gfs2: eliminate GIF_ORDERED in favor of list_empty

In several places, we used the GIF_ORDERED inode flag to determine
if an inode was on the ordered writes list. However, since we always
held the sd_ordered_lock spin_lock during the manipulation, we can
just as easily check list_empty(&ip->i_ordered) instead.
This allows us to keep more than one ordered writes list to make
journal writing improvements.

This patch eliminates GIF_ORDERED in favor of checking list_empty.
Signed-off-by: Bob Peterson <rpeterso@redhat.com>

fs/gfs2/incore.h

@@ -399,7 +399,6 @@ enum {
 	GIF_QD_LOCKED		= 1,
 	GIF_ALLOC_FAILED	= 2,
 	GIF_SW_PAGED		= 3,
-	GIF_ORDERED		= 4,
 	GIF_FREE_VFS_INODE      = 5,
 	GIF_GLOP_PENDING	= 6,
 	GIF_DEFERRED_DELETE	= 7,

fs/gfs2/log.c

@@ -613,6 +613,12 @@ static int ip_cmp(void *priv, struct list_head *a, struct list_head *b)
 	return 0;
 }
 
+static void __ordered_del_inode(struct gfs2_inode *ip)
+{
+	if (!list_empty(&ip->i_ordered))
+		list_del_init(&ip->i_ordered);
+}
+
 static void gfs2_ordered_write(struct gfs2_sbd *sdp)
 {
 	struct gfs2_inode *ip;
@@ -623,8 +629,7 @@ static void gfs2_ordered_write(struct gfs2_sbd *sdp)
 	while (!list_empty(&sdp->sd_log_ordered)) {
 		ip = list_first_entry(&sdp->sd_log_ordered, struct gfs2_inode, i_ordered);
 		if (ip->i_inode.i_mapping->nrpages == 0) {
-			test_and_clear_bit(GIF_ORDERED, &ip->i_flags);
-			list_del(&ip->i_ordered);
+			__ordered_del_inode(ip);
 			continue;
 		}
 		list_move(&ip->i_ordered, &written);
@@ -643,8 +648,7 @@ static void gfs2_ordered_wait(struct gfs2_sbd *sdp)
 	spin_lock(&sdp->sd_ordered_lock);
 	while (!list_empty(&sdp->sd_log_ordered)) {
 		ip = list_first_entry(&sdp->sd_log_ordered, struct gfs2_inode, i_ordered);
-		list_del(&ip->i_ordered);
-		WARN_ON(!test_and_clear_bit(GIF_ORDERED, &ip->i_flags));
+		__ordered_del_inode(ip);
 		if (ip->i_inode.i_mapping->nrpages == 0)
 			continue;
 		spin_unlock(&sdp->sd_ordered_lock);
@@ -659,8 +663,7 @@ void gfs2_ordered_del_inode(struct gfs2_inode *ip)
 	struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
 
 	spin_lock(&sdp->sd_ordered_lock);
-	if (test_and_clear_bit(GIF_ORDERED, &ip->i_flags))
-		list_del(&ip->i_ordered);
+	__ordered_del_inode(ip);
 	spin_unlock(&sdp->sd_ordered_lock);
 }
 

fs/gfs2/log.h

@@ -53,9 +53,9 @@ static inline void gfs2_ordered_add_inode(struct gfs2_inode *ip)
 	if (gfs2_is_jdata(ip) || !gfs2_is_ordered(sdp))
 		return;
 
-	if (!test_bit(GIF_ORDERED, &ip->i_flags)) {
+	if (list_empty(&ip->i_ordered)) {
 		spin_lock(&sdp->sd_ordered_lock);
-		if (!test_and_set_bit(GIF_ORDERED, &ip->i_flags))
+		if (list_empty(&ip->i_ordered))
 			list_add(&ip->i_ordered, &sdp->sd_log_ordered);
 		spin_unlock(&sdp->sd_ordered_lock);
 	}

fs/gfs2/main.c

@@ -39,6 +39,7 @@ static void gfs2_init_inode_once(void *foo)
 	atomic_set(&ip->i_sizehint, 0);
 	init_rwsem(&ip->i_rw_mutex);
 	INIT_LIST_HEAD(&ip->i_trunc_list);
+	INIT_LIST_HEAD(&ip->i_ordered);
 	ip->i_qadata = NULL;
 	gfs2_holder_mark_uninitialized(&ip->i_rgd_gh);
 	memset(&ip->i_res, 0, sizeof(ip->i_res));