diff options
Diffstat (limited to 'block/qcow2-snapshot.c')
| -rw-r--r-- | block/qcow2-snapshot.c | 405 |
1 files changed, 405 insertions, 0 deletions
diff --git a/block/qcow2-snapshot.c b/block/qcow2-snapshot.c new file mode 100644 index 0000000000..2883e5069f --- /dev/null +++ b/block/qcow2-snapshot.c @@ -0,0 +1,405 @@ +/* + * 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_int.h" +#include "block/qcow2.h" + +typedef struct __attribute__((packed)) QCowSnapshotHeader { + /* header is 8 byte aligned */ + uint64_t l1_table_offset; + + uint32_t l1_size; + uint16_t id_str_size; + uint16_t name_size; + + uint32_t date_sec; + uint32_t date_nsec; + + uint64_t vm_clock_nsec; + + uint32_t vm_state_size; + uint32_t extra_data_size; /* for extension */ + /* extra data follows */ + /* id_str follows */ + /* name follows */ +} QCowSnapshotHeader; + +void qcow_free_snapshots(BlockDriverState *bs) +{ + BDRVQcowState *s = bs->opaque; + int i; + + for(i = 0; i < s->nb_snapshots; i++) { + qemu_free(s->snapshots[i].name); + qemu_free(s->snapshots[i].id_str); + } + qemu_free(s->snapshots); + s->snapshots = NULL; + s->nb_snapshots = 0; +} + +int qcow_read_snapshots(BlockDriverState *bs) +{ + BDRVQcowState *s = bs->opaque; + QCowSnapshotHeader h; + QCowSnapshot *sn; + int i, id_str_size, name_size; + int64_t offset; + uint32_t extra_data_size; + + if (!s->nb_snapshots) { + s->snapshots = NULL; + s->snapshots_size = 0; + return 0; + } + + offset = s->snapshots_offset; + s->snapshots = qemu_mallocz(s->nb_snapshots * sizeof(QCowSnapshot)); + for(i = 0; i < s->nb_snapshots; i++) { + offset = align_offset(offset, 8); + if (bdrv_pread(s->hd, offset, &h, sizeof(h)) != sizeof(h)) + 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); + + offset += extra_data_size; + + sn->id_str = qemu_malloc(id_str_size + 1); + if (bdrv_pread(s->hd, offset, sn->id_str, id_str_size) != id_str_size) + goto fail; + offset += id_str_size; + sn->id_str[id_str_size] = '\0'; + + sn->name = qemu_malloc(name_size + 1); + if (bdrv_pread(s->hd, offset, sn->name, name_size) != name_size) + goto fail; + offset += name_size; + sn->name[name_size] = '\0'; + } + s->snapshots_size = offset - s->snapshots_offset; + return 0; + fail: + qcow_free_snapshots(bs); + return -1; +} + +/* add at the end of the file a new list of snapshots */ +static int qcow_write_snapshots(BlockDriverState *bs) +{ + BDRVQcowState *s = bs->opaque; + QCowSnapshot *sn; + QCowSnapshotHeader h; + int i, name_size, id_str_size, snapshots_size; + uint64_t data64; + uint32_t data32; + int64_t offset, snapshots_offset; + + /* 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 += strlen(sn->id_str); + offset += strlen(sn->name); + } + snapshots_size = offset; + + snapshots_offset = alloc_clusters(bs, snapshots_size); + offset = snapshots_offset; + + 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); + 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); + + id_str_size = strlen(sn->id_str); + name_size = strlen(sn->name); + h.id_str_size = cpu_to_be16(id_str_size); + h.name_size = cpu_to_be16(name_size); + offset = align_offset(offset, 8); + if (bdrv_pwrite(s->hd, offset, &h, sizeof(h)) != sizeof(h)) + goto fail; + offset += sizeof(h); + if (bdrv_pwrite(s->hd, offset, sn->id_str, id_str_size) != id_str_size) + goto fail; + offset += id_str_size; + if (bdrv_pwrite(s->hd, offset, sn->name, name_size) != name_size) + goto fail; + offset += name_size; + } + + /* update the various header fields */ + data64 = cpu_to_be64(snapshots_offset); + if (bdrv_pwrite(s->hd, offsetof(QCowHeader, snapshots_offset), + &data64, sizeof(data64)) != sizeof(data64)) + goto fail; + data32 = cpu_to_be32(s->nb_snapshots); + if (bdrv_pwrite(s->hd, offsetof(QCowHeader, nb_snapshots), + &data32, sizeof(data32)) != sizeof(data32)) + goto fail; + + /* free the old snapshot table */ + free_clusters(bs, s->snapshots_offset, s->snapshots_size); + s->snapshots_offset = snapshots_offset; + s->snapshots_size = snapshots_size; + return 0; + fail: + return -1; +} + +static void find_new_snapshot_id(BlockDriverState *bs, + char *id_str, int id_str_size) +{ + BDRVQcowState *s = bs->opaque; + QCowSnapshot *sn; + int i, 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, "%d", id_max + 1); +} + +static int find_snapshot_by_id(BlockDriverState *bs, const char *id_str) +{ + BDRVQcowState *s = bs->opaque; + int i; + + for(i = 0; i < s->nb_snapshots; i++) { + if (!strcmp(s->snapshots[i].id_str, id_str)) + return i; + } + return -1; +} + +static int find_snapshot_by_id_or_name(BlockDriverState *bs, const char *name) +{ + BDRVQcowState *s = bs->opaque; + int i, ret; + + ret = find_snapshot_by_id(bs, name); + if (ret >= 0) + return ret; + for(i = 0; i < s->nb_snapshots; i++) { + if (!strcmp(s->snapshots[i].name, name)) + return i; + } + return -1; +} + +/* if no id is provided, a new one is constructed */ +int qcow_snapshot_create(BlockDriverState *bs, QEMUSnapshotInfo *sn_info) +{ + BDRVQcowState *s = bs->opaque; + QCowSnapshot *snapshots1, sn1, *sn = &sn1; + int i, ret; + uint64_t *l1_table = NULL; + + memset(sn, 0, sizeof(*sn)); + + if (sn_info->id_str[0] == '\0') { + /* compute a new 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(bs, sn_info->id_str) >= 0) + return -ENOENT; + + sn->id_str = qemu_strdup(sn_info->id_str); + if (!sn->id_str) + goto fail; + sn->name = qemu_strdup(sn_info->name); + if (!sn->name) + goto fail; + 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; + + ret = update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size, 1); + if (ret < 0) + goto fail; + + /* create the L1 table of the snapshot */ + sn->l1_table_offset = alloc_clusters(bs, s->l1_size * sizeof(uint64_t)); + sn->l1_size = s->l1_size; + + l1_table = qemu_malloc(s->l1_size * sizeof(uint64_t)); + for(i = 0; i < s->l1_size; i++) { + l1_table[i] = cpu_to_be64(s->l1_table[i]); + } + if (bdrv_pwrite(s->hd, sn->l1_table_offset, + l1_table, s->l1_size * sizeof(uint64_t)) != + (s->l1_size * sizeof(uint64_t))) + goto fail; + qemu_free(l1_table); + l1_table = NULL; + + snapshots1 = qemu_malloc((s->nb_snapshots + 1) * sizeof(QCowSnapshot)); + if (s->snapshots) { + memcpy(snapshots1, s->snapshots, s->nb_snapshots * sizeof(QCowSnapshot)); + qemu_free(s->snapshots); + } + s->snapshots = snapshots1; + s->snapshots[s->nb_snapshots++] = *sn; + + if (qcow_write_snapshots(bs) < 0) + goto fail; +#ifdef DEBUG_ALLOC + check_refcounts(bs); +#endif + return 0; + fail: + qemu_free(sn->name); + qemu_free(l1_table); + return -1; +} + +/* copy the snapshot 'snapshot_name' into the current disk image */ +int qcow_snapshot_goto(BlockDriverState *bs, const char *snapshot_id) +{ + BDRVQcowState *s = bs->opaque; + QCowSnapshot *sn; + int i, snapshot_index, l1_size2; + + snapshot_index = find_snapshot_by_id_or_name(bs, snapshot_id); + if (snapshot_index < 0) + return -ENOENT; + sn = &s->snapshots[snapshot_index]; + + if (update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size, -1) < 0) + goto fail; + + if (grow_l1_table(bs, sn->l1_size) < 0) + goto fail; + + s->l1_size = sn->l1_size; + l1_size2 = s->l1_size * sizeof(uint64_t); + /* copy the snapshot l1 table to the current l1 table */ + if (bdrv_pread(s->hd, sn->l1_table_offset, + s->l1_table, l1_size2) != l1_size2) + goto fail; + if (bdrv_pwrite(s->hd, s->l1_table_offset, + s->l1_table, l1_size2) != l1_size2) + goto fail; + for(i = 0;i < s->l1_size; i++) { + be64_to_cpus(&s->l1_table[i]); + } + + if (update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size, 1) < 0) + goto fail; + +#ifdef DEBUG_ALLOC + check_refcounts(bs); +#endif + return 0; + fail: + return -EIO; +} + +int qcow_snapshot_delete(BlockDriverState *bs, const char *snapshot_id) +{ + BDRVQcowState *s = bs->opaque; + QCowSnapshot *sn; + int snapshot_index, ret; + + snapshot_index = find_snapshot_by_id_or_name(bs, snapshot_id); + if (snapshot_index < 0) + return -ENOENT; + sn = &s->snapshots[snapshot_index]; + + ret = update_snapshot_refcount(bs, sn->l1_table_offset, sn->l1_size, -1); + if (ret < 0) + return ret; + /* must update the copied flag on the current cluster offsets */ + ret = update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size, 0); + if (ret < 0) + return ret; + free_clusters(bs, sn->l1_table_offset, sn->l1_size * sizeof(uint64_t)); + + qemu_free(sn->id_str); + qemu_free(sn->name); + memmove(sn, sn + 1, (s->nb_snapshots - snapshot_index - 1) * sizeof(*sn)); + s->nb_snapshots--; + ret = qcow_write_snapshots(bs); + if (ret < 0) { + /* XXX: restore snapshot if error ? */ + return ret; + } +#ifdef DEBUG_ALLOC + check_refcounts(bs); +#endif + return 0; +} + +int qcow_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 = qemu_mallocz(s->nb_snapshots * sizeof(QEMUSnapshotInfo)); + 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; +} + |