autofs4: make freeing sbi rcu-delayed

makes ->d_managed() safety in RCU mode independent from vfsmount_lock

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

2 files changed, 5 insertions, 9 deletions

diff --git a/fs/autofs4/autofs_i.h b/fs/autofs4/autofs_i.h
index ebab147e9700..4218e26df916 100644
--- a/fs/autofs4/autofs_i.h
+++ b/fs/autofs4/autofs_i.h
@@ -122,6 +122,7 @@ struct autofs_sb_info {
         spinlock_t lookup_lock;
         struct list_head active_list;
         struct list_head expiring_list;
+        struct rcu_head rcu;
 };
 
 static inline struct autofs_sb_info *autofs4_sbi(struct super_block *sb)
diff --git a/fs/autofs4/inode.c b/fs/autofs4/inode.c
index b104726e2d0a..3b9cc9b973c2 100644
--- a/fs/autofs4/inode.c
+++ b/fs/autofs4/inode.c
@@ -56,18 +56,13 @@ void autofs4_kill_sb(struct super_block *sb)
          * just call kill_anon_super when we are called from
          * deactivate_super.
          */
-        if (!sbi)
-                goto out_kill_sb;
-
-        /* Free wait queues, close pipe */
-        autofs4_catatonic_mode(sbi);
-
-        sb->s_fs_info = NULL;
-        kfree(sbi);
+        if (sbi) /* Free wait queues, close pipe */
+                autofs4_catatonic_mode(sbi);
 
-out_kill_sb:
         DPRINTK("shutting down");
         kill_litter_super(sb);
+        if (sbi)
+                kfree_rcu(sbi, rcu);
 }
 
 static int autofs4_show_options(struct seq_file *m, struct dentry *root)