Commit 0b277961 authored by Dan Williams's avatar Dan Williams
Browse files

libnvdimm, pmem: disable dax flushing when pmem is fronting a volatile region 



The pmem driver attaches to both persistent and volatile memory ranges
advertised by the ACPI NFIT. When the region is volatile it is redundant
to spend cycles flushing caches at fsync(). Check if the hosting region
is volatile and do not set dax_write_cache() if it is.

Cc: Jan Kara <jack@suse.cz>
Cc: Jeff Moyer <jmoyer@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: default avatarDan Williams <dan.j.williams@intel.com>
parent 6e0c90d6

drivers/nvdimm/pmem.c

+8 −5
Original line number Diff line number Diff line
@@ -284,10 +284,10 @@ static int pmem_attach_disk(struct device *dev, 
	struct nd_namespace_io *nsio = to_nd_namespace_io(&ndns->dev);

	struct nd_region *nd_region = to_nd_region(dev->parent);

	struct vmem_altmap __altmap, *altmap = NULL;

	int nid = dev_to_node(dev), fua, wbc;

	struct resource *res = &nsio->res;

	struct nd_pfn *nd_pfn = NULL;

	struct dax_device *dax_dev;

	int nid = dev_to_node(dev);

	struct nd_pfn_sb *pfn_sb;

	struct pmem_device *pmem;

	struct resource pfn_res;
@@ -314,9 +314,12 @@ static int pmem_attach_disk(struct device *dev, 
	dev_set_drvdata(dev, pmem);

	pmem->phys_addr = res->start;

	pmem->size = resource_size(res);

	if (!IS_ENABLED(CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE)

			|| nvdimm_has_flush(nd_region) < 0)

	fua = nvdimm_has_flush(nd_region);

	if (!IS_ENABLED(CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE) || fua < 0) {

		dev_warn(dev, "unable to guarantee persistence of writes\n");

		fua = 0;

	}

	wbc = nvdimm_has_cache(nd_region);



	if (!devm_request_mem_region(dev, res->start, resource_size(res),

				dev_name(&ndns->dev))) {
@@ -360,7 +363,7 @@ static int pmem_attach_disk(struct device *dev, 
		return PTR_ERR(addr);

	pmem->virt_addr = addr;



	blk_queue_write_cache(q, true, true);

	blk_queue_write_cache(q, wbc, fua);

	blk_queue_make_request(q, pmem_make_request);

	blk_queue_physical_block_size(q, PAGE_SIZE);

	blk_queue_max_hw_sectors(q, UINT_MAX);
@@ -390,7 +393,7 @@ static int pmem_attach_disk(struct device *dev, 
		put_disk(disk);

		return -ENOMEM;

	}

	dax_write_cache(dax_dev, true);

	dax_write_cache(dax_dev, wbc);

	pmem->dax_dev = dax_dev;



	gendev = disk_to_dev(disk);

drivers/nvdimm/region_devs.c

+6 −0
Original line number Diff line number Diff line
@@ -1060,6 +1060,12 @@ int nvdimm_has_flush(struct nd_region *nd_region) 
}

EXPORT_SYMBOL_GPL(nvdimm_has_flush);



int nvdimm_has_cache(struct nd_region *nd_region)

{

	return is_nd_pmem(&nd_region->dev);

}

EXPORT_SYMBOL_GPL(nvdimm_has_cache);



void __exit nd_region_devs_exit(void)

{

	ida_destroy(&region_ida);

include/linux/libnvdimm.h

+1 −0
Original line number Diff line number Diff line
@@ -165,4 +165,5 @@ void nd_region_release_lane(struct nd_region *nd_region, unsigned int lane); 
u64 nd_fletcher64(void *addr, size_t len, bool le);

void nvdimm_flush(struct nd_region *nd_region);

int nvdimm_has_flush(struct nd_region *nd_region);

int nvdimm_has_cache(struct nd_region *nd_region);

#endif /* __LIBNVDIMM_H__ */

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