netfs: Add a function to extract an iterator into a scatterlist

Provide a function for filling in a scatterlist from the list of pages
contained in an iterator.

If the iterator is UBUF- or IOBUF-type, the pages have a pin taken on them
(as FOLL_PIN).

If the iterator is BVEC-, KVEC- or XARRAY-type, no pin is taken on the
pages and it is left to the caller to manage their lifetime.  It cannot be
assumed that a ref can be validly taken, particularly in the case of a KVEC
iterator.

Signed-off-by: David Howells <[email protected]>
cc: Jeff Layton <[email protected]>
cc: Steve French <[email protected]>
cc: Shyam Prasad N <[email protected]>
cc: Rohith Surabattula <[email protected]>
cc: [email protected]
cc: [email protected]
cc: [email protected]
Signed-off-by: Steve French <[email protected]>

0 files changed, 0 insertions, 0 deletions