[LU-5963] wrong hashing in LU-4647

• Type: Bug
• Resolution: Fixed
• Priority: Blocker
• Fix Version/s: Lustre 2.7.0
• Affects Version/s: Lustre 2.7.0
• Labels: HB nodemap patch
• Environment: master from now.
• Severity: 3
• Assignee: Nathaniel Clark
• Reporter: Alexey Lyashkov

Description

Sometimes recovery-small tests 50-52 failed on 8 CPU box. with leak a export reference. After some investigation i see nodemap don't able to found own entry for an export, but export still linked to node map. (i don't know why intel land something without any debug options in code?). per additional investigation i see someone

commit 83f04354ff68a14d7492e35a9576c91492a1206c
Author: Joshua Walgenbach <[e-mail]>
Date: Mon Mar 3 09:10:20 2014 +0100

LU-4647 nodemap: add mapping functional
Signed-off-by: Joshua Walgenbach <[e-mail]>
Signed-off-by: Kit Westneat <[e-mail]>
Reviewed-on: http://review.whamcloud.com/9299
Tested-by: Jenkins
Reviewed-by: Andreas Dilger <[e-mail]>
Reviewed-by: Nathaniel Clark <[e-mail]>

have a bad inspection and allow to "hash" an export pointer as string.
so if any byte will be changed in export after add - we don't able to find something in hash.

Issue Links

• is related to: LU-5928 sanity test_133f timeout: lprocfs_exp_nodemap_seq_show() oops
• is related to: LU-4647 Add idmapping functions for nodemap

Comments

[Nathaniel Clark]

Merged to master

[Gerrit Updater]

Oleg Drokin ([e-mail]) merged in patch http://review.whamcloud.com/12881/
Subject: LU-5963 nodemap: use proper hashing
Project: fs/lustre-release
Branch: master
Current Patch Set:
Commit: b0236f7b024b5f76d8915334480dd6387f71451f

[Alexey Lyashkov]

http://review.whamcloud.com/12881

[Gerrit Updater]

Alexey Lyashkov ([e-mail]) uploaded a new patch: http://review.whamcloud.com/12881
Subject: LU-5963 nodemap: use proper hashing
Project: fs/lustre-release
Branch: master
Current Patch Set: 1
Commit: b42e666cab01a40d867f88c0691846b03fc3fa25

[Alexey Lyashkov]

this patch fixes problem

@@ -50,7 +52,12 @@ void nm_member_putref(struct obd_export *exp)
 static __u32 nm_member_hashfn(cfs_hash_t *hash_body,
                           const void *key, unsigned mask)
 {
-       return cfs_hash_djb2_hash(key, strlen(key), mask);
+       unsigned long hash;
+//     return cfs_hash_djb2_hash(key, strlen(key), mask);
+       hash = hash_long((unsigned long)key, hash_body->hs_bkt_bits) & mask;
+
+       CDEBUG(D_INFO, "hashing %p -> %lu\n", key, hash);
+       return hash;
 }