Re: [PATCH v7 2/8] iov_iter: Add a function to extract a page list from an iterator

[David Howells]

David Hildenbrand <david@xxxxxxxxxx> wrote:

> How does this work align with the goal of no longer using FOLL_GET for
> O_DIRECT? We should get rid of any FOLL_GET usage for accessing page content.

Would that run the risk of changes being made by the child being visible to
the a DIO write if the parent changes the buffer first?


	PARENT			CHILD
	======			=====
	start-DIO-write
	fork() = pid		fork() = 0
	alter-buffer
	CoW happens
	page copied		original page retained
				alter-buffer
		<DMA-happens>

David