This function is used to read missing data when unaligned writes are
done. This function also concatenate missing data with the given
qiov data in order to prepare a buffer used to look for duplicated
clusters.
---
block/Makefile.objs | 1 +
block/qcow2-dedup.c | 137 +++++++++++++++++++++++++++++++++++++++++++++++++++
block/qcow2.h | 8 +++
3 files changed, 146 insertions(+)
create mode 100644 block/qcow2-dedup.c
diff --git a/block/Makefile.objs b/block/Makefile.objs
index 554f429..790cb5f 100644
--- a/block/Makefile.objs
+++ b/block/Makefile.objs
@@ -1,5 +1,6 @@
block-obj-y += raw.o cow.o qcow.o vdi.o vmdk.o cloop.o dmg.o bochs.o vpc.o
vvfat.o
block-obj-y += qcow2.o qcow2-refcount.o qcow2-cluster.o qcow2-snapshot.o
qcow2-cache.o
+block-obj-y += qcow2-dedup.o
block-obj-y += qed.o qed-gencb.o qed-l2-cache.o qed-table.o qed-cluster.o
block-obj-y += qed-check.o
block-obj-y += parallels.o nbd.o blkdebug.o sheepdog.o blkverify.o
diff --git a/block/qcow2-dedup.c b/block/qcow2-dedup.c
new file mode 100644
index 0000000..9955843
--- /dev/null
+++ b/block/qcow2-dedup.c
@@ -0,0 +1,137 @@
+/*
+ * Deduplication for the QCOW2 format
+ *
+ * Copyright (C) Nodalink, SARL. 2012
+ *
+ * Author:
+ * Benoît Canet <benoit.ca...@irqsave.net>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to
deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "block_int.h"
+#include "qemu-common.h"
+#include "qcow2.h"
+
+/**
+ * Read some data from the QCOW2 file
+ *
+ * @data: the buffer where the data must be stored
+ * @sector_num: the sector number to read in the QCOW2 file
+ * @nb_sectors: the number of sectors to read
+ * @ret: negative on error
+ */
+static int qcow2_dedup_read_missing_cluster_data(BlockDriverState *bs,
+ uint8_t *data,
+ uint64_t sector_num,
+ int nb_sectors)
+{
+ BDRVQcowState *s = bs->opaque;
+ QEMUIOVector qiov;
+ struct iovec iov;
+ int ret;
+
+ iov.iov_len = nb_sectors * BDRV_SECTOR_SIZE;
+ iov.iov_base = data;
+ qemu_iovec_init_external(&qiov, &iov, 1);
+ qemu_co_mutex_unlock(&s->lock);
+ ret = bdrv_co_readv(bs, sector_num, nb_sectors, &qiov);
+ qemu_co_mutex_lock(&s->lock);
+ if (ret < 0) {
+ error_report("failed to read %d sectors at offset %" PRIu64 "\n",
+ nb_sectors, sector_num);
+ }
+
+ return ret;
+}
+
+/*
+ * Prepare a buffer containing all the required data required to compute
cluster
+ * sized deduplication hashes.
+ * If sector_num and nb_sectors are unaligned cluster wize it read the missing
+ * data before and after the qiov.
+ *
+ * @qiov: the qiov for which missing data must be read
+ * @sector_num: the first sectors that must be read into the qiov
+ * @nb_sectors: the number of sectors to read into the qiov
+ * @data: the place where the data will be concatenated and
stored
+ * @nb_data_sectors: the resulting size of the contatenated data (in
sectors)
+ * @ret: negative on error
+ */
+int qcow2_dedup_read_missing_and_concatenate(BlockDriverState *bs,
+ QEMUIOVector *qiov,
+ uint64_t sector_num,
+ int nb_sectors,
+ uint8_t **data,
+ int *nb_data_sectors)
+{
+ BDRVQcowState *s = bs->opaque;
+ int ret;
+ uint64_t cluster_beginning_sector;
+ uint64_t first_sector_after_qiov;
+ int cluster_beginning_nr;
+ int cluster_ending_nr;
+ int unaligned_ending_nr;
+
+ /* compute how much and where to read at the beginning */
+ cluster_beginning_nr = sector_num & (s->cluster_sectors - 1);
+ cluster_beginning_sector = sector_num - cluster_beginning_nr;
+
+ /* for the ending */
+ first_sector_after_qiov = sector_num + nb_sectors;
+ unaligned_ending_nr = first_sector_after_qiov & (s->cluster_sectors - 1);
+ cluster_ending_nr = unaligned_ending_nr ?
+ s->cluster_sectors - unaligned_ending_nr : 0;
+
+ /* compute total size in sectors and allocate memory */
+ *nb_data_sectors = cluster_beginning_nr + nb_sectors + cluster_ending_nr;
+ *data = qemu_blockalign(bs, *nb_data_sectors * BDRV_SECTOR_SIZE);
+
+ /* read beginning */
+ ret = qcow2_dedup_read_missing_cluster_data(bs,
+ *data,
+ cluster_beginning_sector,
+ cluster_beginning_nr);
+
+ if (ret < 0) {
+ goto fail;
+ }
+
+ /* append qiov content */
+ qemu_iovec_to_buf(qiov, 0, *data + cluster_beginning_nr * BDRV_SECTOR_SIZE,
+ qiov->size);
+
+ /* read and add ending */
+ ret = qcow2_dedup_read_missing_cluster_data(bs,
+ *data +
+ (cluster_beginning_nr +
+ nb_sectors) * BDRV_SECTOR_SIZE,
+ first_sector_after_qiov,
+ cluster_ending_nr);
+
+ if (ret < 0) {
+ goto fail;
+ }
+
+ return 0;
+
+fail:
+ qemu_vfree(*data);
+ return ret;
+}
diff --git a/block/qcow2.h b/block/qcow2.h
index e38667c..6e867c8 100644
--- a/block/qcow2.h
+++ b/block/qcow2.h
@@ -356,4 +356,12 @@ int qcow2_cache_get_empty(BlockDriverState *bs, Qcow2Cache
*c, uint64_t offset,
void **table);
int qcow2_cache_put(BlockDriverState *bs, Qcow2Cache *c, void **table);
+/* qcow2-dedup.c functions */
+int qcow2_dedup_read_missing_and_concatenate(BlockDriverState *bs,
+ QEMUIOVector *qiov,
+ uint64_t sector,
+ int sectors_nr,
+ uint8_t **dedup_cluster_data,
+ int *dedup_cluster_data_nr);
+
#endif
--
1.7.10.4
