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Subject[PATCH v9 01/12] nvme-core: introduce nvme_ctrl_get_by_path()
nvme_ctrl_get_by_path() is analagous to blkdev_get_by_path() except it
gets a struct nvme_ctrl from the path to its char dev (/dev/nvme0).
It makes use of filp_open() to open the file and uses the private
data to obtain a pointer to the struct nvme_ctrl. If the fops of the
file do not match, -EINVAL is returned.

The purpose of this function is to support NVMe-OF target passthru.

Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Reviewed-by: Max Gurtovoy <maxg@mellanox.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
---
drivers/nvme/host/core.c | 24 ++++++++++++++++++++++++
drivers/nvme/host/nvme.h | 2 ++
2 files changed, 26 insertions(+)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index fd7dea36c3b6..30f9d91e25e3 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -2950,6 +2950,30 @@ static const struct file_operations nvme_dev_fops = {
.compat_ioctl = nvme_dev_ioctl,
};

+struct nvme_ctrl *nvme_ctrl_get_by_path(const char *path)
+{
+ struct nvme_ctrl *ctrl;
+ struct file *f;
+
+ f = filp_open(path, O_RDWR, 0);
+ if (IS_ERR(f))
+ return ERR_CAST(f);
+
+ if (f->f_op != &nvme_dev_fops) {
+ ctrl = ERR_PTR(-EINVAL);
+ goto out_close;
+ }
+
+ ctrl = f->private_data;
+ nvme_get_ctrl(ctrl);
+
+out_close:
+ filp_close(f, NULL);
+
+ return ctrl;
+}
+EXPORT_SYMBOL_GPL(nvme_ctrl_get_by_path);
+
static ssize_t nvme_sysfs_reset(struct device *dev,
struct device_attribute *attr, const char *buf,
size_t count)
diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
index 38a83ef5bcd3..f83f990e409d 100644
--- a/drivers/nvme/host/nvme.h
+++ b/drivers/nvme/host/nvme.h
@@ -507,6 +507,8 @@ int nvme_get_log(struct nvme_ctrl *ctrl, u32 nsid, u8 log_page, u8 lsp,
extern const struct attribute_group *nvme_ns_id_attr_groups[];
extern const struct block_device_operations nvme_ns_head_ops;

+struct nvme_ctrl *nvme_ctrl_get_by_path(const char *path);
+
#ifdef CONFIG_NVME_MULTIPATH
static inline bool nvme_ctrl_use_ana(struct nvme_ctrl *ctrl)
{
--
2.20.1
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