--- /dev/null
+/*
+ * Block driver for the QCOW version 2 format
+ *
+ * Copyright (c) 2004-2006 Fabrice Bellard
+ *
+ * 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 "qemu-common.h"
+#include "block/block_int.h"
+#include "block/qcow2.h"
+#include "qemu/error-report.h"
+
+void qcow2_free_snapshots(BlockDriverState *bs)
+{
+ BDRVQcowState *s = bs->opaque;
+ int i;
+
+ for(i = 0; i < s->nb_snapshots; i++) {
+ g_free(s->snapshots[i].name);
+ g_free(s->snapshots[i].id_str);
+ }
+ g_free(s->snapshots);
+ s->snapshots = NULL;
+ s->nb_snapshots = 0;
+}
+
+int qcow2_read_snapshots(BlockDriverState *bs)
+{
+ BDRVQcowState *s = bs->opaque;
+ QCowSnapshotHeader h;
+ QCowSnapshotExtraData extra;
+ QCowSnapshot *sn;
+ int i, id_str_size, name_size;
+ int64_t offset;
+ uint32_t extra_data_size;
+ int ret;
+
+ if (!s->nb_snapshots) {
+ s->snapshots = NULL;
+ s->snapshots_size = 0;
+ return 0;
+ }
+
+ offset = s->snapshots_offset;
+ s->snapshots = g_new0(QCowSnapshot, s->nb_snapshots);
+
+ for(i = 0; i < s->nb_snapshots; i++) {
+ /* Read statically sized part of the snapshot header */
+ offset = align_offset(offset, 8);
+ ret = bdrv_pread(bs->file, offset, &h, sizeof(h));
+ if (ret < 0) {
+ goto fail;
+ }
+
+ offset += sizeof(h);
+ sn = s->snapshots + i;
+ sn->l1_table_offset = be64_to_cpu(h.l1_table_offset);
+ sn->l1_size = be32_to_cpu(h.l1_size);
+ sn->vm_state_size = be32_to_cpu(h.vm_state_size);
+ sn->date_sec = be32_to_cpu(h.date_sec);
+ sn->date_nsec = be32_to_cpu(h.date_nsec);
+ sn->vm_clock_nsec = be64_to_cpu(h.vm_clock_nsec);
+ extra_data_size = be32_to_cpu(h.extra_data_size);
+
+ id_str_size = be16_to_cpu(h.id_str_size);
+ name_size = be16_to_cpu(h.name_size);
+
+ /* Read extra data */
+ ret = bdrv_pread(bs->file, offset, &extra,
+ MIN(sizeof(extra), extra_data_size));
+ if (ret < 0) {
+ goto fail;
+ }
+ offset += extra_data_size;
+
+ if (extra_data_size >= 8) {
+ sn->vm_state_size = be64_to_cpu(extra.vm_state_size_large);
+ }
+
+ if (extra_data_size >= 16) {
+ sn->disk_size = be64_to_cpu(extra.disk_size);
+ } else {
+ sn->disk_size = bs->total_sectors * BDRV_SECTOR_SIZE;
+ }
+
+ /* Read snapshot ID */
+ sn->id_str = g_malloc(id_str_size + 1);
+ ret = bdrv_pread(bs->file, offset, sn->id_str, id_str_size);
+ if (ret < 0) {
+ goto fail;
+ }
+ offset += id_str_size;
+ sn->id_str[id_str_size] = '\0';
+
+ /* Read snapshot name */
+ sn->name = g_malloc(name_size + 1);
+ ret = bdrv_pread(bs->file, offset, sn->name, name_size);
+ if (ret < 0) {
+ goto fail;
+ }
+ offset += name_size;
+ sn->name[name_size] = '\0';
+
+ if (offset - s->snapshots_offset > QCOW_MAX_SNAPSHOTS_SIZE) {
+ ret = -EFBIG;
+ goto fail;
+ }
+ }
+
+ assert(offset - s->snapshots_offset <= INT_MAX);
+ s->snapshots_size = offset - s->snapshots_offset;
+ return 0;
+
+fail:
+ qcow2_free_snapshots(bs);
+ return ret;
+}
+
+/* add at the end of the file a new list of snapshots */
