GFS2: Use RCU for glock hash table
This has a number of advantages:
- Reduces contention on the hash table lock
- Makes the code smaller and simpler
- Should speed up glock dumps when under load
- Removes ref count changing in examine_bucket
- No longer need hash chain lock in glock_put() in common case
There are some further changes which this enables and which
we may do in the future. One is to look at using SLAB_RCU,
and another is to look at using a per-cpu counter for the
per-sb glock counter, since that is touched twice in the
lifetime of each glock (but only used at umount time).
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
diff --git a/fs/gfs2/lops.c b/fs/gfs2/lops.c
index bf33f82..11a73ef 100644
--- a/fs/gfs2/lops.c
+++ b/fs/gfs2/lops.c
@@ -91,7 +91,8 @@
}
bd->bd_ail = ai;
list_add(&bd->bd_ail_st_list, &ai->ai_ail1_list);
- clear_bit(GLF_LFLUSH, &bd->bd_gl->gl_flags);
+ if (test_and_clear_bit(GLF_LFLUSH, &bd->bd_gl->gl_flags))
+ gfs2_glock_schedule_for_reclaim(bd->bd_gl);
trace_gfs2_pin(bd, 0);
gfs2_log_unlock(sdp);
unlock_buffer(bh);