Commit fc65c4eb authored by Joao Martins's avatar Joao Martins Committed by Linus Torvalds
Browse files

device-dax: ensure dev_dax->pgmap is valid for dynamic devices 

Right now, only static dax regions have a valid @pgmap pointer in its
struct dev_dax.  Dynamic dax case however, do not.

In preparation for device-dax compound devmap support, make sure that
dev_dax pgmap field is set after it has been allocated and initialized.

dynamic dax device have the @pgmap is allocated at probe() and it's
managed by devm (contrast to static dax region which a pgmap is provided
and dax core kfrees it).  So in addition to ensure a valid @pgmap, clear
the pgmap when the dynamic dax device is released to avoid the same
pgmap ranges to be re-requested across multiple region device reconfigs.

Add a static_dev_dax() and use that helper in dev_dax_probe() to ensure
the initialization differences between dynamic and static regions are
more explicit.  While at it, consolidate the ranges initialization when
we allocate the @pgmap for the dynamic dax region case.  Also take the
opportunity to document the differences between static and dynamic da
regions.

Link: https://lkml.kernel.org/r/20211202204422.26777-8-joao.m.martins@oracle.com


Suggested-by: default avatarDan Williams <dan.j.williams@intel.com>
Signed-off-by: default avatarJoao Martins <joao.m.martins@oracle.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Dave Jiang <dave.jiang@intel.com>
Cc: Jane Chu <jane.chu@oracle.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Vishal Verma <vishal.l.verma@intel.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 09b80137

drivers/dax/bus.c

+32 −0
Original line number Diff line number Diff line
@@ -129,11 +129,35 @@ ATTRIBUTE_GROUPS(dax_drv); 


static int dax_bus_match(struct device *dev, struct device_driver *drv);



/*

 * Static dax regions are regions created by an external subsystem

 * nvdimm where a single range is assigned. Its boundaries are by the external

 * subsystem and are usually limited to one physical memory range. For example,

 * for PMEM it is usually defined by NVDIMM Namespace boundaries (i.e. a

 * single contiguous range)

 *

 * On dynamic dax regions, the assigned region can be partitioned by dax core

 * into multiple subdivisions. A subdivision is represented into one

 * /dev/daxN.M device composed by one or more potentially discontiguous ranges.

 *

 * When allocating a dax region, drivers must set whether it's static

 * (IORESOURCE_DAX_STATIC).  On static dax devices, the @pgmap is pre-assigned

 * to dax core when calling devm_create_dev_dax(), whereas in dynamic dax

 * devices it is NULL but afterwards allocated by dax core on device ->probe().

 * Care is needed to make sure that dynamic dax devices are torn down with a

 * cleared @pgmap field (see kill_dev_dax()).

 */

static bool is_static(struct dax_region *dax_region)

{

	return (dax_region->res.flags & IORESOURCE_DAX_STATIC) != 0;

}



bool static_dev_dax(struct dev_dax *dev_dax)

{

	return is_static(dev_dax->region);

}

EXPORT_SYMBOL_GPL(static_dev_dax);



static u64 dev_dax_size(struct dev_dax *dev_dax)

{

	u64 size = 0;
@@ -363,6 +387,14 @@ void kill_dev_dax(struct dev_dax *dev_dax) 


	kill_dax(dax_dev);

	unmap_mapping_range(inode->i_mapping, 0, 0, 1);



	/*

	 * Dynamic dax region have the pgmap allocated via dev_kzalloc()

	 * and thus freed by devm. Clear the pgmap to not have stale pgmap

	 * ranges on probe() from previous reconfigurations of region devices.

	 */

	if (!static_dev_dax(dev_dax))

		dev_dax->pgmap = NULL;

}

EXPORT_SYMBOL_GPL(kill_dev_dax);

drivers/dax/bus.h

+1 −0
Original line number Diff line number Diff line
@@ -48,6 +48,7 @@ int __dax_driver_register(struct dax_device_driver *dax_drv, 
	__dax_driver_register(driver, THIS_MODULE, KBUILD_MODNAME)

void dax_driver_unregister(struct dax_device_driver *dax_drv);

void kill_dev_dax(struct dev_dax *dev_dax);

bool static_dev_dax(struct dev_dax *dev_dax);



#if IS_ENABLED(CONFIG_DEV_DAX_PMEM_COMPAT)

int dev_dax_probe(struct dev_dax *dev_dax);

drivers/dax/device.c

+21 −8
Original line number Diff line number Diff line
@@ -398,18 +398,34 @@ int dev_dax_probe(struct dev_dax *dev_dax) 
	void *addr;

	int rc, i;



	if (static_dev_dax(dev_dax))  {

		if (dev_dax->nr_range > 1) {

			dev_warn(dev,

				"static pgmap / multi-range device conflict\n");

			return -EINVAL;

		}



		pgmap = dev_dax->pgmap;

	if (dev_WARN_ONCE(dev, pgmap && dev_dax->nr_range > 1,

			"static pgmap / multi-range device conflict\n"))

	} else {

		if (dev_dax->pgmap) {

			dev_warn(dev,

				 "dynamic-dax with pre-populated page map\n");

			return -EINVAL;

		}



	if (!pgmap) {

		pgmap = devm_kzalloc(dev,

                       struct_size(pgmap, ranges, dev_dax->nr_range - 1),

                       GFP_KERNEL);

		if (!pgmap)

			return -ENOMEM;



		pgmap->nr_range = dev_dax->nr_range;

		dev_dax->pgmap = pgmap;



		for (i = 0; i < dev_dax->nr_range; i++) {

			struct range *range = &dev_dax->ranges[i].range;

			pgmap->ranges[i] = *range;

		}

	}



	for (i = 0; i < dev_dax->nr_range; i++) {
@@ -421,9 +437,6 @@ int dev_dax_probe(struct dev_dax *dev_dax) 
					i, range->start, range->end);

			return -EBUSY;

		}

		/* don't update the range for static pgmap */

		if (!dev_dax->pgmap)

			pgmap->ranges[i] = *range;

	}



	pgmap->type = MEMORY_DEVICE_GENERIC;