+static int qcow2_write_snapshots(BlockDriverState *bs)
+{
+ BDRVQcowState *s = bs->opaque;
+ QCowSnapshot *sn;
+ QCowSnapshotHeader h;
+ QCowSnapshotExtraData extra;
+ int i, name_size, id_str_size, snapshots_size;
+ struct {
+ uint32_t nb_snapshots;
+ uint64_t snapshots_offset;
+ } QEMU_PACKED header_data;
+ int64_t offset, snapshots_offset = 0;
+ int ret;
+
+ /* compute the size of the snapshots */
+ offset = 0;
+ for(i = 0; i < s->nb_snapshots; i++) {
+ sn = s->snapshots + i;
+ offset = align_offset(offset, 8);
+ offset += sizeof(h);
+ offset += sizeof(extra);
+ offset += strlen(sn->id_str);
+ offset += strlen(sn->name);
+
+ if (offset > QCOW_MAX_SNAPSHOTS_SIZE) {
+ ret = -EFBIG;
+ goto fail;
+ }
+ }
+
+ assert(offset <= INT_MAX);
+ snapshots_size = offset;
+
+ /* Allocate space for the new snapshot list */
+ snapshots_offset = qcow2_alloc_clusters(bs, snapshots_size);
+ offset = snapshots_offset;
+ if (offset < 0) {
+ ret = offset;
+ goto fail;
+ }
+ ret = bdrv_flush(bs);
+ if (ret < 0) {
+ goto fail;
+ }
+
+ /* The snapshot list position has not yet been updated, so these clusters
+ * must indeed be completely free */
+ ret = qcow2_pre_write_overlap_check(bs, 0, offset, snapshots_size);
+ if (ret < 0) {
+ goto fail;
+ }
+
+
+ /* Write all snapshots to the new list */
+ for(i = 0; i < s->nb_snapshots; i++) {
+ sn = s->snapshots + i;
+ memset(&h, 0, sizeof(h));
+ h.l1_table_offset = cpu_to_be64(sn->l1_table_offset);
+ h.l1_size = cpu_to_be32(sn->l1_size);
+ /* If it doesn't fit in 32 bit, older implementations should treat it
+ * as a disk-only snapshot rather than truncate the VM state */
+ if (sn->vm_state_size <= 0xffffffff) {
+ h.vm_state_size = cpu_to_be32(sn->vm_state_size);
+ }
+ h.date_sec = cpu_to_be32(sn->date_sec);
+ h.date_nsec = cpu_to_be32(sn->date_nsec);
+ h.vm_clock_nsec = cpu_to_be64(sn->vm_clock_nsec);
+ h.extra_data_size = cpu_to_be32(sizeof(extra));
+
+ memset(&extra, 0, sizeof(extra));
+ extra.vm_state_size_large = cpu_to_be64(sn->vm_state_size);
+ extra.disk_size = cpu_to_be64(sn->disk_size);
+
+ id_str_size = strlen(sn->id_str);
+ name_size = strlen(sn->name);
+ assert(id_str_size <= UINT16_MAX && name_size <= UINT16_MAX);
+ h.id_str_size = cpu_to_be16(id_str_size);
+ h.name_size = cpu_to_be16(name_size);
+ offset = align_offset(offset, 8);
+
+ ret = bdrv_pwrite(bs->file, offset, &h, sizeof(h));
+ if (ret < 0) {
+ goto fail;
+ }
+ offset += sizeof(h);
+
+ ret = bdrv_pwrite(bs->file, offset, &extra, sizeof(extra));
+ if (ret < 0) {
+ goto fail;
+ }
+ offset += sizeof(extra);
+
+ ret = bdrv_pwrite(bs->file, offset, sn->id_str, id_str_size);
+ if (ret < 0) {
+ goto fail;
+ }
+ offset += id_str_size;
+
+ ret = bdrv_pwrite(bs->file, offset, sn->name, name_size);
+ if (ret < 0) {
+ goto fail;
+ }
+ offset += name_size;
+ }
+
+ /*
+ * Update the header to point to the new snapshot table. This requires the
+ * new table and its refcounts to be stable on disk.
