Re: [PATCH v3] fs: dax: Adding new return type vm_fault_t
From: Souptick Joarder
Date: Sat Apr 21 2018 - 17:54:55 EST
On Sun, Apr 22, 2018 at 3:04 AM, Matthew Wilcox <willy@xxxxxxxxxxxxx> wrote:
> On Sun, Apr 22, 2018 at 02:35:29AM +0530, Souptick Joarder wrote:
>> Use new return type vm_fault_t for fault handler. For
>> now, this is just documenting that the function returns
>> a VM_FAULT value rather than an errno. Once all instances
>> are converted, vm_fault_t will become a distinct type.
>>
>> commit 1c8f422059ae ("mm: change return type to vm_fault_t")
>>
>> There was an existing bug inside dax_load_hole()
>> if vm_insert_mixed had failed to allocate a page table,
>> we'd return VM_FAULT_NOPAGE instead of VM_FAULT_OOM.
>> With new vmf_insert_mixed() this issue is addressed.
>>
>> vm_insert_mixed_mkwrite has inefficiency when it returns
>> an error value, driver has to convert it to vm_fault_t
>> type. With new vmf_insert_mixed_mkwrite() this limitation
>> will be addressed.
>>
>> As new function vmf_insert_mixed_mkwrite() only called
>> from fs/dax.c, so keeping both the changes in a single
>> patch.
>>
>> Signed-off-by: Souptick Joarder <jrdr.linux@xxxxxxxxx>
>
> Reviewed-by: Matthew Wilcox <mawilcox@xxxxxxxxxxxxx>
>
> There's a couple of minor things which could be tidied up, but not worth
> doing them as a revision to this patch.
Which tree this patch will go through ? mm or fsdevel ?