libext2fs: optimize rb_get_bmap_range()
This simplifies the rb_get_bmap_range() function and speeds it up for
the case where most of the bitmap is zero.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Reviewed-by: Lukas Czerner <lczerner@redhat.com>
diff --git a/lib/ext2fs/blkmap64_rb.c b/lib/ext2fs/blkmap64_rb.c
index 0fc7c57..eb56c85 100644
--- a/lib/ext2fs/blkmap64_rb.c
+++ b/lib/ext2fs/blkmap64_rb.c
@@ -741,32 +741,23 @@
break;
}
- pos = start;
+ memset(out, 0, (num + 7) >> 3);
+
for (; parent != NULL; parent = next) {
next = ext2fs_rb_next(parent);
ext = ext2fs_rb_entry(parent, struct bmap_rb_extent, node);
- while (((pos - start) < num) &&
- (pos < ext->start)) {
- ext2fs_fast_clear_bit64((pos - start), out);
- pos++;
- }
+ pos = ext->start;
+ if (pos < start)
+ pos = start;
- if ((pos - start) >= num)
- return 0;
-
- while (((pos - start) < num) &&
- (pos < (ext->start + ext->count))) {
+ while (pos < (ext->start + ext->count)) {
+ if ((pos - start) >= num)
+ return 0;
ext2fs_fast_set_bit64((pos - start), out);
pos++;
}
}
-
- while ((pos - start) < num) {
- ext2fs_fast_clear_bit64((pos - start), out);
- pos++;
- }
-
return 0;
}