switch the block layer to use kmap_local_page v3

From: Christoph Hellwig
Date: Tue Jul 27 2021 - 02:01:06 EST


Hi all,

this series switches the core block layer code and all users of the
existing bvec kmap helpers to use kmap_local_page. Drivers that
currently use open coded kmap_atomic calls will converted in a follow
on series.

To do so a new kunmap variant is added that calls
flush_kernel_dcache_page. I'm not entirely sure where to call
flush_dcache_page vs flush_kernel_dcache_page, so I've tried to follow
the documentation here, but additional feedback would be welcome.

Note that the ps3disk has a minir conflict with the
flush_kernel_dcache_page removal in linux-next through the -mm tree.
I had hoped that change would go into 5.14, but it seems like it is
being held for 5.15.

Changes since v2:
- rely on the flush_dcache_helpers in memcpy_to_page and memzero_page
that now hit mainline

Changes since v1:
- add more/better comments
- add a new kunmap_local_dirty helper to feal with
flush(_kernel)_dcache_page

Diffstat:
arch/mips/include/asm/mach-rc32434/rb.h | 2 -
block/bio-integrity.c | 14 +++-----
block/bio.c | 37 ++++++----------------
block/blk-map.c | 2 -
block/bounce.c | 39 +++++-------------------
block/t10-pi.c | 16 +++------
drivers/block/ps3disk.c | 19 +----------
drivers/block/rbd.c | 15 +--------
drivers/md/dm-writecache.c | 5 +--
include/linux/bio.h | 42 -------------------------
include/linux/bvec.h | 52 ++++++++++++++++++++++++++++++--
include/linux/highmem-internal.h | 7 ++++
include/linux/highmem.h | 10 ++++--
13 files changed, 102 insertions(+), 158 deletions(-)