GFS2: Fix glock deallocation race

This patch fixes a race in deallocating glocks which was introduced
in the RCU glock patch. We need to ensure that the glock count is
kept correct even in the case that there is a race to add a new
glock into the hash table. Also, to avoid having to wait for an
RCU grace period, the glock counter can be decremented before
call_rcu() is called.

Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

1 files changed, 2 insertions, 2 deletions

diff --git a/fs/gfs2/lock_dlm.c b/fs/gfs2/lock_dlm.c
index c80485cb6f25..98c80d8c2a62 100644
--- a/fs/gfs2/lock_dlm.c
+++ b/fs/gfs2/lock_dlm.c
@@ -30,7 +30,7 @@ static void gdlm_ast(void *arg)
 
         switch (gl->gl_lksb.sb_status) {
         case -DLM_EUNLOCK: /* Unlocked, so glock can be freed */
-                call_rcu(&gl->gl_rcu, gfs2_glock_free);
+                gfs2_glock_free(gl);
                 return;
         case -DLM_ECANCEL: /* Cancel while getting lock */
                 ret |= LM_OUT_CANCELED;
@@ -165,7 +165,7 @@ static void gdlm_put_lock(struct gfs2_glock *gl)
         int error;
 
         if (gl->gl_lksb.sb_lkid == 0) {
-                call_rcu(&gl->gl_rcu, gfs2_glock_free);
+                gfs2_glock_free(gl);
                 return;
         }