---

yaml
---
r: 257367
b: refs/heads/master
c: 12ad3ab
h: refs/heads/master
i:
  257365: 84c7281
  257363: 0f34391
  257359: 06d1ae9
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 09cc9fc7a7c3d872065426d7fb0f0ad6d3eb90fc
+refs/heads/master: 12ad3ab66103e6582ca69c0c9de18b13487eaaef

trunk/fs/fs-writeback.c

@@ -460,32 +460,6 @@ writeback_single_inode(struct inode *inode, struct writeback_control *wbc)
 	return ret;
 }
 
-/*
- * For background writeback the caller does not have the sb pinned
- * before calling writeback. So make sure that we do pin it, so it doesn't
- * go away while we are writing inodes from it.
- */
-static bool pin_sb_for_writeback(struct super_block *sb)
-{
-	spin_lock(&sb_lock);
-	if (list_empty(&sb->s_instances)) {
-		spin_unlock(&sb_lock);
-		return false;
-	}
-
-	sb->s_count++;
-	spin_unlock(&sb_lock);
-
-	if (down_read_trylock(&sb->s_umount)) {
-		if (sb->s_root)
-			return true;
-		up_read(&sb->s_umount);
-	}
-
-	put_super(sb);
-	return false;
-}
-
 /*
  * Write a portion of b_io inodes which belong to @sb.
  *
@@ -585,7 +559,7 @@ void writeback_inodes_wb(struct bdi_writeback *wb,
 		struct inode *inode = wb_inode(wb->b_io.prev);
 		struct super_block *sb = inode->i_sb;
 
-		if (!pin_sb_for_writeback(sb)) {
+		if (!grab_super_passive(sb)) {
 			requeue_io(inode);
 			continue;
 		}

trunk/fs/internal.h

@@ -97,6 +97,7 @@ extern struct file *get_empty_filp(void);
  * super.c
  */
 extern int do_remount_sb(struct super_block *, int, void *, int);
+extern bool grab_super_passive(struct super_block *sb);
 extern void __put_super(struct super_block *sb);
 extern void put_super(struct super_block *sb);
 extern struct dentry *mount_fs(struct file_system_type *,

trunk/fs/super.c

@@ -242,6 +242,39 @@ static int grab_super(struct super_block *s) __releases(sb_lock)
 	return 0;
 }
 
+/*
+ *	grab_super_passive - acquire a passive reference
+ *	@s: reference we are trying to grab
+ *
+ *	Tries to acquire a passive reference. This is used in places where we
+ *	cannot take an active reference but we need to ensure that the
+ *	superblock does not go away while we are working on it. It returns
+ *	false if a reference was not gained, and returns true with the s_umount
+ *	lock held in read mode if a reference is gained. On successful return,
+ *	the caller must drop the s_umount lock and the passive reference when
+ *	done.
+ */
+bool grab_super_passive(struct super_block *sb)
+{
+	spin_lock(&sb_lock);
+	if (list_empty(&sb->s_instances)) {
+		spin_unlock(&sb_lock);
+		return false;
+	}
+
+	sb->s_count++;
+	spin_unlock(&sb_lock);
+
+	if (down_read_trylock(&sb->s_umount)) {
+		if (sb->s_root)
+			return true;
+		up_read(&sb->s_umount);
+	}
+
+	put_super(sb);
+	return false;
+}
+
 /*
  * Superblock locking.  We really ought to get rid of these two.
  */