[RFC v3 2/2] pmem: enable pmem_submit_bio for asynchronous flush

[Pankaj Gupta <pankaj.gupta.linux@gmail.com>]

Return from "pmem_submit_bio" when asynchronous flush is
still in progress in other context.

Signed-off-by: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
---
 drivers/nvdimm/pmem.c        | 15 ++++++++++++---
 drivers/nvdimm/region_devs.c |  4 +++-
 2 files changed, 15 insertions(+), 4 deletions(-)

diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c
index fe7ece1534e1..f20e30277a68 100644
--- a/drivers/nvdimm/pmem.c
+++ b/drivers/nvdimm/pmem.c
@@ -201,8 +201,12 @@ static void pmem_submit_bio(struct bio *bio)
 	struct pmem_device *pmem = bio->bi_bdev->bd_disk->private_data;
 	struct nd_region *nd_region = to_region(pmem);
 
-	if (bio->bi_opf & REQ_PREFLUSH)
+	if (bio->bi_opf & REQ_PREFLUSH) {
 		ret = nvdimm_flush(nd_region, bio);
+		/* asynchronous flush completes in other context */
+		if (ret == -EINPROGRESS)
+			return;
+	}
 
 	do_acct = blk_queue_io_stat(bio->bi_bdev->bd_disk->queue);
 	if (do_acct)
@@ -222,13 +226,18 @@ static void pmem_submit_bio(struct bio *bio)
 	if (do_acct)
 		bio_end_io_acct(bio, start);
 
-	if (bio->bi_opf & REQ_FUA)
+	if (bio->bi_opf & REQ_FUA) {
 		ret = nvdimm_flush(nd_region, bio);
+		/* asynchronous flush completes in other context */
+		if (ret == -EINPROGRESS)
+			return;
+	}
 
 	if (ret)
 		bio->bi_status = errno_to_blk_status(ret);
 
-	bio_endio(bio);
+	if (bio)
+		bio_endio(bio);
 }
 
 static int pmem_rw_page(struct block_device *bdev, sector_t sector,
diff --git a/drivers/nvdimm/region_devs.c b/drivers/nvdimm/region_devs.c
index 9ccf3d608799..8512d2eaed4e 100644
--- a/drivers/nvdimm/region_devs.c
+++ b/drivers/nvdimm/region_devs.c
@@ -1190,7 +1190,9 @@ int nvdimm_flush(struct nd_region *nd_region, struct bio *bio)
 	if (!nd_region->flush)
 		rc = generic_nvdimm_flush(nd_region);
 	else {
-		if (nd_region->flush(nd_region, bio))
+		rc = nd_region->flush(nd_region, bio);
+		/* ongoing flush in other context */
+		if (rc && rc != -EINPROGRESS)
 			rc = -EIO;
 	}
 
-- 
2.25.1