We are gradually moving away from sector-based interfaces, towards
byte-based. Make the change for the internal helper function
get_cluster_offset(), by changing n_start and n_end to by byte
offsets rather than sector indices within the cluster being
allocated. However, assert that these values are still
sector-aligned (at least qcrypto_block_encrypt() still wants that).
For now we get that alignment for free because we still use
sector-based driver callbacks.
A later patch will then switch the qcow driver as a whole over
to byte-based operation; but will still leave things at sector
alignments as it is not worth auditing the qcow image format
to worry about sub-sector requests.
Signed-off-by: Eric Blake <ebl...@redhat.com>
---
v2: assert sector alignment [Max]
---
block/qcow.c | 29 +++++++++++++++--------------
1 file changed, 15 insertions(+), 14 deletions(-)
diff --git a/block/qcow.c b/block/qcow.c
index 3ba2ca25ea5..42d1bbb7643 100644
--- a/block/qcow.c
+++ b/block/qcow.c
@@ -345,8 +345,8 @@ static int qcow_reopen_prepare(BDRVReopenState *state,
*
* 0 to not allocate.
*
- * 1 to allocate a normal cluster (for sector indexes 'n_start' to
- * 'n_end')
+ * 1 to allocate a normal cluster (for sector-aligned byte offsets 'n_start'
+ * to 'n_end' within the cluster)
*
* 2 to allocate a compressed cluster of size
* 'compressed_size'. 'compressed_size' must be > 0 and <
@@ -440,9 +440,10 @@ static int get_cluster_offset(BlockDriverState *bs,
if (!allocate)
return 0;
BLKDBG_EVENT(bs->file, BLKDBG_CLUSTER_ALLOC);
+ assert(QEMU_IS_ALIGNED(n_start | n_end, BDRV_SECTOR_SIZE));
/* allocate a new cluster */
if ((cluster_offset & QCOW_OFLAG_COMPRESSED) &&
- (n_end - n_start) < s->cluster_sectors) {
+ (n_end - n_start) < s->cluster_size) {
/* if the cluster is already compressed, we must
decompress it in the case it is not completely
overwritten */
@@ -480,16 +481,15 @@ static int get_cluster_offset(BlockDriverState *bs,
/* if encrypted, we must initialize the cluster
content which won't be written */
if (bs->encrypted &&
- (n_end - n_start) < s->cluster_sectors) {
- uint64_t start_sect;
+ (n_end - n_start) < s->cluster_size) {
+ uint64_t start_offset;
assert(s->crypto);
- start_sect = (offset & ~(s->cluster_size - 1)) >> 9;
- for(i = 0; i < s->cluster_sectors; i++) {
+ start_offset = offset & ~(s->cluster_size - 1);
+ for (i = 0; i < s->cluster_size; i += BDRV_SECTOR_SIZE) {
if (i < n_start || i >= n_end) {
- memset(s->cluster_data, 0x00, 512);
+ memset(s->cluster_data, 0x00, BDRV_SECTOR_SIZE);
if (qcrypto_block_encrypt(s->crypto,
- (start_sect + i) *
- BDRV_SECTOR_SIZE,
+ start_offset + i,
s->cluster_data,
BDRV_SECTOR_SIZE,
NULL) < 0) {
@@ -497,8 +497,9 @@ static int get_cluster_offset(BlockDriverState *bs,
}
BLKDBG_EVENT(bs->file, BLKDBG_WRITE_AIO);
ret = bdrv_pwrite(bs->file,
- cluster_offset + i * 512,
- s->cluster_data, 512);
+ cluster_offset + i,
+ s->cluster_data,
+ BDRV_SECTOR_SIZE);
if (ret < 0) {
return ret;
}
@@ -758,8 +759,8 @@ static coroutine_fn int qcow_co_writev(BlockDriverState
*bs, int64_t sector_num,
n = nb_sectors;
}
ret = get_cluster_offset(bs, sector_num << 9, 1, 0,
- index_in_cluster,
- index_in_cluster + n, &cluster_offset);
+ index_in_cluster << 9,
+ (index_in_cluster + n) << 9, &cluster_offset);
if (ret < 0) {
break;
}
--
2.14.3
