drivers/md/dm-pcache/cache_dev.c

Source file repositories/reference/linux-study-clean/drivers/md/dm-pcache/cache_dev.c

File Facts

System
Linux kernel
Corpus path
drivers/md/dm-pcache/cache_dev.c
Extension
.c
Size
7043 bytes
Lines
304
Domain
Driver Families
Bucket
drivers/md
Inferred role
Driver Families: implementation source
Status
source implementation candidate

Why This File Exists

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.

Dependency Surface

Detected Declarations

Annotated Snippet

if (chunk <= 0) {
			ret = chunk ? chunk : -EINVAL;
			goto out_free;
		}

		if (!pfn_valid(pfn)) {
			ret = -EOPNOTSUPP;
			goto out_free;
		}

		while (chunk-- && i < total_pages) {
			pages[i++] = pfn_to_page(pfn);
			pfn++;
			if (!(i & 15))
				cond_resched();
		}
	} while (i < total_pages);

	*vaddr = vmap(pages, total_pages, VM_MAP, PAGE_KERNEL);
	if (!*vaddr) {
		ret = -ENOMEM;
		goto out_free;
	}

	ret = 0;

out_free:
	vfree(pages);
	return ret;
}

static int cache_dev_dax_init(struct pcache_cache_dev *cache_dev)
{
	struct dm_pcache	*pcache = CACHE_DEV_TO_PCACHE(cache_dev);
	struct dax_device	*dax_dev;
	long			total_pages, mapped_pages;
	u64			bdev_size;
	void			*vaddr;
	int			ret;
	int			id;
	unsigned long		pfn;

	dax_dev	= cache_dev->dm_dev->dax_dev;
	/* total size check */
	bdev_size = bdev_nr_bytes(cache_dev->dm_dev->bdev);
	if (bdev_size < PCACHE_CACHE_DEV_SIZE_MIN) {
		pcache_dev_err(pcache, "dax device is too small, required at least %llu",
				PCACHE_CACHE_DEV_SIZE_MIN);
		ret = -ENOSPC;
		goto out;
	}

	total_pages = bdev_size >> PAGE_SHIFT;
	/* attempt: direct-map the whole range */
	id = dax_read_lock();
	mapped_pages = dax_direct_access(dax_dev, 0, total_pages,
					 DAX_ACCESS, &vaddr, &pfn);
	if (mapped_pages < 0) {
		pcache_dev_err(pcache, "dax_direct_access failed: %ld\n", mapped_pages);
		ret = mapped_pages;
		goto unlock;
	}

	if (!pfn_valid(pfn)) {
		ret = -EOPNOTSUPP;
		goto unlock;
	}

	if (mapped_pages == total_pages) {
		/* success: contiguous direct mapping */
		cache_dev->mapping = vaddr;
	} else {
		/* need vmap fallback */
		ret = build_vmap(dax_dev, total_pages, &vaddr);
		if (ret) {
			pcache_dev_err(pcache, "vmap fallback failed: %d\n", ret);
			goto unlock;
		}

		cache_dev->mapping	= vaddr;
		cache_dev->use_vmap	= true;
	}
	dax_read_unlock(id);

	return 0;
unlock:
	dax_read_unlock(id);
out:
	return ret;
}

Annotation

Implementation Notes