[LU-1716] Race in setting connection flags and using them on 2.x client connect

• Type: Bug
• Resolution: Fixed
• Priority: Blocker
• Fix Version/s: Lustre 2.3.0, Lustre 2.4.0, Lustre 2.1.4
• Affects Version/s: Lustre 2.3.0
• Severity: 3
• Assignee: Bob Glossman (Inactive)
• Reporter: Andriy Skulysh

Description

Lustre 2.1 client fails to connect to Lustre 2.2 server

> c0-0c2s6n1 LustreError: 11-0: an error occurred while communicating with 10.149.3.5@o2ib. The mgs_config_read operation failed with -524
> c0-0c2s6n1 LustreError: 4645:0:(mgc_request.c:1917:mgc_process_config()) Cannot process recover llog -524
> c0-0c2s6n1 LustreError: 15c-8: MGC10.149.3.5@o2ib: The configuration from log 'snxs2-client' failed (-524). This may be the result of communication errors between this node and the MGS, a bad configuration, or other errors. See the syslog for more information.
> c0-0c2s6n1 LustreError: 4645:0:(llite_lib.c:983:ll_fill_super()) Unable to process log: -524

the race can be reproduced with following patch:

diff --git a/lustre/ptlrpc/import.c b/lustre/ptlrpc/import.c
index 2953352..a69e6b9 100644
— a/lustre/ptlrpc/import.c
+++ b/lustre/ptlrpc/import.c
@@ -805,6 +805,7 @@ static int ptlrpc_connect_interpret(const struct lu_env *env,
                 } else {
                         IMPORT_SET_STATE(imp, LUSTRE_IMP_FULL);
                         ptlrpc_activate_import(imp);
+                        OBD_FAIL_TIMEOUT(0x5555, 2);
                 }
 
                 GOTO(finish, rc = 0);