I've been using btrfs for my primary file system for a Linux Mint 20 install I did a couple of months ago. Today I had reason to want to extend the partition the btrfs filesystem is on, and gparted did a filesystem check beforehand and then refused to extend the partition due to file system errors. So I did a btrfs check on the partition (while it was unmounted; booted from a "Live CD" USB stick) and got 13 errors saying Counts for qgroup id 0/1234 are different (with varying ID numbers; below).
According to Wikipedia, quota groups (qgroups) relate to limiting the size of snapshots. I've only done snapshots indirectly via timeshift so I'm afraid I don't know the details there. I can get rid of those snapshots if needed.
What do the errors mean, and how do I fix them? The manpage for btrfs check is really quite adamant about not using the --repair option without knowing what you're doing...which I don't. :-)
Here is the output of the btrfs check (whitespace may have been slightly mangled, I copied and pasted to a Google Docs doc while running the Live CD and didn't think about whitespace):
Opening filesystem to check... Checking filesystem on /dev/sda3 UUID: 1cf835e0-2f64-493e-ae63-035dbd007cc3 [1/7] checking root items [2/7] checking extents [3/7] checking free space cache [4/7] checking fs roots [5/7] checking only csums items (without verifying data) [6/7] checking root refs [7/7] checking quota groups Counts for qgroup id: 0/256 are different our: referenced 15140220928 referenced compressed 15140220928 disk: referenced 15170641920 referenced compressed 15170641920 diff: referenced -30420992 referenced compressed -30420992 our: exclusive 847220736 exclusive compressed 847220736 disk: exclusive 847220736 exclusive compressed 847220736 Counts for qgroup id: 0/257 are different our: referenced 1181160329216 referenced compressed 1181160329216 disk: referenced 1181156818944 referenced compressed 1181156818944 diff: referenced 3510272 referenced compressed 3510272 our: exclusive 1181160329216 exclusive compressed 1181160329216 disk: exclusive 1181156818944 exclusive compressed 1181156818944 diff: exclusive 3510272 exclusive compressed 3510272 Counts for qgroup id: 0/1026 are different our: referenced 9243115520 referenced compressed 9243115520 disk: referenced 9243115520 referenced compressed 9243115520 our: exclusive 696569856 exclusive compressed 696569856 disk: exclusive 682135552 exclusive compressed 682135552 diff: exclusive 14434304 exclusive compressed 14434304 Counts for qgroup id: 0/2848 are different our: referenced 13068500992 referenced compressed 13068500992 disk: referenced 13098921984 referenced compressed 13098921984 diff: referenced -30420992 referenced compressed -30420992 our: exclusive 1556750336 exclusive compressed 1556750336 disk: exclusive 1556750336 exclusive compressed 1556750336 Counts for qgroup id: 0/2882 are different our: referenced 14523535360 referenced compressed 14523535360 disk: referenced 14553956352 referenced compressed 14553956352 diff: referenced -30420992 referenced compressed -30420992 our: exclusive 1373368320 exclusive compressed 1373368320 disk: exclusive 1373368320 exclusive compressed 1373368320 Counts for qgroup id: 0/2935 are different our: referenced 14761443328 referenced compressed 14761443328 disk: referenced 14791864320 referenced compressed 14791864320 diff: referenced -30420992 referenced compressed -30420992 our: exclusive 232054784 exclusive compressed 232054784 disk: exclusive 232054784 exclusive compressed 232054784 Counts for qgroup id: 0/2937 are different our: referenced 14889074688 referenced compressed 14889074688 disk: referenced 14919495680 referenced compressed 14919495680 diff: referenced -30420992 referenced compressed -30420992 our: exclusive 244756480 exclusive compressed 244756480 disk: exclusive 244756480 exclusive compressed 244756480 Counts for qgroup id: 0/2951 are different our: referenced 15147077632 referenced compressed 15147077632 disk: referenced 15177498624 referenced compressed 15177498624 diff: referenced -30420992 referenced compressed -30420992 our: exclusive 239132672 exclusive compressed 239132672 disk: exclusive 239132672 exclusive compressed 239132672 Counts for qgroup id: 0/2953 are different our: referenced 15282089984 referenced compressed 15282089984 disk: referenced 15312510976 referenced compressed 15312510976 diff: referenced -30420992 referenced compressed -30420992 our: exclusive 229437440 exclusive compressed 229437440 disk: exclusive 229437440 exclusive compressed 229437440 Counts for qgroup id: 0/2965 are different our: referenced 14960881664 referenced compressed 14960881664 disk: referenced 14991302656 referenced compressed 14991302656 diff: referenced -30420992 referenced compressed -30420992 our: exclusive 221765632 exclusive compressed 221765632 disk: exclusive 221765632 exclusive compressed 221765632 Counts for qgroup id: 0/2970 are different our: referenced 15028105216 referenced compressed 15028105216 disk: referenced 15058526208 referenced compressed 15058526208 diff: referenced -30420992 referenced compressed -30420992 our: exclusive 226172928 exclusive compressed 226172928 disk: exclusive 226172928 exclusive compressed 226172928 Counts for qgroup id: 0/2971 are different our: referenced 15051378688 referenced compressed 15051378688 disk: referenced 15081799680 referenced compressed 15081799680 diff: referenced -30420992 referenced compressed -30420992 our: exclusive 221945856 exclusive compressed 221945856 disk: exclusive 221945856 exclusive compressed 221945856 Counts for qgroup id: 0/2972 are different our: referenced 15066845184 referenced compressed 15066845184 disk: referenced 15097266176 referenced compressed 15097266176 diff: referenced -30420992 referenced compressed -30420992 our: exclusive 244789248 exclusive compressed 244789248 disk: exclusive 244789248 exclusive compressed 244789248 found 1210188607488 bytes used, error(s) found total csum bytes: 1175644964 total tree bytes: 5449875456 total fs tree bytes: 3953197056 total extent tree bytes: 239271936 btree space waste bytes: 804352655 file data blocks allocated: 7189404340224 referenced 1204569280512
