root / block / qcow2-snapshot.c @ 5d757b56
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/*
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* Block driver for the QCOW version 2 format
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*
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* Copyright (c) 2004-2006 Fabrice Bellard
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*/
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#include "qemu-common.h" |
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#include "block_int.h" |
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#include "block/qcow2.h" |
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typedef struct __attribute__((packed)) QCowSnapshotHeader { |
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/* header is 8 byte aligned */
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uint64_t l1_table_offset; |
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uint32_t l1_size; |
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uint16_t id_str_size; |
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uint16_t name_size; |
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uint32_t date_sec; |
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uint32_t date_nsec; |
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uint64_t vm_clock_nsec; |
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uint32_t vm_state_size; |
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uint32_t extra_data_size; /* for extension */
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/* extra data follows */
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/* id_str follows */
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/* name follows */
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} QCowSnapshotHeader; |
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void qcow2_free_snapshots(BlockDriverState *bs)
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{ |
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BDRVQcowState *s = bs->opaque; |
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int i;
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for(i = 0; i < s->nb_snapshots; i++) { |
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qemu_free(s->snapshots[i].name); |
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qemu_free(s->snapshots[i].id_str); |
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} |
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qemu_free(s->snapshots); |
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s->snapshots = NULL;
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s->nb_snapshots = 0;
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} |
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int qcow2_read_snapshots(BlockDriverState *bs)
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{ |
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BDRVQcowState *s = bs->opaque; |
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QCowSnapshotHeader h; |
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QCowSnapshot *sn; |
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int i, id_str_size, name_size;
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int64_t offset; |
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uint32_t extra_data_size; |
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if (!s->nb_snapshots) {
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s->snapshots = NULL;
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s->snapshots_size = 0;
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return 0; |
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} |
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offset = s->snapshots_offset; |
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s->snapshots = qemu_mallocz(s->nb_snapshots * sizeof(QCowSnapshot));
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for(i = 0; i < s->nb_snapshots; i++) { |
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offset = align_offset(offset, 8);
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if (bdrv_pread(s->hd, offset, &h, sizeof(h)) != sizeof(h)) |
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goto fail;
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offset += sizeof(h);
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sn = s->snapshots + i; |
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sn->l1_table_offset = be64_to_cpu(h.l1_table_offset); |
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sn->l1_size = be32_to_cpu(h.l1_size); |
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sn->vm_state_size = be32_to_cpu(h.vm_state_size); |
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sn->date_sec = be32_to_cpu(h.date_sec); |
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sn->date_nsec = be32_to_cpu(h.date_nsec); |
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sn->vm_clock_nsec = be64_to_cpu(h.vm_clock_nsec); |
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extra_data_size = be32_to_cpu(h.extra_data_size); |
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id_str_size = be16_to_cpu(h.id_str_size); |
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name_size = be16_to_cpu(h.name_size); |
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offset += extra_data_size; |
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sn->id_str = qemu_malloc(id_str_size + 1);
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if (bdrv_pread(s->hd, offset, sn->id_str, id_str_size) != id_str_size)
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goto fail;
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offset += id_str_size; |
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sn->id_str[id_str_size] = '\0';
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sn->name = qemu_malloc(name_size + 1);
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if (bdrv_pread(s->hd, offset, sn->name, name_size) != name_size)
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goto fail;
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offset += name_size; |
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sn->name[name_size] = '\0';
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} |
