[PATCH 1/1] Revert "nvme: don't bother to look up a namespace for controller ioctls"

[Minwoo Im]

This reverts commit 3557a4409701a132e8f86ad234ac8cf6e97b052e.

If we simply retrieve namespace from the given subsystem, controller to
be retrieved might not be the one which is really attached to the given
namespace.  We should consider the namespace attachment with controllers
in the subsystem, so this patch simply reverts the previous commit.

Signed-off-by: Minwoo Im <minwoo.im.dev at gmail.com>
---
 drivers/nvme/host/ioctl.c | 47 +++++++++++++++++++++------------------
 1 file changed, 25 insertions(+), 22 deletions(-)

diff --git a/drivers/nvme/host/ioctl.c b/drivers/nvme/host/ioctl.c
index 8e05d65c9e93..9494e3d11e89 100644
--- a/drivers/nvme/host/ioctl.c
+++ b/drivers/nvme/host/ioctl.c
@@ -358,40 +358,43 @@ int nvme_ioctl(struct block_device *bdev, fmode_t mode,
 }
 
 #ifdef CONFIG_NVME_MULTIPATH
-static int nvme_ns_head_ctrl_ioctl(struct nvme_ns_head *head,
-		unsigned int cmd, void __user *argp)
+static int nvme_ns_head_ctrl_ioctl(struct nvme_ns *ns, unsigned int cmd,
+		void __user *argp, struct nvme_ns_head *head, int srcu_idx)
 {
-	struct nvme_ctrl *ctrl = nvme_find_get_live_ctrl(head->subsys);
+	struct nvme_ctrl *ctrl = ns->ctrl;
 	int ret;
 
-	if (IS_ERR(ctrl))
-		return PTR_ERR(ctrl);
-	ret = nvme_ctrl_ioctl(ctrl, cmd, argp);
-	nvme_put_ctrl(ctrl);
-	return ret;
-}
+	nvme_get_ctrl(ns->ctrl);
+	nvme_put_ns_from_disk(head, srcu_idx);
+	ret = nvme_ctrl_ioctl(ns->ctrl, cmd, argp);
 
-static int nvme_ns_head_ns_ioctl(struct nvme_ns_head *head,
-		unsigned int cmd, void __user *argp)
-{
-	int srcu_idx = srcu_read_lock(&head->srcu);
-	struct nvme_ns *ns = nvme_find_path(head);
-	int ret = -EWOULDBLOCK;
-
-	if (ns)
-		ret = nvme_ns_ioctl(ns, cmd, argp);
-	srcu_read_unlock(&head->srcu, srcu_idx);
+	nvme_put_ctrl(ctrl);
 	return ret;
 }
 
 int nvme_ns_head_ioctl(struct block_device *bdev, fmode_t mode,
 		unsigned int cmd, unsigned long arg)
 {
-	struct nvme_ns_head *head = bdev->bd_disk->private_data;
+	struct nvme_ns_head *head = NULL;
+	void __user *argp = (void __user *)arg;
+	struct nvme_ns *ns;
+	int srcu_idx, ret;
+
+	ns = nvme_get_ns_from_disk(bdev->bd_disk, &head, &srcu_idx);
+	if (unlikely(!ns))
+		return -EWOULDBLOCK;
 
+	/*
+	 * Handle ioctls that apply to the controller instead of the namespace
+	 * seperately and drop the ns SRCU reference early.  This avoids a
+	 * deadlock when deleting namespaces using the passthrough interface.
+	 */
 	if (is_ctrl_ioctl(cmd))
-		return nvme_ns_head_ctrl_ioctl(head, cmd, (void __user *)arg);
-	return nvme_ns_head_ns_ioctl(head, cmd, (void __user *)arg);
+		return nvme_ns_head_ctrl_ioctl(ns, cmd, argp, head, srcu_idx);
+
+	ret = nvme_ns_ioctl(ns, cmd, argp);
+	nvme_put_ns_from_disk(head, srcu_idx);
+	return ret;
 }
 #endif /* CONFIG_NVME_MULTIPATH */
 
-- 
2.27.0