BTRFS-errors on a 20TB filesystem

Paul-Erik Törrönen
2020-07-06T10:47:43Z

OS: CentOS8 with updated kernel and btrfs-tools
Kernel: 5.4.17-2011.3.2.1.el8uek.x86_64
btrfs version: 5.6.1

Some background. The file server had been running for quite some time
before I reinstalled it with CentOS 8, at which point I noticed (after
having installed the Oracle UEK kernel which still supports btrfs) the
errors when mounting the partition. I updated the btrfs-tools to latest
and ran the 'btrfs check --repair /dev/sdc1', but despite this, still
have errors when accessing certain files on the FS. Dmesg shows them as
following:

[1681476.647521] BTRFS error (device sdc1): block=3154170920960 read
time tree block corruption detected
[1681476.694520] BTRFS critical (device sdc1): corrupt leaf: root=5
block=3154170920960 slot=9 ino=13286681 file_offset=204800, extent end
overflow, have file offset 204800 extent num bytes 18446744073709481984

There does not appear to be any HW-related errors in the logs.

With the help of darkling on Freenode IRC #btrfs collected the following
information:

btrfs inspect dump-tree -b 3154170920960 /dev/sdc1 ->

btrfs-progs v5.6.1
leaf 3154170920960 items 97 free space 6102 generation 1326633 owner
FS_TREE
leaf 3154170920960 flags 0x1(WRITTEN) backref revision 1
fs uuid 519a6725-10d4-4d82-bc4a-32de7dfb923f
chunk uuid 4d1fe695-d2cb-43bc-bac6-d3101dc0725b
item 0 key (13286391 INODE_REF 2479498) itemoff 16245 itemsize
38
index 8927 namelen 28 name: file_28-2
item 1 key (13286391 EXTENT_DATA 0) itemoff 15384 itemsize 861
generation 152266 type 0 (inline)
inline extent data size 840 ram_bytes 840 compression 0
(none)
item 2 key (13286679 INODE_ITEM 0) itemoff 15224 itemsize 160
generation 148004 transid 1326604 size 0 nbytes 0
block group 0 mode 40700 links 1 uid 941400003 gid 513
rdev 0
sequence 5 flags 0x0(none)
atime 1592086804.669979287 (2020-06-14 01:20:04)
ctime 1488735439.699720907 (2017-03-05 19:37:19)
mtime 1488735439.699720907 (2017-03-05 19:37:19)
otime 1488735439.699720907 (2017-03-05 19:37:19)
item 3 key (13286679 INODE_REF 900409) itemoff 15200 itemsize 24
index 156 namelen 14 name: file_14
item 4 key (13286681 INODE_ITEM 0) itemoff 15040 itemsize 160
generation 148002 transid 1102464 size 203197 nbytes
204800
block group 0 mode 100644 links 1 uid 941400003 gid 513
rdev 0
sequence 43 flags 0x10(PREALLOC)
atime 1550596828.990479215 (2019-02-19 19:20:28)
ctime 1488735117.417279715 (2017-03-05 19:31:57)
mtime 1488735117.417279715 (2017-03-05 19:31:57)
otime 2562566064006200577.1311248627 (-399890746-03-05
07:02:57)
item 5 key (13286681 INODE_REF 2479479) itemoff 15005 itemsize
35
index 10704 namelen 25 name: file_25-1
item 6 key (13286681 EXTENT_DATA 0) itemoff 14952 itemsize 53
generation 148002 type 1 (regular)
extent data disk byte 2584805376 nr 204800
extent data offset 0 nr 90112 ram 204800
extent compression 0 (none)
item 7 key (13286681 EXTENT_DATA 90112) itemoff 14899 itemsize
53
generation 148002 type 2 (prealloc)
prealloc data disk byte 2584805376 nr 204800
prealloc data offset 90112 nr 45056
item 8 key (13286681 EXTENT_DATA 135168) itemoff 14846 itemsize
53
generation 148002 type 2 (prealloc)
prealloc data disk byte 2584805376 nr 204800
prealloc data offset 135168 nr 69632
item 9 key (13286681 EXTENT_DATA 204800) itemoff 14793 itemsize
53
generation 148002 type 1 (regular)
extent data disk byte 0 nr 0
extent data offset 0 nr 18446744073709481984 ram
18446744073709481984
extent compression 0 (none)
item 10 key (13286688 INODE_ITEM 0) itemoff 14633 itemsize 160
generation 148004 transid 1102464 size 260920 nbytes
262144
block group 0 mode 100600 links 1 uid 941400003 gid 513
rdev 0
sequence 16 flags 0x0(none)
atime 1550596832.43520915 (2019-02-19 19:20:32)
ctime 1488735464.584054948 (2017-03-05 19:37:44)
mtime 1488735464.582054920 (2017-03-05 19:37:44)
otime 1488735448.969845407 (2017-03-05 19:37:28)
item 11 key (13286688 INODE_REF 2479498) itemoff 14595 itemsize
38
index 8938 namelen 28 name: file_28-3
