static int nd_pfn_init()

in pfn_devs.c [718:829]

• 79 lines of code
• 11 McCabe index (conditional complexity)

static int nd_pfn_init(struct nd_pfn *nd_pfn)
{
	struct nd_namespace_common *ndns = nd_pfn->ndns;
	struct nd_namespace_io *nsio = to_nd_namespace_io(&ndns->dev);
	resource_size_t start, size;
	struct nd_region *nd_region;
	unsigned long npfns, align;
	u32 end_trunc;
	struct nd_pfn_sb *pfn_sb;
	phys_addr_t offset;
	const char *sig;
	u64 checksum;
	int rc;

	pfn_sb = devm_kmalloc(&nd_pfn->dev, sizeof(*pfn_sb), GFP_KERNEL);
	if (!pfn_sb)
		return -ENOMEM;

	nd_pfn->pfn_sb = pfn_sb;
	if (is_nd_dax(&nd_pfn->dev))
		sig = DAX_SIG;
	else
		sig = PFN_SIG;

	rc = nd_pfn_validate(nd_pfn, sig);
	if (rc == 0)
		return nd_pfn_clear_memmap_errors(nd_pfn);
	if (rc != -ENODEV)
		return rc;

	/* no info block, do init */;
	memset(pfn_sb, 0, sizeof(*pfn_sb));

	nd_region = to_nd_region(nd_pfn->dev.parent);
	if (nd_region->ro) {
		dev_info(&nd_pfn->dev,
				"%s is read-only, unable to init metadata\n",
				dev_name(&nd_region->dev));
		return -ENXIO;
	}

	/*
	 * Note, we use 64 here for the standard size of struct page,
	 * debugging options may cause it to be larger in which case the
	 * implementation will limit the pfns advertised through
	 * ->direct_access() to those that are included in the memmap.
	 */
	start = nsio->res.start;
	size = resource_size(&nsio->res);
	npfns = PHYS_PFN(size - SZ_8K);
	align = max(nd_pfn->align, memremap_compat_align());

	/*
	 * When @start is misaligned fail namespace creation. See
	 * the 'struct nd_pfn_sb' commentary on why ->start_pad is not
	 * an option.
	 */
	if (!IS_ALIGNED(start, memremap_compat_align())) {
		dev_err(&nd_pfn->dev, "%s: start %pa misaligned to %#lx\n",
				dev_name(&ndns->dev), &start,
				memremap_compat_align());
		return -EINVAL;
	}
	end_trunc = start + size - ALIGN_DOWN(start + size, align);
	if (nd_pfn->mode == PFN_MODE_PMEM) {
		/*
		 * The altmap should be padded out to the block size used
		 * when populating the vmemmap. This *should* be equal to
		 * PMD_SIZE for most architectures.
		 *
		 * Also make sure size of struct page is less than 64. We
		 * want to make sure we use large enough size here so that
		 * we don't have a dynamic reserve space depending on
		 * struct page size. But we also want to make sure we notice
		 * when we end up adding new elements to struct page.
		 */
		BUILD_BUG_ON(sizeof(struct page) > MAX_STRUCT_PAGE_SIZE);
		offset = ALIGN(start + SZ_8K + MAX_STRUCT_PAGE_SIZE * npfns, align)
			- start;
	} else if (nd_pfn->mode == PFN_MODE_RAM)
		offset = ALIGN(start + SZ_8K, align) - start;
	else
		return -ENXIO;

	if (offset >= size) {
		dev_err(&nd_pfn->dev, "%s unable to satisfy requested alignment\n",
				dev_name(&ndns->dev));
		return -ENXIO;
	}

	npfns = PHYS_PFN(size - offset - end_trunc);
	pfn_sb->mode = cpu_to_le32(nd_pfn->mode);
	pfn_sb->dataoff = cpu_to_le64(offset);
	pfn_sb->npfns = cpu_to_le64(npfns);
	memcpy(pfn_sb->signature, sig, PFN_SIG_LEN);
	memcpy(pfn_sb->uuid, nd_pfn->uuid, 16);
	memcpy(pfn_sb->parent_uuid, nd_dev_to_uuid(&ndns->dev), 16);
	pfn_sb->version_major = cpu_to_le16(1);
	pfn_sb->version_minor = cpu_to_le16(4);
	pfn_sb->end_trunc = cpu_to_le32(end_trunc);
	pfn_sb->align = cpu_to_le32(nd_pfn->align);
	pfn_sb->page_struct_size = cpu_to_le16(MAX_STRUCT_PAGE_SIZE);
	pfn_sb->page_size = cpu_to_le32(PAGE_SIZE);
	checksum = nd_sb_checksum((struct nd_gen_sb *) pfn_sb);
	pfn_sb->checksum = cpu_to_le64(checksum);

	rc = nd_pfn_clear_memmap_errors(nd_pfn);
	if (rc)
		return rc;

	return nvdimm_write_bytes(ndns, SZ_4K, pfn_sb, sizeof(*pfn_sb), 0);
}