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[Qemu-devel] [PATCH v4 07/18] hbitmap: Fix merge when b is empty, and re
From: |
John Snow |
Subject: |
[Qemu-devel] [PATCH v4 07/18] hbitmap: Fix merge when b is empty, and result is not an alias of a |
Date: |
Tue, 9 Jul 2019 19:25:39 -0400 |
Nobody calls the function like this currently, but we neither prohibit
or cope with this behavior. I decided to make the function cope with it.
Signed-off-by: John Snow <address@hidden>
Reviewed-by: Max Reitz <address@hidden>
---
util/hbitmap.c | 13 ++++++++++---
1 file changed, 10 insertions(+), 3 deletions(-)
diff --git a/util/hbitmap.c b/util/hbitmap.c
index 7905212a8b..3b6acae42b 100644
--- a/util/hbitmap.c
+++ b/util/hbitmap.c
@@ -781,8 +781,9 @@ bool hbitmap_can_merge(const HBitmap *a, const HBitmap *b)
}
/**
- * Given HBitmaps A and B, let A := A (BITOR) B.
- * Bitmap B will not be modified.
+ * Given HBitmaps A and B, let R := A (BITOR) B.
+ * Bitmaps A and B will not be modified,
+ * except when bitmap R is an alias of A or B.
*
* @return true if the merge was successful,
* false if it was not attempted.
@@ -797,7 +798,13 @@ bool hbitmap_merge(const HBitmap *a, const HBitmap *b,
HBitmap *result)
}
assert(hbitmap_can_merge(b, result));
- if (hbitmap_count(b) == 0) {
+ if ((!hbitmap_count(a) && result == b) ||
+ (!hbitmap_count(b) && result == a)) {
+ return true;
+ }
+
+ if (!hbitmap_count(a) && !hbitmap_count(b)) {
+ hbitmap_reset_all(result);
return true;
}
--
2.21.0
- [Qemu-devel] [PATCH v4 00/18] bitmaps: introduce 'bitmap' sync mode, John Snow, 2019/07/09
- [Qemu-devel] [PATCH v4 07/18] hbitmap: Fix merge when b is empty, and result is not an alias of a,
John Snow <=
- [Qemu-devel] [PATCH v4 06/18] block/backup: add 'never' policy to bitmap sync mode, John Snow, 2019/07/09
- [Qemu-devel] [PATCH v4 03/18] blockdev-backup: utilize do_backup_common, John Snow, 2019/07/09
- [Qemu-devel] [PATCH v4 08/18] hbitmap: enable merging across granularities, John Snow, 2019/07/09
- [Qemu-devel] [PATCH v4 04/18] qapi: add BitmapSyncMode enum, John Snow, 2019/07/09
- [Qemu-devel] [PATCH v4 02/18] drive-backup: create do_backup_common, John Snow, 2019/07/09
- [Qemu-devel] [PATCH v4 10/18] block/dirty-bitmap: add bdrv_dirty_bitmap_get, John Snow, 2019/07/09
- [Qemu-devel] [PATCH v4 01/18] qapi/block-core: Introduce BackupCommon, John Snow, 2019/07/09