[Cluster-devel] [PATCH 09/13] GFS2: Replace run_queue with new GL_ST_RUN state in state machine

[Bob Peterson <rpeterso@redhat.com>]

Now we replace the run_queue function with a new state in the glock
state machine which does the same thing.

Signed-off-by: Bob Peterson <rpeterso@redhat.com>
---
 fs/gfs2/glock.c | 60 +++++++++++++++++++++----------------------------
 fs/gfs2/glock.h |  1 +
 2 files changed, 27 insertions(+), 34 deletions(-)

diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c
index 6048867b2d66..82c4614793b3 100644
--- a/fs/gfs2/glock.c
+++ b/fs/gfs2/glock.c
@@ -60,9 +60,6 @@ struct gfs2_glock_iter {
 
 typedef void (*glock_examiner) (struct gfs2_glock * gl);
 
-static void __state_machine(struct gfs2_glock *gl, int new_state);
-static void state_machine(struct gfs2_glock *gl, int new_state);
-
 static struct dentry *gfs2_root;
 static struct workqueue_struct *glock_workqueue;
 struct workqueue_struct *gfs2_delete_workqueue;
@@ -610,34 +607,11 @@ static inline struct gfs2_holder *find_first_holder(const struct gfs2_glock *gl)
 	return NULL;
 }
 
-/**
- * run_queue - do all outstanding tasks related to a glock
- * @gl: The glock in question
- * @nonblock: True if we must not block in run_queue
- *
- */
-
-static void run_queue(struct gfs2_glock *gl, const int nonblock)
-__releases(&gl->gl_lockref.lock)
-__acquires(&gl->gl_lockref.lock)
-{
-	if (test_and_set_bit(GLF_LOCK, &gl->gl_flags))
-		return;
-
-	GLOCK_BUG_ON(gl, test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags));
-
-	if (test_bit(GLF_DEMOTE, &gl->gl_flags) &&
-	    gl->gl_demote_state != gl->gl_state)
-		__state_machine(gl, nonblock ? GL_ST_DEMOTE_NONBLOCK :
-				GL_ST_BLOCKING_DEMOTE);
-	else
-		__state_machine(gl, GL_ST_PROMOTE);
-}
-
 /**
  * __state_machine - the glock state machine
  * @gl: pointer to the glock we are transitioning
  * @new_state: The new state we need to execute
+ * @nonblock: True if we must not block while demoting
  *
  * This function handles state transitions for glocks.
  * When the state_machine is called, it's given a new state that needs to be
@@ -646,7 +620,8 @@ __acquires(&gl->gl_lockref.lock)
  * The lock might be released inside some of the states, so we may need react
  * to state changes from other calls.
  */
-static void __state_machine(struct gfs2_glock *gl, int new_state)
+static void __state_machine(struct gfs2_glock *gl, int new_state,
+			    const int nonblock)
 {
 	struct gfs2_holder *gh = NULL;
 	int ret;
@@ -727,6 +702,22 @@ static void __state_machine(struct gfs2_glock *gl, int new_state)
 				do_error(gl, 0); /* Fail queued try locks */
 			gl->gl_mch = GL_ST_DO_XMOTE;
 			break;
+
+		case GL_ST_RUN:
+			gl->gl_mch = GL_ST_IDLE;
+			if (test_and_set_bit(GLF_LOCK, &gl->gl_flags))
+				break;
+
+			GLOCK_BUG_ON(gl, test_bit(GLF_DEMOTE_IN_PROGRESS,
+						  &gl->gl_flags));
+
+			if (test_bit(GLF_DEMOTE, &gl->gl_flags) &&
+			    gl->gl_demote_state != gl->gl_state)
+				gl->gl_mch = nonblock ? GL_ST_DEMOTE_NONBLOCK :
+					GL_ST_BLOCKING_DEMOTE;
+			else
+				gl->gl_mch = GL_ST_PROMOTE;
+			break;
 		}
 	} while (gl->gl_mch != GL_ST_IDLE);
 }
@@ -738,12 +729,13 @@ static void __state_machine(struct gfs2_glock *gl, int new_state)
  *
  * Just like __state_machine but it acquires the gl_lockref lock
  */
-static void state_machine(struct gfs2_glock *gl, int new_state)
+static void state_machine(struct gfs2_glock *gl, int new_state,
+			  const int nonblock)
 __releases(&gl->gl_lockref.lock)
 __acquires(&gl->gl_lockref.lock)
 {
 	spin_lock(&gl->gl_lockref.lock);
-	__state_machine(gl, new_state);
+	__state_machine(gl, new_state, nonblock);
 	spin_unlock(&gl->gl_lockref.lock);
 }
 
@@ -776,7 +768,7 @@ static void glock_work_func(struct work_struct *work)
 	unsigned int drop_refs = 1;
 
 	if (test_and_clear_bit(GLF_REPLY_PENDING, &gl->gl_flags)) {
-		state_machine(gl, GL_ST_FINISH_XMOTE);
+		state_machine(gl, GL_ST_FINISH_XMOTE, 0);
 		drop_refs++;
 	}
 	spin_lock(&gl->gl_lockref.lock);
@@ -794,7 +786,7 @@ static void glock_work_func(struct work_struct *work)
 			set_bit(GLF_DEMOTE, &gl->gl_flags);
 		}
 	}
-	run_queue(gl, 0);
+	__state_machine(gl, GL_ST_RUN, 0);
 	if (delay) {
 		/* Keep one glock reference for the work we requeue. */
 		drop_refs--;
@@ -1189,7 +1181,7 @@ int gfs2_glock_nq(struct gfs2_holder *gh)
 		gl->gl_lockref.count++;
 		__gfs2_glock_queue_work(gl, 0);
 	}
-	run_queue(gl, 1);
+	__state_machine(gl, GL_ST_RUN, 1);
 	spin_unlock(&gl->gl_lockref.lock);
 
 	if (!(gh->gh_flags & GL_ASYNC))
@@ -1733,7 +1725,7 @@ void gfs2_glock_finish_truncate(struct gfs2_inode *ip)
 
 	spin_lock(&gl->gl_lockref.lock);
 	clear_bit(GLF_LOCK, &gl->gl_flags);
-	run_queue(gl, 1);
+	__state_machine(gl, GL_ST_RUN, 1);
 	spin_unlock(&gl->gl_lockref.lock);
 }
 
diff --git a/fs/gfs2/glock.h b/fs/gfs2/glock.h
index 76db63d1efae..0239d3a9040c 100644
--- a/fs/gfs2/glock.h
+++ b/fs/gfs2/glock.h
@@ -129,6 +129,7 @@ enum gl_machine_states {
 	GL_ST_DEMOTE_NONBLOCK = 4, /* Demote is in progress - non-blocking */
 	GL_ST_BLOCKING_DEMOTE = 5, /* Demote is in progress - blocking */
 	GL_ST_PROMOTE = 6,	   /* Promote the lock */
+	GL_ST_RUN = 7,		/* "Run" or progress the lock */
 };
 
 struct lm_lockops {
-- 
2.19.1