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>
(cherry picked from commit e439bb12e75c2807029853493fa787c6d70c763a)

Orabug: 25130845

Signed-off-by: Ashok Vairavan <ashok.vairavan@oracle.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index a90819b064a9f2da593ea9aa86ed020a3bddffdd..970c19e8079a5b964eac106b58b67079687cdc4f 100644 (file)
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -68,11 +68,21 @@ 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)
@@ -486,7 +496,10 @@ 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 7ffc0834302c9dcd8753c9accc1a3d466ec73b8d..e54bedf1c089b84252026a7360d5b7426dbf9f97 100644 (file)
--- a/drivers/nvme/host/nvme.h
+++ b/drivers/nvme/host/nvme.h
@@ -110,6 +110,7 @@ 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 4fe21962be46c87e2cfc5fc9b6b5d89f7d00211a..66a92e5813660783920c95582ca79ec57642028a 100644 (file)
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -2076,6 +2076,7 @@ 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,