[GFS2] Handle multiple glock demote requests

Fix a race condition where multiple glock demote requests are sent to
a node back-to-back. This patch does a check inside handle_callback()
to see whether a demote request is in progress. If true, it sets a flag
to make sure run_queue() will loop again to handle the new request,
instead of erronously setting gl_demote_state to a different state.

Signed-off-by: S. Wendy Cheng <wcheng@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/fs/gfs2/incore.h b/fs/gfs2/incore.h
index eaddfb5a8e6f..662182bfbff7 100644
--- a/fs/gfs2/incore.h
+++ b/fs/gfs2/incore.h
@@ -171,6 +171,7 @@ enum {
         GLF_DEMOTE              = 3,
         GLF_PENDING_DEMOTE      = 4,
         GLF_DIRTY               = 5,
+        GLF_DEMOTE_IN_PROGRESS  = 6,
 };
 
 struct gfs2_glock {
@@ -190,6 +191,7 @@ struct gfs2_glock {
         struct list_head gl_holders;
         struct list_head gl_waiters1;   /* HIF_MUTEX */
         struct list_head gl_waiters3;   /* HIF_PROMOTE */
+        int gl_waiters2;                /* GIF_DEMOTE */
 
         const struct gfs2_glock_operations *gl_ops;