bcache stat cache_readaheads was removed from Linux kernel 5.13

[sarbian]

Host operating system: output of uname -a

Linux sarbian 5.13.5-arch1-1 #1 SMP PREEMPT Sun, 25 Jul 2021 18:02:58 +0000 x86_64 GNU/Linux

node_exporter version: output of node_exporter --version

node_exporter, version 1.2.0 (branch: tarball, revision: 1.2.0) build user: someone@builder build date: go version: go1.16.5 platform: linux/amd64

node_exporter command line flags

--collector.systemd --collector.perf --collector.interrupts --no-collector.rapl --collector.bcache --collector.bcache.priorityStats --collector.textfile.directory=/var/lib/prometheus/node-exporter

Are you running node_exporter in Docker?

No

What did you do that produced an error?

Updated to kernel 5.13 from 5.11

What did you expect to see?

Metrics starting with node_bcache like node_bcache_cache_hits_total

What did you see instead?

No bcache metrics at all $ curl -s 192.168.1.3:9100/metrics | grep node_bcache | wc -l
0

Errors filling the service log: Jul 28 20:48:27 sarbian prometheus-node-exporter[2198407]: level=error ts=2021-07-28T18:48:27.138Z caller=collector.go:169 msg="collector failed" name=bcache duration_seconds=0.004825363 err="failed to retrieve bcache stats: failed to read: /sys/fs/bcache/13838fb3-547e-404f-bbd1-d4da4aec10ae/stats_five_minute/cache_readaheads"

$ ls -l ls -l /sys/fs/bcache/13838fb3-547e-404f-bbd1-d4da4aec10ae/stats_five_minute total 0 -r--r--r-- 1 root root 4096 Jul 26 18:10 bypassed -r--r--r-- 1 root root 4096 Jul 26 18:10 cache_bypass_hits -r--r--r-- 1 root root 4096 Jul 26 18:10 cache_bypass_misses -r--r--r-- 1 root root 4096 Jul 28 20:47 cache_hit_ratio -r--r--r-- 1 root root 4096 Jul 26 18:10 cache_hits -r--r--r-- 1 root root 4096 Jul 26 18:10 cache_miss_collisions -r--r--r-- 1 root root 4096 Jul 26 18:10 cache_misses

cache_readaheads was removed in Linux kernel 5.13: https://lkml.org/lkml/2021/5/31/1602

[ryester19]

Can confirm this being an issue for me as well

[espux]

I'm having the same issue, any chance for it to be fixed?

[discordianfish]

It seems straight forward to skip it, just nobody has gotten to do it yet. PRs welcome! :)