69-bcache.rules Tries to Re-register bcache that is already registered and attached

[Joshua Diamant]

I have been using bcache for two drives (/dev/sda and /dev/sdb). The cache is registered correctly, but it looks like the UDEV rules in 69-bcache.rules need to be tweaked to identify if a bcache is already mounted when jumping to bcache_backing_found (line 22 is where the bcache-register command is run).

/var/log/messages

Sep 15 10:29:15 HTPC-Xeon systemd-udevd[3213322]: sda: Process 'bcache-register /dev/sda' failed with exit code 1.
Sep 15 10:29:15 HTPC-Xeon kernel: [132665.473836] bcache: register_bcache() error : device already registered
Sep 15 10:29:17 HTPC-Xeon systemd-udevd[3213322]: sdb: Process 'bcache-register /dev/sdb' failed with exit code 1.
Sep 15 10:29:17 HTPC-Xeon kernel: [132668.109215] bcache: register_bcache() error : device already registered
Sep 15 10:29:18 HTPC-Xeon systemd-udevd[3213433]: sda: Process 'bcache-register /dev/sda' failed with exit code 1.
Sep 15 10:29:18 HTPC-Xeon kernel: [132668.472411] bcache: register_bcache() error : device already registered
Sep 15 10:29:19 HTPC-Xeon systemd-udevd[3213433]: message repeated 46 times: [ sda: Process 'bcache-register /dev/sda' failed with exit code 1.]
Sep 15 10:29:19 HTPC-Xeon systemd-udevd[3213481]: sdb: Process 'bcache-register /dev/sdb' failed with exit code 1.
Sep 15 10:29:19 HTPC-Xeon kernel: [132669.919959] bcache: register_bcache() error : device already registered
Sep 15 10:29:19 HTPC-Xeon systemd-udevd[3213433]: sdb: Process 'bcache-register /dev/sdb' failed with exit code 1.
Sep 15 10:29:19 HTPC-Xeon kernel: [132669.970662] bcache: register_bcache() error : device already registered
Sep 15 10:29:20 HTPC-Xeon systemd-udevd[3213433]: message repeated 45 times: [ sdb: Process 'bcache-register /dev/sdb' failed with exit code 1.]

root@HTPC-Xeon:/# bcache-super-show /dev/sda
sb.magic ok
sb.first_sector 8 [match]
sb.csum 6AEA0E3D0A952CEF [match]
sb.version 4 [backing device]

dev.label NAS
dev.uuid 6b52e51f-6c9f-4b7e-a245-9d2b63fc4bc5
dev.sectors_per_block 1
dev.sectors_per_bucket 1024
dev.data.first_sector 645120
dev.data.cache_mode 1 [writeback]
dev.data.cache_state 1 [clean]

cset.uuid e960d897-9990-47ab-90f9-69163b7d45b0

root@HTPC-Xeon:/# bcache-super-show /dev/sdb
sb.magic ok
sb.first_sector 8 [match]
sb.csum D19F0AAACEBB036B [match]
sb.version 4 [backing device]

dev.label BACKUP
dev.uuid 6c18a7f6-73ba-46a1-973f-9f296a42175b
dev.sectors_per_block 1
dev.sectors_per_bucket 1024
dev.data.first_sector 645120
dev.data.cache_mode 1 [writeback]
dev.data.cache_state 2 [dirty]

cset.uuid e960d897-9990-47ab-90f9-69163b7d45b0

root@HTPC-Xeon:/# bcache-status
--- bcache ---
Device /dev/sda (8:0)
UUID e960d897-9990-47ab-90f9-69163b7d45b0
Block Size 0.50KiB
Bucket Size 512.00KiB
Congested? False
Read Congestion 2.0ms
Write Congestion 20.0ms
Total Cache Size 1.09TiB
Total Cache Used 1.09TiB (100%)
Total Cache Unused 0B (0%)
Dirty Data 0.50KiB (0%)
Evictable Cache 905.42GiB (81%)
Replacement Policy [lru] fifo random
Cache Mode writethrough [writeback] writearound none
Total Hits 1916371 (63%)
Total Misses 1117878
Total Bypass Hits 791703 (24%)
Total Bypass Misses 2470122
Total Bypassed 103.00GiB

root@HTPC-Xeon:/# apt-cache policy bcache-tools
bcache-tools:
  Installed: 1.0.8-4ubuntu3
  Candidate: 1.0.8-4ubuntu3
  Version table:
 *** 1.0.8-4ubuntu3 500
        500 http://us.archive.ubuntu.com/ubuntu jammy/main amd64 Packages
        100 /var/lib/dpkg/status
root@HTPC-Xeon:/# lsb_release -rd
Description: Ubuntu 22.04.1 LTS
Release: 22.04

[Joshua Diamant (joshdi)]

If I add this line below after line 5 of /lib/udev/rules.d/69-bcache.rules, the errors go away and when I reboot the bcache is correctly mounted/registered.

ACTION=="change", GOTO="bcache_end"

Is there any risk to adding this? Is there a better way to fix this problem? Thank you!

[Lena Voytek (lvoytek)]

Hello,
Thank you for taking the time to make this bug report. This seems like a valid solution to the issue, but I'd be curious to see if upstream has anything specific to say about it. I noticed you added the bug upstream, thank you for that. I will add its status here. In the meantime I created a PPA that contains your change on line 6 of 69-bcache.rules, located here if you need it:
https://launchpad.net/~lvoytek/+archive/ubuntu/bcache-fix-attempted-re-register-jammy