Bug 210447

Summary: Transaction aborted (error -27) in btrfs_create_pending_block_groups
Product: File System Reporter: Guan Xin (guanx.bac)
Component: btrfsAssignee: BTRFS virtual assignee (fs_btrfs)
Status: RESOLVED CODE_FIX    
Severity: high CC: dsterba, guanx.bac
Priority: P1    
Hardware: x86-64   
OS: Linux   
Kernel Version: 5.4.84 Subsystem:
Regression: No Bisected commit-id:

Description Guan Xin 2020-12-02 02:42:56 UTC 
*** The following error occurred when write files:

[382606.972617] ------------[ cut here ]------------
[382606.972620] BTRFS: Transaction aborted (error -27)
[382606.972676] WARNING: CPU: 7 PID: 5411 at fs/btrfs/block-group.c:1909 btrfs_create_pending_block_groups+0x1d4/0x200 [btrfs]
[382606.972677] Modules linked in: fuse coretemp intel_rapl_msr intel_rapl_common isst_if_common i2c_dev mlx5_ib ib_uverbs ib_core skx_edac ipmi_ssif ipv6 nfit x86_pkg_temp_thermal kvm_intel kvm irqbypass crct10dif_pclmul crc32_pclmul ghash_clmulni_intel rapl intel_cstate mlx5_core mlxfw pci_hyperv_intf ast drm_vram_helper ses ttm drm_kms_helper enclosure drm btrfs agpgart ixgbe i2c_algo_bit fb_sys_fops libphy mei_me syscopyarea zstd_compress mdio sysfillrect joydev ioatdma zstd_decompress sysimgblt i2c_i801 lpc_ich mei dca evdev ipmi_si ipmi_devintf ipmi_msghandler acpi_power_meter button loop megaraid_sas ext4 mbcache jbd2 hid_multitouch hid_microsoft hid_lenovo hid_logitech_hidpp hid_logitech_dj hid_logitech hid_cherry hid_asus asus_wmi battery sparse_keymap rfkill wmi video hwmon hid_generic i2c_hid i2c_core usbhid hid uhci_hcd ohci_pci ehci_pci ohci_hcd ehci_hcd xhci_pci xhci_hcd
[382606.972706] CPU: 7 PID: 5411 Comm: rsync Not tainted 5.4.80 #1
[382606.972707] Hardware name: Inspur AS13000G5-M60/YZMB-01900-103, BIOS 3.1.9 08/21/2020
[382606.972723] RIP: 0010:btrfs_create_pending_block_groups+0x1d4/0x200 [btrfs]
[382606.972725] Code: 8b 45 50 f0 48 0f ba a8 30 11 00 00 02 72 1d 41 83 fc fb 74 17 41 83 fc e2 74 11 44 89 e6 48 c7 c7 70 87 a2 c0 e8 bc f6 6c c1 <0f> 0b 44 89 e1 ba 75 07 00 00 48 c7 c6 a0 8d a1 c0 48 89 ef e8 39
[382606.972726] RSP: 0018:ffff9fb34eb03658 EFLAGS: 00010286
[382606.972727] RAX: 0000000000000000 RBX: ffff8b6448414520 RCX: 0000000000000006
[382606.972727] RDX: 0000000000000007 RSI: 0000000000000086 RDI: ffff8b783fbd6580
[382606.972728] RBP: ffff8b6038100c98 R08: 000000000002da9c R09: 000000000000077c
[382606.972729] R10: ffff8b702a76f120 R11: 000000000000077c R12: 00000000ffffffe5
[382606.972729] R13: ffff8b6038100cf0 R14: ffff8b7822d6e000 R15: ffff8b9836b20000
[382606.972730] FS:  00007f5220879700(0000) GS:ffff8b783fbc0000(0000) knlGS:0000000000000000
[382606.972731] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[382606.972732] CR2: 0000564ccddc4000 CR3: 00000037a8d42002 CR4: 00000000007606e0
