Re: [PATCH v5 02/25] fs/dax: Return unmapped busy pages from dax_layout_busy_page_range()

[Dan Williams]

Alistair Popple wrote:
> dax_layout_busy_page_range() is used by file systems to scan the DAX
> page-cache to unmap mapping pages from user-space and to determine if
> any pages in the given range are busy, either due to ongoing DMA or
> other get_user_pages() usage.
> 
> Currently it checks to see the file mapping is mapped into user-space
> with mapping_mapped() and returns early if not, skipping the check for
> DMA busy pages. This is wrong as pages may still be undergoing DMA
> access even if they have subsequently been unmapped from
> user-space. Fix this by dropping the check for mapping_mapped().
> 
> Signed-off-by: Alistair Popple <apopple@xxxxxxxxxx>
> Suggested-by: Dan Williams <dan.j.williams@xxxxxxxxx>

Reviewed-by: Dan Williams <dan.j.williams@xxxxxxxxx>