From: Sagi Grimberg <sagig@mellanox.com>
Date: Wed, 10 Feb 2016 18:03:29 +0000 (-0800)
Subject: nvme/host: reference the fabric module for each bdev open callout
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=e439bb12e75c2807029853493fa787c6d70c763a;p=linux-beck.git

nvme/host: reference the fabric module for each bdev open callout

We don't want to be able to unload the fabric driver when we have
openened referenced to our namespaces. Thus, for each nvme_open we
take a reference on the fabric driver and put it in nvme_release.
This behavior is consistent with the scsi model.

This resolves the panic when unloading a fabric module with
mpath holders.

Signed-off-by: Sagi Grimberg <sagig@mellanox.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Ian Bakshan <ianb@mellanox.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Ming Lin <ming.l@ssi.samsung.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
---

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index a7c29f24976c..c9cd07f02cc2 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -71,11 +71,21 @@ static struct nvme_ns *nvme_get_ns_from_disk(struct gendisk *disk)
 
 	spin_lock(&dev_list_lock);
 	ns = disk->private_data;
-	if (ns && !kref_get_unless_zero(&ns->kref))
-		ns = NULL;
+	if (ns) {
+		if (!kref_get_unless_zero(&ns->kref))
+			goto fail;
+		if (!try_module_get(ns->ctrl->ops->module))
+			goto fail_put_ns;
+	}
 	spin_unlock(&dev_list_lock);
 
 	return ns;
+
+fail_put_ns:
+	kref_put(&ns->kref, nvme_free_ns);
+fail:
+	spin_unlock(&dev_list_lock);
+	return NULL;
 }
 
 void nvme_requeue_req(struct request *req)
@@ -499,7 +509,10 @@ static int nvme_open(struct block_device *bdev, fmode_t mode)
 
 static void nvme_release(struct gendisk *disk, fmode_t mode)
 {
-	nvme_put_ns(disk->private_data);
+	struct nvme_ns *ns = disk->private_data;
+
+	module_put(ns->ctrl->ops->module);
+	nvme_put_ns(ns);
 }
 
 static int nvme_getgeo(struct block_device *bdev, struct hd_geometry *geo)
diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
index 4fb5bb737868..9f77386f7d1e 100644
--- a/drivers/nvme/host/nvme.h
+++ b/drivers/nvme/host/nvme.h
@@ -117,6 +117,7 @@ struct nvme_ns {
 };
 
 struct nvme_ctrl_ops {
+	struct module *module;
 	int (*reg_read32)(struct nvme_ctrl *ctrl, u32 off, u32 *val);
 	int (*reg_write32)(struct nvme_ctrl *ctrl, u32 off, u32 val);
 	int (*reg_read64)(struct nvme_ctrl *ctrl, u32 off, u64 *val);
diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index f2f55b504cf2..cb303ac91b9d 100644
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -2036,6 +2036,7 @@ static int nvme_pci_reset_ctrl(struct nvme_ctrl *ctrl)
 }
 
 static const struct nvme_ctrl_ops nvme_pci_ctrl_ops = {
+	.module			= THIS_MODULE,
 	.reg_read32		= nvme_pci_reg_read32,
 	.reg_write32		= nvme_pci_reg_write32,
 	.reg_read64		= nvme_pci_reg_read64,