vserver 1.9.3

[linux-2.6.git] / fs / super.c

diff --git a/fs/super.c b/fs/super.c
index 37b76d7..998fc47 100644 (file)
--- a/fs/super.c
+++ b/fs/super.c
@@ -118,6 +118,27 @@ int __put_super(struct super_block *sb)
        return ret;
 }
 
+/*
+ * Drop a superblock's refcount.
+ * Returns non-zero if the superblock is about to be destroyed and
+ * at least is already removed from super_blocks list, so if we are
+ * making a loop through super blocks then we need to restart.
+ * The caller must hold sb_lock.
+ */
+int __put_super_and_need_restart(struct super_block *sb)
+{
+       /* check for race with generic_shutdown_super() */
+       if (list_empty(&sb->s_list)) {
+               /* super block is removed, need to restart... */
+               __put_super(sb);
+               return 1;
+       }
+       /* can't be the last, since s_list is still in use */
+       sb->s_count--;
+       BUG_ON(sb->s_count == 0);
+       return 0;
+}
+
 /**
  *     put_super       -       drop a temporary reference to superblock
  *     @s: superblock in question
@@ -231,7 +252,8 @@ void generic_shutdown_super(struct super_block *sb)
                unlock_super(sb);
        }
        spin_lock(&sb_lock);
-       list_del(&sb->s_list);
+       /* should be initialized for __put_super_and_need_restart() */
+       list_del_init(&sb->s_list);
        list_del(&sb->s_instances);
        spin_unlock(&sb_lock);
        up_write(&sb->s_umount);
@@ -284,7 +306,7 @@ retry:
        }
        s->s_type = type;
        strlcpy(s->s_id, type->name, sizeof(s->s_id));
-       list_add(&s->s_list, super_blocks.prev);
+       list_add_tail(&s->s_list, &super_blocks);
        list_add(&s->s_instances, &type->fs_supers);
        spin_unlock(&sb_lock);
        get_filesystem(type);