hostfs: Handle page write errors correctly

If a page can't be written back, we need to call mapping_set_error(),
not clear the page's Uptodate flag.  Also remove the clearing of PageError
on success; that flag is used for read errors, not write errors.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>

fs/hostfs/hostfs_kern.c

@@ -416,15 +416,15 @@ static int hostfs_writepage(struct page *page, struct writeback_control *wbc)
 
 	err = write_file(HOSTFS_I(inode)->fd, &base, buffer, count);
 	if (err != count) {
-		ClearPageUptodate(page);
+		if (err >= 0)
+			err = -EIO;
+		mapping_set_error(mapping, err);
 		goto out;
 	}
 
 	if (base > inode->i_size)
 		inode->i_size = base;
 
-	if (PageError(page))
-		ClearPageError(page);
 	err = 0;
 
  out: