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[Qemu-devel] [PATCH v10 18/20] qcow2: Switch store_bitmap_data() to byte
From: |
Eric Blake |
Subject: |
[Qemu-devel] [PATCH v10 18/20] qcow2: Switch store_bitmap_data() to byte-based iteration |
Date: |
Mon, 25 Sep 2017 09:55:24 -0500 |
Now that we have adjusted the majority of the calls this function
makes to be byte-based, it is easier to read the code if it makes
passes over the image using bytes rather than sectors.
iotests 165 was rather weak - on a default 64k-cluster image, where
bitmap granularity also defaults to 64k bytes, a single cluster of
the bitmap table thus covers (64*1024*8) bits which each cover 64k
bytes, or 32G of image space. But the test only uses a 1G image,
so it cannot trigger any more than one loop of the code in
store_bitmap_data(); and it was writing to the first cluster. In
order to test that we are properly aligning which portions of the
bitmap are being written to the file, we really want to test a case
where the first dirty bit returned by bdrv_dirty_iter_next() is not
aligned to the start of a cluster, which we can do by modifying the
test to write data that doesn't happen to fall in the first cluster
of the image.
Signed-off-by: Eric Blake <address@hidden>
Reviewed-by: Vladimir Sementsov-Ogievskiy<address@hidden>
---
v10: no change, add R-b
v9: update iotests to show why aligning down is needed [Kevin], R-b dropped
v8: no change
v7: rebase to earlier change, make rounding of offset obvious (no semantic
change, so R-b kept) [Kevin]
v5-v6: no change
v4: new patch
---
block/qcow2-bitmap.c | 31 ++++++++++++++++---------------
tests/qemu-iotests/165 | 2 +-
2 files changed, 17 insertions(+), 16 deletions(-)
diff --git a/block/qcow2-bitmap.c b/block/qcow2-bitmap.c
index 692ce0de88..df957c66d5 100644
--- a/block/qcow2-bitmap.c
+++ b/block/qcow2-bitmap.c
@@ -1072,10 +1072,9 @@ static uint64_t *store_bitmap_data(BlockDriverState *bs,
{
int ret;
BDRVQcow2State *s = bs->opaque;
- int64_t sector;
- uint64_t limit, sbc;
+ int64_t offset;
+ uint64_t limit;
uint64_t bm_size = bdrv_dirty_bitmap_size(bitmap);
- uint64_t bm_sectors = DIV_ROUND_UP(bm_size, BDRV_SECTOR_SIZE);
const char *bm_name = bdrv_dirty_bitmap_name(bitmap);
uint8_t *buf = NULL;
BdrvDirtyBitmapIter *dbi;
@@ -1100,18 +1099,22 @@ static uint64_t *store_bitmap_data(BlockDriverState *bs,
dbi = bdrv_dirty_iter_new(bitmap);
buf = g_malloc(s->cluster_size);
limit = bytes_covered_by_bitmap_cluster(s, bitmap);
- sbc = limit >> BDRV_SECTOR_BITS;
assert(DIV_ROUND_UP(bm_size, limit) == tb_size);
- while ((sector = bdrv_dirty_iter_next(dbi) >> BDRV_SECTOR_BITS) >= 0) {
- uint64_t cluster = sector / sbc;
+ while ((offset = bdrv_dirty_iter_next(dbi)) >= 0) {
+ uint64_t cluster = offset / limit;
uint64_t end, write_size;
int64_t off;
- sector = cluster * sbc;
- end = MIN(bm_sectors, sector + sbc);
- write_size = bdrv_dirty_bitmap_serialization_size(bitmap,
- sector * BDRV_SECTOR_SIZE, (end - sector) * BDRV_SECTOR_SIZE);
+ /*
+ * We found the first dirty offset, but want to write out the
+ * entire cluster of the bitmap that includes that offset,
+ * including any leading zero bits.
