Messages in this thread | | | Date | Fri, 15 Sep 2023 20:45:20 +0100 | From | Matthew Wilcox <> | Subject | Re: [RFC 05/23] filemap: align index to mapping_min_order in filemap_range_has_page() |
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On Fri, Sep 15, 2023 at 08:38:30PM +0200, Pankaj Raghav wrote: > From: Luis Chamberlain <mcgrof@kernel.org> > > page cache is mapping min_folio_order aligned. Use mapping min_folio_order > to align the start_byte and end_byte in filemap_range_has_page().
What goes wrong if you don't? Seems to me like it should work.
> Signed-off-by: Luis Chamberlain <mcgrof@kernel.org> > --- > mm/filemap.c | 7 +++++-- > 1 file changed, 5 insertions(+), 2 deletions(-) > > diff --git a/mm/filemap.c b/mm/filemap.c > index 2c47729dc8b0..4dee24b5b61c 100644 > --- a/mm/filemap.c > +++ b/mm/filemap.c > @@ -477,9 +477,12 @@ EXPORT_SYMBOL(filemap_flush); > bool filemap_range_has_page(struct address_space *mapping, > loff_t start_byte, loff_t end_byte) > { > + unsigned int min_order = mapping_min_folio_order(mapping); > + unsigned int nrpages = 1UL << min_order; > + pgoff_t index = round_down(start_byte >> PAGE_SHIFT, nrpages); > struct folio *folio; > - XA_STATE(xas, &mapping->i_pages, start_byte >> PAGE_SHIFT); > - pgoff_t max = end_byte >> PAGE_SHIFT; > + XA_STATE(xas, &mapping->i_pages, index); > + pgoff_t max = round_down(end_byte >> PAGE_SHIFT, nrpages); > > if (end_byte < start_byte) > return false; > -- > 2.40.1 >
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