qcow2: Add function for refcount order amendment
Add a function qcow2_change_refcount_order() which allows changing the refcount order of a qcow2 image. Signed-off-by: Max Reitz <mreitz@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Max Reitz
Kevin Wolf
parent
c293a80927
commit
791c9a004e
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@ -2467,3 +2467,450 @@ int qcow2_pre_write_overlap_check(BlockDriverState *bs, int ign, int64_t offset,
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return 0;
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}
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/* A pointer to a function of this type is given to walk_over_reftable(). That
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* function will create refblocks and pass them to a RefblockFinishOp once they
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* are completed (@refblock). @refblock_empty is set if the refblock is
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* completely empty.
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*
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* Along with the refblock, a corresponding reftable entry is passed, in the
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* reftable @reftable (which may be reallocated) at @reftable_index.
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*
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* @allocated should be set to true if a new cluster has been allocated.
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*/
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typedef int (RefblockFinishOp)(BlockDriverState *bs, uint64_t **reftable,
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uint64_t reftable_index, uint64_t *reftable_size,
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void *refblock, bool refblock_empty,
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bool *allocated, Error **errp);
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/**
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* This "operation" for walk_over_reftable() allocates the refblock on disk (if
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* it is not empty) and inserts its offset into the new reftable. The size of
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* this new reftable is increased as required.
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*/
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static int alloc_refblock(BlockDriverState *bs, uint64_t **reftable,
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uint64_t reftable_index, uint64_t *reftable_size,
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void *refblock, bool refblock_empty, bool *allocated,
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Error **errp)
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{
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BDRVQcow2State *s = bs->opaque;
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int64_t offset;
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if (!refblock_empty && reftable_index >= *reftable_size) {
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uint64_t *new_reftable;
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uint64_t new_reftable_size;
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new_reftable_size = ROUND_UP(reftable_index + 1,
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s->cluster_size / sizeof(uint64_t));
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if (new_reftable_size > QCOW_MAX_REFTABLE_SIZE / sizeof(uint64_t)) {
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error_setg(errp,
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"This operation would make the refcount table grow "
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"beyond the maximum size supported by QEMU, aborting");
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return -ENOTSUP;
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}
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new_reftable = g_try_realloc(*reftable, new_reftable_size *
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sizeof(uint64_t));
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if (!new_reftable) {
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error_setg(errp, "Failed to increase reftable buffer size");
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return -ENOMEM;
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}
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memset(new_reftable + *reftable_size, 0,
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(new_reftable_size - *reftable_size) * sizeof(uint64_t));
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*reftable = new_reftable;
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*reftable_size = new_reftable_size;
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}
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if (!refblock_empty && !(*reftable)[reftable_index]) {
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offset = qcow2_alloc_clusters(bs, s->cluster_size);
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if (offset < 0) {
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error_setg_errno(errp, -offset, "Failed to allocate refblock");
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return offset;
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}
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(*reftable)[reftable_index] = offset;
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*allocated = true;
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}
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return 0;
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}
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/**
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* This "operation" for walk_over_reftable() writes the refblock to disk at the
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* offset specified by the new reftable's entry. It does not modify the new
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* reftable or change any refcounts.
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*/
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static int flush_refblock(BlockDriverState *bs, uint64_t **reftable,
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uint64_t reftable_index, uint64_t *reftable_size,
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void *refblock, bool refblock_empty, bool *allocated,
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Error **errp)
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{
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BDRVQcow2State *s = bs->opaque;
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int64_t offset;
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int ret;
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if (reftable_index < *reftable_size && (*reftable)[reftable_index]) {
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offset = (*reftable)[reftable_index];
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ret = qcow2_pre_write_overlap_check(bs, 0, offset, s->cluster_size);
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if (ret < 0) {
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error_setg_errno(errp, -ret, "Overlap check failed");
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return ret;
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}
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ret = bdrv_pwrite(bs->file->bs, offset, refblock, s->cluster_size);
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if (ret < 0) {
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error_setg_errno(errp, -ret, "Failed to write refblock");
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return ret;
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}
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} else {
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assert(refblock_empty);
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}
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return 0;
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}
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/**
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* This function walks over the existing reftable and every referenced refblock;
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* if @new_set_refcount is non-NULL, it is called for every refcount entry to
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* create an equal new entry in the passed @new_refblock. Once that
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* @new_refblock is completely filled, @operation will be called.