item 12 key (13286688 EXTENT_DATA 0) itemoff 14542 itemsize 53
generation 148004 type 1 (regular)
extent data disk byte 9637261312 nr 4096
extent data offset 0 nr 4096 ram 4096
extent compression 0 (none)
item 13 key (13286688 EXTENT_DATA 4096) itemoff 14489 itemsize
53
generation 148004 type 1 (regular)
extent data disk byte 9657868288 nr 262144
extent data offset 4096 nr 258048 ram 262144
extent compression 0 (none)
item 14 key (13286689 INODE_ITEM 0) itemoff 14329 itemsize 160
generation 148004 transid 1102464 size 260920 nbytes
262144
block group 0 mode 100600 links 1 uid 941400003 gid 513
rdev 0
sequence 20 flags 0x0(none)
atime 1550596832.58521110 (2019-02-19 19:20:32)
ctime 1488738351.833534788 (2017-03-05 20:25:51)
mtime 1488738351.820533449 (2017-03-05 20:25:51)
otime 1488735464.569054738 (2017-03-05 19:37:44)
item 15 key (13286689 INODE_REF 2479498) itemoff 14291 itemsize
38
index 8943 namelen 28 name: file_28-4
item 16 key (13286689 EXTENT_DATA 0) itemoff 14238 itemsize 53
generation 148006 type 1 (regular)
extent data disk byte 11572387840 nr 4096
extent data offset 0 nr 4096 ram 4096
extent compression 0 (none)
item 17 key (13286689 EXTENT_DATA 4096) itemoff 14185 itemsize
53
generation 148004 type 1 (regular)
extent data disk byte 11674513408 nr 262144
extent data offset 4096 nr 258048 ram 262144
extent compression 0 (none)
item 18 key (13286690 INODE_ITEM 0) itemoff 14025 itemsize 160
generation 148006 transid 1326604 size 32 nbytes 0
block group 0 mode 40700 links 1 uid 941400003 gid 513
rdev 0
sequence 3 flags 0x0(none)
atime 1592086804.800980991 (2020-06-14 01:20:04)
ctime 1488738347.123047782 (2017-03-05 20:25:47)
mtime 1488738347.123047782 (2017-03-05 20:25:47)
otime 1488738346.417975047 (2017-03-05 20:25:46)
item 19 key (13286690 INODE_REF 900409) itemoff 14001 itemsize
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index 157 namelen 14 name: file_14-3
item 20 key (13286690 DIR_ITEM 2066004016) itemoff 13964
itemsize 37
location key (13286691 INODE_ITEM 0) type SOCK
transid 148006 data_len 0 name_len 7
name: control
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itemsize 36
location key (13286697 INODE_ITEM 0) type SOCK
transid 148006 data_len 0 name_len 6
name: pkcs11
item 22 key (13286690 DIR_ITEM 3872833404) itemoff 13895
itemsize 33
location key (13286695 INODE_ITEM 0) type SOCK
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name: ssh
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location key (13286691 INODE_ITEM 0) type SOCK
transid 148006 data_len 0 name_len 7
name: control
item 24 key (13286690 DIR_INDEX 3) itemoff 13825 itemsize 33
location key (13286695 INODE_ITEM 0) type SOCK
transid 148006 data_len 0 name_len 3
name: ssh
item 25 key (13286690 DIR_INDEX 4) itemoff 13789 itemsize 36
location key (13286697 INODE_ITEM 0) type SOCK
transid 148006 data_len 0 name_len 6
name: pkcs11
item 26 key (13286691 INODE_ITEM 0) itemoff 13629 itemsize 160
generation 148006 transid 148006 size 0 nbytes 0
block group 0 mode 140755 links 1 uid 941400003 gid 513
rdev 0
sequence 0 flags 0x0(none)
atime 1488738346.419975253 (2017-03-05 20:25:46)
ctime 1488738346.419975253 (2017-03-05 20:25:46)
mtime 1488738346.419975253 (2017-03-05 20:25:46)
otime 1488738346.419975253 (2017-03-05 20:25:46)
item 27 key (13286691 INODE_REF 13286690) itemoff 13612 itemsize
17
index 2 namelen 7 name: file_7
item 28 key (13286695 INODE_ITEM 0) itemoff 13452 itemsize 160
generation 148006 transid 148006 size 0 nbytes 0
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rdev 0
sequence 0 flags 0x0(none)
atime 1488738347.96044974 (2017-03-05 20:25:47)
ctime 1488738347.96044974 (2017-03-05 20:25:47)
mtime 1488738347.96044974 (2017-03-05 20:25:47)
otime 1488738347.96044974 (2017-03-05 20:25:47)
item 29 key (13286695 INODE_REF 13286690) itemoff 13439 itemsize
13
index 3 namelen 3 name: file_3
item 30 key (13286697 INODE_ITEM 0) itemoff 13279 itemsize 160
generation 148006 transid 148006 size 0 nbytes 0
block group 0 mode 140755 links 1 uid 941400003 gid 513
rdev 0
sequence 0 flags 0x0(none)