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s->snapshots_size = offset - s->snapshots_offset; |
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return 0; |
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fail:
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qcow2_free_snapshots(bs); |
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return -1; |
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} |
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/* add at the end of the file a new list of snapshots */
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static int qcow_write_snapshots(BlockDriverState *bs) |
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{ |
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BDRVQcowState *s = bs->opaque; |
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QCowSnapshot *sn; |
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QCowSnapshotHeader h; |
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int i, name_size, id_str_size, snapshots_size;
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uint64_t data64; |
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uint32_t data32; |
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int64_t offset, snapshots_offset; |
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/* compute the size of the snapshots */
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offset = 0;
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for(i = 0; i < s->nb_snapshots; i++) { |
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sn = s->snapshots + i; |
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offset = align_offset(offset, 8);
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offset += sizeof(h);
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offset += strlen(sn->id_str); |
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offset += strlen(sn->name); |
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} |
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snapshots_size = offset; |
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snapshots_offset = qcow2_alloc_clusters(bs, snapshots_size); |
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offset = snapshots_offset; |
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if (offset < 0) { |
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return offset;
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} |
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for(i = 0; i < s->nb_snapshots; i++) { |
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sn = s->snapshots + i; |
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memset(&h, 0, sizeof(h)); |
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h.l1_table_offset = cpu_to_be64(sn->l1_table_offset); |
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h.l1_size = cpu_to_be32(sn->l1_size); |
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h.vm_state_size = cpu_to_be32(sn->vm_state_size); |
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h.date_sec = cpu_to_be32(sn->date_sec); |
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h.date_nsec = cpu_to_be32(sn->date_nsec); |
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h.vm_clock_nsec = cpu_to_be64(sn->vm_clock_nsec); |
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id_str_size = strlen(sn->id_str); |
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name_size = strlen(sn->name); |
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h.id_str_size = cpu_to_be16(id_str_size); |
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h.name_size = cpu_to_be16(name_size); |
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offset = align_offset(offset, 8);
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if (bdrv_pwrite(s->hd, offset, &h, sizeof(h)) != sizeof(h)) |
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goto fail;
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offset += sizeof(h);
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if (bdrv_pwrite(s->hd, offset, sn->id_str, id_str_size) != id_str_size)
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goto fail;
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offset += id_str_size; |
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if (bdrv_pwrite(s->hd, offset, sn->name, name_size) != name_size)
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goto fail;
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offset += name_size; |
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} |
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/* update the various header fields */
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data64 = cpu_to_be64(snapshots_offset); |
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if (bdrv_pwrite(s->hd, offsetof(QCowHeader, snapshots_offset),
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&data64, sizeof(data64)) != sizeof(data64)) |
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goto fail;
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data32 = cpu_to_be32(s->nb_snapshots); |
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if (bdrv_pwrite(s->hd, offsetof(QCowHeader, nb_snapshots),
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&data32, sizeof(data32)) != sizeof(data32)) |
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goto fail;
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/* free the old snapshot table */
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qcow2_free_clusters(bs, s->snapshots_offset, s->snapshots_size); |
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s->snapshots_offset = snapshots_offset; |
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s->snapshots_size = snapshots_size; |
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return 0; |
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fail:
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return -1; |
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} |
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static void find_new_snapshot_id(BlockDriverState *bs, |
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char *id_str, int id_str_size) |
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{ |
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BDRVQcowState *s = bs->opaque; |
