Am 21.11.2011 08:12, schrieb Lan Tianyu:
> When meeting request to write the cluster without copied flag,
> allocate a new cluster and write original data with modification
> to the new cluster. This also adds support for the writing operation
> of the qcow2 compressed image. After testing, image file can pass
> through "qemu-img check". The performance is needed to be improved.
>
> Signed-off-by: Lan Tianyu <[email protected]>
> ---
> tools/kvm/disk/qcow.c | 411
> +++++++++++++++++++++++++++++-------------
> tools/kvm/include/kvm/qcow.h | 2 +
> 2 files changed, 285 insertions(+), 128 deletions(-)
> @@ -766,122 +872,166 @@ static ssize_t qcow_write_cluster(struct qcow *q, u64
> offset, void *buf, u32 src
> if (l2t_idx >= l2t_size)
> return -1;
>
> - clust_off = get_cluster_offset(q, offset);
> - if (clust_off >= clust_sz)
> - return -1;
> -
> - len = clust_sz - clust_off;
> - if (len > src_len)
> - len = src_len;
> -
> - mutex_lock(&q->mutex);
> -
> l2t_offset = be64_to_cpu(l1t->l1_table[l1t_idx]);
> - if (l2t_offset & QCOW2_OFLAG_COMPRESSED) {
> - pr_warning("compressed clusters are not supported");
> - goto error;
> - }
> - if (!(l2t_offset & QCOW2_OFLAG_COPIED)) {
> - pr_warning("L2 copy-on-write clusters are not supported");
> - goto error;
> - }
> -
> - l2t_offset &= QCOW2_OFFSET_MASK;
> - if (l2t_offset) {
> - /* read and cache l2 table */
> + if (l2t_offset & QCOW2_OFLAG_COPIED) {
> + l2t_offset &= ~QCOW2_OFLAG_COPIED;
> l2t = qcow_read_l2_table(q, l2t_offset);
> if (!l2t)
> goto error;
> } else {
> - l2t = new_cache_table(q, l2t_offset);
> - if (!l2t)
> + l2t_new_offset = qcow_alloc_clusters(q, l2t_size*sizeof(u64));
> + if (l2t_new_offset < 0)
> goto error;
>
> - /* Capture the state of the consistent QCOW image */
> - f_sz = file_size(q->fd);
> - if (!f_sz)
> - goto free_cache;
> + l2t = new_cache_table(q, l2t_new_offset);
> + if (!l2t)
> + goto free_cluster;
>
> - /* Write the l2 table of 0's at the end of the file */
> - l2t_offset = qcow_write_l2_table(q, l2t->table);
> - if (!l2t_offset)
> + if (l2t_offset) {
> + l2t = qcow_read_l2_table(q, l2t_offset);
> + if (!l2t)
> + goto free_cache;
> + } else
> + memset(l2t->table, 0x00, l2t_size * sizeof(u64));
> +
> + /*write l2 table*/
> + l2t->dirty = 1;
> + if (qcow_l2_cache_write(q, l2t) < 0)
> goto free_cache;
>
> - if (cache_table(q, l2t) < 0) {
> - if (ftruncate(q->fd, f_sz) < 0)
> - goto free_cache;
> + /*cache l2 table*/
> + cache_table(q, l2t);
You're ignoring the return value here.
Otherwise I didn't find any obvious problem in a quick scan.
Kevin
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