Re: [PATCH v9 8/8] block: convert bio_map_user_iov to use iov_iter_extract_pages

[Christoph Hellwig]

On Tue, Jan 24, 2023 at 05:01:08PM +0000, David Howells wrote:
> This will pin pages or leave them unaltered rather than getting a ref on
> them as appropriate to the iterator.
> 
> The pages need to be pinned for DIO rather than having refs taken on them
> to prevent VM copy-on-write from malfunctioning during a concurrent fork()
> (the result of the I/O could otherwise end up being visible to/affected by
> the child process).

Reviewed-by: Christoph Hellwig <hch@xxxxxx>