block: convert bio_map_user_iov to use iov_iter_extract_pages

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).

Signed-off-by: David Howells <[email protected]>
Reviewed-by: Christoph Hellwig <[email protected]>
Reviewed-by: John Hubbard <[email protected]>
cc: Al Viro <[email protected]>
cc: Jens Axboe <[email protected]>
cc: Jan Kara <[email protected]>
cc: Matthew Wilcox <[email protected]>
cc: Logan Gunthorpe <[email protected]>
cc: [email protected]
Reviewed-by: Jan Kara <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jens Axboe <[email protected]>

0 files changed, 0 insertions, 0 deletions