hugetlb: make use of ->free_inode()

moving synchronous parts of ->destroy_inode() to ->evict_inode() is
not possible here - they are balancing the stuff done in ->alloc_inode(),
not the things acquired while using it or sanity checks.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
index 9285dd4..c74ef44 100644
--- a/fs/hugetlbfs/inode.c
+++ b/fs/hugetlbfs/inode.c
@@ -1051,9 +1051,8 @@ static struct inode *hugetlbfs_alloc_inode(struct super_block *sb)
 	return &p->vfs_inode;
 }
 
-static void hugetlbfs_i_callback(struct rcu_head *head)
+static void hugetlbfs_free_inode(struct inode *inode)
 {
-	struct inode *inode = container_of(head, struct inode, i_rcu);
 	kmem_cache_free(hugetlbfs_inode_cachep, HUGETLBFS_I(inode));
 }
 
@@ -1061,7 +1060,6 @@ static void hugetlbfs_destroy_inode(struct inode *inode)
 {
 	hugetlbfs_inc_free_inodes(HUGETLBFS_SB(inode->i_sb));
 	mpol_free_shared_policy(&HUGETLBFS_I(inode)->policy);
-	call_rcu(&inode->i_rcu, hugetlbfs_i_callback);
 }
 
 static const struct address_space_operations hugetlbfs_aops = {
@@ -1108,6 +1106,7 @@ static const struct inode_operations hugetlbfs_inode_operations = {
 
 static const struct super_operations hugetlbfs_ops = {
 	.alloc_inode    = hugetlbfs_alloc_inode,
+	.free_inode     = hugetlbfs_free_inode,
 	.destroy_inode  = hugetlbfs_destroy_inode,
 	.evict_inode	= hugetlbfs_evict_inode,
 	.statfs		= hugetlbfs_statfs,