+ */
+ ret = bdrv_flush(bs);
+ if (ret < 0) {
+ goto fail;
+ }
+
+ QEMU_BUILD_BUG_ON(offsetof(QCowHeader, snapshots_offset) !=
+ offsetof(QCowHeader, nb_snapshots) + sizeof(header_data.nb_snapshots));
+
+ header_data.nb_snapshots = cpu_to_be32(s->nb_snapshots);
+ header_data.snapshots_offset = cpu_to_be64(snapshots_offset);
+
+ ret = bdrv_pwrite_sync(bs->file, offsetof(QCowHeader, nb_snapshots),
+ &header_data, sizeof(header_data));
+ if (ret < 0) {
+ goto fail;
+ }
+
+ /* free the old snapshot table */
+ qcow2_free_clusters(bs, s->snapshots_offset, s->snapshots_size,
+ QCOW2_DISCARD_SNAPSHOT);
+ s->snapshots_offset = snapshots_offset;
+ s->snapshots_size = snapshots_size;
+ return 0;
+
+fail:
+ if (snapshots_offset > 0) {
+ qcow2_free_clusters(bs, snapshots_offset, snapshots_size,
+ QCOW2_DISCARD_ALWAYS);
+ }
+ return ret;
+}
+
+static void find_new_snapshot_id(BlockDriverState *bs,
+ char *id_str, int id_str_size)
+{
+ BDRVQcowState *s = bs->opaque;
+ QCowSnapshot *sn;
+ int i;
+ unsigned long id, id_max = 0;
+
+ for(i = 0; i < s->nb_snapshots; i++) {
+ sn = s->snapshots + i;
+ id = strtoul(sn->id_str, NULL, 10);
+ if (id > id_max)
+ id_max = id;
+ }
+ snprintf(id_str, id_str_size, "%lu", id_max + 1);
+}
+
+static int find_snapshot_by_id_and_name(BlockDriverState *bs,
+ const char *id,
+ const char *name)
+{
+ BDRVQcowState *s = bs->opaque;
+ int i;
+
+ if (id && name) {
+ for (i = 0; i < s->nb_snapshots; i++) {
+ if (!strcmp(s->snapshots[i].id_str, id) &&
+ !strcmp(s->snapshots[i].name, name)) {
+ return i;
+ }
+ }
+ } else if (id) {
+ for (i = 0; i < s->nb_snapshots; i++) {
+ if (!strcmp(s->snapshots[i].id_str, id)) {
+ return i;
+ }
+ }
+ } else if (name) {
+ for (i = 0; i < s->nb_snapshots; i++) {
+ if (!strcmp(s->snapshots[i].name, name)) {
+ return i;
+ }
+ }
+ }
+
+ return -1;
+}
+
+static int find_snapshot_by_id_or_name(BlockDriverState *bs,
+ const char *id_or_name)
+{
+ int ret;
+
+ ret = find_snapshot_by_id_and_name(bs, id_or_name, NULL);
+ if (ret >= 0) {
+ return ret;
+ }
+ return find_snapshot_by_id_and_name(bs, NULL, id_or_name);
+}
+
+/* if no id is provided, a new one is constructed */
+int qcow2_snapshot_create(BlockDriverState *bs, QEMUSnapshotInfo *sn_info)
+{
+ BDRVQcowState *s = bs->opaque;
+ QCowSnapshot *new_snapshot_list = NULL;
+ QCowSnapshot *old_snapshot_list = NULL;
+ QCowSnapshot sn1, *sn = &sn1;
+ int i, ret;
+ uint64_t *l1_table = NULL;
+ int64_t l1_table_offset;
+
+ if (s->nb_snapshots >= QCOW_MAX_SNAPSHOTS) {
+ return -EFBIG;
+ }
+
+ memset(sn, 0, sizeof(*sn));
+
+ /* Generate an ID */
+ find_new_snapshot_id(bs, sn_info->id_str, sizeof(sn_info->id_str));
+
+ /* Check that the ID is unique */
+ if (find_snapshot_by_id_and_name(bs, sn_info->id_str, NULL) >= 0) {
+ return -EEXIST;
+ }
+
+ /* Populate sn with passed data */
+ sn->id_str = g_strdup(sn_info->id_str);
+ sn->name = g_strdup(sn_info->name);
+
+ sn->disk_size = bs->total_sectors * BDRV_SECTOR_SIZE;
+ sn->vm_state_size = sn_info->vm_state_size;
+ sn->date_sec = sn_info->date_sec;
+ sn->date_nsec = sn_info->date_nsec;