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*
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* @status_cb and @cb_opaque are used for the amend operation's status callback.
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* @index is the index of the walk_over_reftable() calls and @total is the total
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* number of walk_over_reftable() calls per amend operation. Both are used for
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* calculating the parameters for the status callback.
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*
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* @allocated is set to true if a new cluster has been allocated.
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*/
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static int walk_over_reftable(BlockDriverState *bs, uint64_t **new_reftable,
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uint64_t *new_reftable_index,
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uint64_t *new_reftable_size,
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void *new_refblock, int new_refblock_size,
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int new_refcount_bits,
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RefblockFinishOp *operation, bool *allocated,
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Qcow2SetRefcountFunc *new_set_refcount,
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BlockDriverAmendStatusCB *status_cb,
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void *cb_opaque, int index, int total,
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Error **errp)
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{
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BDRVQcow2State *s = bs->opaque;
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uint64_t reftable_index;
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bool new_refblock_empty = true;
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int refblock_index;
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int new_refblock_index = 0;
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int ret;
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for (reftable_index = 0; reftable_index < s->refcount_table_size;
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reftable_index++)
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{
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uint64_t refblock_offset = s->refcount_table[reftable_index]
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& REFT_OFFSET_MASK;
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status_cb(bs, (uint64_t)index * s->refcount_table_size + reftable_index,
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(uint64_t)total * s->refcount_table_size, cb_opaque);
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if (refblock_offset) {
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void *refblock;
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if (offset_into_cluster(s, refblock_offset)) {
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qcow2_signal_corruption(bs, true, -1, -1, "Refblock offset %#"
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PRIx64 " unaligned (reftable index: %#"
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PRIx64 ")", refblock_offset,
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reftable_index);
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error_setg(errp,
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"Image is corrupt (unaligned refblock offset)");
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return -EIO;
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}
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ret = qcow2_cache_get(bs, s->refcount_block_cache, refblock_offset,
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&refblock);
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if (ret < 0) {
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error_setg_errno(errp, -ret, "Failed to retrieve refblock");
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return ret;
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}
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for (refblock_index = 0; refblock_index < s->refcount_block_size;
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refblock_index++)
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{
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uint64_t refcount;
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if (new_refblock_index >= new_refblock_size) {
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/* new_refblock is now complete */
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ret = operation(bs, new_reftable, *new_reftable_index,
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new_reftable_size, new_refblock,
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new_refblock_empty, allocated, errp);
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if (ret < 0) {
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qcow2_cache_put(bs, s->refcount_block_cache, &refblock);
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return ret;
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}
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(*new_reftable_index)++;
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new_refblock_index = 0;
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new_refblock_empty = true;
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}
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refcount = s->get_refcount(refblock, refblock_index);
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if (new_refcount_bits < 64 && refcount >> new_refcount_bits) {
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uint64_t offset;
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qcow2_cache_put(bs, s->refcount_block_cache, &refblock);
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offset = ((reftable_index << s->refcount_block_bits)
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+ refblock_index) << s->cluster_bits;
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error_setg(errp, "Cannot decrease refcount entry width to "
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"%i bits: Cluster at offset %#" PRIx64 " has a "
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"refcount of %" PRIu64, new_refcount_bits,
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offset, refcount);
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return -EINVAL;
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}
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if (new_set_refcount) {
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new_set_refcount(new_refblock, new_refblock_index++,
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refcount);
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} else {
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new_refblock_index++;
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}
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new_refblock_empty = new_refblock_empty && refcount == 0;
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}
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qcow2_cache_put(bs, s->refcount_block_cache, &refblock);
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} else {
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/* No refblock means every refcount is 0 */
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for (refblock_index = 0; refblock_index < s->refcount_block_size;
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refblock_index++)
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{
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if (new_refblock_index >= new_refblock_size) {
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/* new_refblock is now complete */
