Hi Christoph, David,
Since Christoph asked nicely[1] ;-), here are three patches that go on top
of the similar patches for bio structs now in the block tree that make the
old block direct-IO code use iov_iter_extract_pages() and page pinning.
There are three patches:
(1) Make page pinning not add or remove a pin to/from the ZERO_PAGE,
thereby allowing the dio code to insert zero pages in the middle of
dealing with pinned pages.
(2) Provide a function to allow an additional pin to be taken on a page we
already have pinned (and do nothing for the zero page).
(3) Switch direct-io.c over to using page pinning and to use
iov_iter_extract_pages() so that pages from non-user-backed iterators
aren't pinned.
Note that I haven't managed to test this yet as SELinux is refusing to let
me mount things like ext2 filesystems on account of it not having xattrs:-/
I've pushed the patches here also:
https://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs.git/log/?h=iov-old-dio
David
Link: https://lore.kernel.org/r/ZGxfrOLZ4aN9/MvE@xxxxxxxxxxxxx/ [1]
David Howells (3):
mm: Don't pin ZERO_PAGE in pin_user_pages()
mm: Provide a function to get an additional pin on a page
block: Use iov_iter_extract_pages() and page pinning in direct-io.c
fs/direct-io.c | 68 ++++++++++++++++++++++++++++------------------
include/linux/mm.h | 1 +
mm/gup.c | 54 +++++++++++++++++++++++++++++++++++-
3 files changed, 95 insertions(+), 28 deletions(-)
