[PATCH] nvme: add 'fail_if_no_path' sysfs attribute

Hannes Reinecke
2021-02-19T14:47:10Z

In some setups like RAID we need to return an I/O error
once all paths are unavailable to allow the upper layers
to start their own error recovery (like redirecting I/O
to other mirrors).
This patch adds a sysfs attribute 'fail_if_no_path' to
allow the admin to enable that behaviour instead of the
current 'queue until a path becomes available' policy.

Signed-off-by: Hannes Reinecke <hare@suse.de>
---
drivers/nvme/host/core.c | 5 +++++
drivers/nvme/host/multipath.c | 36 ++++++++++++++++++++++++++++++++++-
drivers/nvme/host/nvme.h | 2 ++
3 files changed, 42 insertions(+), 1 deletion(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 9879153d8d28..eee42d0b3400 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -3440,6 +3440,7 @@ static struct attribute *nvme_ns_id_attrs[] = {
#ifdef CONFIG_NVME_MULTIPATH
&dev_attr_ana_grpid.attr,
&dev_attr_ana_state.attr,
+ &dev_attr_fail_if_no_path.attr,
#endif
NULL,
};
@@ -3470,6 +3471,10 @@ static umode_t nvme_ns_id_attrs_are_visible(struct kobject *kobj,
if (!nvme_ctrl_use_ana(nvme_get_ns_from_dev(dev)->ctrl))
return 0;
}
+ if (a == &dev_attr_fail_if_no_path.attr) {
+ if (dev_to_disk(dev)->fops == &nvme_bdev_ops)
+ return 0;
+ }
#endif
return a->mode;
}
diff --git a/drivers/nvme/host/multipath.c b/drivers/nvme/host/multipath.c
index 9ac762b28811..47fecb3f9434 100644
--- a/drivers/nvme/host/multipath.c
+++ b/drivers/nvme/host/multipath.c
@@ -283,10 +283,13 @@ static bool nvme_available_path(struct nvme_ns_head *head)
continue;
switch (ns->ctrl->state) {
case NVME_CTRL_LIVE:
+ return true;
case NVME_CTRL_RESETTING:
case NVME_CTRL_CONNECTING:
/* fallthru */
- return true;
+ if (!test_bit(NVME_NSHEAD_FAIL_IF_NO_PATH,
+ &head->flags))
+ return true;
default:
break;
}
@@ -641,6 +644,37 @@ static ssize_t ana_state_show(struct device *dev, struct device_attribute *attr,
}
DEVICE_ATTR_RO(ana_state);

+static ssize_t fail_if_no_path_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct gendisk *disk = dev_to_disk(dev);
+ struct nvme_ns_head *head = disk->private_data;
+
+ return sprintf(buf, "%d\n",
+ test_bit(NVME_NSHEAD_FAIL_IF_NO_PATH, &head->flags) ?
+ 1 : 0);
+}
+
+static ssize_t fail_if_no_path_store(struct device *dev,
+ struct device_attribute *attr, const char *buf, size_t count)
+{
+ struct gendisk *disk = dev_to_disk(dev);
+ struct nvme_ns_head *head = disk->private_data;
+ int fail_if_no_path, err;
+
+ err = kstrtoint(buf, 10, &fail_if_no_path);
+ if (err)
+ return -EINVAL;
+
+ else if (fail_if_no_path <= 0)
+ clear_bit(NVME_NSHEAD_FAIL_IF_NO_PATH, &head->flags);
+ else
+ set_bit(NVME_NSHEAD_FAIL_IF_NO_PATH, &head->flags);
+ return count;
+}
+DEVICE_ATTR(fail_if_no_path, S_IRUGO | S_IWUSR,
+ fail_if_no_path_show, fail_if_no_path_store);
+
static int nvme_lookup_ana_group_desc(struct nvme_ctrl *ctrl,
struct nvme_ana_group_desc *desc, void *data)
{
diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
index 09d142a9628c..f3ba741d44d0 100644
--- a/drivers/nvme/host/nvme.h
+++ b/drivers/nvme/host/nvme.h
@@ -411,6 +411,7 @@ struct nvme_ns_head {
struct mutex lock;
unsigned long flags;
#define NVME_NSHEAD_DISK_LIVE 0
+#define NVME_NSHEAD_FAIL_IF_NO_PATH 1
struct nvme_ns __rcu *current_path[];
#endif
};
@@ -684,6 +685,7 @@ static inline void nvme_trace_bio_complete(struct request *req)

extern struct device_attribute dev_attr_ana_grpid;
extern struct device_attribute dev_attr_ana_state;
+extern struct device_attribute dev_attr_fail_if_no_path;
extern struct device_attribute subsys_attr_iopolicy;

#else
--
2.29.2