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qcow: Switch get_cluster_offset to be byte-based

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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 be 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 <eblake@redhat.com>
Reviewed-by: Jeff Cody <jcody@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Eric Blake 2018-06-28 15:15:19 -05:00 committed by Kevin Wolf
parent d08c2a245f
commit 787993a543
1 changed files with 15 additions and 14 deletions
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29
block/qcow.c
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@ -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;
}