[DLM] fix oops in kref_put when removing a lockspace

Now that the lockspace struct is freed when the last sysfs object is released
this patch prevents use of that lockspace by sysfs. We attempt to re-get the
lockspace from the lockspace list and fail the request if it has been removed.

Signed-Off-By: Patrick Caulfield <pcaulfie@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

1 files changed, 5 insertions, 0 deletions

diff --git a/fs/dlm/lockspace.c b/fs/dlm/lockspace.c
index 499ee1156365..f8842ca443c2 100644
--- a/fs/dlm/lockspace.c
+++ b/fs/dlm/lockspace.c
@@ -43,6 +43,10 @@ static ssize_t dlm_control_store(struct dlm_ls *ls, const char *buf, size_t len)
         ssize_t ret = len;
         int n = simple_strtol(buf, NULL, 0);
 
+        ls = dlm_find_lockspace_local(ls->ls_local_handle);
+        if (!ls)
+                return -EINVAL;
+
         switch (n) {
         case 0:
                 dlm_ls_stop(ls);
@@ -53,6 +57,7 @@ static ssize_t dlm_control_store(struct dlm_ls *ls, const char *buf, size_t len)
         default:
                 ret = -EINVAL;
         }
+        dlm_put_lockspace(ls);
         return ret;
 }