mm: fix false-positive WARN_ON() in truncate/invalidate for hugetlb

Hugetlb pages have ->index in size of the huge pages (PMD_SIZE or
PUD_SIZE), not in PAGE_SIZE as other types of pages.  This means we
cannot user page_to_pgoff() to check whether we've got the right page
for the radix-tree index.

Let's introduce page_to_index() which would return radix-tree index for
given page.

We will be able to get rid of this once hugetlb will be switched to
multi-order entries.

Fixes: fc127da085c2 ("truncate: handle file thp")
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Kirill A. Shutemov <[email protected]>
Reported-by: Doug Nelson <[email protected]>
Tested-by: Doug Nelson <[email protected]>
Reviewed-by: Naoya Horiguchi <[email protected]>
Cc: <[email protected]>	[4.8+]
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

0 files changed, 0 insertions, 0 deletions