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QCowSnapshot *sn; |
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int i, id, id_max = 0; |
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for(i = 0; i < s->nb_snapshots; i++) { |
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sn = s->snapshots + i; |
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id = strtoul(sn->id_str, NULL, 10); |
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if (id > id_max)
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id_max = id; |
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} |
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snprintf(id_str, id_str_size, "%d", id_max + 1); |
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} |
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static int find_snapshot_by_id(BlockDriverState *bs, const char *id_str) |
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{ |
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BDRVQcowState *s = bs->opaque; |
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int i;
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for(i = 0; i < s->nb_snapshots; i++) { |
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if (!strcmp(s->snapshots[i].id_str, id_str))
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return i;
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} |
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return -1; |
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} |
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static int find_snapshot_by_id_or_name(BlockDriverState *bs, const char *name) |
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{ |
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BDRVQcowState *s = bs->opaque; |
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int i, ret;
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ret = find_snapshot_by_id(bs, name); |
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if (ret >= 0) |
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return ret;
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for(i = 0; i < s->nb_snapshots; i++) { |
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if (!strcmp(s->snapshots[i].name, name))
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return i;
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} |
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return -1; |
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} |
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/* if no id is provided, a new one is constructed */
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int qcow2_snapshot_create(BlockDriverState *bs, QEMUSnapshotInfo *sn_info)
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{ |
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BDRVQcowState *s = bs->opaque; |
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QCowSnapshot *snapshots1, sn1, *sn = &sn1; |
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int i, ret;
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uint64_t *l1_table = NULL;
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int64_t l1_table_offset; |
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memset(sn, 0, sizeof(*sn)); |
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if (sn_info->id_str[0] == '\0') { |
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/* compute a new id */
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find_new_snapshot_id(bs, sn_info->id_str, sizeof(sn_info->id_str));
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} |
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/* check that the ID is unique */
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if (find_snapshot_by_id(bs, sn_info->id_str) >= 0) |
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return -ENOENT;
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sn->id_str = qemu_strdup(sn_info->id_str); |
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if (!sn->id_str)
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goto fail;
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sn->name = qemu_strdup(sn_info->name); |
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if (!sn->name)
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goto fail;
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sn->vm_state_size = sn_info->vm_state_size; |
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sn->date_sec = sn_info->date_sec; |
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sn->date_nsec = sn_info->date_nsec; |
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sn->vm_clock_nsec = sn_info->vm_clock_nsec; |
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ret = qcow2_update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size, 1);
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if (ret < 0) |
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goto fail;
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/* create the L1 table of the snapshot */
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l1_table_offset = qcow2_alloc_clusters(bs, s->l1_size * sizeof(uint64_t));
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if (l1_table_offset < 0) { |
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goto fail;
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} |
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sn->l1_table_offset = l1_table_offset; |
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sn->l1_size = s->l1_size; |
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if (s->l1_size != 0) { |
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l1_table = qemu_malloc(s->l1_size * sizeof(uint64_t));
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} else {
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l1_table = NULL;
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} |
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for(i = 0; i < s->l1_size; i++) { |
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l1_table[i] = cpu_to_be64(s->l1_table[i]); |
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} |
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if (bdrv_pwrite(s->hd, sn->l1_table_offset,
