root / block / qcow2-snapshot.c @ 7267c094
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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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|
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uint32_t date_sec; |
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uint32_t date_nsec; |
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|
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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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|
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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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|
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for(i = 0; i < s->nb_snapshots; i++) { |
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g_free(s->snapshots[i].name); |
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g_free(s->snapshots[i].id_str); |
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} |
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g_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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|
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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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|
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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 = g_malloc0(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(bs->file, 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 = g_malloc(id_str_size + 1);
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if (bdrv_pread(bs->file, 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 = g_malloc(name_size + 1);
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if (bdrv_pread(bs->file, 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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|
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/* add at the end of the file a new list of snapshots */
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static int qcow2_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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bdrv_flush(bs->file); |
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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_sync(bs->file, offset, &h, sizeof(h)) < 0) |
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goto fail;
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offset += sizeof(h);
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if (bdrv_pwrite_sync(bs->file, offset, sn->id_str, id_str_size) < 0) |
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goto fail;
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offset += id_str_size; |
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if (bdrv_pwrite_sync(bs->file, offset, sn->name, name_size) < 0) |
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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_sync(bs->file, offsetof(QCowHeader, snapshots_offset),
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&data64, sizeof(data64)) < 0) |
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goto fail;
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data32 = cpu_to_be32(s->nb_snapshots); |
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if (bdrv_pwrite_sync(bs->file, offsetof(QCowHeader, nb_snapshots),
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&data32, sizeof(data32)) < 0) |
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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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|
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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 = g_strdup(sn_info->id_str); |
256 |
if (!sn->id_str)
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goto fail;
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sn->name = g_strdup(sn_info->name); |
259 |
if (!sn->name)
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goto fail;
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sn->vm_state_size = sn_info->vm_state_size; |
262 |
sn->date_sec = sn_info->date_sec; |
263 |
sn->date_nsec = sn_info->date_nsec; |
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sn->vm_clock_nsec = sn_info->vm_clock_nsec; |
265 |
|
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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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|
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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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} |
275 |
bdrv_flush(bs->file); |
276 |
|
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sn->l1_table_offset = l1_table_offset; |
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sn->l1_size = s->l1_size; |
279 |
|
280 |
if (s->l1_size != 0) { |
281 |
l1_table = g_malloc(s->l1_size * sizeof(uint64_t));
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} else {
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283 |
l1_table = NULL;
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} |
285 |
|
286 |
for(i = 0; i < s->l1_size; i++) { |
287 |
l1_table[i] = cpu_to_be64(s->l1_table[i]); |
288 |
} |
289 |
if (bdrv_pwrite_sync(bs->file, sn->l1_table_offset,
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290 |
l1_table, s->l1_size * sizeof(uint64_t)) < 0) |
