| #!/bin/sh |
| # |
| # This program reads the bcache superblock on bcacheX slaves to extract the |
| # dev.uuid and dev.label which refer to a specific backing device. |
| # |
| # It integrates with udev 'import' by writing CACHED_UUID=X and optionally |
| # CACHED_LABEL=X for the backing device of the provided bcache device. |
| # Ignore caching devices by skipping unless sb.version=1 |
| # |
| # There is 1 and only 1 backing device (slaves/*) for a bcache device. |
| |
| TEMPNODE=${1} # /dev/bcacheN |
| DEVNAME=${TEMPNODE##*/} # /dev/bcacheN -> bcacheN |
| |
| for slave in "/sys/class/block/$DEVNAME/slaves"/*; do |
| [ -d "$slave" ] || continue |
| bcache-super-show "/dev/${slave##*/}" | |
| awk '$1 == "sb.version" { sbver=$2; } |
| $1 == "dev.uuid" { uuid=$2; } |
| $1 == "dev.label" && $2 != "(empty)" { label=$2; } |
| END { |
| if (sbver == 1 && uuid) { |
| print("CACHED_UUID=" uuid) |
| if (label) print("CACHED_LABEL=" label) |
| exit(0) |
| } |
| exit(1); |
| }' |
| # awk exits 0 if it found a backing device. |
| [ $? -eq 0 ] && exit 0 |
| done |