erofs: put metabuf in error path in fscache mode

For tail packing layout, put metabuf when error is encountered.

Fixes: 1ae9470c ("erofs: clean up .read_folio() and .readahead() in fscache mode")
Signed-off-by: Jingbo Xu <jefflexu@linux.alibaba.com>
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Reviewed-by: Jia Zhu <zhujia.zj@bytedance.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Link: https://lore.kernel.org/r/20221104054028.52208-2-jefflexu@linux.alibaba.comSigned-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>

fs/erofs/fscache.c

@@ -287,8 +287,10 @@ static int erofs_fscache_data_read(struct address_space *mapping,
 			return PTR_ERR(src);
 
 		iov_iter_xarray(&iter, READ, &mapping->i_pages, pos, PAGE_SIZE);
-		if (copy_to_iter(src + offset, size, &iter) != size)
+		if (copy_to_iter(src + offset, size, &iter) != size) {
+			erofs_put_metabuf(&buf);
 			return -EFAULT;
+		}
 		iov_iter_zero(PAGE_SIZE - size, &iter);
 		erofs_put_metabuf(&buf);
 		return PAGE_SIZE;