atime 1488738347.123047782 (2017-03-05 20:25:47)
ctime 1488738347.123047782 (2017-03-05 20:25:47)
mtime 1488738347.123047782 (2017-03-05 20:25:47)
otime 1488738347.123047782 (2017-03-05 20:25:47)
item 31 key (13286697 INODE_REF 13286690) itemoff 13263 itemsize
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index 4 namelen 6 name: file_6
item 32 key (13286702 INODE_ITEM 0) itemoff 13103 itemsize 160
generation 148006 transid 1102464 size 260920 nbytes
262144
block group 0 mode 100600 links 1 uid 941400003 gid 513
rdev 0
sequence 35 flags 0x0(none)
atime 1550596832.69521253 (2019-02-19 19:20:32)
ctime 1488738366.693069142 (2017-03-05 20:26:06)
mtime 1488738366.691068936 (2017-03-05 20:26:06)
otime 1488738351.808532213 (2017-03-05 20:25:51)
item 33 key (13286702 INODE_REF 2479498) itemoff 13065 itemsize
38
index 8954 namelen 28 name: file_28-5
item 34 key (13286702 EXTENT_DATA 0) itemoff 13012 itemsize 53
generation 148006 type 1 (regular)
extent data disk byte 11247833088 nr 4096
extent data offset 0 nr 4096 ram 4096
extent compression 0 (none)
item 35 key (13286702 EXTENT_DATA 4096) itemoff 12959 itemsize
53
generation 148006 type 1 (regular)
extent data disk byte 11297587200 nr 262144
extent data offset 4096 nr 258048 ram 262144
extent compression 0 (none)
item 36 key (13286703 INODE_ITEM 0) itemoff 12799 itemsize 160
generation 148006 transid 1102464 size 260920 nbytes
262144
block group 0 mode 100600 links 1 uid 941400003 gid 513
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sequence 20 flags 0x0(none)
atime 1550596832.79521383 (2019-02-19 19:20:32)
ctime 1488886782.768250242 (2017-03-07 13:39:42)
mtime 1488886782.754250046 (2017-03-07 13:39:42)
otime 1488738366.683068112 (2017-03-05 20:26:06)
item 37 key (13286703 INODE_REF 2479498) itemoff 12761 itemsize
38
index 8959 namelen 28 name: file_28-6
item 38 key (13286703 EXTENT_DATA 0) itemoff 12708 itemsize 53
generation 148129 type 1 (regular)
extent data disk byte 11437883392 nr 4096
extent data offset 0 nr 4096 ram 4096
extent compression 0 (none)
item 39 key (13286703 EXTENT_DATA 4096) itemoff 12655 itemsize
53
generation 148006 type 1 (regular)
extent data disk byte 11438669824 nr 262144
extent data offset 4096 nr 258048 ram 262144
extent compression 0 (none)
item 40 key (13297612 INODE_ITEM 0) itemoff 12495 itemsize 160
generation 148121 transid 1325358 size 1061600571 nbytes
1061601280
block group 0 mode 100644 links 1 uid 1008 gid 100 rdev
0
sequence 2126 flags 0x0(none)
atime 1590315849.886896471 (2020-05-24 13:24:09)
ctime 1584291921.928542285 (2020-03-15 19:05:21)
mtime 1488831483.0 (2017-03-06 22:18:03)
otime 1488881824.206510455 (2017-03-07 12:17:04)
item 41 key (13297612 INODE_REF 1135595) itemoff 12442 itemsize
53
index 426 namelen 43 name:
big_file_with_43_chars_in_name
item 42 key (13297612 EXTENT_DATA 0) itemoff 12389 itemsize 53
generation 148121 type 1 (regular)
extent data disk byte 15798103609344 nr 132284416
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item 43 key (13297612 EXTENT_DATA 132284416) itemoff 12336
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generation 148121 type 1 (regular)
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itemsize 53
generation 148121 type 1 (regular)
extent data disk byte 15798355927040 nr 6811648
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itemsize 53
generation 148121 type 1 (regular)
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itemsize 53
generation 148121 type 1 (regular)
extent data disk byte 15798450745344 nr 29892608
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generation 148121 type 1 (regular)
extent data disk byte 15815371431936 nr 66527232
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itemsize 53
generation 148121 type 1 (regular)
extent data disk byte 15815437959168 nr 5242880
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itemsize 53
generation 148121 type 1 (regular)
extent data disk byte 15815443202048 nr 134217728
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generation 148121 type 1 (regular)
