From dca332528bc69e05f67161e1ed59929633d5e63d Mon Sep 17 00:00:00 2001
From: Al Viro <viro@zeniv.linux.org.uk>
Date: Sun, 25 Jul 2010 02:31:46 +0400
Subject: no need for list_for_each_entry_safe()/resetting with superblock list

just delay __put_super() a bit

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
 fs/dcache.c | 12 +++++++-----
 fs/super.c  | 36 +++++++++++++++++++++---------------
 2 files changed, 28 insertions(+), 20 deletions(-)

diff --git a/fs/dcache.c b/fs/dcache.c
index caf0857..9f2c134 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -536,7 +536,7 @@ restart:
  */
 static void prune_dcache(int count)
 {
-	struct super_block *sb, *n;
+	struct super_block *sb, *p = NULL;
 	int w_count;
 	int unused = dentry_stat.nr_unused;
 	int prune_ratio;
@@ -550,7 +550,7 @@ static void prune_dcache(int count)
 	else
 		prune_ratio = unused / count;
 	spin_lock(&sb_lock);
-	list_for_each_entry_safe(sb, n, &super_blocks, s_list) {
+	list_for_each_entry(sb, &super_blocks, s_list) {
 		if (list_empty(&sb->s_instances))
 			continue;
 		if (sb->s_nr_dentry_unused == 0)
@@ -590,14 +590,16 @@ static void prune_dcache(int count)
 			up_read(&sb->s_umount);
 		}
 		spin_lock(&sb_lock);
-		/* lock was dropped, must reset next */
-		list_safe_reset_next(sb, n, s_list);
+		if (p)
+			__put_super(p);
 		count -= pruned;
-		__put_super(sb);
+		p = sb;
 		/* more work left to do? */
 		if (count <= 0)
 			break;
 	}
+	if (p)
+		__put_super(p);
 	spin_unlock(&sb_lock);
 	spin_unlock(&dcache_lock);
 }
diff --git a/fs/super.c b/fs/super.c
index bd9eea4..9674ab2 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -363,10 +363,10 @@ EXPORT_SYMBOL(drop_super);
  */
 void sync_supers(void)
 {
-	struct super_block *sb, *n;
+	struct super_block *sb, *p = NULL;
 
 	spin_lock(&sb_lock);
-	list_for_each_entry_safe(sb, n, &super_blocks, s_list) {
+	list_for_each_entry(sb, &super_blocks, s_list) {
 		if (list_empty(&sb->s_instances))
 			continue;
 		if (sb->s_op->write_super && sb->s_dirt) {
@@ -379,11 +379,13 @@ void sync_supers(void)
 			up_read(&sb->s_umount);
 
 			spin_lock(&sb_lock);
-			/* lock was dropped, must reset next */
-			list_safe_reset_next(sb, n, s_list);
-			__put_super(sb);
+			if (p)
+				__put_super(p);
+			p = sb;
 		}
 	}
+	if (p)
+		__put_super(p);
 	spin_unlock(&sb_lock);
 }
 
@@ -397,10 +399,10 @@ void sync_supers(void)
  */
 void iterate_supers(void (*f)(struct super_block *, void *), void *arg)
 {
-	struct super_block *sb, *n;
+	struct super_block *sb, *p = NULL;
 
 	spin_lock(&sb_lock);
-	list_for_each_entry_safe(sb, n, &super_blocks, s_list) {
+	list_for_each_entry(sb, &super_blocks, s_list) {
 		if (list_empty(&sb->s_instances))
 			continue;
 		sb->s_count++;
@@ -412,10 +414,12 @@ void iterate_supers(void (*f)(struct super_block *, void *), void *arg)
 		up_read(&sb->s_umount);
 
 		spin_lock(&sb_lock);
-		/* lock was dropped, must reset next */
-		list_safe_reset_next(sb, n, s_list);
-		__put_super(sb);
+		if (p)
+			__put_super(p);
+		p = sb;
 	}
+	if (p)
+		__put_super(p);
 	spin_unlock(&sb_lock);
 }
 
@@ -577,10 +581,10 @@ int do_remount_sb(struct super_block *sb, int flags, void *data, int force)
 
 static void do_emergency_remount(struct work_struct *work)
 {
-	struct super_block *sb, *n;
+	struct super_block *sb, *p = NULL;
 
 	spin_lock(&sb_lock);
-	list_for_each_entry_safe(sb, n, &super_blocks, s_list) {
+	list_for_each_entry(sb, &super_blocks, s_list) {
 		if (list_empty(&sb->s_instances))
 			continue;
 		sb->s_count++;
@@ -594,10 +598,12 @@ static void do_emergency_remount(struct work_struct *work)
 		}
 		up_write(&sb->s_umount);
 		spin_lock(&sb_lock);
-		/* lock was dropped, must reset next */
-		list_safe_reset_next(sb, n, s_list);
-		__put_super(sb);
+		if (p)
+			__put_super(p);
+		p = sb;
 	}
+	if (p)
+		__put_super(p);
 	spin_unlock(&sb_lock);
 	kfree(work);
 	printk("Emergency Remount complete\n");
-- 
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