+ sn->vm_clock_nsec = sn_info->vm_clock_nsec;
+
+ /* Allocate the L1 table of the snapshot and copy the current one there. */
+ l1_table_offset = qcow2_alloc_clusters(bs, s->l1_size * sizeof(uint64_t));
+ if (l1_table_offset < 0) {
+ ret = l1_table_offset;
+ goto fail;
+ }
+
+ sn->l1_table_offset = l1_table_offset;
+ sn->l1_size = s->l1_size;
+
+ l1_table = g_try_new(uint64_t, s->l1_size);
+ if (s->l1_size && l1_table == NULL) {
+ ret = -ENOMEM;
+ goto fail;
+ }
+
+ for(i = 0; i < s->l1_size; i++) {
+ l1_table[i] = cpu_to_be64(s->l1_table[i]);
+ }
+
+ ret = qcow2_pre_write_overlap_check(bs, 0, sn->l1_table_offset,
+ s->l1_size * sizeof(uint64_t));
+ if (ret < 0) {
+ goto fail;
+ }
+
+ ret = bdrv_pwrite(bs->file, sn->l1_table_offset, l1_table,
+ s->l1_size * sizeof(uint64_t));
+ if (ret < 0) {
+ goto fail;
+ }
+
+ g_free(l1_table);
+ l1_table = NULL;
+
+ /*
+ * Increase the refcounts of all clusters and make sure everything is
+ * stable on disk before updating the snapshot table to contain a pointer
+ * to the new L1 table.
+ */
+ ret = qcow2_update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size, 1);
+ if (ret < 0) {
+ goto fail;
+ }
+
+ /* Append the new snapshot to the snapshot list */
+ new_snapshot_list = g_new(QCowSnapshot, s->nb_snapshots + 1);
+ if (s->snapshots) {
+ memcpy(new_snapshot_list, s->snapshots,
+ s->nb_snapshots * sizeof(QCowSnapshot));
+ old_snapshot_list = s->snapshots;
+ }
+ s->snapshots = new_snapshot_list;
+ s->snapshots[s->nb_snapshots++] = *sn;
+
+ ret = qcow2_write_snapshots(bs);
+ if (ret < 0) {
+ g_free(s->snapshots);
+ s->snapshots = old_snapshot_list;
+ s->nb_snapshots--;
+ goto fail;
+ }
+
+ g_free(old_snapshot_list);
+
+ /* The VM state isn't needed any more in the active L1 table; in fact, it
+ * hurts by causing expensive COW for the next snapshot. */
+ qcow2_discard_clusters(bs, qcow2_vm_state_offset(s),
+ align_offset(sn->vm_state_size, s->cluster_size)
+ >> BDRV_SECTOR_BITS,
+ QCOW2_DISCARD_NEVER, false);
+
+#ifdef DEBUG_ALLOC
+ {
+ BdrvCheckResult result = {0};
+ qcow2_check_refcounts(bs, &result, 0);
+ }
+#endif
+ return 0;
+
+fail:
+ g_free(sn->id_str);
+ g_free(sn->name);
+ g_free(l1_table);
+
+ return ret;
+}
+
+/* copy the snapshot 'snapshot_name' into the current disk image */
+int qcow2_snapshot_goto(BlockDriverState *bs, const char *snapshot_id)
+{
+ BDRVQcowState *s = bs->opaque;
+ QCowSnapshot *sn;
+ int i, snapshot_index;
+ int cur_l1_bytes, sn_l1_bytes;
+ int ret;
+ uint64_t *sn_l1_table = NULL;
+
+ /* Search the snapshot */
+ snapshot_index = find_snapshot_by_id_or_name(bs, snapshot_id);
+ if (snapshot_index < 0) {
+ return -ENOENT;
+ }
+ sn = &s->snapshots[snapshot_index];
+
+ if (sn->disk_size != bs->total_sectors * BDRV_SECTOR_SIZE) {
+ error_report("qcow2: Loading snapshots with different disk "
+ "size is not implemented");
+ ret = -ENOTSUP;
+ goto fail;
+ }
+
+ /*
+ * Make sure that the current L1 table is big enough to contain the whole
+ * L1 table of the snapshot. If the snapshot L1 table is smaller, the
+ * current one must be padded with zeros.
