Re: [PATCH v14 062/138] mm/migrate: Add folio_migrate_copy()

[Matthew Wilcox]

On Thu, Aug 12, 2021 at 01:56:24PM +0200, Vlastimil Babka wrote:
> On 7/15/21 5:35 AM, Matthew Wilcox (Oracle) wrote:
> > This is the folio equivalent of migrate_page_copy(), which is retained
> > as a wrapper for filesystems which are not yet converted to folios.
> > Also convert copy_huge_page() to folio_copy().
> > 
> > Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
> 
> Acked-by: Vlastimil Babka <vbabka@xxxxxxx>
> 
> The way folio_copy() avoids cond_resched() for single page would IMHO deserve a
> comment though, so it's not buried only in this thread.

I think folio_copy() deserves kernel-doc.

/**
 * folio_copy - Copy the contents of one folio to another.
 * @dst: Folio to copy to.
 * @src: Folio to copy from.
 *
 * The bytes in the folio represented by @src are copied to @dst.
 * Assumes the caller has validated that @dst is at least as large as @src.
 * Can be called in atomic context for order-0 folios, but if the folio is
 * larger, it may sleep.
 */