+ */
+ offset = QEMU_ALIGN_DOWN(offset, limit);
+ end = MIN(bm_size, offset + limit);
+ write_size = bdrv_dirty_bitmap_serialization_size(bitmap, offset,
+ end - offset);
assert(write_size <= s->cluster_size);
off = qcow2_alloc_clusters(bs, s->cluster_size);
@@ -1123,9 +1126,7 @@ static uint64_t *store_bitmap_data(BlockDriverState *bs,
}
tb[cluster] = off;
- bdrv_dirty_bitmap_serialize_part(bitmap, buf,
- sector * BDRV_SECTOR_SIZE,
- (end - sector) * BDRV_SECTOR_SIZE);
+ bdrv_dirty_bitmap_serialize_part(bitmap, buf, offset, end - offset);
if (write_size < s->cluster_size) {
memset(buf + write_size, 0, s->cluster_size - write_size);
}
@@ -1143,11 +1144,11 @@ static uint64_t *store_bitmap_data(BlockDriverState *bs,
goto fail;
}
- if (end >= bm_sectors) {
+ if (end >= bm_size) {
break;
}
- bdrv_set_dirty_iter(dbi, end * BDRV_SECTOR_SIZE);
+ bdrv_set_dirty_iter(dbi, end);
}
*bitmap_table_size = tb_size;
diff --git a/tests/qemu-iotests/165 b/tests/qemu-iotests/165
index 74d7b79a0b..a3932db3de 100755
--- a/tests/qemu-iotests/165
+++ b/tests/qemu-iotests/165
@@ -27,7 +27,7 @@ disk = os.path.join(iotests.test_dir, 'disk')
disk_size = 0x40000000 # 1G
# regions for qemu_io: (start, count) in bytes
-regions1 = ((0, 0x100000),
+regions1 = ((0x0fff00, 0x10000),
(0x200000, 0x100000))
regions2 = ((0x10000000, 0x20000),
--
2.13.5
- [Qemu-devel] [PATCH v10 09/20] qcow2: Switch sectors_covered_by_bitmap_cluster() to byte-based, (continued)
- [Qemu-devel] [PATCH v10 09/20] qcow2: Switch sectors_covered_by_bitmap_cluster() to byte-based, Eric Blake, 2017/09/25
- [Qemu-devel] [PATCH v10 10/20] dirty-bitmap: Set iterator start by offset, not sector, Eric Blake, 2017/09/25
- [Qemu-devel] [PATCH v10 11/20] dirty-bitmap: Change bdrv_dirty_iter_next() to report byte offset, Eric Blake, 2017/09/25
- [Qemu-devel] [PATCH v10 12/20] dirty-bitmap: Change bdrv_get_dirty_count() to report bytes, Eric Blake, 2017/09/25
- [Qemu-devel] [PATCH v10 13/20] dirty-bitmap: Change bdrv_get_dirty_locked() to take bytes, Eric Blake, 2017/09/25
- [Qemu-devel] [PATCH v10 15/20] mirror: Switch mirror_dirty_init() to byte-based iteration, Eric Blake, 2017/09/25
- [Qemu-devel] [PATCH v10 14/20] dirty-bitmap: Change bdrv_[re]set_dirty_bitmap() to use bytes, Eric Blake, 2017/09/25
- [Qemu-devel] [PATCH v10 16/20] qcow2: Switch qcow2_measure() to byte-based iteration, Eric Blake, 2017/09/25
- [Qemu-devel] [PATCH v10 17/20] qcow2: Switch load_bitmap_data() to byte-based iteration, Eric Blake, 2017/09/25
- [Qemu-devel] [PATCH v10 19/20] dirty-bitmap: Switch bdrv_set_dirty() to bytes, Eric Blake, 2017/09/25
- [Qemu-devel] [PATCH v10 18/20] qcow2: Switch store_bitmap_data() to byte-based iteration,
Eric Blake <=
- [Qemu-devel] [PATCH v10 20/20] dirty-bitmap: Convert internal hbitmap size/granularity, Eric Blake, 2017/09/25
- Re: [Qemu-devel] [PATCH v10 00/20] make dirty-bitmap byte-based, John Snow, 2017/09/25