+ */
+ ret = qcow2_grow_l1_table(bs, sn->l1_size, true);
+ if (ret < 0) {
+ goto fail;
+ }
+
+ cur_l1_bytes = s->l1_size * sizeof(uint64_t);
+ sn_l1_bytes = sn->l1_size * sizeof(uint64_t);
+
+ /*
+ * Copy the snapshot L1 table to the current L1 table.
+ *
+ * Before overwriting the old current L1 table on disk, make sure to
+ * increase all refcounts for the clusters referenced by the new one.
+ * Decrease the refcount referenced by the old one only when the L1
+ * table is overwritten.
+ */
+ sn_l1_table = g_try_malloc0(cur_l1_bytes);
+ if (cur_l1_bytes && sn_l1_table == NULL) {
+ ret = -ENOMEM;
+ goto fail;
+ }
+
+ ret = bdrv_pread(bs->file, sn->l1_table_offset, sn_l1_table, sn_l1_bytes);
+ if (ret < 0) {
+ goto fail;
+ }
+
+ ret = qcow2_update_snapshot_refcount(bs, sn->l1_table_offset,
+ sn->l1_size, 1);
+ if (ret < 0) {
+ goto fail;
+ }
+
+ ret = qcow2_pre_write_overlap_check(bs, QCOW2_OL_ACTIVE_L1,
+ s->l1_table_offset, cur_l1_bytes);
+ if (ret < 0) {
+ goto fail;
+ }
+
+ ret = bdrv_pwrite_sync(bs->file, s->l1_table_offset, sn_l1_table,
+ cur_l1_bytes);
+ if (ret < 0) {
+ goto fail;
+ }
+
+ /*
+ * Decrease refcount of clusters of current L1 table.
+ *
+ * At this point, the in-memory s->l1_table points to the old L1 table,
+ * whereas on disk we already have the new one.
+ *
+ * qcow2_update_snapshot_refcount special cases the current L1 table to use
+ * the in-memory data instead of really using the offset to load a new one,
+ * which is why this works.
+ */
+ ret = qcow2_update_snapshot_refcount(bs, s->l1_table_offset,
+ s->l1_size, -1);
+
+ /*
+ * Now update the in-memory L1 table to be in sync with the on-disk one. We
+ * need to do this even if updating refcounts failed.
+ */
+ for(i = 0;i < s->l1_size; i++) {
+ s->l1_table[i] = be64_to_cpu(sn_l1_table[i]);
+ }
+
+ if (ret < 0) {
+ goto fail;
+ }
+
+ g_free(sn_l1_table);
+ sn_l1_table = NULL;
+
+ /*
+ * Update QCOW_OFLAG_COPIED in the active L1 table (it may have changed
+ * when we decreased the refcount of the old snapshot.
+ */
+ ret = qcow2_update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size, 0);
+ if (ret < 0) {
+ goto fail;
+ }
+
+#ifdef DEBUG_ALLOC
+ {
+ BdrvCheckResult result = {0};
+ qcow2_check_refcounts(bs, &result, 0);
+ }
+#endif
+ return 0;
+
+fail:
+ g_free(sn_l1_table);
+ return ret;
+}
+
+int qcow2_snapshot_delete(BlockDriverState *bs,
+ const char *snapshot_id,
+ const char *name,
+ Error **errp)
+{
+ BDRVQcowState *s = bs->opaque;
+ QCowSnapshot sn;
+ int snapshot_index, ret;
+
+ /* Search the snapshot */
+ snapshot_index = find_snapshot_by_id_and_name(bs, snapshot_id, name);
+ if (snapshot_index < 0) {
+ error_setg(errp, "Can't find the snapshot");
+ return -ENOENT;
+ }
+ sn = s->snapshots[snapshot_index];
+
+ /* Remove it from the snapshot list */
+ memmove(s->snapshots + snapshot_index,
+ s->snapshots + snapshot_index + 1,
+ (s->nb_snapshots - snapshot_index - 1) * sizeof(sn));
+ s->nb_snapshots--;
+ ret = qcow2_write_snapshots(bs);
+ if (ret < 0) {
+ error_setg_errno(errp, -ret,
+ "Failed to remove snapshot from snapshot list");
+ return ret;
+ }
+
+ /*
+ * The snapshot is now unused, clean up. If we fail after this point, we
+ * won't recover but just leak clusters.
