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There are many places where kmap/memove/kunmap patterns occur. This pattern exists in the core common function copy_highpage(). Use copy_highpage to avoid open coding the use of kmap and leverages the core functions use of kmap_local_page(). Development of this patch was aided by the following coccinelle script: // <smpl> // SPDX-License-Identifier: GPL-2.0-only // Find kmap/copypage/kunmap pattern and replace with copy_highpage calls // // NOTE: The expressions in the copy page version of this kmap pattern are // overly complex and so these all need individual attention. // // Confidence: Low // Copyright: (C) 2021 Intel Corporation // URL: http://coccinelle.lip6.fr/ // Comments: // Options: // // Then a copy_page where we have 2 pages involved. // @ copy_page_rule @ expression page, page2, To, From, Size; identifier ptr, ptr2; type VP, VP2; @@ /* kmap */ ( -VP ptr = kmap(page); ... -VP2 ptr2 = kmap(page2); | -VP ptr = kmap_atomic(page); ... -VP2 ptr2 = kmap_atomic(page2); | -ptr = kmap(page); ... -ptr2 = kmap(page2); | -ptr = kmap_atomic(page); ... -ptr2 = kmap_atomic(page2); ) // 1 or more copy versions of the entire page <+... ( -copy_page(To, From); +copy_highpage(To, From); | -memmove(To, From, Size); +memmoveExtra(To, From, Size); ) ...+> /* kunmap */ ( -kunmap(page2); ... -kunmap(page); | -kunmap(page); ... -kunmap(page2); | -kmap_atomic(ptr2); ... -kmap_atomic(ptr); ) // Remove any pointers left unused @ depends on copy_page_rule @ identifier copy_page_rule.ptr; identifier copy_page_rule.ptr2; type VP, VP1; type VP2, VP21; @@ -VP ptr; ... when != ptr; ? VP1 ptr; -VP2 ptr2; ... when != ptr2; ? VP21 ptr2; // </smpl> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Ira Weiny <ira.weiny@intel.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.