Re: [Qemu-devel] [PATCH v4 2/5] qcow2-cluster: Expand zero clusters
Am 02.09.2013 17:13, schrieb Kevin Wolf:
Am 02.09.2013 um 12:04 hat Max Reitz geschrieben:
Add functionality for expanding zero clusters. This is necessary for
downgrading the image version to one without zero cluster support.
For non-backed images, this function may also just discard zero clusters
instead of truly expanding them.
Signed-off-by: Max Reitz
---
block/qcow2-cluster.c | 228 +
block/qcow2-refcount.c | 29 ---
block/qcow2.h | 5 ++
3 files changed, 248 insertions(+), 14 deletions(-)
diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c
index 2d5aa92..c90fb51 100644
--- a/block/qcow2-cluster.c
+++ b/block/qcow2-cluster.c
@@ -1497,3 +1497,231 @@ fail:
return ret;
}
+
+/*
+ * Expands all zero clusters in a specific L1 table (or deallocates them, for
+ * non-backed non-pre-allocated zero clusters).
+ *
+ * expanded_clusters is a bitmap where every bit corresponds to one cluster in
+ * the image file; a bit gets set if the corresponding cluster has been used
for
+ * zero expansion (i.e., has been filled with zeroes and is referenced from an
+ * L2 table). nb_clusters contains the total cluster count of the image file,
+ * i.e., the number of bits in expanded_clusters.
+ */
+static int expand_zero_clusters_in_l1(BlockDriverState *bs, uint64_t *l1_table,
+ int l1_size, uint8_t *expanded_clusters,
+ uint64_t nb_clusters)
+{
+BDRVQcowState *s = bs->opaque;
+bool is_active_l1 = (l1_table == s->l1_table);
+uint64_t *l2_table = NULL;
+int ret;
+int i, j;
+
+if (!is_active_l1) {
+/* inactive L2 tables require a buffer to be stored in when loading
+ * them from disk */
+l2_table = qemu_blockalign(bs, s->cluster_size);
+}
+
+for (i = 0; i < l1_size; i++) {
+uint64_t l2_offset = l1_table[i] & L1E_OFFSET_MASK;
+bool l2_dirty = false;
+
+if (!l2_offset) {
+/* unallocated */
+continue;
+}
+
+if (is_active_l1) {
+/* get active L2 tables from cache */
+ret = qcow2_cache_get(bs, s->l2_table_cache, l2_offset,
+(void **)&l2_table);
+} else {
+/* load inactive L2 tables from disk */
+ret = bdrv_read(bs->file, l2_offset / BDRV_SECTOR_SIZE,
+(void *)l2_table, s->cluster_sectors);
+}
+if (ret < 0) {
+goto fail;
+}
+
+for (j = 0; j < s->l2_size; j++) {
+uint64_t l2_entry = be64_to_cpu(l2_table[j]);
+int64_t offset = l2_entry & L2E_OFFSET_MASK, cluster_index;
+int cluster_type = qcow2_get_cluster_type(l2_entry);
+
+if (cluster_type == QCOW2_CLUSTER_NORMAL) {
+cluster_index = offset >> s->cluster_bits;
+assert((cluster_index >= 0) && (cluster_index < nb_clusters));
+if (expanded_clusters[cluster_index / 8] &
+(1 << (cluster_index % 8))) {
+/* Probably a shared L2 table; this cluster was a zero
+ * cluster which has been expanded, its refcount
+ * therefore most likely requires an update. */
+ret = qcow2_update_cluster_refcount(bs, cluster_index, 1,
+QCOW2_DISCARD_NEVER);
+if (ret < 0) {
+goto fail;
+}
+/* Since we just increased the refcount, the COPIED flag
may
+ * no longer be set. */
+l2_table[j] = cpu_to_be64(l2_entry & ~QCOW_OFLAG_COPIED);
+l2_dirty = true;
+}
+continue;
+}
+else if (qcow2_get_cluster_type(l2_entry) != QCOW2_CLUSTER_ZERO) {
+continue;
+}
+
+if (!offset) {
+/* not preallocated */
+if (!bs->backing_hd) {
+/* not backed; therefore we can simply deallocate the
+ * cluster */
+l2_table[j] = 0;
+l2_dirty = true;
+continue;
+}
+
+offset = qcow2_alloc_clusters(bs, s->cluster_size);
+if (offset < 0) {
+ret = offset;
+goto fail;
+}
+}
+
+ret = qcow2_pre_write_overlap_check(bs, QCOW2_OL_DEFAULT,
+offset, s->cluster_size);
+if (ret < 0) {
+qcow2_free_clusters(bs, offset, s->cluster_size,
+QCOW2_DISCARD_ALWAYS);
+goto fail;
+}
+
+ret = bdrv_write_zeroes(bs->file, offset / BDRV_SECTOR_SIZE,
+
Re: [Qemu-devel] [PATCH v4 2/5] qcow2-cluster: Expand zero clusters
Am 02.09.2013 um 12:04 hat Max Reitz geschrieben:
> Add functionality for expanding zero clusters. This is necessary for
> downgrading the image version to one without zero cluster support.
