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[Qemu-devel] [PULL 07/36] hbitmap: Fix merge when b is empty, and result
From: |
John Snow |
Subject: |
[Qemu-devel] [PULL 07/36] hbitmap: Fix merge when b is empty, and result is not an alias of a |
Date: |
Fri, 16 Aug 2019 19:12:49 -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>
Message-id: address@hidden
Signed-off-by: John Snow <address@hidden>
---
util/hbitmap.c | 13 ++++++++++---
1 file changed, 10 insertions(+), 3 deletions(-)
diff --git a/util/hbitmap.c b/util/hbitmap.c
index bcc0acdc6a0..83927f3c08a 100644
--- a/util/hbitmap.c
+++ b/util/hbitmap.c
@@ -785,8 +785,9 @@ 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.
@@ -801,7 +802,13 @@ 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] [PULL 00/36] Bitmaps patches, John Snow, 2019/08/16
- [Qemu-devel] [PULL 03/36] blockdev-backup: utilize do_backup_common, John Snow, 2019/08/16
- [Qemu-devel] [PULL 01/36] qapi/block-core: Introduce BackupCommon, John Snow, 2019/08/16
- [Qemu-devel] [PULL 02/36] drive-backup: create do_backup_common, John Snow, 2019/08/16
- [Qemu-devel] [PULL 06/36] block/backup: add 'never' policy to bitmap sync mode, John Snow, 2019/08/16
- [Qemu-devel] [PULL 04/36] qapi: add BitmapSyncMode enum, John Snow, 2019/08/16
- [Qemu-devel] [PULL 08/36] hbitmap: enable merging across granularities, John Snow, 2019/08/16
- [Qemu-devel] [PULL 07/36] hbitmap: Fix merge when b is empty, and result is not an alias of a,
John Snow <=
- [Qemu-devel] [PULL 09/36] block/dirty-bitmap: add bdrv_dirty_bitmap_merge_internal, John Snow, 2019/08/16
- [Qemu-devel] [PULL 10/36] block/dirty-bitmap: add bdrv_dirty_bitmap_get, John Snow, 2019/08/16
- [Qemu-devel] [PULL 05/36] block/backup: Add mirror sync mode 'bitmap', John Snow, 2019/08/16
- [Qemu-devel] [PULL 14/36] iotests: teach run_job to cancel pending jobs, John Snow, 2019/08/16
- [Qemu-devel] [PULL 15/36] iotests: teach FilePath to produce multiple paths, John Snow, 2019/08/16
- [Qemu-devel] [PULL 13/36] iotests: add testing shim for script-style python tests, John Snow, 2019/08/16
- [Qemu-devel] [PULL 18/36] block/backup: loosen restriction on readonly bitmaps, John Snow, 2019/08/16
- [Qemu-devel] [PULL 16/36] iotests: Add virtio-scsi device helper, John Snow, 2019/08/16
- [Qemu-devel] [PULL 12/36] block/backup: add 'always' bitmap sync policy, John Snow, 2019/08/16
- [Qemu-devel] [PULL 11/36] block/backup: upgrade copy_bitmap to BdrvDirtyBitmap, John Snow, 2019/08/16