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ret = operation(bs, new_reftable, *new_reftable_index,
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new_reftable_size, new_refblock,
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new_refblock_empty, allocated, errp);
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if (ret < 0) {
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return ret;
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}
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(*new_reftable_index)++;
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new_refblock_index = 0;
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new_refblock_empty = true;
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}
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if (new_set_refcount) {
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new_set_refcount(new_refblock, new_refblock_index++, 0);
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} else {
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new_refblock_index++;
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}
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}
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}
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}
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if (new_refblock_index > 0) {
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/* Complete the potentially existing partially filled final refblock */
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if (new_set_refcount) {
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for (; new_refblock_index < new_refblock_size;
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new_refblock_index++)
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{
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new_set_refcount(new_refblock, new_refblock_index, 0);
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}
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}
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ret = operation(bs, new_reftable, *new_reftable_index,
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new_reftable_size, new_refblock, new_refblock_empty,
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allocated, errp);
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if (ret < 0) {
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return ret;
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}
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(*new_reftable_index)++;
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}
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status_cb(bs, (uint64_t)(index + 1) * s->refcount_table_size,
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(uint64_t)total * s->refcount_table_size, cb_opaque);
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return 0;
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}
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int qcow2_change_refcount_order(BlockDriverState *bs, int refcount_order,
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BlockDriverAmendStatusCB *status_cb,
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void *cb_opaque, Error **errp)
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{
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BDRVQcow2State *s = bs->opaque;
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Qcow2GetRefcountFunc *new_get_refcount;
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Qcow2SetRefcountFunc *new_set_refcount;
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void *new_refblock = qemu_blockalign(bs->file->bs, s->cluster_size);
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uint64_t *new_reftable = NULL, new_reftable_size = 0;
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uint64_t *old_reftable, old_reftable_size, old_reftable_offset;
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uint64_t new_reftable_index = 0;
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uint64_t i;
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int64_t new_reftable_offset = 0, allocated_reftable_size = 0;
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int new_refblock_size, new_refcount_bits = 1 << refcount_order;
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int old_refcount_order;
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int walk_index = 0;
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int ret;
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bool new_allocation;
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assert(s->qcow_version >= 3);
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assert(refcount_order >= 0 && refcount_order <= 6);
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/* see qcow2_open() */
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new_refblock_size = 1 << (s->cluster_bits - (refcount_order - 3));
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new_get_refcount = get_refcount_funcs[refcount_order];
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new_set_refcount = set_refcount_funcs[refcount_order];
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do {
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int total_walks;
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new_allocation = false;
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/* At least we have to do this walk and the one which writes the
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* refblocks; also, at least we have to do this loop here at least
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* twice (normally), first to do the allocations, and second to
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* determine that everything is correctly allocated, this then makes
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* three walks in total */
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total_walks = MAX(walk_index + 2, 3);
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/* First, allocate the structures so they are present in the refcount
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* structures */
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ret = walk_over_reftable(bs, &new_reftable, &new_reftable_index,
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&new_reftable_size, NULL, new_refblock_size,
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new_refcount_bits, &alloc_refblock,
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&new_allocation, NULL, status_cb, cb_opaque,
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walk_index++, total_walks, errp);
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if (ret < 0) {
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goto done;
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}
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new_reftable_index = 0;
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if (new_allocation) {
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if (new_reftable_offset) {
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qcow2_free_clusters(bs, new_reftable_offset,
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allocated_reftable_size * sizeof(uint64_t),
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QCOW2_DISCARD_NEVER);
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}
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new_reftable_offset = qcow2_alloc_clusters(bs, new_reftable_size *
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sizeof(uint64_t));
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if (new_reftable_offset < 0) {
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error_setg_errno(errp, -new_reftable_offset,
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"Failed to allocate the new reftable");
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ret = new_reftable_offset;
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goto done;
