Messages in this thread | | | Date | Tue, 17 Jan 2023 09:47:58 +0100 | Subject | Re: [PATCH v6 03/34] iov_iter: Pass I/O direction into iov_iter_get_pages*() | From | David Hildenbrand <> |
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On 17.01.23 09:44, David Howells wrote: > Christoph Hellwig <hch@infradead.org> 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
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