[LU-12134] llog_reader (incorrectly?) reports a corrupted changelog

• Type: Bug
• Resolution: Done
• Priority: Minor
• Affects Version/s: Upstream
• Labels: ORNL
• Severity: 3
• Assignee: Mikhail Pershin
• Reporter: CEA

Description

I have been following LU-11205 and am trying to reproduce it. I experimented with the llog_reader:

[root]# lustre/tests/llmount.sh
[root]# mkdir /mnt/ldiskfs-mdt0
[root]# mount -t ldiskfs /dev/mapper/mds1_flakey /mnt/ldiskfs-mdt0
[root]# lctl --device lustre-MDT0000 changelog_register
lustre-MDT0000: Registered changelog userid 'cl1'
[root]# lustre/utils/llog_reader /mnt/ldiskfs-mdt0/changelog_users
llog_reader: Error allocating -16 bytes for recs_buf: Cannot allocate memory (12)
llog_reader: Could not pack buffer.: Cannot allocate memory (12)
[root]# lustre/utils/llog_reader /mnt/ldiskfs-mdt0/changelog_catalog
llog_reader: File too small for llog header: need 8192, size 0
: Success (0)
llog_reader: Could not pack buffer.: Input/output error (5)

... Not ideal, but this is probably because there are not any changelog records yet. So I generate one:

[root]# touch /mnt/lustre/file
[root]# lustre/utils/llog_reader /mnt/ldiskfs-mdt0/changelog_users
llog_reader: Error allocating -16 bytes for recs_buf: Cannot allocate memory (12)
llog_reader: Could not pack buffer.: Cannot allocate memory (12)
[root]# lustre/utils/llog_reader /mnt/ldiskfs-mdt0/changelog_catalog
rec #1 type=1064553b len=64 offset 8192
Header size : 8192
Time : Fri Mar 29 14:12:30 2019
Number of records: 1
Target uuid : 
-----------------------
#01 (064)id=[0xa:0x1:0x0]:0 path=O/1/d10/10

Everything is fine now (well, the users changelog is still broken, but I do not really need it). But what happens if I try and generate a few more?

[root]# for _ in {0..15}; do touch /mnt/lustre/file-{0..1023}; rm /mnt/lustre/file-{0..1023}; done
[root]# lustre/utils/llog_reader /mnt/ldiskfs-mdt0/changelog_catalog
rec #1 type=1064553b len=64 offset 8192
off 8256 skip 8128 to next chunk.
The log is corrupt (too big at 0)
llog_reader: Could not pack buffer.: Invalid argument (22)

Back to a broken changelog...
lfs changelog seems to be doing fine though:

[root]# lfs changelog lustre-MDT0000
1 01CREAT 14:14:51.291849812 2019.03.29 0x0 t=[0x200000401:0x12:0x0] j=touch.0 ef=0xf u=0:0 nid=0@lo p=[0x200000007:0x1:0x0] file
2 11CLOSE 14:14:51.293009818 2019.03.29 0x42 t=[0x200000401:0x12:0x0] j=touch.0 ef=0xf u=0:0 nid=0@lo
3 01CREAT 14:23:23.124863776 2019.03.29 0x0 t=[0x200000401:0x13:0x0] j=touch.0 ef=0xf u=0:0 nid=0@lo p=[0x200000007:0x1:0x0] file-0
4 11CLOSE 14:23:23.139933635 2019.03.29 0x42 t=[0x200000401:0x13:0x0] j=touch.0 ef=0xf u=0:0 nid=0@lo
5 01CREAT 14:23:23.140437103 2019.03.29 0x0 t=[0x200000401:0x14:0x0] j=touch.0 ef=0xf u=0:0 nid=0@lo p=[0x200000007:0x1:0x0] file-1
(...)
49153 06UNLNK 14:23:57.498329392 2019.03.29 0x1 t=[0x200000401:0x4011:0x0] j=rm.0 ef=0xf u=0:0 nid=0@lo p=[0x200000007:0x1:0x0] file-1022
49154 06UNLNK 14:23:57.499430628 2019.03.29 0x1 t=[0x200000401:0x4012:0x0] j=rm.0 ef=0xf u=0:0 nid=0@lo p=[0x200000007:0x1:0x0] file-1023

Which makes me hope the issue is only with the llog_reader.

Issue Links

• is related to: LU-11205 Failure to clear the changelog for user 1 on MDT