dquot: move dquot drop responsibility into the filesystem

Currently clear_inode calls vfs_dq_drop directly.  This means
we tie the quota code into the VFS.  Get rid of that and make the
filesystem responsible for the drop inside the ->clear_inode
superblock operation.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jan Kara <jack@suse.cz>
diff --git a/fs/ufs/super.c b/fs/ufs/super.c
index 143c20b..95d61cb 100644
--- a/fs/ufs/super.c
+++ b/fs/ufs/super.c
@@ -1432,6 +1432,11 @@
 	kmem_cache_destroy(ufs_inode_cachep);
 }
 
+static void ufs_clear_inode(struct inode *inode)
+{
+	vfs_dq_drop(inode);
+}
+
 #ifdef CONFIG_QUOTA
 static ssize_t ufs_quota_read(struct super_block *, int, char *,size_t, loff_t);
 static ssize_t ufs_quota_write(struct super_block *, int, const char *, size_t, loff_t);
@@ -1442,6 +1447,7 @@
 	.destroy_inode	= ufs_destroy_inode,
 	.write_inode	= ufs_write_inode,
 	.delete_inode	= ufs_delete_inode,
+	.clear_inode	= ufs_clear_inode,
 	.put_super	= ufs_put_super,
 	.write_super	= ufs_write_super,
 	.sync_fs	= ufs_sync_fs,