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generation 148121 type 1 (regular)
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generation 148121 type 1 (regular)
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generation 148121 type 1 (regular)
extent data disk byte 15815722663936 nr 60813312
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generation 148121 type 1 (regular)
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generation 148121 type 1 (regular)
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itemsize 53
generation 148121 type 1 (regular)
extent data disk byte 15823424454656 nr 17825792
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extent compression 0 (none)
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itemsize 53
generation 148121 type 1 (regular)
extent data disk byte 15823442280448 nr 90701824
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item 59 key (13297612 EXTENT_DATA 954208256) itemoff 11488
itemsize 53
generation 148121 type 1 (regular)
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generation 148121 type 1 (regular)
extent data disk byte 15823543468032 nr 96907264
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atime 1592086805.267986802 (2020-06-14 01:20:05)
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index 158 namelen 14 name: small_file_14
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index 281 namelen 38 name: file_38
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index 284 namelen 32 name: file_32
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item 86 key (13308140 INODE_REF 919572) itemoff 9389 itemsize 38
index 324 namelen 28 name: file_28
item 87 key (13308140 EXTENT_DATA 0) itemoff 9336 itemsize 53
generation 148514 type 1 (regular)
extent data disk byte 2637307904 nr 20480
extent data offset 0 nr 20480 ram 20480
extent compression 0 (none)
item 88 key (13308665 INODE_ITEM 0) itemoff 9176 itemsize 160
generation 148535 transid 1102480 size 503083 nbytes
503808
block group 0 mode 100644 links 1 uid 941400003 gid 513
rdev 0
sequence 20 flags 0x0(none)
atime 1550597353.479573444 (2019-02-19 19:29:13)
ctime 1488899523.16541683 (2017-03-07 17:12:03)
mtime 1488899523.16541683 (2017-03-07 17:12:03)
otime 1488898633.34617131 (2017-03-07 16:57:13)
item 89 key (13308665 INODE_REF 904993) itemoff 9144 itemsize 32
index 2476 namelen 22 name: file_22
item 90 key (13308665 EXTENT_DATA 0) itemoff 9091 itemsize 53
generation 148563 type 1 (regular)
extent data disk byte 36053782528 nr 503808
extent data offset 0 nr 503808 ram 503808
extent compression 0 (none)
item 91 key (13309142 INODE_ITEM 0) itemoff 8931 itemsize 160
generation 148563 transid 1102480 size 258827 nbytes
262144
block group 0 mode 100644 links 1 uid 941400003 gid 513
rdev 0
sequence 25 flags 0x0(none)
atime 1550597353.493573639 (2019-02-19 19:29:13)
ctime 1488899528.464614493 (2017-03-07 17:12:08)
mtime 1488899528.464614493 (2017-03-07 17:12:08)
otime 1488899528.460614441 (2017-03-07 17:12:08)
item 92 key (13309142 INODE_REF 904993) itemoff 8899 itemsize 32
index 2479 namelen 22 name: file_22-1
item 93 key (13309142 EXTENT_DATA 0) itemoff 8846 itemsize 53
generation 148563 type 1 (regular)
extent data disk byte 11277266944 nr 262144
extent data offset 0 nr 262144 ram 262144
extent compression 0 (none)
item 94 key (13309570 INODE_ITEM 0) itemoff 8686 itemsize 160
generation 148586 transid 1218524 size 88 nbytes 88
block group 0 mode 100644 links 1 uid 1008 gid 100 rdev
0
sequence 161 flags 0x0(none)
atime 1569660109.297597210 (2019-09-28 11:41:49)
ctime 1509809344.497370791 (2017-11-04 17:29:04)
mtime 1488921844.229452654 (2017-03-07 23:24:04)
otime 1488901959.581903054 (2017-03-07 17:52:39)
item 95 key (13309570 INODE_REF 933100) itemoff 8636 itemsize
50a
index 533 namelen 40 name: file_40
item 96 key (13309570 EXTENT_DATA 0) itemoff 8527 itemsize 109
generation 148681 type 0 (inline)
inline extent data size 88 ram_bytes 88 compression 0
(none)

