copy: be more careful when trying to reflink

2015-09-22 16:30:12 +02:00
parent c97e586d8a
commit c622fbdb8d
1 changed files with 5 additions and 1 deletions
@@ -37,7 +37,11 @@ int copy_bytes(int fdf, int fdt, uint64_t max_bytes, bool try_reflink) {
        assert(fdt >= 0);

        /* Try btrfs reflinks first. */
-        if (try_reflink && max_bytes == (uint64_t) -1) {
+        if (try_reflink &&
+            max_bytes == (uint64_t) -1 &&
+            lseek(fdf, 0, SEEK_CUR) == 0 &&
+            lseek(fdt, 0, SEEK_CUR) == 0) {
+
                r = btrfs_reflink(fdf, fdt);
                if (r >= 0)
                        return r;