2020-05-14 17:26:03

by Logan Gunthorpe

Subject: [PATCH v13 5/9] 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 <[email protected]>
Reviewed-by: Max Gurtovoy <[email protected]>
Reviewed-by: Sagi Grimberg <[email protected]>
---
drivers/nvme/host/core.c | 31 +++++++++++++++++++++++++++++++
drivers/nvme/host/nvme.h | 9 +++++++++
2 files changed, 40 insertions(+)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 2ead7ad45a9d..2604971362d8 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -4305,6 +4305,37 @@ void nvme_sync_queues(struct nvme_ctrl *ctrl)
}
EXPORT_SYMBOL_GPL(nvme_sync_queues);

+#ifdef CONFIG_NVME_TARGET_PASSTHRU
+/*
+ * The exports that follow within this ifdef are only for
+ * use by the nvmet-passthru and should not be used for
+ * other things.
+ */
+
+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);
+#endif /* CONFIG_NVME_TARGET_PASSTHRU */
+
/*
* Check we didn't inadvertently grow the command structure sizes:
*/
diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
index 2e04a36296d9..9195dd97b61b 100644
--- a/drivers/nvme/host/nvme.h
+++ b/drivers/nvme/host/nvme.h
@@ -689,4 +689,13 @@ void nvme_hwmon_init(struct nvme_ctrl *ctrl);
static inline void nvme_hwmon_init(struct nvme_ctrl *ctrl) { }
#endif

+#ifdef CONFIG_NVME_TARGET_PASSTHRU
+/*
+ * The exports that follow within this ifdef are only for
+ * use by the nvmet-passthru and should not be used for
+ * other things.
+ */
+struct nvme_ctrl *nvme_ctrl_get_by_path(const char *path);
+#endif /* CONFIG_NVME_TARGET_PASSTHRU */
+
#endif /* _NVME_H */
--
2.20.1

2020-06-11 23:05:25

by Chaitanya Kulkarni

Subject: Re: [PATCH v13 5/9] nvme-core: Introduce nvme_ctrl_get_by_path()

On 5/14/20 10:23 AM, Logan Gunthorpe wrote:
> +#ifdef CONFIG_NVME_TARGET_PASSTHRU
> +/*
> + * The exports that follow within this ifdef are only for
> + * use by the nvmet-passthru and should not be used for
> + * other things.
> + */

The above comment is duplicate #ifdef is self explanatory and I didn't
find similar style in existing repo (e.g. CONFIG_NVME_MULTIPATH,
CONFIG_BLK_SED_OPAL) so let's not introduce new style which will create
confusion to future code.

2020-06-11 23:12:33

by Logan Gunthorpe

Subject: Re: [PATCH v13 5/9] nvme-core: Introduce nvme_ctrl_get_by_path()

On 2020-06-11 5:02 p.m., Chaitanya Kulkarni wrote:
> On 5/14/20 10:23 AM, Logan Gunthorpe wrote:
>> +#ifdef CONFIG_NVME_TARGET_PASSTHRU
>> +/*
>> + * The exports that follow within this ifdef are only for
>> + * use by the nvmet-passthru and should not be used for
>> + * other things.
>> + */
>
> The above comment is duplicate #ifdef is self explanatory and I didn't
> find similar style in existing repo (e.g. CONFIG_NVME_MULTIPATH,
> CONFIG_BLK_SED_OPAL) so let's not introduce new style which will create
> confusion to future code.

Christoph specifically asked for this ifdef and comment.

Logan