[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[PULL v3 01/19] util/hbitmap: strict hbitmap_reset
From: |
John Snow |
Subject: |
[PULL v3 01/19] util/hbitmap: strict hbitmap_reset |
Date: |
Thu, 17 Oct 2019 17:54:18 -0400 |
From: Vladimir Sementsov-Ogievskiy <address@hidden>
hbitmap_reset has an unobvious property: it rounds requested region up.
It may provoke bugs, like in recently fixed write-blocking mode of
mirror: user calls reset on unaligned region, not keeping in mind that
there are possible unrelated dirty bytes, covered by rounded-up region
and information of this unrelated "dirtiness" will be lost.
Make hbitmap_reset strict: assert that arguments are aligned, allowing
only one exception when @start + @count == hb->orig_size. It's needed
to comfort users of hbitmap_next_dirty_area, which cares about
hb->orig_size.
Signed-off-by: Vladimir Sementsov-Ogievskiy <address@hidden>
Reviewed-by: Max Reitz <address@hidden>
Message-Id: <address@hidden>
[Maintainer edit: Max's suggestions from on-list. --js]
[Maintainer edit: Eric's suggestion for aligned macro. --js]
Signed-off-by: John Snow <address@hidden>
---
include/qemu/hbitmap.h | 5 +++++
tests/test-hbitmap.c | 2 +-
util/hbitmap.c | 4 ++++
3 files changed, 10 insertions(+), 1 deletion(-)
diff --git a/include/qemu/hbitmap.h b/include/qemu/hbitmap.h
index 4afbe6292e..1bf944ca3d 100644
--- a/include/qemu/hbitmap.h
+++ b/include/qemu/hbitmap.h
@@ -132,6 +132,11 @@ void hbitmap_set(HBitmap *hb, uint64_t start, uint64_t
count);
* @count: Number of bits to reset.
*
* Reset a consecutive range of bits in an HBitmap.
+ * @start and @count must be aligned to bitmap granularity. The only exception
+ * is resetting the tail of the bitmap: @count may be equal to hb->orig_size -
+ * @start, in this case @count may be not aligned. The sum of @start + @count
is
+ * allowed to be greater than hb->orig_size, but only if @start < hb->orig_size
+ * and @start + @count = ALIGN_UP(hb->orig_size, granularity).
*/
void hbitmap_reset(HBitmap *hb, uint64_t start, uint64_t count);
diff --git a/tests/test-hbitmap.c b/tests/test-hbitmap.c
index eed5d288cb..e1f867085f 100644
--- a/tests/test-hbitmap.c
+++ b/tests/test-hbitmap.c
@@ -423,7 +423,7 @@ static void test_hbitmap_granularity(TestHBitmapData *data,
hbitmap_test_check(data, 0);
hbitmap_test_set(data, 0, 3);
g_assert_cmpint(hbitmap_count(data->hb), ==, 4);
- hbitmap_test_reset(data, 0, 1);
+ hbitmap_test_reset(data, 0, 2);
g_assert_cmpint(hbitmap_count(data->hb), ==, 2);
}
diff --git a/util/hbitmap.c b/util/hbitmap.c
index fd44c897ab..66db87c6ff 100644
--- a/util/hbitmap.c
+++ b/util/hbitmap.c
@@ -476,6 +476,10 @@ void hbitmap_reset(HBitmap *hb, uint64_t start, uint64_t
count)
/* Compute range in the last layer. */
uint64_t first;
uint64_t last = start + count - 1;
+ uint64_t gran = 1ULL << hb->granularity;
+
+ assert(QEMU_IS_ALIGNED(start, gran));
+ assert(QEMU_IS_ALIGNED(count, gran) || (start + count == hb->orig_size));
trace_hbitmap_reset(hb, start, count,
start >> hb->granularity, last >> hb->granularity);
--
2.21.0
- [PULL v3 00/19] Bitmaps patches, John Snow, 2019/10/17
- [PULL v3 01/19] util/hbitmap: strict hbitmap_reset,
John Snow <=
- [PULL v3 02/19] block: move bdrv_can_store_new_dirty_bitmap to block/dirty-bitmap.c, John Snow, 2019/10/17
- [PULL v3 03/19] block/dirty-bitmap: return int from bdrv_remove_persistent_dirty_bitmap, John Snow, 2019/10/17
- [PULL v3 04/19] block/qcow2: proper locking on bitmap add/remove paths, John Snow, 2019/10/17
- [PULL v3 05/19] block/dirty-bitmap: drop meta, John Snow, 2019/10/17
- [PULL v3 07/19] block/dirty-bitmap: drop BdrvDirtyBitmap.mutex, John Snow, 2019/10/17
- [PULL v3 06/19] block/dirty-bitmap: add bs link, John Snow, 2019/10/17
- [PULL v3 08/19] block/dirty-bitmap: refactor bdrv_dirty_bitmap_next, John Snow, 2019/10/17
- [PULL v3 10/19] block: reverse order for reopen commits, John Snow, 2019/10/17
- [PULL v3 09/19] block: switch reopen queue from QSIMPLEQ to QTAILQ, John Snow, 2019/10/17
- [PULL v3 12/19] block/qcow2-bitmap: get rid of bdrv_has_changed_persistent_bitmaps, John Snow, 2019/10/17