The dmesg log lists the following unique blocks:
2627479830528 slot=10 extent data offset 0 nr 18446744073709457408 ram
18446744073709457408
2627928588288 slot=10 No extent data line - (seems to be a file with
stat data)
28710276399104 slot=79 extent data offset 0 nr 18446744073709420544 ram
18446744073709420544
28710639370240 slot=79 extent data offset 0 nr 18446744073709420544 ram
18446744073709420544
30933479342080 slot=27 extent data offset 0 nr 18446744073709395968 ram
18446744073709395968
3154170920960 slot=9 extent data offset 0 nr 18446744073709481984 ram
18446744073709481984
3154170970112 slot=59 extent data offset 0 nr 18446744073709527040 ram
18446744073709527040
3154171035648 slot=27 extent data offset 0 nr 18446744073709514752 ram
18446744073709514752
3154217795584 slot=102 102 item does not exist
3154257952768 slot=59 59 -"-
3154259034112 slot=27 No extent data line
3154291228672 slot=9 -"-

The curious part are the two which list non-existing slots. These errors
have been present in the dmesg-log ever since booting the server and
while I mounted, as per instructions from the btrfs-Wiki, as readonly,
so I don't think it is a case of changed files.

All the data on the partition is copied elsewhere, so there is no issue
of losing files and recreating the FS on the partition is the most
probable outcome of this. Thought nonetheless that investigating this
may be something of interest to the btrfs-developers as I can keep the
current FS around for couple of days.

Poltsi