos, PMD_SIZE,
>> -						NULL, &pfn);
>> +						&kaddr, &pfn);
>>   		if (error < 0)
>>   			goto finish_iomap;
>>   
>>   		entry = dax_insert_entry(&xas, mapping, vmf, entry, pfn,
>>   						DAX_PMD, write && !sync);
>>   
>> +		if (srcmap.type != IOMAP_HOLE) {
> 
> Same here.

Thanks for suggestion.  I'll try it.


--
Thanks,
Ruan Shiyang.
> 
>