fs: convert simple fs to new truncate

Convert simple filesystems: ramfs, configfs, sysfs, block_dev to new truncate
sequence.

Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/configfs/inode.c

@@ -72,16 +72,11 @@ int configfs_setattr(struct dentry * dentry, struct iattr * iattr)
 	if (!sd)
 		return -EINVAL;
 
+	error = simple_setattr(dentry, iattr);
+	if (error)
+		return error;
+
 	sd_iattr = sd->s_iattr;
-
-	error = inode_change_ok(inode, iattr);
-	if (error)
-		return error;
-
-	error = inode_setattr(inode, iattr);
-	if (error)
-		return error;
-
 	if (!sd_iattr) {
 		/* setting attributes for the first time, allocate now */
 		sd_iattr = kzalloc(sizeof(struct iattr), GFP_KERNEL);