>
> For non-backed images, this function may also just discard zero clusters
> instead of truly expanding them.
>
> Signed-off-by: Max Reitz
> ---
> block/qcow2-cluster.c | 228
> +
> block/qcow2-refcount.c | 29 ---
> block/qcow2.h | 5 ++
> 3 files changed, 248 insertions(+), 14 deletions(-)
>
> diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c
> index 2d5aa92..c90fb51 100644
> --- a/block/qcow2-cluster.c
> +++ b/block/qcow2-cluster.c
> @@ -1497,3 +1497,231 @@ fail:
>
> return ret;
> }
> +
> +/*
> + * Expands all zero clusters in a specific L1 table (or deallocates them, for
> + * non-backed non-pre-allocated zero clusters).
> + *
> + * expanded_clusters is a bitmap where every bit corresponds to one cluster
> in
> + * the image file; a bit gets set if the corresponding cluster has been used
> for
> + * zero expansion (i.e., has been filled with zeroes and is referenced from
> an
> + * L2 table). nb_clusters contains the total cluster count of the image file,
> + * i.e., the number of bits in expanded_clusters.
> + */
> +static int expand_zero_clusters_in_l1(BlockDriverState *bs, uint64_t
> *l1_table,
> + int l1_size, uint8_t
> *expanded_clusters,
> + uint64_t nb_clusters)
> +{
> +BDRVQcowState *s = bs->opaque;
> +bool is_active_l1 = (l1_table == s->l1_table);
> +uint64_t *l2_table = NULL;
> +int ret;
> +int i, j;
> +
> +if (!is_active_l1) {
> +/* inactive L2 tables require a buffer to be stored in when loading
> + * them from disk */
> +l2_table = qemu_blockalign(bs, s->cluster_size);
> +}
> +
> +for (i = 0; i < l1_size; i++) {
> +uint64_t l2_offset = l1_table[i] & L1E_OFFSET_MASK;
> +bool l2_dirty = false;
> +
> +if (!l2_offset) {
> +/* unallocated */
> +continue;
> +}
> +
> +if (is_active_l1) {
> +/* get active L2 tables from cache */
> +ret = qcow2_cache_get(bs, s->l2_table_cache, l2_offset,
> +(void **)&l2_table);
> +} else {
> +/* load inactive L2 tables from disk */
> +ret = bdrv_read(bs->file, l2_offset / BDRV_SECTOR_SIZE,
> +(void *)l2_table, s->cluster_sectors);
> +}
> +if (ret < 0) {
> +goto fail;
> +}
> +
> +for (j = 0; j < s->l2_size; j++) {
> +uint64_t l2_entry = be64_to_cpu(l2_table[j]);
> +int64_t offset = l2_entry & L2E_OFFSET_MASK, cluster_index;
> +int cluster_type = qcow2_get_cluster_type(l2_entry);
> +
> +if (cluster_type == QCOW2_CLUSTER_NORMAL) {
> +cluster_index = offset >> s->cluster_bits;
> +assert((cluster_index >= 0) && (cluster_index <
> nb_clusters));
> +if (expanded_clusters[cluster_index / 8] &
> +(1 << (cluster_index % 8))) {
> +/* Probably a shared L2 table; this cluster was a zero
> + * cluster which has been expanded, its refcount
> + * therefore most likely requires an update. */
> +ret = qcow2_update_cluster_refcount(bs, cluster_index, 1,
> +QCOW2_DISCARD_NEVER);
> +if (ret < 0) {
> +goto fail;
> +}
> +/* Since we just increased the refcount, the COPIED flag
> may
> + * no longer be set. */
> +l2_table[j] = cpu_to_be64(l2_entry & ~QCOW_OFLAG_COPIED);
> +l2_dirty = true;
> +}
> +continue;
> +}
> +else if (qcow2_get_cluster_type(l2_entry) != QCOW2_CLUSTER_ZERO)
> {
> +continue;
> +}
> +
> +if (!offset) {
> +/* not preallocated */
> +if (!bs->backing_hd) {
> +/* not backed; therefore we can simply deallocate the
> + * cluster */
> +l2_table[j] = 0;
> +l2_dirty = true;
> +continue;
> +}
> +
> +offset = qcow2_alloc_clusters(bs, s->cluster_size);
> +if (offset < 0) {
> +ret = offset;
> +goto fail;
> +}
> +}
> +
> +ret = qcow2_pre_write_overlap_check(bs, QCOW2_OL_DEFAULT,
> +offset, s->cluster_size);
> +if (ret < 0) {
> +qcow2_free_clusters(bs, offset, s
[Qemu-devel] [PATCH v4 2/5] qcow2-cluster: Expand zero clusters
Add functionality for expanding zero clusters. This is necessary for
downgrading the image version to one without zero cluster support.