291 |
goto fail;
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292 |
g_free(l1_table); |
293 |
l1_table = NULL;
|
294 |
|
295 |
snapshots1 = g_malloc((s->nb_snapshots + 1) * sizeof(QCowSnapshot)); |
296 |
if (s->snapshots) {
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297 |
memcpy(snapshots1, s->snapshots, s->nb_snapshots * sizeof(QCowSnapshot));
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298 |
g_free(s->snapshots); |
299 |
} |
300 |
s->snapshots = snapshots1; |
301 |
s->snapshots[s->nb_snapshots++] = *sn; |
302 |
|
303 |
if (qcow2_write_snapshots(bs) < 0) |
304 |
goto fail;
|
305 |
#ifdef DEBUG_ALLOC
|
306 |
qcow2_check_refcounts(bs); |
307 |
#endif
|
308 |
return 0; |
309 |
fail:
|
310 |
g_free(sn->name); |
311 |
g_free(l1_table); |
312 |
return -1; |
313 |
} |
314 |
|
315 |
/* copy the snapshot 'snapshot_name' into the current disk image */
|
316 |
int qcow2_snapshot_goto(BlockDriverState *bs, const char *snapshot_id) |
317 |
{ |
318 |
BDRVQcowState *s = bs->opaque; |
319 |
QCowSnapshot *sn; |
320 |
int i, snapshot_index;
|
321 |
int cur_l1_bytes, sn_l1_bytes;
|
322 |
|
323 |
snapshot_index = find_snapshot_by_id_or_name(bs, snapshot_id); |
324 |
if (snapshot_index < 0) |
325 |
return -ENOENT;
|
326 |
sn = &s->snapshots[snapshot_index]; |
327 |
|
328 |
if (qcow2_update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size, -1) < 0) |
329 |
goto fail;
|
330 |
|
331 |
if (qcow2_grow_l1_table(bs, sn->l1_size, true) < 0) |
332 |
goto fail;
|
333 |
|
334 |
cur_l1_bytes = s->l1_size * sizeof(uint64_t);
|
335 |
sn_l1_bytes = sn->l1_size * sizeof(uint64_t);
|
336 |
|
337 |
if (cur_l1_bytes > sn_l1_bytes) {
|
338 |
memset(s->l1_table + sn->l1_size, 0, cur_l1_bytes - sn_l1_bytes);
|
339 |
} |
340 |
|
341 |
/* copy the snapshot l1 table to the current l1 table */
|
342 |
if (bdrv_pread(bs->file, sn->l1_table_offset,
|
343 |
s->l1_table, sn_l1_bytes) < 0)
|
344 |
goto fail;
|
345 |
if (bdrv_pwrite_sync(bs->file, s->l1_table_offset,
|
346 |
s->l1_table, cur_l1_bytes) < 0)
|
347 |
goto fail;
|
348 |
for(i = 0;i < s->l1_size; i++) { |
349 |
be64_to_cpus(&s->l1_table[i]); |
350 |
} |
351 |
|
352 |
if (qcow2_update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size, 1) < 0) |
353 |
goto fail;
|
354 |
|
355 |
#ifdef DEBUG_ALLOC
|
356 |
qcow2_check_refcounts(bs); |
357 |
#endif
|
358 |
return 0; |
359 |
fail:
|
360 |
return -EIO;
|
361 |
} |
362 |
|
363 |
int qcow2_snapshot_delete(BlockDriverState *bs, const char *snapshot_id) |
364 |
{ |
365 |
BDRVQcowState *s = bs->opaque; |
366 |
QCowSnapshot *sn; |
367 |
int snapshot_index, ret;
|
368 |
|
369 |
snapshot_index = find_snapshot_by_id_or_name(bs, snapshot_id); |
370 |
if (snapshot_index < 0) |
371 |
return -ENOENT;
|
372 |
sn = &s->snapshots[snapshot_index]; |
373 |
|
374 |
ret = qcow2_update_snapshot_refcount(bs, sn->l1_table_offset, sn->l1_size, -1);
|
375 |
if (ret < 0) |
376 |
return ret;
|
377 |
/* must update the copied flag on the current cluster offsets */
|
378 |
ret = qcow2_update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size, 0);
|
379 |
if (ret < 0) |
380 |
return ret;
|
381 |
qcow2_free_clusters(bs, sn->l1_table_offset, sn->l1_size * sizeof(uint64_t));
|
382 |
|
383 |
g_free(sn->id_str); |
384 |
g_free(sn->name); |
385 |
memmove(sn, sn + 1, (s->nb_snapshots - snapshot_index - 1) * sizeof(*sn)); |
386 |
s->nb_snapshots--; |
387 |
ret = qcow2_write_snapshots(bs); |
388 |
if (ret < 0) { |
389 |
/* XXX: restore snapshot if error ? */
|
390 |
return ret;
|
391 |
} |
392 |
#ifdef DEBUG_ALLOC
|
393 |
qcow2_check_refcounts(bs); |
394 |
#endif
|
395 |
return 0; |
396 |
} |
397 |
|
398 |
int qcow2_snapshot_list(BlockDriverState *bs, QEMUSnapshotInfo **psn_tab)
|
399 |
{ |
400 |
BDRVQcowState *s = bs->opaque; |
401 |
QEMUSnapshotInfo *sn_tab, *sn_info; |
402 |
QCowSnapshot *sn; |
403 |
int i;
|
404 |
|
405 |
if (!s->nb_snapshots) {
|
406 |
*psn_tab = NULL;
|
407 |
return s->nb_snapshots;
|
408 |
} |
409 |
|
410 |
sn_tab = g_malloc0(s->nb_snapshots * sizeof(QEMUSnapshotInfo));
|
411 |
for(i = 0; i < s->nb_snapshots; i++) { |
412 |
sn_info = sn_tab + i; |
413 |
sn = s->snapshots + i; |
414 |
pstrcpy(sn_info->id_str, sizeof(sn_info->id_str),
|
415 |
sn->id_str); |
416 |
pstrcpy(sn_info->name, sizeof(sn_info->name),
|
417 |
sn->name); |
418 |
sn_info->vm_state_size = sn->vm_state_size; |
419 |
sn_info->date_sec = sn->date_sec; |
420 |
sn_info->date_nsec = sn->date_nsec; |
421 |
sn_info->vm_clock_nsec = sn->vm_clock_nsec; |
422 |
} |
423 |
*psn_tab = sn_tab; |
424 |
return s->nb_snapshots;
|
425 |
} |
426 |
|
427 |
int qcow2_snapshot_load_tmp(BlockDriverState *bs, const char *snapshot_name) |
428 |
{ |
429 |
int i, snapshot_index, l1_size2;
|
430 |
BDRVQcowState *s = bs->opaque; |
431 |
QCowSnapshot *sn; |
432 |
|
433 |
snapshot_index = find_snapshot_by_id_or_name(bs, snapshot_name); |
434 |
if (snapshot_index < 0) { |
435 |
return -ENOENT;
|
436 |
} |
437 |
|
438 |
sn = &s->snapshots[snapshot_index]; |
439 |
s->l1_size = sn->l1_size; |
440 |
l1_size2 = s->l1_size * sizeof(uint64_t);
|
441 |
if (s->l1_table != NULL) { |
442 |
g_free(s->l1_table); |
443 |
} |
444 |
|
445 |
s->l1_table_offset = sn->l1_table_offset; |
446 |
s->l1_table = g_malloc0(align_offset(l1_size2, 512));
|
447 |
|
448 |
if (bdrv_pread(bs->file, sn->l1_table_offset,
|
449 |
s->l1_table, l1_size2) != l1_size2) { |
450 |
return -1; |
451 |
} |
452 |
|
453 |
for(i = 0;i < s->l1_size; i++) { |
454 |
be64_to_cpus(&s->l1_table[i]); |
455 |
} |
456 |
return 0; |
457 |
} |