[Cluster-devel] [PATCH 07/13] GFS2: Add blocking and non-blocking demote to state machine

[Bob Peterson <rpeterso@redhat.com>]

Before this patch, function run_queue would do special processing
before calling the state machine for the blocking and non-blocking
demote-in-progress cases. This function rolls those functions into
the state machine, which will allow us to eventually simplify with
later patches.

Signed-off-by: Bob Peterson <rpeterso@redhat.com>
---
 fs/gfs2/glock.c | 44 +++++++++++++++++++++++++++++---------------
 fs/gfs2/glock.h |  2 ++
 2 files changed, 31 insertions(+), 15 deletions(-)

diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c
index 8dc98d069afa..023e2186b374 100644
--- a/fs/gfs2/glock.c
+++ b/fs/gfs2/glock.c
@@ -631,21 +631,9 @@ __acquires(&gl->gl_lockref.lock)
 
 	if (test_bit(GLF_DEMOTE, &gl->gl_flags) &&
 	    gl->gl_demote_state != gl->gl_state) {
-		if (find_first_holder(gl)) {
-			clear_bit(GLF_LOCK, &gl->gl_flags);
-			smp_mb__after_atomic();
-			return;
-		}
-		if (nonblock) {
-			clear_bit(GLF_LOCK, &gl->gl_flags);
-			smp_mb__after_atomic();
-			gl->gl_lockref.count++;
-			__gfs2_glock_queue_work(gl, 0);
-			return;
-		}
-		set_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags);
-		GLOCK_BUG_ON(gl, gl->gl_demote_state == LM_ST_EXCLUSIVE);
-		gl->gl_target = gl->gl_demote_state;
+		__state_machine(gl, nonblock ? GL_ST_DEMOTE_NONBLOCK :
+				GL_ST_BLOCKING_DEMOTE);
+		return;
 	} else {
 		if (test_bit(GLF_DEMOTE, &gl->gl_flags))
 			gfs2_demote_wake(gl);
@@ -713,6 +701,32 @@ static void __state_machine(struct gfs2_glock *gl, int new_state)
 			if (ret == -EAGAIN)
 				gl->gl_mch = GL_ST_FINISH_XMOTE;
 			break;
+
+		case GL_ST_BLOCKING_DEMOTE:
+			gl->gl_mch = GL_ST_IDLE;
+			if (find_first_holder(gl)) {
+				clear_bit(GLF_LOCK, &gl->gl_flags);
+				smp_mb__after_atomic();
+				break;
+			}
+			set_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags);
+			GLOCK_BUG_ON(gl, gl->gl_demote_state == LM_ST_EXCLUSIVE);
+			gl->gl_target = gl->gl_demote_state;
+			gl->gl_mch = GL_ST_DO_XMOTE;
+			break;
+
+		case GL_ST_DEMOTE_NONBLOCK:
+			gl->gl_mch = GL_ST_IDLE;
+			if (find_first_holder(gl)) {
+				clear_bit(GLF_LOCK, &gl->gl_flags);
+				smp_mb__after_atomic();
+				break;
+			}
+			clear_bit(GLF_LOCK, &gl->gl_flags);
+			smp_mb__after_atomic();
+			gl->gl_lockref.count++;
+			__gfs2_glock_queue_work(gl, 0);
+			break;
 		}
 	} while (gl->gl_mch != GL_ST_IDLE);
 }
diff --git a/fs/gfs2/glock.h b/fs/gfs2/glock.h
index 8333bbc5a197..c8b704a73638 100644
--- a/fs/gfs2/glock.h
+++ b/fs/gfs2/glock.h
@@ -126,6 +126,8 @@ enum gl_machine_states {
 	GL_ST_DO_XMOTE = 2,	/* Promote or demote a waiter */
 	GL_ST_DO_XMOTE_UNLOCK = 3, /* Promote or demote a waiter after a failed
 				      state change attempt from dlm. */
+	GL_ST_DEMOTE_NONBLOCK = 4, /* Demote is in progress - non-blocking */
+	GL_ST_BLOCKING_DEMOTE = 5, /* Demote is in progress - blocking */
 };
 
 struct lm_lockops {
-- 
2.19.1