[PATCH 2/3] nvmet: add helper to open block device

[Chaitanya Kulkarni]

From: Chaitanya Kulkarni <kch at nvidia.com>

In order to support block device backend in the buffered I/O mode
we keep the ns->bdev handle open so we can reavalidate the ns->size
in nvmet_file_ns_revalidate() using bdev_nr_bytes(). Also, instead of
duplicating the code for opening block device we move the existing code
into the nvme_bdev_open() helper and call from nvmet_bdev_ns_enable().

This newly added helper will be called in the next patch to open and set
the ns->size and ns->blksize_shift values when block device is
configured with buffere I/O mode from file backend code.

Signed-off-by: Chaitanya Kulkarni <kch at nvidia.com>
---
 drivers/nvme/target/io-cmd-bdev.c | 14 ++++++++++++--
 drivers/nvme/target/nvmet.h       |  1 +
 2 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/drivers/nvme/target/io-cmd-bdev.c b/drivers/nvme/target/io-cmd-bdev.c
index 70ca9dfc1771..58907304587e 100644
--- a/drivers/nvme/target/io-cmd-bdev.c
+++ b/drivers/nvme/target/io-cmd-bdev.c
@@ -72,9 +72,9 @@ static void nvmet_bdev_ns_enable_integrity(struct nvmet_ns *ns)
 	}
 }
 
-int nvmet_bdev_ns_enable(struct nvmet_ns *ns)
+int nvmet_bdev_ns_open(struct nvmet_ns *ns)
 {
-	int ret;
+	int ret = 0;
 
 	ns->bdev = blkdev_get_by_path(ns->device_path,
 			FMODE_READ | FMODE_WRITE, NULL);
@@ -89,6 +89,16 @@ int nvmet_bdev_ns_enable(struct nvmet_ns *ns)
 	}
 	ns->size = bdev_nr_bytes(ns->bdev);
 	ns->blksize_shift = blksize_bits(bdev_logical_block_size(ns->bdev));
+	return ret;
+}
+
+int nvmet_bdev_ns_enable(struct nvmet_ns *ns)
+{
+	int ret;
+
+	ret = nvmet_bdev_ns_open(ns);
+	if (ret)
+		return ret;
 
 	ns->pi_type = 0;
 	ns->metadata_size = 0;
diff --git a/drivers/nvme/target/nvmet.h b/drivers/nvme/target/nvmet.h
index af193423c10b..534fe2b32e99 100644
--- a/drivers/nvme/target/nvmet.h
+++ b/drivers/nvme/target/nvmet.h
@@ -533,6 +533,7 @@ extern struct rw_semaphore nvmet_ana_sem;
 
 bool nvmet_host_allowed(struct nvmet_subsys *subsys, const char *hostnqn);
 
+int nvmet_bdev_ns_open(struct nvmet_ns *ns);
 int nvmet_bdev_ns_enable(struct nvmet_ns *ns);
 int nvmet_file_ns_enable(struct nvmet_ns *ns);
 void nvmet_bdev_ns_disable(struct nvmet_ns *ns);
-- 
2.29.0