fix a couple of ecryptfs leaks

First of all, get_sb_nodev() grabs anon dev minor and we
never free it in ecryptfs ->kill_sb().  Moreover, on one
of the failure exits in ecryptfs_get_sb() we leak things -
it happens before we set ->s_root and ->put_super() won't
be called in that case.  Solution: kill ->put_super(), do
all that stuff in ->kill_sb().  And use kill_anon_sb() instead
of generic_shutdown_super() to deal with anon dev leak.

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

fs/ecryptfs/main.c

@@ -633,11 +633,16 @@ static int ecryptfs_get_sb(struct file_system_type *fs_type, int flags,
  * @sb: The ecryptfs super block
  *
  * Used to bring the superblock down and free the private data.
- * Private data is free'd in ecryptfs_put_super()
  */
 static void ecryptfs_kill_block_super(struct super_block *sb)
 {
-	generic_shutdown_super(sb);
+	struct ecryptfs_sb_info *sb_info = ecryptfs_superblock_to_private(sb);
+	kill_anon_super(sb);
+	if (!sb_info)
+		return;
+	ecryptfs_destroy_mount_crypt_stat(&sb_info->mount_crypt_stat);
+	bdi_destroy(&sb_info->bdi);
+	kmem_cache_free(ecryptfs_sb_info_cache, sb_info);
 }
 
 static struct file_system_type ecryptfs_fs_type = {

fs/ecryptfs/super.c

@@ -108,27 +108,6 @@ void ecryptfs_init_inode(struct inode *inode, struct inode *lower_inode)
 	inode->i_mapping->a_ops = &ecryptfs_aops;
 }
 
-/**
- * ecryptfs_put_super
- * @sb: Pointer to the ecryptfs super block
- *
- * Final actions when unmounting a file system.
- * This will handle deallocation and release of our private data.
- */
-static void ecryptfs_put_super(struct super_block *sb)
-{
-	struct ecryptfs_sb_info *sb_info = ecryptfs_superblock_to_private(sb);
-
-	lock_kernel();
-
-	ecryptfs_destroy_mount_crypt_stat(&sb_info->mount_crypt_stat);
-	bdi_destroy(&sb_info->bdi);
-	kmem_cache_free(ecryptfs_sb_info_cache, sb_info);
-	ecryptfs_set_superblock_private(sb, NULL);
-
-	unlock_kernel();
-}
-
 /**
  * ecryptfs_statfs
  * @sb: The ecryptfs super block
@@ -203,7 +182,6 @@ const struct super_operations ecryptfs_sops = {
 	.alloc_inode = ecryptfs_alloc_inode,
 	.destroy_inode = ecryptfs_destroy_inode,
 	.drop_inode = generic_delete_inode,
-	.put_super = ecryptfs_put_super,
 	.statfs = ecryptfs_statfs,
 	.remount_fs = NULL,
 	.clear_inode = ecryptfs_clear_inode,