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: 52f019d43c22 ("block: add a hard-readonly flag to struct gendisk")
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Vishal Verma <vishal.l.verma@intel.com>
Tested-by: Vishal Verma <vishal.l.verma@intel.com>
Reviewed-by: Christoph 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: Dan Williams <dan.j.williams@intel.com>

diff --git a/drivers/nvdimm/bus.c b/drivers/nvdimm/bus.c
index 48f0985..3a777d0 100644 (file)
--- a/drivers/nvdimm/bus.c
+++ b/drivers/nvdimm/bus.c
@@ -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);
 

diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c
index b8a85bf..7daac79 100644 (file)
--- a/drivers/nvdimm/pmem.c
+++ b/drivers/nvdimm/pmem.c
@@ -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);

diff --git a/drivers/nvdimm/region_devs.c b/drivers/nvdimm/region_devs.c
index ef23119..51870eb 100644 (file)
--- a/drivers/nvdimm/region_devs.c
+++ b/drivers/nvdimm/region_devs.c
@@ -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);

diff --git a/include/linux/nd.h b/include/linux/nd.h
index cec526c..ee9ad76 100644 (file)
--- a/include/linux/nd.h
+++ b/include/linux/nd.h
@@ -11,6 +11,7 @@
 
 enum nvdimm_event {
        NVDIMM_REVALIDATE_POISON,
+       NVDIMM_REVALIDATE_REGION,
 };
 
 enum nvdimm_claim_class {