[382606.972732] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[382606.972733] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[382606.972733] PKRU: 55555554
[382606.972734] Call Trace:
[382606.972753]  btrfs_chunk_alloc+0x228/0x2c0 [btrfs]
[382606.972764]  find_free_extent+0xc8e/0xff0 [btrfs]
[382606.972776]  btrfs_reserve_extent+0xa5/0x190 [btrfs]
[382606.972788]  btrfs_alloc_tree_block+0xb6/0x4f0 [btrfs]
[382606.972794]  ? __remove_hrtimer+0x35/0x70
[382606.972804]  alloc_tree_block_no_bg_flush+0x43/0x60 [btrfs]
[382606.972815]  __btrfs_cow_block+0x126/0x570 [btrfs]
[382606.972825]  btrfs_cow_block+0xfc/0x1f0 [btrfs]
[382606.972835]  btrfs_search_slot+0x437/0x960 [btrfs]
[382606.972845]  ? btrfs_leaf_free_space+0x49/0x90 [btrfs]
[382606.972855]  btrfs_insert_empty_items+0x67/0xc0 [btrfs]
[382606.972865]  insert_with_overflow+0x44/0x100 [btrfs]
[382606.972876]  btrfs_insert_dir_item+0xc6/0x270 [btrfs]
[382606.972890]  btrfs_add_link+0xc7/0x470 [btrfs]
[382606.972903]  btrfs_create+0x1b1/0x1f0 [btrfs]
[382606.972908]  path_openat+0x12f1/0x13c0
[382606.972911]  do_filp_open+0x99/0x110
[382606.972915]  ? __dentry_kill+0x112/0x160
[382606.972919]  ? __check_object_size+0x172/0x1b0
[382606.972920]  ? __alloc_fd+0x3d/0x170
[382606.972922]  ? do_sys_open+0x12a/0x220
[382606.972924]  do_sys_open+0x12a/0x220
[382606.972927]  do_syscall_64+0x4c/0x170
[382606.972931]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
[382606.972933] RIP: 0033:0x7f521fda5bf0
[382606.972934] Code: 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 83 3d 99 1b 2d 00 00 75 10 b8 02 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 31 c3 48 83 ec 08 e8 de df 01 00 48 89 04 24
[382606.972935] RSP: 002b:00007fff9ae4af68 EFLAGS: 00000246 ORIG_RAX: 0000000000000002
[382606.972936] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f521fda5bf0
[382606.972936] RDX: 0000000000000180 RSI: 00000000000000c2 RDI: 00007fff9ae4d1d0
[382606.972937] RBP: 000000000003a2f8 R08: 0000000000000039 R09: 0000000000000000
[382606.972937] R10: 0000000000000000 R11: 0000000000000246 R12: 00007fff9ae4d209
[382606.972938] R13: 8421084210842109 R14: 00000000000000c2 R15: 00007f521fe42940
[382606.972939] ---[ end trace 51450a00be89b62e ]---
[382606.972941] BTRFS: error (device sdc) in btrfs_create_pending_block_groups:1909: errno=-27 unknown
[382606.973400] BTRFS info (device sdc): forced readonly
[382608.191227] BTRFS warning (device sdc): Skipping commit of aborted transaction.
[382608.197211] BTRFS info (device sdc): delayed_refs has NO entry

*** A btrfs check shows no error:

# btrfs check /dev/sdc
Opening filesystem to check...
