Ridiculous or not, here is version 3 of the block device trigger for "freaking blinkenlights". It addresses basically all of the points raised in response to the v2 patchset. * The main body of the code is moved from the block directory into the LED triggers directory (drivers/leds/trigger/ledtrig-blkdev.c) The downside of this is that it requires adding an API to the block subsystem - get_disk_by_name() - which allows the trigger code to resolve a gendisk when asked to monitor it. I know of no good way to do this today, and I don't know of a good way to implement the sysfs API requested by Pavel and Marek without something like this API. Other than that, changes to the block subsystem are as minimal as I can make them - a single pointer added to struct gendisk and init/cleanup calls when a gendisk is added or deleted. * This also implements Marek's suggestion of periodically checking devices for activity, rather than directly blinking LEDs in the I/O path. This change has the unanticipated benefit of making the trigger work on pretty much all types of virtual block devices (device mapper, MD RAID, zRAM, etc.), as well as NVMe SSDs. * Relationships between devices and LEDs are now many-to-many. An LED can monitor multiple devices, and multiple LEDs can monitor any one device. The current "associations" are reflected in two sysfs directories. - /sys/class/leds/<led>/block_devices contains links to all devices associated with an LED, and - /sys/block/<disk>/blkdev_leds contains links to all LEDs with which the device is associated. (The latter directory only exists when the device is associated with at least one LED.) * Each LED can be set to show read activity, write activity, or both. Discards and cache flushes are considered to be writes, as they affect the state of the device's non-volatile storage. Ian Pilcher (18): docs: Add block device (blkdev) LED trigger documentation block: Add get_disk_by_name() for use by blkdev LED trigger ledtrig-blkdev: Add file (ledtrig-blkdev.c) for block device LED trigger ledtrig-blkdev: Add misc. helper functions to blkdev LED trigger ledtrig-blkdev: Periodically check devices for activity & blink LEDs block: Add LED trigger pointer to struct gendisk ledtrig-blkdev: Add function to initialize gendisk ledtrig member ledtrig-blkdev: Add function to remove LED/device association ledtrig-blkdev: Add function to disassociate a device from all LEDs block: Call LED trigger init/cleanup functions ledtrig-blkdev: Add function to associate a device with an LED ledtrig-blkdev: Add sysfs attributes to [dis]associate LEDs & devices ledtrig-blkdev: Add blink_time & interval sysfs attributes ledtrig-blkdev: Add mode (read/write/rw) sysfs attributue ledtrig-blkdev: Add function to associate blkdev trigger with LED ledtrig-blkdev: Add function to disassociate an LED from the trigger ledtrig-blkdev: Add initialization function ledtrig-blkdev: Add config option to enable the trigger Documentation/ABI/testing/sysfs-block | 9 + .../testing/sysfs-class-led-trigger-blkdev | 48 ++ Documentation/leds/index.rst | 1 + Documentation/leds/ledtrig-blkdev.rst | 132 +++ block/genhd.c | 28 + drivers/leds/trigger/Kconfig | 9 + drivers/leds/trigger/Makefile | 1 + drivers/leds/trigger/ledtrig-blkdev.c | 770 ++++++++++++++++++ include/linux/genhd.h | 13 + include/linux/leds.h | 20 + 10 files changed, 1031 insertions(+) create mode 100644 Documentation/ABI/testing/sysfs-class-led-trigger-blkdev create mode 100644 Documentation/leds/ledtrig-blkdev.rst create mode 100644 drivers/leds/trigger/ledtrig-blkdev.c -- 2.31.1