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qcow2: remove n_start and n_end of qcow2_alloc_cluster_offset()

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n_start can be actually calculated from offset. The number of
sectors to be allocated(n_end - n_start) can be passed in in
num. By removing n_start and n_end, we can save two parameters.

The side effect is there is a bug in qcow2.c:preallocate() that
passes incorrect n_start to qcow2_alloc_cluster_offset() is
fixed. The bug can be triggerred by a larger cluster size than
the default value(65536), for example:

./qemu-img create -f qcow2 \
  -o 'cluster_size=131072,preallocation=metadata' file.img 4G

Signed-off-by: Hu Tao <hutao@cn.fujitsu.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Benoit Canet <benoit@irqsave.net>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Hu Tao 2014-01-26 11:12:37 +08:00 committed by Kevin Wolf
parent 5d259fc7da
commit 16f0587e0a
4 changed files with 15 additions and 16 deletions
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14
block/qcow2-cluster.c
View File

@ -1182,7 +1182,7 @@ fail:
* Return 0 on success and -errno in error cases
*/
int qcow2_alloc_cluster_offset(BlockDriverState *bs, uint64_t offset,
int n_start, int n_end, int *num, uint64_t *host_offset, QCowL2Meta **m)
int *num, uint64_t *host_offset, QCowL2Meta **m)
{
BDRVQcowState *s = bs->opaque;
uint64_t start, remaining;
@ -1190,15 +1190,13 @@ int qcow2_alloc_cluster_offset(BlockDriverState *bs, uint64_t offset,
uint64_t cur_bytes;
int ret;
trace_qcow2_alloc_clusters_offset(qemu_coroutine_self(), offset,
n_start, n_end);
trace_qcow2_alloc_clusters_offset(qemu_coroutine_self(), offset, *num);
assert(n_start * BDRV_SECTOR_SIZE == offset_into_cluster(s, offset));
offset = start_of_cluster(s, offset);
assert((offset & ~BDRV_SECTOR_MASK) == 0);
again:
start = offset + (n_start << BDRV_SECTOR_BITS);
remaining = (n_end - n_start) << BDRV_SECTOR_BITS;
start = offset;
remaining = *num << BDRV_SECTOR_BITS;
cluster_offset = 0;
*host_offset = 0;
cur_bytes = 0;
@ -1284,7 +1282,7 @@ again:
}
}
*num = (n_end - n_start) - (remaining >> BDRV_SECTOR_BITS);
*num -= remaining >> BDRV_SECTOR_BITS;
assert(*num > 0);
assert(*host_offset != 0);

13
block/qcow2.c
View File

@ -1000,7 +1000,6 @@ static coroutine_fn int qcow2_co_writev(BlockDriverState *bs,
{
BDRVQcowState *s = bs->opaque;
int index_in_cluster;
int n_end;
int ret;
int cur_nr_sectors; /* number of sectors in current iteration */
uint64_t cluster_offset;
@ -1024,14 +1023,16 @@ static coroutine_fn int qcow2_co_writev(BlockDriverState *bs,
trace_qcow2_writev_start_part(qemu_coroutine_self());
index_in_cluster = sector_num & (s->cluster_sectors - 1);
n_end = index_in_cluster + remaining_sectors;
cur_nr_sectors = remaining_sectors;
if (s->crypt_method &&
n_end > QCOW_MAX_CRYPT_CLUSTERS * s->cluster_sectors) {
n_end = QCOW_MAX_CRYPT_CLUSTERS * s->cluster_sectors;
cur_nr_sectors >
QCOW_MAX_CRYPT_CLUSTERS * s->cluster_sectors - index_in_cluster) {
cur_nr_sectors =
QCOW_MAX_CRYPT_CLUSTERS * s->cluster_sectors - index_in_cluster;
}
ret = qcow2_alloc_cluster_offset(bs, sector_num << 9,
index_in_cluster, n_end, &cur_nr_sectors, &cluster_offset, &l2meta);
&cur_nr_sectors, &cluster_offset, &l2meta);
if (ret < 0) {
goto fail;
}
@ -1408,7 +1409,7 @@ static int preallocate(BlockDriverState *bs)
while (nb_sectors) {
num = MIN(nb_sectors, INT_MAX >> 9);
ret = qcow2_alloc_cluster_offset(bs, offset, 0, num, &num,
ret = qcow2_alloc_cluster_offset(bs, offset, &num,
&host_offset, &meta);
if (ret < 0) {
return ret;

2
block/qcow2.h
View File

@ -468,7 +468,7 @@ void qcow2_encrypt_sectors(BDRVQcowState *s, int64_t sector_num,
int qcow2_get_cluster_offset(BlockDriverState *bs, uint64_t offset,
int *num, uint64_t *cluster_offset);
int qcow2_alloc_cluster_offset(BlockDriverState *bs, uint64_t offset,
int n_start, int n_end, int *num, uint64_t *host_offset, QCowL2Meta **m);
int *num, uint64_t *host_offset, QCowL2Meta **m);
uint64_t qcow2_alloc_compressed_cluster_offset(BlockDriverState *bs,
uint64_t offset,
int compressed_size);

2
trace-events
View File

@ -495,7 +495,7 @@ qcow2_writev_done_part(void *co, int cur_nr_sectors) "co %p cur_nr_sectors %d"
qcow2_writev_data(void *co, uint64_t offset) "co %p offset %" PRIx64
# block/qcow2-cluster.c
qcow2_alloc_clusters_offset(void *co, uint64_t offset, int n_start, int n_end) "co %p offet %" PRIx64 " n_start %d n_end %d"
qcow2_alloc_clusters_offset(void *co, uint64_t offset, int num) "co %p offet %" PRIx64 " num %d"
qcow2_handle_copied(void *co, uint64_t guest_offset, uint64_t host_offset, uint64_t bytes) "co %p guest_offet %" PRIx64 " host_offset %" PRIx64 " bytes %" PRIx64
qcow2_handle_alloc(void *co, uint64_t guest_offset, uint64_t host_offset, uint64_t bytes) "co %p guest_offet %" PRIx64 " host_offset %" PRIx64 " bytes %" PRIx64
qcow2_do_alloc_clusters_offset(void *co, uint64_t guest_offset, uint64_t host_offset, int nb_clusters) "co %p guest_offet %" PRIx64 " host_offset %" PRIx64 " nb_clusters %d"