Le Thursday 23 Jan 2014 à 11:04:05 (+0800), Hu Tao a écrit :
> 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
>
> Reviewed-by: Max Reitz <mre...@redhat.com>
> Signed-off-by: Hu Tao <hu...@cn.fujitsu.com>
> ---
> block/qcow2-cluster.c | 14 ++++++--------
> block/qcow2.c | 11 +++--------
> block/qcow2.h | 2 +-
> trace-events | 2 +-
> 4 files changed, 11 insertions(+), 18 deletions(-)
>
> diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c
> index 8534084..c57f39d 100644
> --- a/block/qcow2-cluster.c
> +++ b/block/qcow2-cluster.c
> @@ -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);
Why replace something that would round gently an unaligned offset
(start_of_cluster) by an assert that would make QEMU exit ?
Best regards
Benoît
>
> 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);
>
> diff --git a/block/qcow2.c b/block/qcow2.c
> index 8ec9db1..0a310cc 100644
> --- a/block/qcow2.c
> +++ b/block/qcow2.c
> @@ -992,7 +992,6 @@ 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;
> @@ -1016,14 +1015,10 @@ 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;
> - 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 = remaining_sectors;
>
> 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;
> }
> @@ -1400,7 +1395,7 @@ 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;
> diff --git a/block/qcow2.h b/block/qcow2.h
> index 303eb26..84e1344 100644
> --- a/block/qcow2.h
> +++ b/block/qcow2.h
> @@ -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);
> diff --git a/trace-events b/trace-events
> index 9f4456a..9b4e586 100644
> --- a/trace-events
> +++ b/trace-events
> @@ -494,7 +494,7 @@ 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"
> --
> 1.8.5.2.229.g4448466
>
>
