Commit 2361db89 authored by Dan Williams's avatar Dan Williams
Browse files

libnvdimm: Notify disk drivers to revalidate region read-only 



Previous kernels allowed the BLKROSET to override the disk's read-only
status. With that situation fixed the pmem driver needs to rely on
notification events to reevaluate the disk read-only status after the
host region has been marked read-write.

Recall that when libnvdimm determines that the persistent memory has
lost persistence (for example lack of energy to flush from DRAM to FLASH
on an NVDIMM-N device) it marks the region read-only, but that state can
be overridden by the user via:

   echo 0 > /sys/bus/nd/devices/regionX/read_only

...to date there is no notification that the region has restored
persistence, so the user override is the only recovery.

Fixes: 52f019d4 ("block: add a hard-readonly flag to struct gendisk")
Reported-by: default avatarkernel test robot <lkp@intel.com>
Reported-by: default avatarVishal Verma <vishal.l.verma@intel.com>
Tested-by: default avatarVishal Verma <vishal.l.verma@intel.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Ming Lei <ming.lei@redhat.com>
Cc: Martin K. Petersen <martin.petersen@oracle.com>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Jens Axboe <axboe@kernel.dk>
Link: https://lore.kernel.org/r/161534060720.528671.2341213328968989192.stgit@dwillia2-desk3.amr.corp.intel.com


Signed-off-by: default avatarDan Williams <dan.j.williams@intel.com>
parent e49d033b

drivers/nvdimm/bus.c

+6 −8
Original line number Diff line number Diff line
@@ -631,16 +631,14 @@ void nvdimm_check_and_set_ro(struct gendisk *disk) 
	struct nd_region *nd_region = to_nd_region(dev->parent);

	int disk_ro = get_disk_ro(disk);



	/*

	 * Upgrade to read-only if the region is read-only preserve as

	 * read-only if the disk is already read-only.

	 */

	if (disk_ro || nd_region->ro == disk_ro)

	/* catch the disk up with the region ro state */

	if (disk_ro == nd_region->ro)

		return;



	dev_info(dev, "%s read-only, marking %s read-only\n",

			dev_name(&nd_region->dev), disk->disk_name);

	set_disk_ro(disk, 1);

	dev_info(dev, "%s read-%s, marking %s read-%s\n",

		 dev_name(&nd_region->dev), nd_region->ro ? "only" : "write",

		 disk->disk_name, nd_region->ro ? "only" : "write");

	set_disk_ro(disk, nd_region->ro);

}

EXPORT_SYMBOL(nvdimm_check_and_set_ro);

drivers/nvdimm/pmem.c

+33 −4
Original line number Diff line number Diff line
@@ -26,6 +26,7 @@ 
#include <linux/mm.h>

#include <asm/cacheflush.h>

#include "pmem.h"

#include "btt.h"

#include "pfn.h"

#include "nd.h"
@@ -585,7 +586,7 @@ static void nd_pmem_shutdown(struct device *dev) 
	nvdimm_flush(to_nd_region(dev->parent), NULL);

}



static void nd_pmem_notify(struct device *dev, enum nvdimm_event event)

static void pmem_revalidate_poison(struct device *dev)

{

	struct nd_region *nd_region;

	resource_size_t offset = 0, end_trunc = 0;
@@ -595,9 +596,6 @@ static void nd_pmem_notify(struct device *dev, enum nvdimm_event event) 
	struct range range;

	struct kernfs_node *bb_state;



	if (event != NVDIMM_REVALIDATE_POISON)

		return;



	if (is_nd_btt(dev)) {

		struct nd_btt *nd_btt = to_nd_btt(dev);
@@ -635,6 +633,37 @@ static void nd_pmem_notify(struct device *dev, enum nvdimm_event event) 
		sysfs_notify_dirent(bb_state);

}



static void pmem_revalidate_region(struct device *dev)

{

	struct pmem_device *pmem;



	if (is_nd_btt(dev)) {

		struct nd_btt *nd_btt = to_nd_btt(dev);

		struct btt *btt = nd_btt->btt;



		nvdimm_check_and_set_ro(btt->btt_disk);

		return;

	}



	pmem = dev_get_drvdata(dev);

	nvdimm_check_and_set_ro(pmem->disk);

}



static void nd_pmem_notify(struct device *dev, enum nvdimm_event event)

{

	switch (event) {

	case NVDIMM_REVALIDATE_POISON:

		pmem_revalidate_poison(dev);

		break;

	case NVDIMM_REVALIDATE_REGION:

		pmem_revalidate_region(dev);

		break;

	default:

		dev_WARN_ONCE(dev, 1, "notify: unknown event: %d\n", event);

		break;

	}

}



MODULE_ALIAS("pmem");

MODULE_ALIAS_ND_DEVICE(ND_DEVICE_NAMESPACE_IO);

MODULE_ALIAS_ND_DEVICE(ND_DEVICE_NAMESPACE_PMEM);

drivers/nvdimm/region_devs.c

+7 −0
Original line number Diff line number Diff line
@@ -518,6 +518,12 @@ static ssize_t read_only_show(struct device *dev, 
	return sprintf(buf, "%d\n", nd_region->ro);

}



static int revalidate_read_only(struct device *dev, void *data)

{

	nd_device_notify(dev, NVDIMM_REVALIDATE_REGION);

	return 0;

}



static ssize_t read_only_store(struct device *dev,

		struct device_attribute *attr, const char *buf, size_t len)

{
@@ -529,6 +535,7 @@ static ssize_t read_only_store(struct device *dev, 
		return rc;



	nd_region->ro = ro;

	device_for_each_child(dev, NULL, revalidate_read_only);

	return len;

}

static DEVICE_ATTR_RW(read_only);

include/linux/nd.h

+1 −0
Original line number Diff line number Diff line
@@ -11,6 +11,7 @@ 


enum nvdimm_event {

	NVDIMM_REVALIDATE_POISON,

	NVDIMM_REVALIDATE_REGION,

};



enum nvdimm_claim_class {