[LU-16405] regression in create that may cause directory entries with the same name

• Type: Bug
• Resolution: Fixed
• Priority: Critical
• Fix Version/s: Lustre 2.16.0
• Severity: 3
• Assignee: Alex Zhuravlev
• Reporter: Lai Siyao

Description

In LU-10235, name lookup is moved before parent locking to avoid unnecessary lock revoke, and it's believed that backend filesystem will check name before entry insert, but some test shows this is not always true.

# ls -lisad pan_*
162139365236040503 4 lrwxrwxrwx 1 rdx rd   65 Dec  8 01:51 pan_000 -> /ec/fws5/sb/work/rd/cxsj/hvxz/MMSF/2017050100/longrange/an_centre
162139357216535883 4 drwxr-x--- 2 rdx rd 4096 Dec  8 01:51 pan_001
162139341278207222 4 drwxr-x--- 2 rdx rd 4096 Dec  8 01:51 pan_002
162139365689006218 4 drwxr-x--- 2 rdx rd 4096 Dec  8 01:51 pan_003
162139362014851225 4 drwxr-x--- 2 rdx rd 4096 Dec  8 01:51 pan_004
162139364397192377 4 drwxr-x--- 2 rdx rd 4096 Dec  8 01:51 pan_005
162139362031645470 4 drwxr-x--- 2 rdx rd 4096 Dec  8 01:51 pan_006
162139361696099316 4 drwxr-x--- 2 rdx rd 4096 Dec  8 01:51 pan_007
162139361343777112 4 drwxr-x--- 2 rdx rd 4096 Dec  8 01:51 pan_008
162139353626266212 4 drwxr-x--- 2 rdx rd 4096 Dec  8 01:51 pan_009
162139350539298147 4 drwxr-x--- 2 rdx rd 4096 Dec  8 01:51 pan_010
162139350539298147 4 drwxr-x--- 2 rdx rd 4096 Dec  8 01:51 pan_010   ## Here 
162139362769806682 4 drwxr-x--- 2 rdx rd 4096 Dec  8 01:51 pan_011
162139353609530857 4 drwxr-x--- 2 rdx rd 4096 Dec  8 01:51 pan_012
162139356226776195 4 drwxr-x--- 2 rdx rd 4096 Dec  8 01:51 pan_013
162139346428878656 4 drwxr-x--- 2 rdx rd 4096 Dec  8 01:51 pan_014
162139361343777140 4 drwxr-x--- 2 rdx rd 4096 Dec  8 01:51 pan_015
162139366141987047 4 drwxr-x--- 2 rdx rd 4096 Dec  8 01:51 pan_016
162139358508461812 4 drwxr-x--- 2 rdx rd 4096 Dec  8 01:51 pan_017
162139353072661755 4 drwxr-x--- 2 rdx rd 4096 Dec  8 01:51 pan_018
162139353072661755 4 drwxr-x--- 2 rdx rd 4096 Dec  8 01:51 pan_018 ## and there

The problem is hit with single-block directories, so is not related to htree split or similar:

#> debugfs -c /dev/mapper/vg_mdt0003_f02-mdt0003
debugfs 1.46.2.wc3 (18-Jun-2021)
/dev/mapper/vg_mdt0003_f02-mdt0003: catastrophic mode - not reading inode or group bitmaps
debugfs:  cd REMOTE_PARENT_DIR/0x240007130:0x1:0x0/work/2017050100/longrange
debugfs: ls
[...snip]
 1032403872  (44) psuhvxz14.noSnow    1032403874  (1020) psuhvxz14
 1038197629  (36) pan_004    1032401372  (48) __ICMGG3.noSnow.tmp
 1039177323  (36) pan_010    1039222784  (36) pan_010
 1032971017  (48) targethvxz20170501002    1032401160  (36) pert_001
[...]
debugfs:  stat <1039177323>
Inode: 1039177323   Type: directory    Mode:  0750   Flags: 0x20000000
Generation: 3276743085    Version: 0x0000002f:d1139426
User:   388   Group:  1100   Project:    13   Size: 4096
File ACL: 0
Links: 2   Blockcount: 8
Fragment:  Address: 0    Number: 0    Size: 0
 ctime: 0x63914328:4490c0f0 -- Thu Dec  8 01:51:36 2022
 atime: 0x63988ad8:00000000 -- Tue Dec 13 14:23:20 2022
 mtime: 0x63914328:4490c0f0 -- Thu Dec  8 01:51:36 2022
crtime: 0x63914328:4490c0f0 -- Thu Dec  8 01:51:36 2022
Size of extra inode fields: 32
Extended attributes:
  lma: fid=[0x24008e159:0x1e563:0x0] compat=0 incompat=0
  linkea: idx=0 parent=[0x24008e347:0x14e34:0x0] name='pan_010'
BLOCKS:
(0):649617594
TOTAL: 1

debugfs:  stat <1039222784>
Inode: 1039222784   Type: directory    Mode:  0750   Flags: 0x20000000
Generation: 3276743100    Version: 0x0000002f:d1139472
User:   388   Group:  1100   Project:    13   Size: 4096
File ACL: 0
Links: 2   Blockcount: 8
Fragment:  Address: 0    Number: 0    Size: 0
 ctime: 0x6391432b:00000000 -- Thu Dec  8 01:51:39 2022
 atime: 0x63914328:450ad5a4 -- Thu Dec  8 01:51:36 2022
 mtime: 0x6391432b:00000000 -- Thu Dec  8 01:51:39 2022
crtime: 0x63914328:450ad5a4 -- Thu Dec  8 01:51:36 2022
Size of extra inode fields: 32
Extended attributes:
  lma: fid=[0x24008e422:0x1fcab:0x0] compat=0 incompat=0
  linkea: idx=0 parent=[0x24008e347:0x14e34:0x0] name='pan_010'
debugfs:  ls <1039177323>
 1039177323  (12) .    1032400653  (4084) ..
debugfs:  ls <1039222784>
 1039222784  (12) .    1032400653  (28) ..    1039271133  (40) ICMSHhvxzINIT
 1039279349  (40) ICMGGhvxzINIT    1039281023  (3976) ggml199

Issue Links

• is related to: LU-10235 mkdir should check for directory existence on client before taking write lock