e2d8b4289c
Use pageref->offset instead of page->index for deferred-I/O writeback where appropriate. Distinguishes between file-mapping offset and video- memory offset. While at it, also remove unnecessary references to struct page. Fbdev's deferred-I/O code uses the two related page->index and pageref->offset. The former is the page offset in the mapped file, the latter is the byte offset in the video memory (or fbdev screen buffer). It's the same value for fbdev drivers, but for DRM the values can be different. Because GEM buffer objects are mapped at an offset in the DRM device file, page->index has this offset added to it as well. We currently don't hit this case in DRM, because all affected mappings of GEM memory are performed with an internal, intermediate shadow buffer. The value of page->index is required by page_mkclean(), which we call to reset the mappings during the writeback phase of the deferred I/O. The value of pageref->offset is for conveniently getting an offset into video memory in fb helpers. v4: * fix commit message (Javier) Suggested-by: Javier Martinez Canillas <javierm@redhat.com> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de> Reviewed-by: Javier Martinez Canillas <javierm@redhat.com> Link: https://patchwork.freedesktop.org/patch/msgid/20220429100834.18898-6-tzimmermann@suse.de
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.