This patch series adds configurable (i.e. user-defined) block device LED triggers. * Triggers can be created, listed, and deleted via sysfs block class attributes (led_trigger_{new,list,del}). * Once created, block device LED triggers are associated with LEDs just like any other LED trigger (via /sys/class/leds/${LED}/trigger). * Each block device gains a new device attribute (led_trigger) that can be used to associate the device with a trigger or clear its association. * My expectation is that most configuration will be done via sysfs (driven by udev), but there also in-kernel APIs for creating, deleting, and (dis)associating triggers. * Multiple devices can be associated with one trigger, so this supports a single LED driven by multiple devices, multiple device-specific LEDs, or arbitrary combinations. Along with support for more than just ATA devices, this is the main difference between this function and the current disk activity trigger. It makes it suitable for use on systems like the Thecus N5550 NAS, which has a software-driven activity LEDs for each disk. * In addition to physical block devices, many types of virtual block devices can drive LEDs; device mapper, MD RAID, and loop devices work (but zram swap devices do not). * The led trigger is "blinked" (75 msec on, 25 msec off) when a request is successfully sent to the low-level driver. The intent is to provide a visual indication of device activity, not any sort of exact measurement. * Related to the previous bullet, if the blink function is unable to immediately acquire a lock on the device's LED trigger information it simply returns, so that I/O processing can continue. It's probably obvious that I'm basically a complete newbie at kernel development, so I welcome feedback. Thanks! Ian Pilcher (8): docs: Add block device LED trigger documentation block: Add block device LED trigger list block: Add kernel APIs to create & delete block device LED triggers block: Add block class attributes to manage LED trigger list block: Add block device LED trigger info to struct genhd block: Add kernel APIs to set & clear per-block device LED triggers block: Add block device attributes to set & clear LED triggers block: Blink device LED when request is sent to low-level driver Documentation/block/index.rst | 1 + Documentation/block/led-triggers.rst | 124 ++++++ block/Kconfig | 10 + block/Makefile | 1 + block/blk-ledtrig.c | 570 +++++++++++++++++++++++++++ block/blk-ledtrig.h | 51 +++ block/blk-mq.c | 2 + block/genhd.c | 14 + include/linux/blk-ledtrig.h | 24 ++ include/linux/genhd.h | 4 + 10 files changed, 801 insertions(+) create mode 100644 Documentation/block/led-triggers.rst create mode 100644 block/blk-ledtrig.c create mode 100644 block/blk-ledtrig.h create mode 100644 include/linux/blk-ledtrig.h -- 2.31.1