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With the introduction of mapping_wrprotect_range() there is no need to use folio_mkclean() in order to write-protect mappings of frame buffer pages, and therefore no need to inappropriately set kernel-allocated page->index, mapping fields to permit this operation. Instead, store the pointer to the page cache object for the mapped driver in the fb_deferred_io object, and use the already stored page offset from the pageref object to look up mappings in order to write-protect them. This is justified, as for the page objects to store a mapping pointer at the point of assignment of pages, they must all reference the same underlying address_space object. Since the life time of the pagerefs is also the lifetime of the fb_deferred_io object, storing the pointer here makes sense. This eliminates the need for all of the logic around setting and maintaining page->index,mapping which we remove. This eliminates the use of folio_mkclean() entirely but otherwise should have no functional change. [lorenzo.stoakes@oracle.com: fixup unused variable warnings] Link: https://lkml.kernel.org/r/d4018405-2762-4385-a816-e54cc23839ac@lucifer.local Link: https://lkml.kernel.org/r/81171ab16c14e3df28f6de9d14982cee528d8519.1739029358.git.lorenzo.stoakes@oracle.com Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com> Tested-by: Kajtar Zsolt <soci@c64.rulez.org> Acked-by: Thomas Zimmermann <tzimmermann@suse.de> Cc: David Hildenbrand <david@redhat.com> Cc: Helge Deller <deller@gmx.de> Cc: Jaya Kumar <jayakumar.lkml@gmail.com> Cc: Maíra Canal <mcanal@igalia.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Simona Vetter <simona.vetter@ffwll.ch> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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 reStructuredText 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.