Hey Qu. I was giving your patches a try, again on the very same fs (which saw however writes in the meantime), from my initial report.
btrfs-progs v4.9 WITHOUT patch: ******************************* # btrfs check /dev/nbd0 ; echo $? checking extents checking free space cache checking fs roots checking csums checking root refs Checking filesystem on /dev/nbd0 UUID: 326d292d-f97b-43ca-b1e8-c722d3474719 found 7519512838144 bytes used err is 0 total csum bytes: 7330834320 total tree bytes: 10902437888 total fs tree bytes: 2019704832 total extent tree bytes: 1020149760 btree space waste bytes: 925714197 file data blocks allocated: 7509228494848 referenced 7630551511040 0 # btrfs check --mode=lowmem /dev/nbd0 ; echo $? checking extents ERROR: block group[74117545984 1073741824] used 1073741824 but extent items used 0 ERROR: block group[239473786880 1073741824] used 1073741824 but extent items used 1207959552 ERROR: block group[500393050112 1073741824] used 1073741824 but extent items used 1207959552 ERROR: block group[581997428736 1073741824] used 1073741824 but extent items used 0 ERROR: block group[626557714432 1073741824] used 1073741824 but extent items used 0 ERROR: block group[668433645568 1073741824] used 1073741824 but extent items used 0 ERROR: block group[948680261632 1073741824] used 1073741824 but extent items used 0 ERROR: block group[982503129088 1073741824] used 1073741824 but extent items used 0 ERROR: block group[1039411445760 1073741824] used 1073741824 but extent items used 0 ERROR: block group[1054443831296 1073741824] used 1073741824 but extent items used 1207959552 ERROR: block group[1190809042944 1073741824] used 1073741824 but extent items used 0 ERROR: block group[1279392743424 1073741824] used 1073741824 but extent items used 0 ERROR: block group[1481256206336 1073741824] used 1073741824 but extent items used 0 ERROR: block group[1620842643456 1073741824] used 1073741824 but extent items used 1207959552 ERROR: block group[1914511032320 1073741824] used 1073741824 but extent items used 1207959552 ERROR: block group[3055361720320 1073741824] used 1073741824 but extent items used 0 ERROR: block group[3216422993920 1073741824] used 1073741824 but extent items used 0 ERROR: block group[3670615785472 1073741824] used 1073741824 but extent items used 1207959552 ERROR: block group[3801612288000 1073741824] used 1073741824 but extent items used 1207959552 ERROR: block group[3828455833600 1073741824] used 1073741824 but extent items used 1207959552 ERROR: block group[4250973241344 1073741824] used 1073741824 but extent items used 0 ERROR: block group[4261710659584 1073741824] used 1073741824 but extent items used 1074266112 ERROR: block group[4392707162112 1073741824] used 1073741824 but extent items used 0 ERROR: block group[4558063403008 1073741824] used 1073741824 but extent items used 0 ERROR: block group[4607455526912 1073741824] used 1073741824 but extent items used 0 ERROR: block group[4635372814336 1073741824] used 1073741824 but extent items used 0 ERROR: block group[4640204652544 1073741824] used 1073741824 but extent items used 0 ERROR: block group[4642352136192 1073741824] used 1073741824 but extent items used 1207959552 ERROR: block group[4681006841856 1073741824] used 1073741824 but extent items used 0 ERROR: block group[5063795802112 1073741824] used 1073741824 but extent items used 0 ERROR: block group[5171169984512 1073741824] used 1073741824 but extent items used 1207959552 ERROR: block group[5216267141120 1073741824] used 1073741824 but extent items used 1207959552 ERROR: block group[5290355326976 1073741824] used 1073741824 but extent items used 0 ERROR: block group[5445511020544 1073741824] used 1073741824 but extent items used 1074266112 ERROR: block group[6084387405824 1073741824] used 1073741824 but extent items used 0 ERROR: block group[6104788500480 1073741824] used 1073741824 but extent items used 0 ERROR: block group[6878956355584 1073741824] used 1073741824 but extent items used 0 ERROR: block group[6997067956224 1073741824] used 1073741824 but extent items used 0 ERROR: block group[7702516334592 1073741824] used 1073741824 but extent items used 0 ERROR: block group[8051482427392 1073741824] used 1073741824 but extent items used 1084751872 ERROR: block group[8116980678656 1073741824] used 1073741824 but extent items used 0 ERROR: errors found in extent allocation tree or chunk allocation checking free space cache checking fs roots Checking filesystem on /dev/nbd0 UUID: 326d292d-f97b-43ca-b1e8-c722d3474719 found 7519512838144 bytes used err is -5 total csum bytes: 7330834320 total tree bytes: 10902437888 total fs tree bytes: 2019704832 total extent tree bytes: 1020149760 btree space waste bytes: 925714197 file data blocks allocated: 7509228494848 referenced 7630551511040 1 => so the fs would still show the symptoms Then, with no RW mount to the fs in between, 4.9 with the following of your patches: 0001-btrfs-progs-lowmem-check-Fix-wrong-block-group-check.patch 0003-btrfs-progs-fsck-Output-verbose-error-when-fsck-foun.patch 0004-btrfs-progs-lowmem-check-Fix-false-alert-in-checking.patch 0005-btrfs-progs-lowmem-check-Fix-extent-item-size-false-.patch the others were anyway just tests related, AFAICS. btrfs-progs v4.9 WITH patches: **************************** checking extents checking free space cache checking fs roots checking csums checking root refs Checking filesystem on /dev/nbd0 UUID: 326d292d-f97b-43ca-b1e8-c722d3474719 found 7519512838144 bytes used, no error found total csum bytes: 7330834320 total tree bytes: 10902437888 total fs tree bytes: 2019704832 total extent tree bytes: 1020149760 btree space waste bytes: 925714197 file data blocks allocated: 7509228494848 referenced 7630551511040 0 => bon! # btrfs check --mode=lowmem /dev/nbd0 ; echo $? checking extents checking free space cache checking fs roots ERROR: root 6031 EXTENT_DATA[277 524288] datasum missing ERROR: errors found in fs roots Checking filesystem on /dev/nbd0 UUID: 326d292d-f97b-43ca-b1e8-c722d3474719 found 7519512838144 bytes used, error(s) found total csum bytes: 7330834320 total tree bytes: 10902437888 total fs tree bytes: 2019704832 total extent tree bytes: 1020149760 btree space waste bytes: 925714197 file data blocks allocated: 7509228494848 referenced 7630551511040 1 => some new errors :-( Not sure though, whether this is an issue in your patch or a new problem due to my writes (I did just another round of incremental send -p/receive) Any ideas? Best, Chris.
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