vfs: keep list of mounts for each superblock

Keep track of vfsmounts belonging to a superblock.  List is protected
by vfsmount_lock.

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Tested-by: Toshiyuki Okajima <toshi.okajima@jp.fujitsu.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 2 insertions, 0 deletions

diff --git a/fs/super.c b/fs/super.c
index 0413f51a9f0f..993ca8f128d6 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -142,6 +142,7 @@ static struct super_block *alloc_super(struct file_system_type *type)
                 INIT_LIST_HEAD(&s->s_dentry_lru);
                 INIT_LIST_HEAD(&s->s_inode_lru);
                 spin_lock_init(&s->s_inode_lru_lock);
+                INIT_LIST_HEAD(&s->s_mounts);
                 init_rwsem(&s->s_umount);
                 mutex_init(&s->s_lock);
                 lockdep_set_class(&s->s_umount, &type->s_umount_key);
@@ -200,6 +201,7 @@ static inline void destroy_super(struct super_block *s)
         free_percpu(s->s_files);
 #endif
         security_sb_free(s);
+        WARN_ON(!list_empty(&s->s_mounts));
         kfree(s->s_subtype);
         kfree(s->s_options);
         kfree(s);