diff options
| author | Srinivas Eeda | 2014-12-10 15:41:48 -0800 |
|---|---|---|
| committer | Linus Torvalds | 2014-12-10 17:41:03 -0800 |
| commit | cb79662bc2f83f7b3b60970ad88df43085f96514 (patch) | |
| tree | f4a154486a41682ed7a1288d73ced7e8d2814a6d | |
| parent | f5425fcea72eec084c50f36db4d25f697227c602 (diff) | |
ocfs2: o2dlm: fix a race between purge and master query
Node A sends master query request to node B which is the master. At this
time lockres happens to be on purgelist. dlm_master_request_handler gets
the dlm spinlock, finds the resource and releases the dlm spin lock.
Right at this dlm_thread on this node could purge the lockres.
dlm_master_request_handler can then acquire lockres spinlock and reply to
Node A that node B is the master even though lockres on node B is purged.
The above scenario will now make node A falsely think node B is the master
which is inconsistent. Further if another node C tries to master the same
resource, every node will respond they are not the master. Node C then
masters the resource and sends assert master to all nodes. This will now
make node A crash with the following message.
dlm_assert_master_handler:1831 ERROR: DIE! Mastery assert from 9, but current
owner is 10!
Signed-off-by: Srinivas Eeda <srinivas.eeda@oracle.com>
Cc: Mark Fasheh <mfasheh@suse.com>
Cc: Joel Becker <jlbec@evilplan.org>
Reviewed-by: Wengang Wang <wen.gang.wang@oracle.com>
Tested-by: Joseph Qi <joseph.qi@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | fs/ocfs2/dlm/dlmmaster.c | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/fs/ocfs2/dlm/dlmmaster.c b/fs/ocfs2/dlm/dlmmaster.c index 215e41abf101..3689b3592042 100644 --- a/fs/ocfs2/dlm/dlmmaster.c +++ b/fs/ocfs2/dlm/dlmmaster.c @@ -1460,6 +1460,18 @@ way_up_top: /* take care of the easy cases up front */ spin_lock(&res->spinlock); + + /* + * Right after dlm spinlock was released, dlm_thread could have + * purged the lockres. Check if lockres got unhashed. If so + * start over. + */ + if (hlist_unhashed(&res->hash_node)) { + spin_unlock(&res->spinlock); + dlm_lockres_put(res); + goto way_up_top; + } + if (res->state & (DLM_LOCK_RES_RECOVERING| DLM_LOCK_RES_MIGRATING)) { spin_unlock(&res->spinlock); |