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ocfs2: do not return DLM_MIGRATE_RESPONSE_MASTERY_REF to avoid endless, loop during umount

PATCH New jiangyiwen 1 participant 1 message Mar 4, 2014 OCFS2

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jiangyiwen

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PATCH 1/1 ocfs2: do not return DLM_MIGRATE_RESPONSE_MASTERY_REF to avoid endless, loop during umount

The following case may lead to endless loop during umount.

node A node B node C node D
umount volume,
migrate lockres1
to B
want to lock lockres1, send MASTER_REQUEST_MSG to C
init block mle
send
MIGRATE_REQUEST_MSG
to C
find a block
mle, and then
return DLM_MIGRATE_RESPONSE_MASTERY_REF to B
set C in refmap
umount successfully
try to umount, endless
loop occurs when migrate
lockres1 since C is in
refmap

So we can fix this endless loop case by only returning DLM_MIGRATE_RESPONSE_MASTERY_REF if it has a mastery mle when receiving MIGRATE_REQUEST_MSG.

Signed-off-by jiangyiwen <[email protected]>
---
 fs/ocfs2/dlm/dlmmaster.c | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)
fs/ocfs2/dlm/dlmmaster.c +9 -5
index af3f7aa..1b11a47 100644
@@ -3084,11 +3084,15 @@ static int dlm_add_migration_mle(struct dlm_ctxt *dlm,
                        /* remove it so that only one mle will be found */
                        __dlm_unlink_mle(dlm, tmp);
                        __dlm_mle_detach_hb_events(dlm, tmp);
-                       ret = DLM_MIGRATE_RESPONSE_MASTERY_REF;
-                       mlog(0, "%s:%.*s: master=%u, newmaster=%u, "
-                           "telling master to get ref for cleared out mle "
-                           "during migration\n", dlm->name, namelen, name,
-                           master, new_master);
+                       if (tmp->type == DLM_MLE_MASTER) {
+                               ret = DLM_MIGRATE_RESPONSE_MASTERY_REF;
+                               mlog(0, "%s:%.*s: master=%u, newmaster=%u, "
+                                               "telling master to get ref "
+                                               "for cleared out mle during "
+                                               "migration\n", dlm->name,
+                                               namelen, name, master,
+                                               new_master);
+                       }
                }
                spin_unlock(&tmp->spinlock);
        }

--
1.8.4.3