Re: [PATCH] fs/vboxsf: Replace kmap() with kmap_local_{page, folio}()

[Hans de Goede]

Hi Matthew,

On 6/27/23 19:48, Matthew Wilcox wrote:
> On Tue, Jun 27, 2023 at 06:51:15AM -0700, Sumitra Sharma wrote:
>> +++ b/fs/vboxsf/file.c
>> @@ -234,7 +234,7 @@ static int vboxsf_read_folio(struct file *file, struct folio *folio)
>>  	u8 *buf;
>>  	int err;
>>  
>> -	buf = kmap(page);
>> +	buf = kmap_local_folio(folio, off);
> 
> Did you test this?  'off' is the offset in the _file_.  Whereas
> kmap_local_folio() takes the offset within the _folio_.  They have
> different types (loff_t vs size_t) to warn you that they're different
> things.


Ah yes you are completely right, off is the offset in the file
and buf should point to the *start* of a mapping of the page.

Regards,

Hans