Checking filesystem on /dev/sdc
UUID: 1fd69cb6-5c6a-4f30-b2aa-9e8c1e11a3f0
[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 skipped (not enabled on this FS)
found 204585718599680 bytes used, no error found
total csum bytes: 199537301156
total tree bytes: 208911122432
total fs tree bytes: 170835968
total extent tree bytes: 1066713088
btree space waste bytes: 5795278077
file data blocks allocated: 204376807477248
 referenced 204376807477248

*** However, mounting the filesystem read-write and running btrfs scrub triggers the same error, and the scrub aborts with filesystem forced read-only:

[16486.566499] BTRFS info (device sdc): scrub: started on devid 1
[16486.791715] BTRFS info (device sdc): scrub: started on devid 6
[16486.791730] BTRFS info (device sdc): scrub: started on devid 7
[16487.019927] BTRFS info (device sdc): scrub: started on devid 8
[16487.241911] BTRFS info (device sdc): scrub: started on devid 9
[16487.470014] BTRFS info (device sdc): scrub: started on devid 10
[16487.700170] BTRFS info (device sdc): scrub: started on devid 3
[16487.700185] BTRFS info (device sdc): scrub: started on devid 4
[16487.741638] BTRFS info (device sdc): scrub: started on devid 5
[16487.775879] BTRFS info (device sdc): scrub: started on devid 2
[16487.800986] BTRFS info (device sdc): scrub: started on devid 11
[16488.026192] BTRFS info (device sdc): scrub: started on devid 12
[16488.196768] BTRFS info (device sdc): scrub: started on devid 13
[16488.430757] BTRFS info (device sdc): scrub: started on devid 14
[16488.448529] BTRFS info (device sdc): scrub: started on devid 15
[16488.448541] BTRFS info (device sdc): scrub: started on devid 16
[16488.456989] BTRFS info (device sdc): scrub: started on devid 17
[16488.665341] BTRFS info (device sdc): scrub: started on devid 18
[16488.700696] BTRFS info (device sdc): scrub: started on devid 19
[16488.731566] BTRFS info (device sdc): scrub: started on devid 20
[16488.755640] BTRFS info (device sdc): scrub: started on devid 21
[16488.844078] BTRFS info (device sdc): scrub: started on devid 22
[16488.869788] BTRFS info (device sdc): scrub: started on devid 23
[16489.096730] BTRFS info (device sdc): scrub: started on devid 24
[16489.194654] BTRFS info (device sdc): scrub: started on devid 25
[16489.230010] BTRFS info (device sdc): scrub: started on devid 26
[16489.276815] BTRFS info (device sdc): scrub: started on devid 27
[16489.282140] BTRFS info (device sdc): scrub: started on devid 28
[16489.290036] BTRFS info (device sdc): scrub: started on devid 29
[16489.316006] BTRFS info (device sdc): scrub: started on devid 30
[16489.356053] BTRFS info (device sdc): scrub: started on devid 31
[16489.381773] BTRFS info (device sdc): scrub: started on devid 32
[16489.432681] BTRFS info (device sdc): scrub: started on devid 33
[16489.453858] BTRFS info (device sdc): scrub: started on devid 34
[16489.484655] BTRFS info (device sdc): scrub: started on devid 35
[16489.499716] BTRFS info (device sdc): scrub: started on devid 36
[16489.528706] BTRFS info (device sdc): scrub: started on devid 37
[16489.563081] BTRFS info (device sdc): scrub: started on devid 38
[16489.786751] BTRFS info (device sdc): scrub: started on devid 39
[16489.786760] BTRFS info (device sdc): scrub: started on devid 40
[16489.838573] BTRFS info (device sdc): scrub: started on devid 41
[16489.872703] BTRFS info (device sdc): scrub: started on devid 42
[16489.908914] BTRFS info (device sdc): scrub: started on devid 43
[16489.943560] BTRFS info (device sdc): scrub: started on devid 44
[16490.013383] BTRFS info (device sdc): scrub: started on devid 45
[16490.238302] BTRFS info (device sdc): scrub: started on devid 46
[16490.466952] BTRFS info (device sdc): scrub: started on devid 47
[16490.480929] BTRFS info (device sdc): scrub: started on devid 48
[16490.705736] BTRFS info (device sdc): scrub: started on devid 49
