diff options
Diffstat (limited to 'qemu/block/qcow2-snapshot.c')
| -rw-r--r-- | qemu/block/qcow2-snapshot.c | 738 |
1 files changed, 0 insertions, 738 deletions
diff --git a/qemu/block/qcow2-snapshot.c b/qemu/block/qcow2-snapshot.c deleted file mode 100644 index 5f4a17e47..000000000 --- a/qemu/block/qcow2-snapshot.c +++ /dev/null @@ -1,738 +0,0 @@ -/* - * 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/osdep.h" -#include "qapi/error.h" -#include "block/block_int.h" -#include "block/qcow2.h" -#include "qemu/error-report.h" -#include "qemu/cutils.h" - -void qcow2_free_snapshots(BlockDriverState *bs) -{ - BDRVQcow2State *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) -{ - BDRVQcow2State *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->bs, 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->bs, 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->bs, 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->bs, 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) -{ - BDRVQcow2State *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->bs, offset, &h, sizeof(h)); - if (ret < 0) { - goto fail; - } - offset += sizeof(h); - - ret = bdrv_pwrite(bs->file->bs, offset, &extra, sizeof(extra)); - if (ret < 0) { - goto fail; - } - offset += sizeof(extra); - - ret = bdrv_pwrite(bs->file->bs, offset, sn->id_str, id_str_size); - if (ret < 0) { - goto fail; - } - offset += id_str_size; - - ret = bdrv_pwrite(bs->file->bs, 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->bs, 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) -{ - BDRVQcow2State *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) -{ - BDRVQcow2State *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) -{ - BDRVQcow2State *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->bs, 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) -{ - BDRVQcow2State *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->bs, 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->bs, 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) -{ - BDRVQcow2State *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) -{ - BDRVQcow2State *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; - BDRVQcow2State *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->bs, - align_offset(new_l1_bytes, 512)); - if (new_l1_table == NULL) { - return -ENOMEM; - } - - ret = bdrv_pread(bs->file->bs, 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; -} |