[PATCH] libnvdimm/pmem: Fix blk_cleanup_disk() usage

[Dan Williams]

The queue_to_disk() helper can not be used after del_gendisk()
communicate @disk via the pgmap->owner.

Reported-by: Sachin Sant <sachinp at linux.vnet.ibm.com>
Fixes: 87eb73b2ca7c ("nvdimm-pmem: convert to blk_alloc_disk/blk_cleanup_disk")
Cc: Christoph Hellwig <hch at lst.de>
Cc: Ulf Hansson <ulf.hansson at linaro.org>
Cc: Jens Axboe <axboe at kernel.dk>
Signed-off-by: Dan Williams <dan.j.williams at intel.com>
---
Jens,

Please take or fold this into your tree after Sachin has a chance
to test it out. It's passing my tests.

 drivers/nvdimm/pmem.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c
index 31f3c4bd6f72..fc6b78dd2d24 100644
--- a/drivers/nvdimm/pmem.c
+++ b/drivers/nvdimm/pmem.c
@@ -337,8 +337,9 @@ static void pmem_pagemap_cleanup(struct dev_pagemap *pgmap)
 {
 	struct request_queue *q =
 		container_of(pgmap->ref, struct request_queue, q_usage_counter);
+	struct pmem_device *pmem = pgmap->owner;
 
-	blk_cleanup_disk(queue_to_disk(q));
+	blk_cleanup_disk(pmem->disk);
 }
 
 static void pmem_release_queue(void *pgmap)
@@ -427,6 +428,7 @@ static int pmem_attach_disk(struct device *dev,
 	q = disk->queue;
 
 	pmem->disk = disk;
+	pmem->pgmap.owner = pmem;
 	pmem->pfn_flags = PFN_DEV;
 	pmem->pgmap.ref = &q->q_usage_counter;
 	if (is_nd_pfn(dev)) {