[16490.745208] BTRFS info (device sdc): scrub: started on devid 50
[16490.778085] BTRFS info (device sdc): scrub: started on devid 51
[16490.828206] BTRFS info (device sdc): scrub: started on devid 52
[16490.856726] BTRFS info (device sdc): scrub: started on devid 53
[16490.868866] BTRFS info (device sdc): scrub: started on devid 54
[16490.910975] BTRFS info (device sdc): scrub: started on devid 55
[16490.948032] BTRFS info (device sdc): scrub: started on devid 56
[16490.978097] BTRFS info (device sdc): scrub: started on devid 57
[16491.017945] BTRFS info (device sdc): scrub: started on devid 58
[16491.025234] BTRFS info (device sdc): scrub: started on devid 59
[16491.078808] BTRFS info (device sdc): scrub: started on devid 60
[16519.794829] ------------[ cut here ]------------
[16519.794833] BTRFS: Transaction aborted (error -27)
[16519.794951] WARNING: CPU: 6 PID: 2642 at fs/btrfs/block-group.c:1909 btrfs_create_pending_block_groups+0x1d4/0x200 [btrfs]
[16519.794953] Modules linked in: fuse coretemp intel_rapl_msr intel_rapl_common isst_if_common i2c_dev mlx5_ib skx_edac nfit x86_pkg_temp_thermal kvm_intel kvm ib_uverbs ib_core irqbypass crct10dif_pclmul crc32_pclmul ghash_clmulni_intel rapl ipv6 ipmi_ssif intel_cstate mlx5_core mlxfw pci_hyperv_intf ast drm_vram_helper ttm drm_kms_helper drm ses agpgart btrfs enclosure ixgbe i2c_algo_bit fb_sys_fops libphy mei_me syscopyarea mdio ioatdma zstd_compress sysfillrect joydev zstd_decompress sysimgblt i2c_i801 lpc_ich mei dca evdev ipmi_si ipmi_devintf ipmi_msghandler acpi_power_meter button loop megaraid_sas ext4 mbcache jbd2 hid_multitouch hid_microsoft hid_lenovo hid_logitech_hidpp hid_logitech_dj hid_logitech hid_cherry hid_asus asus_wmi battery sparse_keymap rfkill wmi video hwmon hid_generic i2c_hid i2c_core usbhid hid uhci_hcd ohci_pci ehci_pci ohci_hcd ehci_hcd xhci_pci xhci_hcd
[16519.795019] CPU: 6 PID: 2642 Comm: btrfs Not tainted 5.4.80 #1
[16519.795021] Hardware name: Inspur AS13000G5-M60/YZMB-01900-103, BIOS 3.1.9 08/21/2020
[16519.795067] RIP: 0010:btrfs_create_pending_block_groups+0x1d4/0x200 [btrfs]
[16519.795071] Code: 8b 45 50 f0 48 0f ba a8 30 11 00 00 02 72 1d 41 83 fc fb 74 17 41 83 fc e2 74 11 44 89 e6 48 c7 c7 70 07 bb c0 e8 bc 76 54 ce <0f> 0b 44 89 e1 ba 75 07 00 00 48 c7 c6 a0 0d ba c0 48 89 ef e8 39
[16519.795074] RSP: 0018:ffffb89e4cc0fb20 EFLAGS: 00010282
[16519.795077] RAX: 0000000000000000 RBX: ffff8a276f7bd120 RCX: 0000000000000006
[16519.795078] RDX: 0000000000000007 RSI: 0000000000000092 RDI: ffff8a277fb96580
[16519.795080] RBP: ffff8a277f291f70 R08: 000000000002e2cc R09: 00000000000007a6
[16519.795082] R10: 0000000000000001 R11: 00000000000007a6 R12: 00000000ffffffe5
[16519.795083] R13: ffff8a277f291fc8 R14: ffff8a2776e90000 R15: ffff8a2747d4f000
[16519.795086] FS:  00007fc096269700(0000) GS:ffff8a277fb80000(0000) knlGS:0000000000000000
[16519.795088] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[16519.795090] CR2: 00007fc0990502a0 CR3: 0000001fa4e76006 CR4: 00000000007606e0
[16519.795092] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[16519.795093] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[16519.795095] PKRU: 55555554
[16519.795096] Call Trace:
[16519.795142]  __btrfs_end_transaction+0x58/0x1c0 [btrfs]
[16519.795185]  btrfs_inc_block_group_ro+0xbd/0x150 [btrfs]
[16519.795230]  scrub_enumerate_chunks+0x1d5/0x570 [btrfs]
[16519.795240]  ? try_to_wake_up+0x520/0x5b0
[16519.795283]  btrfs_scrub_dev+0x2e3/0x650 [btrfs]
[16519.795291]  ? __kmalloc_track_caller+0x57/0x280
[16519.795296]  ? __check_object_size+0x172/0x1b0
[16519.795340]  btrfs_ioctl+0x178c/0x2dd0 [btrfs]
[16519.795351]  ? __switch_to_asm+0x40/0x70
[16519.795355]  ? __switch_to_asm+0x34/0x70
[16519.795358]  ? __switch_to_asm+0x40/0x70
[16519.795361]  ? __switch_to_asm+0x34/0x70
[16519.795369]  do_vfs_ioctl+0xa1/0x620
[16519.795377]  ? create_task_io_context+0x95/0xf0