For non-backed images, this function may also just discard zero clusters
instead of truly expanding them.
Signed-off-by: Max Reitz
---
block/qcow2-cluster.c | 228 +
block/qcow2-refcount.c | 29 ---
block/qcow2.h | 5 ++
3 files changed, 248 insertions(+), 14 deletions(-)
diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c
index 2d5aa92..c90fb51 100644
--- a/block/qcow2-cluster.c
+++ b/block/qcow2-cluster.c
@@ -1497,3 +1497,231 @@ fail:
return ret;
}
+
+/*
+ * Expands all zero clusters in a specific L1 table (or deallocates them, for
+ * non-backed non-pre-allocated zero clusters).
+ *
+ * expanded_clusters is a bitmap where every bit corresponds to one cluster in
+ * the image file; a bit gets set if the corresponding cluster has been used
for
+ * zero expansion (i.e., has been filled with zeroes and is referenced from an
+ * L2 table). nb_clusters contains the total cluster count of the image file,
+ * i.e., the number of bits in expanded_clusters.
+ */
+static int expand_zero_clusters_in_l1(BlockDriverState *bs, uint64_t *l1_table,
+ int l1_size, uint8_t *expanded_clusters,
+ uint64_t nb_clusters)
+{
+BDRVQcowState *s = bs->opaque;
+bool is_active_l1 = (l1_table == s->l1_table);
+uint64_t *l2_table = NULL;
+int ret;
+int i, j;
+
+if (!is_active_l1) {
+/* inactive L2 tables require a buffer to be stored in when loading
+ * them from disk */
+l2_table = qemu_blockalign(bs, s->cluster_size);
+}
+
+for (i = 0; i < l1_size; i++) {
+uint64_t l2_offset = l1_table[i] & L1E_OFFSET_MASK;
+bool l2_dirty = false;
+
+if (!l2_offset) {
+/* unallocated */
+continue;
+}
+
+if (is_active_l1) {
+/* get active L2 tables from cache */
+ret = qcow2_cache_get(bs, s->l2_table_cache, l2_offset,
+(void **)&l2_table);
+} else {
+/* load inactive L2 tables from disk */
+ret = bdrv_read(bs->file, l2_offset / BDRV_SECTOR_SIZE,
+(void *)l2_table, s->cluster_sectors);
+}
+if (ret < 0) {
+goto fail;
+}
+
+for (j = 0; j < s->l2_size; j++) {
+uint64_t l2_entry = be64_to_cpu(l2_table[j]);
+int64_t offset = l2_entry & L2E_OFFSET_MASK, cluster_index;
+int cluster_type = qcow2_get_cluster_type(l2_entry);
+
+if (cluster_type == QCOW2_CLUSTER_NORMAL) {
+cluster_index = offset >> s->cluster_bits;
+assert((cluster_index >= 0) && (cluster_index < nb_clusters));
+if (expanded_clusters[cluster_index / 8] &
+(1 << (cluster_index % 8))) {
+/* Probably a shared L2 table; this cluster was a zero
+ * cluster which has been expanded, its refcount
+ * therefore most likely requires an update. */
+ret = qcow2_update_cluster_refcount(bs, cluster_index, 1,
+QCOW2_DISCARD_NEVER);
+if (ret < 0) {
+goto fail;
+}
+/* Since we just increased the refcount, the COPIED flag
may
+ * no longer be set. */
+l2_table[j] = cpu_to_be64(l2_entry & ~QCOW_OFLAG_COPIED);
+l2_dirty = true;
+}
+continue;
+}
+else if (qcow2_get_cluster_type(l2_entry) != QCOW2_CLUSTER_ZERO) {
+continue;
+}
+
+if (!offset) {
+/* not preallocated */
+if (!bs->backing_hd) {
+/* not backed; therefore we can simply deallocate the
+ * cluster */
+l2_table[j] = 0;
+l2_dirty = true;
+continue;
+}
+
+offset = qcow2_alloc_clusters(bs, s->cluster_size);
+if (offset < 0) {
+ret = offset;
+goto fail;
+}
+}
+
+ret = qcow2_pre_write_overlap_check(bs, QCOW2_OL_DEFAULT,
+offset, s->cluster_size);
+if (ret < 0) {
+qcow2_free_clusters(bs, offset, s->cluster_size,
+QCOW2_DISCARD_ALWAYS);
+goto fail;
+}
+
+ret = bdrv_write_zeroes(bs->file, offset / BDRV_SECTOR_SIZE,
+s->cluster_sectors);
+if (ret < 0) {
+qcow2_free_clusters(bs, offse
