Revision 68d000a3 block/qcow2-cluster.c
| b/block/qcow2-cluster.c | ||
|---|---|---|
| 367 | 367 |
* |
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* on exit, *num is the number of contiguous sectors we can read. |
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* |
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* Return 0, if the offset is found |
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* Return -errno, otherwise. |
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* |
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* Returns the cluster type (QCOW2_CLUSTER_*) on success, -errno in error |
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* cases. |
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*/ |
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|
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int qcow2_get_cluster_offset(BlockDriverState *bs, uint64_t offset, |
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int *num, uint64_t *cluster_offset) |
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{
|
| ... | ... | |
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/* seek the the l2 offset in the l1 table */ |
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l1_index = offset >> l1_bits; |
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if (l1_index >= s->l1_size) |
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if (l1_index >= s->l1_size) {
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ret = QCOW2_CLUSTER_UNALLOCATED; |
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goto out; |
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} |
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l2_offset = s->l1_table[l1_index]; |
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|
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/* seek the l2 table of the given l2 offset */ |
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|
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if (!l2_offset) |
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l2_offset = s->l1_table[l1_index] & L1E_OFFSET_MASK; |
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if (!l2_offset) {
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ret = QCOW2_CLUSTER_UNALLOCATED; |
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goto out; |
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} |
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/* load the l2 table in memory */ |
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l2_offset &= ~QCOW_OFLAG_COPIED; |
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ret = l2_load(bs, l2_offset, &l2_table); |
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if (ret < 0) {
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return ret; |
| ... | ... | |
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*cluster_offset = be64_to_cpu(l2_table[l2_index]); |
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nb_clusters = size_to_clusters(s, nb_needed << 9); |
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if (!*cluster_offset) {
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ret = qcow2_get_cluster_type(*cluster_offset); |
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switch (ret) {
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case QCOW2_CLUSTER_COMPRESSED: |
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/* Compressed clusters can only be processed one by one */ |
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c = 1; |
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*cluster_offset &= L2E_COMPRESSED_OFFSET_SIZE_MASK; |
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break; |
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case QCOW2_CLUSTER_UNALLOCATED: |
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/* how many empty clusters ? */ |
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c = count_contiguous_free_clusters(nb_clusters, &l2_table[l2_index]); |
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} else {
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*cluster_offset = 0; |
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break; |
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case QCOW2_CLUSTER_NORMAL: |
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/* how many allocated clusters ? */ |
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c = count_contiguous_clusters(nb_clusters, s->cluster_size, |
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&l2_table[l2_index], 0, QCOW_OFLAG_COPIED); |
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*cluster_offset &= L2E_OFFSET_MASK; |
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break; |
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} |
| 442 | 451 |
|
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qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table); |
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nb_available = (c * s->cluster_sectors); |
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nb_available = (c * s->cluster_sectors); |
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|
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out: |
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if (nb_available > nb_needed) |
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nb_available = nb_needed; |
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*num = nb_available - index_in_cluster; |
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*cluster_offset &=~QCOW_OFLAG_COPIED; |
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return 0; |
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return ret; |
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} |
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/* |
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