[16519.795381]  ? get_task_io_context+0x41/0x80
[16519.795386]  ksys_ioctl+0x66/0x70
[16519.795391]  __x64_sys_ioctl+0x16/0x20
[16519.795397]  do_syscall_64+0x4c/0x170
[16519.795402]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
[16519.795406] RIP: 0033:0x7fc098b6b9e7
[16519.795410] Code: 00 00 00 48 8b 05 b1 64 2c 00 64 c7 00 26 00 00 00 48 c7 c0 ff ff ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 b8 10 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 81 64 2c 00 f7 d8 64 89 01 48
[16519.795412] RSP: 002b:00007fc096268d68 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
[16519.795415] RAX: ffffffffffffffda RBX: 00000000007ae580 RCX: 00007fc098b6b9e7
[16519.795417] RDX: 00000000007ae580 RSI: 00000000c400941b RDI: 0000000000000003
[16519.795418] RBP: 0000000000000000 R08: 00007fc096269700 R09: 0000000000000000
[16519.795420] R10: 00007fc096269700 R11: 0000000000000246 R12: 0000000000000000
[16519.795421] R13: 00007ffd2ded878f R14: 00007fc096269700 R15: 0000000000000000
[16519.795425] ---[ end trace 5bec0a8e7d328f43 ]---
[16519.795430] BTRFS: error (device sdc) in btrfs_create_pending_block_groups:1909: errno=-27 unknown
[16519.796920] BTRFS info (device sdc): forced readonly
[16519.797239] BTRFS warning (device sdc): Skipping commit of aborted transaction.
[16519.797245] BTRFS: error (device sdc) in cleanup_transaction:1832: errno=-27 unknown
[16519.797446] BTRFS warning (device sdc): failed setting block group ro: -30
[16519.799709] BTRFS info (device sdc): scrub: not finished on devid 13 with status: -30
[16519.801611] BTRFS info (device sdc): scrub: not finished on devid 6 with status: -125
[16519.822921] BTRFS info (device sdc): scrub: not finished on devid 34 with status: -125
[16519.830431] BTRFS info (device sdc): scrub: not finished on devid 56 with status: -125
[16519.839946] BTRFS info (device sdc): scrub: not finished on devid 25 with status: -125
[16519.875562] BTRFS info (device sdc): scrub: not finished on devid 48 with status: -125
[16519.878894] BTRFS info (device sdc): scrub: not finished on devid 58 with status: -125
[16519.892284] BTRFS info (device sdc): scrub: not finished on devid 17 with status: -125
[16519.896221] BTRFS info (device sdc): scrub: not finished on devid 35 with status: -125
[16519.898573] BTRFS info (device sdc): scrub: not finished on devid 2 with status: -125
[16519.898885] BTRFS info (device sdc): scrub: not finished on devid 54 with status: -125
[16519.909258] BTRFS info (device sdc): scrub: not finished on devid 24 with status: -125
[16519.909522] BTRFS info (device sdc): scrub: not finished on devid 4 with status: -125
[16519.918839] BTRFS info (device sdc): scrub: not finished on devid 31 with status: -125
[16519.919567] BTRFS info (device sdc): scrub: not finished on devid 60 with status: -125
[16519.919595] BTRFS info (device sdc): scrub: not finished on devid 10 with status: -125
[16519.921518] BTRFS info (device sdc): scrub: not finished on devid 22 with status: -125
[16519.922294] BTRFS info (device sdc): scrub: not finished on devid 7 with status: -125
[16519.923704] BTRFS info (device sdc): scrub: not finished on devid 53 with status: -125
[16519.929702] BTRFS info (device sdc): scrub: not finished on devid 9 with status: -125
[16519.931179] BTRFS info (device sdc): scrub: not finished on devid 59 with status: -125
[16519.931277] BTRFS info (device sdc): scrub: not finished on devid 37 with status: -125
[16519.932547] BTRFS info (device sdc): scrub: not finished on devid 11 with status: -125
[16519.933496] BTRFS info (device sdc): scrub: not finished on devid 16 with status: -125
[16519.933872] BTRFS info (device sdc): scrub: not finished on devid 51 with status: -125
[16519.933927] BTRFS info (device sdc): scrub: not finished on devid 21 with status: -125
[16519.935514] BTRFS info (device sdc): scrub: not finished on devid 52 with status: -125
