On 17.01.23 09:44, David Howells wrote:
Christoph Hellwig <hch@xxxxxxxxxxxxx> wrote:
On Mon, Jan 16, 2023 at 11:08:24PM +0000, David Howells wrote:
Define FOLL_SOURCE_BUF and FOLL_DEST_BUF to indicate to get_user_pages*()
and iov_iter_get_pages*() how the buffer is intended to be used in an I/O
operation. Don't use READ and WRITE as a read I/O writes to memory and
vice versa - which causes confusion.
The direction is checked against the iterator's data_source.
Why can't we use the existing FOLL_WRITE?
Because FOLL_WRITE doesn't mean the same as WRITE:
(1) It looks like it should really be FOLL_CHECK_PTES_WRITABLE. It's not
defined as being anything to do with the I/O.
Especially combined with FOLL_FORCE, this is not true.
--
Thanks,
David / dhildenb