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l1_table, s->l1_size * sizeof(uint64_t)) !=
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(s->l1_size * sizeof(uint64_t)))
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goto fail;
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qemu_free(l1_table); |
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l1_table = NULL;
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snapshots1 = qemu_malloc((s->nb_snapshots + 1) * sizeof(QCowSnapshot)); |
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if (s->snapshots) {
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memcpy(snapshots1, s->snapshots, s->nb_snapshots * sizeof(QCowSnapshot));
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qemu_free(s->snapshots); |
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} |
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s->snapshots = snapshots1; |
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s->snapshots[s->nb_snapshots++] = *sn; |
301 |
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if (qcow_write_snapshots(bs) < 0) |
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goto fail;
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#ifdef DEBUG_ALLOC
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qcow2_check_refcounts(bs); |
306 |
#endif
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return 0; |
308 |
fail:
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qemu_free(sn->name); |
310 |
qemu_free(l1_table); |
311 |
return -1; |
312 |
} |
313 |
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/* copy the snapshot 'snapshot_name' into the current disk image */
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int qcow2_snapshot_goto(BlockDriverState *bs, const char *snapshot_id) |
316 |
{ |
317 |
BDRVQcowState *s = bs->opaque; |
318 |
QCowSnapshot *sn; |
319 |
int i, snapshot_index, l1_size2;
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320 |
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321 |
snapshot_index = find_snapshot_by_id_or_name(bs, snapshot_id); |
322 |
if (snapshot_index < 0) |
323 |
return -ENOENT;
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324 |
sn = &s->snapshots[snapshot_index]; |
325 |
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if (qcow2_update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size, -1) < 0) |
327 |
goto fail;
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328 |
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329 |
if (qcow2_grow_l1_table(bs, sn->l1_size) < 0) |
330 |
goto fail;
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331 |
|
332 |
s->l1_size = sn->l1_size; |
333 |
l1_size2 = s->l1_size * sizeof(uint64_t);
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334 |
/* copy the snapshot l1 table to the current l1 table */
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335 |
if (bdrv_pread(s->hd, sn->l1_table_offset,
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336 |
s->l1_table, l1_size2) != l1_size2) |
337 |
goto fail;
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338 |
if (bdrv_pwrite(s->hd, s->l1_table_offset,
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339 |
s->l1_table, l1_size2) != l1_size2) |
340 |
goto fail;
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341 |
for(i = 0;i < s->l1_size; i++) { |
342 |
be64_to_cpus(&s->l1_table[i]); |
343 |
} |
344 |
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345 |
if (qcow2_update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size, 1) < 0) |
346 |
goto fail;
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347 |
|
348 |
#ifdef DEBUG_ALLOC
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349 |
qcow2_check_refcounts(bs); |
350 |
#endif
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351 |
return 0; |
352 |
fail:
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353 |
return -EIO;
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354 |
} |
355 |
|
356 |
int qcow2_snapshot_delete(BlockDriverState *bs, const char *snapshot_id) |
357 |
{ |
358 |
BDRVQcowState *s = bs->opaque; |
359 |
QCowSnapshot *sn; |
360 |
int snapshot_index, ret;
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361 |
|
362 |
snapshot_index = find_snapshot_by_id_or_name(bs, snapshot_id); |
363 |
if (snapshot_index < 0) |
364 |
return -ENOENT;
|
365 |
sn = &s->snapshots[snapshot_index]; |
366 |
|
367 |
ret = qcow2_update_snapshot_refcount(bs, sn->l1_table_offset, sn->l1_size, -1);
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368 |
if (ret < 0) |
369 |
return ret;
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370 |
/* must update the copied flag on the current cluster offsets */
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371 |
ret = qcow2_update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size, 0);
|
372 |
if (ret < 0) |
373 |
return ret;
|
374 |
qcow2_free_clusters(bs, sn->l1_table_offset, sn->l1_size * sizeof(uint64_t));
|
375 |
|
376 |
qemu_free(sn->id_str); |
377 |
qemu_free(sn->name); |
378 |
memmove(sn, sn + 1, (s->nb_snapshots - snapshot_index - 1) * sizeof(*sn)); |
379 |
s->nb_snapshots--; |
380 |
ret = qcow_write_snapshots(bs); |
381 |
if (ret < 0) { |
382 |
/* XXX: restore snapshot if error ? */
|
383 |
return ret;
|
384 |
} |
385 |
#ifdef DEBUG_ALLOC
|
386 |
qcow2_check_refcounts(bs); |
387 |
#endif
|
388 |
return 0; |
389 |
} |
390 |
|
391 |
int qcow2_snapshot_list(BlockDriverState *bs, QEMUSnapshotInfo **psn_tab)
|
392 |
{ |
393 |
BDRVQcowState *s = bs->opaque; |
394 |
QEMUSnapshotInfo *sn_tab, *sn_info; |
395 |
QCowSnapshot *sn; |
396 |
int i;
|
397 |
|
398 |
if (!s->nb_snapshots) {
|
399 |
*psn_tab = NULL;
|
400 |
return s->nb_snapshots;
|
401 |
} |
402 |
|
403 |
sn_tab = qemu_mallocz(s->nb_snapshots * sizeof(QEMUSnapshotInfo));
|
404 |
for(i = 0; i < s->nb_snapshots; i++) { |
405 |
sn_info = sn_tab + i; |
406 |
sn = s->snapshots + i; |
407 |
pstrcpy(sn_info->id_str, sizeof(sn_info->id_str),
|
408 |
sn->id_str); |
409 |
pstrcpy(sn_info->name, sizeof(sn_info->name),
|
410 |
sn->name); |
411 |
sn_info->vm_state_size = sn->vm_state_size; |
412 |
sn_info->date_sec = sn->date_sec; |
413 |
sn_info->date_nsec = sn->date_nsec; |
414 |
sn_info->vm_clock_nsec = sn->vm_clock_nsec; |
415 |
} |
416 |
*psn_tab = sn_tab; |
417 |
return s->nb_snapshots;
|
418 |
} |
419 |
|