[16519.938768] BTRFS info (device sdc): scrub: not finished on devid 46 with status: -125
[16519.939499] BTRFS info (device sdc): scrub: not finished on devid 43 with status: -125
[16519.939822] BTRFS info (device sdc): scrub: not finished on devid 29 with status: -125
[16519.940269] BTRFS info (device sdc): scrub: not finished on devid 33 with status: -125
[16519.940346] BTRFS info (device sdc): scrub: not finished on devid 14 with status: -125
[16519.941315] BTRFS info (device sdc): scrub: not finished on devid 57 with status: -125
[16519.941346] BTRFS info (device sdc): scrub: not finished on devid 32 with status: -125
[16519.941636] BTRFS info (device sdc): scrub: not finished on devid 47 with status: -125
[16519.941828] BTRFS info (device sdc): scrub: not finished on devid 3 with status: -125
[16519.941920] BTRFS info (device sdc): scrub: not finished on devid 39 with status: -125
[16519.942036] BTRFS info (device sdc): scrub: not finished on devid 8 with status: -125
[16519.942446] BTRFS info (device sdc): scrub: not finished on devid 50 with status: -125
[16519.943584] BTRFS info (device sdc): scrub: not finished on devid 36 with status: -125
[16519.945863] BTRFS info (device sdc): scrub: not finished on devid 15 with status: -125
[16519.946731] BTRFS info (device sdc): scrub: not finished on devid 49 with status: -125
[16519.947675] BTRFS info (device sdc): scrub: not finished on devid 27 with status: -125
[16519.947939] BTRFS info (device sdc): scrub: not finished on devid 18 with status: -125
[16519.948010] BTRFS info (device sdc): scrub: not finished on devid 20 with status: -125
[16519.948331] BTRFS info (device sdc): scrub: not finished on devid 1 with status: -125
[16519.948787] BTRFS info (device sdc): scrub: not finished on devid 45 with status: -125
[16519.950018] BTRFS info (device sdc): scrub: not finished on devid 23 with status: -125
[16519.950555] BTRFS info (device sdc): scrub: not finished on devid 28 with status: -125
[16519.950932] BTRFS info (device sdc): scrub: not finished on devid 26 with status: -125
[16519.953639] BTRFS info (device sdc): scrub: not finished on devid 44 with status: -125
[16519.953956] BTRFS info (device sdc): scrub: not finished on devid 42 with status: -125
[16519.956154] BTRFS info (device sdc): scrub: not finished on devid 41 with status: -125
[16519.958777] BTRFS info (device sdc): scrub: not finished on devid 30 with status: -125
[16519.959204] BTRFS info (device sdc): scrub: not finished on devid 19 with status: -125
[16519.959648] BTRFS info (device sdc): scrub: not finished on devid 38 with status: -125
[16519.961986] BTRFS info (device sdc): scrub: not finished on devid 12 with status: -125
[16519.962834] BTRFS info (device sdc): scrub: not finished on devid 40 with status: -125
[16519.970538] BTRFS info (device sdc): scrub: not finished on devid 55 with status: -125
[16519.980011] BTRFS info (device sdc): scrub: not finished on devid 5 with status: -125

*** The filesystem also appears to be very slow. When mounted read-write,
dd if=/dev/zero of=/mount-point/test.dat bs=1M count=10k conv=fdatasync
yields 68MB/s only.
The same command on a similarly filled btrfs on another machine with exactly the same hardware configuration gives 800~900MB/s.

*** Neither dmesg nor smartctl showed any error in the member disks.
Comment 1 Guan Xin 2020-12-18 16:40:09 UTC 
This bug not showing up in Linux 5.10.1. Seems that some critical bugfix was not backported to the LTS Linux 5.4. (Well I think it's critical enough not being able to write to nor to scrub a btrfs that's about 26% full, even though no data loss occurred.)
Comment 2 David Sterba 2021-03-17 09:46:22 UTC 
I think it's been fixed by https://git.kernel.org/linus/b12de52896c0e8213f , first in 5.5 and not backported to 5.4. There seem to be no dependencies so I'll send a backport.
Comment 3 David Sterba 2021-03-19 11:00:02 UTC 
Patch queued up for 5.4.107.