Re: [PATCH v5 15/17] dax: add struct iomap based DAX PMD support

From: Christoph Hellwig
Date: Mon Oct 10 2016 - 11:59:24 EST


On Fri, Oct 07, 2016 at 03:09:02PM -0600, Ross Zwisler wrote:
> - if (RADIX_DAX_TYPE(entry) == RADIX_DAX_PMD)
> + if ((unsigned long)entry & RADIX_DAX_PMD)

Please introduce a proper inline helper that mask all the possible type
bits out of the radix tree entry, and use them wherever you do the
open cast.

> restart:
> spin_lock_irq(&mapping->tree_lock);
> entry = get_unlocked_mapping_entry(mapping, index, &slot);
> +
> + if (entry) {
> + if (size_flag & RADIX_DAX_PMD) {
> + if (!radix_tree_exceptional_entry(entry) ||
> + !((unsigned long)entry & RADIX_DAX_PMD)) {
> + entry = ERR_PTR(-EEXIST);
> + goto out_unlock;
> + }
> + } else { /* trying to grab a PTE entry */
> + if (radix_tree_exceptional_entry(entry) &&
> + ((unsigned long)entry & RADIX_DAX_PMD) &&
> + ((unsigned long)entry &
> + (RADIX_DAX_HZP|RADIX_DAX_EMPTY))) {

And when we do these cases N times next to each other we should
have a local variable the valid flag bits of entry.