scsi: documentation: Document Fibre Channel sysfs node for appid

Update documentation for sysfs node within /sys/class/fc/fc_udev_device/.

Link: https://lore.kernel.org/r/20210913015853.2086512-1-muneendra.kumar@broadcom.com
Reviewed-by: Himanshu Madhani <himanshu.madhani@oracle.com>
Signed-off-by: Muneendra Kumar <muneendra.kumar@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
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Muneendra Kumar 2021-09-12 18:58:53 -07:00 committed by Martin K. Petersen
parent 0a5e20fc8c
commit e9d73bfa8e

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What: /sys/class/fc/fc_udev_device/appid_store
Date: Aug 2021
Contact: Muneendra Kumar <muneendra.kumar@broadconm.com>
Description:
This interface allows an admin to set an FC application
identifier in the blkcg associated with a cgroup id. The
identifier is typically a UUID that is associated with
an application or logical entity such as a virtual
machine or container group. The application or logical
entity utilizes a block device via the cgroup id.
FC adapter drivers may query the identifier and tag FC
traffic based on the identifier. FC host and FC fabric
entities can utilize the application id and FC traffic
tag to identify traffic sources.
The interface expects a string "<cgroupid>:<appid>" where:
<cgroupid> is inode of the cgroup in hexadecimal
<appid> is user provided string upto 128 characters
in length.
If an appid_store is done for a cgroup id that already
has an appid set, the new value will override the
previous value.
If an admin wants to remove an FC application identifier
from a cgroup, an appid_store should be done with the
following string: "<cgroupid>:"