This adds systemd-report-diskhealth, which reports the key health
parameters of NVMe and ATA disks, plus basic identity information about
all disks.
For all hardware backed disks (including USB ones) size, logical and
physical sector size are reported from sysfs, and model, vendor and serial
from the udev database, preferring hwdb data, and falling back to the PCI
or USB device if the block device itself carries no model/vendor
information.
For NVMe disks the SMART / Health Information log page is read via the
NVMe admin command ioctl, and the critical warning bitmask, available
spare, percentage used and media error counter are reported. For ATA
disks with SMART enabled the overall SMART status is read via SG_IO ATA
pass-through, and for rotating ones also the reallocated, pending and
offline uncorrectable sector counts (SMART attributes 5, 197, 198), since
various SSD vendors reused these attributes with incompatible semantics.
Power-on hours and power cycle counts are reported for both
under a common metric name, for ATA disks taken from the standardized
Device Statistics log rather than from the vendor specific SMART
attributes. ATA disks in standby are not queried, in order not to spin
them up, and neither are ATA disks behind USB bridges.
The temperature is deliberately not reported, since systemd-report-hwmon
covers that already.
