[PATCH v6 03/16] nvme: Added a newsysfs attribute appid_store

[Muneendra]

Added a new sysfs attribute appid_store under
/sys/class/fc/fc_udev_device/*

With this new interface the user can set the application identfier
in  the blkcg associted with cgroup id.

Once the application identifer has set with this interface it allows
identification of traffic sources at an individual cgroup based
Applications (ex:virtual machine (VM))level in both host and
fabric infrastructure(FC).

Below is the interface provided to set the app_id

echo "<cgroupid>:<appid>" >> /sys/class/fc/fc_udev_device/appid_store
echo "457E:100000109b521d27" >> /sys/class/fc/fc_udev_device/appid_store

Signed-off-by: Muneendra <muneendra.kumar at broadcom.com>

---
v6:
No change

v5:
Replaced APPID_LEN with FC_APPID_LEN

v4:
No change

v3:
Replaced blkcg_set_app_identifier function with blkcg_set_fc_appid

v2:
New Patch
---
 drivers/nvme/host/fc.c | 73 +++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 72 insertions(+), 1 deletion(-)

diff --git a/drivers/nvme/host/fc.c b/drivers/nvme/host/fc.c
index 3c002bdcace3..ed689ba773b1 100644
--- a/drivers/nvme/host/fc.c
+++ b/drivers/nvme/host/fc.c
@@ -9,7 +9,7 @@
 #include <uapi/scsi/fc/fc_els.h>
 #include <linux/delay.h>
 #include <linux/overflow.h>
-
+#include <linux/blk-cgroup.h>
 #include "nvme.h"
 #include "fabrics.h"
 #include <linux/nvme-fc-driver.h>
@@ -3821,10 +3821,81 @@ static ssize_t nvme_fc_nvme_discovery_store(struct device *dev,
 
 	return count;
 }
+
+/*parse the Cgroup id from a buf and returns the length of cgrpid*/
+static int fc_parse_cgrpid(const char *buf, u64 *id)
+{
+	char cgrp_id[16+1];
+	int cgrpid_len, j;
+
+	memset(cgrp_id, 0x0, sizeof(cgrp_id));
+	for (cgrpid_len = 0, j = 0; cgrpid_len < 17; cgrpid_len++) {
+		if (buf[cgrpid_len] != ':')
+			cgrp_id[cgrpid_len] = buf[cgrpid_len];
+		else {
+			j = 1;
+			break;
+		}
+	}
+	if (!j)
+		return -EINVAL;
+	if (kstrtou64(cgrp_id, 16, id) < 0)
+		return -EINVAL;
+	return cgrpid_len;
+}
+
+/*
+ * fc_update_appid :parses and updates the appid in the blkcg associated with
+ * cgroupid.
+ * @buf: buf contains both cgrpid and appid info
+ * @count: size of the buffer
+ */
+static int fc_update_appid(const char *buf, size_t count)
+{
+	u64 cgrp_id;
+	int appid_len = 0;
+	int cgrpid_len = 0;
+	char app_id[FC_APPID_LEN];
+	int ret = 0;
+
+	if (buf[count-1] == '\n')
+		count--;
+
+	if ((count > (16+1+FC_APPID_LEN)) || (!strchr(buf, ':')))
+		return -EINVAL;
+
+	cgrpid_len = fc_parse_cgrpid(buf, &cgrp_id);
+	if (cgrpid_len < 0)
+		return -EINVAL;
+	/*appid len is count - cgrpid_len -1 (: + \n) */
+	appid_len = count - cgrpid_len - 1;
+	if (appid_len > FC_APPID_LEN)
+		return -EINVAL;
+
+	memset(app_id, 0x0, sizeof(app_id));
+	memcpy(app_id, &buf[cgrpid_len+1], appid_len);
+	ret = blkcg_set_fc_appid(app_id, cgrp_id, sizeof(app_id));
+	if (ret < 0)
+		return ret;
+	return count;
+}
+
+static ssize_t fc_appid_store(struct device *dev,
+		struct device_attribute *attr, const char *buf, size_t count)
+{
+	int ret  = 0;
+
+	ret = fc_update_appid(buf, count);
+	if (ret < 0)
+		return -EINVAL;
+	return count;
+}
 static DEVICE_ATTR(nvme_discovery, 0200, NULL, nvme_fc_nvme_discovery_store);
+static DEVICE_ATTR(appid_store, 0200, NULL, fc_appid_store);
 
 static struct attribute *nvme_fc_attrs[] = {
 	&dev_attr_nvme_discovery.attr,
+	&dev_attr_appid_store.attr,
 	NULL
 };
 
-- 
2.26.2


-- 
This electronic communication and the information and any files transmitted 
with it, or attached to it, are confidential and are intended solely for 
the use of the individual or entity to whom it is addressed and may contain 
information that is confidential, legally privileged, protected by privacy 
laws, or otherwise restricted from disclosure to anyone else. If you are 
not the intended recipient or the person responsible for delivering the 
e-mail to the intended recipient, you are hereby notified that any use, 
copying, distributing, dissemination, forwarding, printing, or copying of 
this e-mail is strictly prohibited. If you received this e-mail in error, 
please return the e-mail to the sender, delete it from your computer, and 
destroy any printed copy of it.
-------------- next part --------------
A non-text attachment was scrubbed...
Name: smime.p7s
Type: application/pkcs7-signature
Size: 4177 bytes
Desc: S/MIME Cryptographic Signature
URL: <http://lists.infradead.org/pipermail/linux-nvme/attachments/20201222/950d2b3a/attachment.p7s>