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    Subject[PATCH v3 13/16] /dev/mem: Only set filp->f_mapping
    Date
    When we care about pagecache maintenance, we need to make sure that
    both f_mapping and i_mapping point at the right mapping.

    But for iomem mappings we only care about the virtual/pte side of
    things, so f_mapping is enough. Also setting inode->i_mapping was
    confusing me as a driver maintainer, since in e.g. drivers/gpu we
    don't do that. Per Dan this seems to be copypasta from places which do
    care about pagecache consistency, but not needed. Hence remove it for
    slightly less confusion.

    Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
    Cc: Jason Gunthorpe <jgg@ziepe.ca>
    Cc: Kees Cook <keescook@chromium.org>
    Cc: Dan Williams <dan.j.williams@intel.com>
    Cc: Andrew Morton <akpm@linux-foundation.org>
    Cc: John Hubbard <jhubbard@nvidia.com>
    Cc: Jérôme Glisse <jglisse@redhat.com>
    Cc: Jan Kara <jack@suse.cz>
    Cc: Dan Williams <dan.j.williams@intel.com>
    Cc: linux-mm@kvack.org
    Cc: linux-arm-kernel@lists.infradead.org
    Cc: linux-samsung-soc@vger.kernel.org
    Cc: linux-media@vger.kernel.org
    Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.com>
    ---
    drivers/char/mem.c | 1 -
    1 file changed, 1 deletion(-)

    diff --git a/drivers/char/mem.c b/drivers/char/mem.c
    index abd4ffdc8cde..5502f56f3655 100644
    --- a/drivers/char/mem.c
    +++ b/drivers/char/mem.c
    @@ -864,7 +864,6 @@ static int open_port(struct inode *inode, struct file *filp)
    * revocations when drivers want to take over a /dev/mem mapped
    * range.
    */
    - inode->i_mapping = devmem_inode->i_mapping;
    filp->f_mapping = inode->i_mapping;

    return 0;
    --
    2.28.0
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