On Tue, Feb 09, 2021 at 10:22:13PM -0800, ira.weiny@intel.com wrote:

From: Ira Weiny <redacted>

Changes from V1:
	Rework commit messages because they were very weak
	Change 'fs/btrfs: X' to 'btrfs: x'
		https://lore.kernel.org/lkml/20210209151442.GU1993@suse.cz/ (local)
	Per Andrew
		Split out changes to highmem.h
			The addition memcpy, memmove, and memset page functions
			The change from kmap_atomic to kmap_local_page
			The addition of BUG_ON
			The conversion of memzero_page to zero_user in iov_iter
		Change BUG_ON to VM_BUG_ON
	While we are refactoring adjust the line length down per Chaitany


There are many places where kmap/<operation>/kunmap patterns occur.  We lift a
couple of these patterns to the core common functions and use them as well as
existing core functions in the btrfs file system.  At the same time we convert
those core functions to use kmap_local_page() which is more efficient in those
calls.

Per the conversation on V1 it looks like Andrew would like this to go through
the btrfs tree.  I think that is fine.  The other users of
memcpy_[to|from]_page are probably not ready and I believe could be taken in an
early rc after David submits.

Is that ok with you David?

Yes.

The branch is now in
https://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux.git/log/?h=kmap-conversion
let me know if I've missed acked-by or reviewed-by, I added those sent
to the mailinglist and added mine to the btrfs ones and to the iov_iter
patch.

I'll add the patchset to my for-next so it gets picked by linux-next and
will keep testing it for at least a week.

Though this is less than the expected time before merge window, the
reasoning is that it's exporting helpers that are going to be used in
various subsystems. The changes in btrfs are simple and would allow to
focus on the other less trivial conversions. ETA for the pull request is
mid of the 2nd week of the merge window or after rc1.