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}
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allocated_reftable_size = new_reftable_size;
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}
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} while (new_allocation);
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/* Second, write the new refblocks */
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ret = walk_over_reftable(bs, &new_reftable, &new_reftable_index,
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&new_reftable_size, new_refblock,
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new_refblock_size, new_refcount_bits,
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&flush_refblock, &new_allocation, new_set_refcount,
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status_cb, cb_opaque, walk_index, walk_index + 1,
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errp);
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if (ret < 0) {
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goto done;
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}
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assert(!new_allocation);
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/* Write the new reftable */
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ret = qcow2_pre_write_overlap_check(bs, 0, new_reftable_offset,
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new_reftable_size * sizeof(uint64_t));
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if (ret < 0) {
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error_setg_errno(errp, -ret, "Overlap check failed");
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goto done;
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}
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for (i = 0; i < new_reftable_size; i++) {
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cpu_to_be64s(&new_reftable[i]);
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}
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ret = bdrv_pwrite(bs->file->bs, new_reftable_offset, new_reftable,
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new_reftable_size * sizeof(uint64_t));
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for (i = 0; i < new_reftable_size; i++) {
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be64_to_cpus(&new_reftable[i]);
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}
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if (ret < 0) {
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error_setg_errno(errp, -ret, "Failed to write the new reftable");
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goto done;
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}
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/* Empty the refcount cache */
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ret = qcow2_cache_flush(bs, s->refcount_block_cache);
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if (ret < 0) {
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error_setg_errno(errp, -ret, "Failed to flush the refblock cache");
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goto done;
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}
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/* Update the image header to point to the new reftable; this only updates
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* the fields which are relevant to qcow2_update_header(); other fields
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* such as s->refcount_table or s->refcount_bits stay stale for now
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* (because we have to restore everything if qcow2_update_header() fails) */
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old_refcount_order = s->refcount_order;
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old_reftable_size = s->refcount_table_size;
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old_reftable_offset = s->refcount_table_offset;
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s->refcount_order = refcount_order;
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s->refcount_table_size = new_reftable_size;
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s->refcount_table_offset = new_reftable_offset;
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ret = qcow2_update_header(bs);
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if (ret < 0) {
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s->refcount_order = old_refcount_order;
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s->refcount_table_size = old_reftable_size;
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s->refcount_table_offset = old_reftable_offset;
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error_setg_errno(errp, -ret, "Failed to update the qcow2 header");
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goto done;
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}
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/* Now update the rest of the in-memory information */
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old_reftable = s->refcount_table;
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s->refcount_table = new_reftable;
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s->refcount_bits = 1 << refcount_order;
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s->refcount_max = UINT64_C(1) << (s->refcount_bits - 1);
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s->refcount_max += s->refcount_max - 1;
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s->refcount_block_bits = s->cluster_bits - (refcount_order - 3);
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s->refcount_block_size = 1 << s->refcount_block_bits;
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s->get_refcount = new_get_refcount;
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s->set_refcount = new_set_refcount;
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/* For cleaning up all old refblocks and the old reftable below the "done"
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* label */
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new_reftable = old_reftable;
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new_reftable_size = old_reftable_size;
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new_reftable_offset = old_reftable_offset;
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done:
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if (new_reftable) {
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/* On success, new_reftable actually points to the old reftable (and
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* new_reftable_size is the old reftable's size); but that is just
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* fine */
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for (i = 0; i < new_reftable_size; i++) {
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uint64_t offset = new_reftable[i] & REFT_OFFSET_MASK;
|
||||
if (offset) {
|
||||
qcow2_free_clusters(bs, offset, s->cluster_size,
|
||||
QCOW2_DISCARD_OTHER);
|
||||
}
|
||||
}
|
||||
g_free(new_reftable);
|
||||
|
||||
if (new_reftable_offset > 0) {
|
||||
qcow2_free_clusters(bs, new_reftable_offset,
|
||||
new_reftable_size * sizeof(uint64_t),
|
||||
QCOW2_DISCARD_OTHER);
|
||||
}
|
||||
}
|
||||
|
||||
qemu_vfree(new_refblock);
|
||||
return ret;
|
||||
}
|
||||
|
|
|
|||
|
|
@ -529,6 +529,10 @@ int qcow2_check_metadata_overlap(BlockDriverState *bs, int ign, int64_t offset,
|
|||
int qcow2_pre_write_overlap_check(BlockDriverState *bs, int ign, int64_t offset,
|
||||
int64_t size);
|
||||
|
||||
int qcow2_change_refcount_order(BlockDriverState *bs, int refcount_order,
|
||||
BlockDriverAmendStatusCB *status_cb,
|
||||
void *cb_opaque, Error **errp);
|
||||
|
||||
/* qcow2-cluster.c functions */
|
||||
int qcow2_grow_l1_table(BlockDriverState *bs, uint64_t min_size,
|
||||
bool exact_size);
|
||||
|
|
|
|||
Loading…
Reference in New Issue