Sorry for the long reply time - personal issues came up. On Sun, Nov 8, 2020 at 7:36 PM Matthew Wilcox <wi...@infradead.org> wrote: > > On Sun, Nov 08, 2020 at 05:54:14PM -0800, Amy Parker wrote: > > On Sun, Nov 8, 2020 at 5:50 PM Matthew Wilcox <wi...@infradead.org> wrote: > > > > > > On Sun, Nov 08, 2020 at 05:33:22PM -0800, Darrick J. Wong wrote: > > > > On Sun, Nov 08, 2020 at 05:15:55PM -0800, Amy Parker wrote: > > > > > XA_ZERO_ENTRY > > > > > is defined in include/linux/xarray.h, where it's defined using > > > > > xa_mk_internal(257). This function returns a void pointer, which > > > > > is incompatible with the bitwise arithmetic it is performed on with. > > > > > > We don't really perform bitwise arithmetic on it, outside of: > > > > > > static int dax_is_zero_entry(void *entry) > > > { > > > return xa_to_value(entry) & DAX_ZERO_PAGE; > > > } > > > > We also have: > > > > if (dax_is_zero_entry(entry) && !(flags & DAX_ZERO_PAGE)) { > > unsigned long index = xas->xa_index; > > /* we are replacing a zero page with block mapping */ > > if (dax_is_pmd_entry(entry)) > > unmap_mapping_pages(mapping, index & ~PG_PMD_COLOUR, > > PG_PMD_NR, false); > > else /* pte entry */ > > unmap_mapping_pages(mapping, index, 1, false); > > } > > > > and: > > > > *entry = dax_insert_entry(xas, mapping, vmf, *entry, pfn, > > DAX_PMD | DAX_ZERO_PAGE, false); > > Right. We need to be able to distinguish whether an entry represents > a PMD size. So maybe we need XA_ZERO_PMD_ENTRY ... ? Or we could use > the recently-added xa_get_order().
I could add an additional dependent patch for this. Where would we want XA_ZERO_PMD_ENTRY declared? Considering we're dependent on DAX_PMD, I'd say in fs/dax.c, but if there's a better solution I'm missing... > > > > That'd probably be a better idea - so what should we do about the type > > issue? Not typecasting it causes it not to compile. > > I don't think you'll need to do any casting once the bit operations go > away ... True, but what're we going to do about dax_is_zero_entry? We haven't figured out what to do about that yet... a typecast back to void* of xa_to_value locally could work, as it itself is just shifting an entry right by 1 bit and then typecasting it to unsigned long. Thoughts? Best regards, Amy Parker (she/her) _______________________________________________ Linux-nvdimm mailing list -- linux-nvdimm@lists.01.org To unsubscribe send an email to linux-nvdimm-le...@lists.01.org