+ */
+ g_free(sn.id_str);
+ g_free(sn.name);
+
+ /*
+ * Now decrease the refcounts of clusters referenced by the snapshot and
+ * free the L1 table.
+ */
+ ret = qcow2_update_snapshot_refcount(bs, sn.l1_table_offset,
+ sn.l1_size, -1);
+ if (ret < 0) {
+ error_setg_errno(errp, -ret, "Failed to free the cluster and L1 table");
+ return ret;
+ }
+ qcow2_free_clusters(bs, sn.l1_table_offset, sn.l1_size * sizeof(uint64_t),
+ QCOW2_DISCARD_SNAPSHOT);
+
+ /* must update the copied flag on the current cluster offsets */
+ ret = qcow2_update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size, 0);
+ if (ret < 0) {
+ error_setg_errno(errp, -ret,
+ "Failed to update snapshot status in disk");
+ return ret;
+ }
+
+#ifdef DEBUG_ALLOC
+ {
+ BdrvCheckResult result = {0};
+ qcow2_check_refcounts(bs, &result, 0);
+ }
+#endif
+ return 0;
+}
+
+int qcow2_snapshot_list(BlockDriverState *bs, QEMUSnapshotInfo **psn_tab)
+{
+ BDRVQcowState *s = bs->opaque;
+ QEMUSnapshotInfo *sn_tab, *sn_info;
+ QCowSnapshot *sn;
+ int i;
+
+ if (!s->nb_snapshots) {
+ *psn_tab = NULL;
+ return s->nb_snapshots;
+ }
+
+ sn_tab = g_new0(QEMUSnapshotInfo, s->nb_snapshots);
+ for(i = 0; i < s->nb_snapshots; i++) {
+ sn_info = sn_tab + i;
+ sn = s->snapshots + i;
+ pstrcpy(sn_info->id_str, sizeof(sn_info->id_str),
+ sn->id_str);
+ pstrcpy(sn_info->name, sizeof(sn_info->name),
+ sn->name);
+ sn_info->vm_state_size = sn->vm_state_size;
+ sn_info->date_sec = sn->date_sec;
+ sn_info->date_nsec = sn->date_nsec;
+ sn_info->vm_clock_nsec = sn->vm_clock_nsec;
+ }
+ *psn_tab = sn_tab;
+ return s->nb_snapshots;
+}
+
+int qcow2_snapshot_load_tmp(BlockDriverState *bs,
+ const char *snapshot_id,
+ const char *name,
+ Error **errp)
+{
+ int i, snapshot_index;
+ BDRVQcowState *s = bs->opaque;
+ QCowSnapshot *sn;
+ uint64_t *new_l1_table;
+ int new_l1_bytes;
+ int ret;
+
+ assert(bs->read_only);
+
+ /* Search the snapshot */
+ snapshot_index = find_snapshot_by_id_and_name(bs, snapshot_id, name);
+ if (snapshot_index < 0) {
+ error_setg(errp,
+ "Can't find snapshot");
+ return -ENOENT;
+ }
+ sn = &s->snapshots[snapshot_index];
+
+ /* Allocate and read in the snapshot's L1 table */
+ if (sn->l1_size > QCOW_MAX_L1_SIZE / sizeof(uint64_t)) {
+ error_setg(errp, "Snapshot L1 table too large");
+ return -EFBIG;
+ }
+ new_l1_bytes = sn->l1_size * sizeof(uint64_t);
+ new_l1_table = qemu_try_blockalign(bs->file,
+ align_offset(new_l1_bytes, 512));
+ if (new_l1_table == NULL) {
+ return -ENOMEM;
+ }
+
+ ret = bdrv_pread(bs->file, sn->l1_table_offset, new_l1_table, new_l1_bytes);
+ if (ret < 0) {
+ error_setg(errp, "Failed to read l1 table for snapshot");
+ qemu_vfree(new_l1_table);
+ return ret;
+ }
+
+ /* Switch the L1 table */
+ qemu_vfree(s->l1_table);
+
+ s->l1_size = sn->l1_size;
+ s->l1_table_offset = sn->l1_table_offset;
+ s->l1_table = new_l1_table;
+
+ for(i = 0;i < s->l1_size; i++) {
+ be64_to_cpus(&s->l1_table[i]);
+ }
+
+ return 0;
+}
Code Review / kvmfornfv.git / blobdiff