[Cluster-devel] [PATCH 08/13] GFS2: Add a new GL_ST_PROMOTE state to glock state machine

[Bob Peterson <rpeterso@redhat.com>]

Before this patch, function run_queue did a bunch of logic when
glocks are being promoted. This patch moves the logic to the glock
state machine and simplifies run_queue further.

Signed-off-by: Bob Peterson <rpeterso@redhat.com>
---
 fs/gfs2/glock.c | 46 +++++++++++++++++++++++-----------------------
 fs/gfs2/glock.h |  1 +
 2 files changed, 24 insertions(+), 23 deletions(-)

diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c
index 023e2186b374..6048867b2d66 100644
--- a/fs/gfs2/glock.c
+++ b/fs/gfs2/glock.c
@@ -621,37 +621,17 @@ static void run_queue(struct gfs2_glock *gl, const int nonblock)
 __releases(&gl->gl_lockref.lock)
 __acquires(&gl->gl_lockref.lock)
 {
-	struct gfs2_holder *gh = NULL;
-	int ret;
-
 	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) {
+	    gl->gl_demote_state != gl->gl_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);
-		ret = do_promote(gl);
-		if (ret == 0) {
-			clear_bit(GLF_LOCK, &gl->gl_flags);
-			smp_mb__after_atomic();
-			return;
-		}
-		if (ret == 2)
-			return;
-		gh = find_first_waiter(gl);
-		gl->gl_target = gh->gh_state;
-		if (!(gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)))
-			do_error(gl, 0); /* Fail queued try locks */
-	}
-	__state_machine(gl, GL_ST_DO_XMOTE);
-	return;
+	else
+		__state_machine(gl, GL_ST_PROMOTE);
 }
 
 /**
@@ -668,6 +648,7 @@ __acquires(&gl->gl_lockref.lock)
  */
 static void __state_machine(struct gfs2_glock *gl, int new_state)
 {
+	struct gfs2_holder *gh = NULL;
 	int ret;
 
 	BUG_ON(!spin_is_locked(&gl->gl_lockref.lock));
@@ -727,6 +708,25 @@ static void __state_machine(struct gfs2_glock *gl, int new_state)
 			gl->gl_lockref.count++;
 			__gfs2_glock_queue_work(gl, 0);
 			break;
+
+		case GL_ST_PROMOTE:
+			gl->gl_mch = GL_ST_IDLE;
+			if (test_bit(GLF_DEMOTE, &gl->gl_flags))
+				gfs2_demote_wake(gl);
+			ret = do_promote(gl);
+			if (ret == 0) {
+				clear_bit(GLF_LOCK, &gl->gl_flags);
+				smp_mb__after_atomic();
+				break;
+			}
+			if (ret == 2)
+				break;
+			gh = find_first_waiter(gl);
+			gl->gl_target = gh->gh_state;
+			if (!(gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)))
+				do_error(gl, 0); /* Fail queued try locks */
+			gl->gl_mch = GL_ST_DO_XMOTE;
+			break;
 		}
 	} while (gl->gl_mch != GL_ST_IDLE);
 }
diff --git a/fs/gfs2/glock.h b/fs/gfs2/glock.h
index c8b704a73638..76db63d1efae 100644
--- a/fs/gfs2/glock.h
+++ b/fs/gfs2/glock.h
@@ -128,6 +128,7 @@ enum gl_machine_states {
 				      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 */
+	GL_ST_PROMOTE = 6,	   /* Promote the lock */
 };
 
 struct lm_lockops {
-- 
2.19.1