On Wed, Mar 17, 2010 at 8:35 AM, Anthony Liguori <anth...@codemonkey.ws>wrote:
> On 03/08/2010 07:13 PM, Rob Earhart wrote:
>
>> Modify the snapshot load path to find and load snapshots contained in
>> backing
>> disks, useful when the current disk is a differencing disk.
>>
>> Add the source of a snapshot when listing snapshots.
>>
>> This should only break backwards compatibility for scenarios depending on
>> not
>> being able to load snapshots from backing disks (which doesn't seem like a
>> problem), and for code which parses the snapshot list output (if any).
>>
>> Signed-off-by: Rob Earhart<earh...@google.com>
>>
>>
>
> Your patch is whitespace damaged. Please use a different mailer (like
> git-send-email).
>
> Regards,
>
> Anthony Liguori
>
>
If git-send-email worked in my environment, I'd be happy to. :-) I'll work
on it. I still need to address Kevin's comments from last week before I
worry about that, though.
)Rob
>
> ---
>> block.c | 10 +++++
>> block.h | 2 +
>> block/qcow2-snapshot.c | 105
>> ++++++++++++++++++++++++++++++++++++------------
>> qemu-img.c | 25 +++++++-----
>> savevm.c | 92 +++++++++++++++++++++++++++++-------------
>> 5 files changed, 170 insertions(+), 64 deletions(-)
>>
>> diff --git a/block.c b/block.c
>> index 31d1ba4..3588700 100644
>> --- a/block.c
>> +++ b/block.c
>> @@ -1481,6 +1481,16 @@ void bdrv_get_backing_filename(BlockDriverState
>> *bs,
>> }
>> }
>>
>> +const char *bdrv_get_filename(BlockDriverState *bs)
>> +{
>> + return bs->filename;
>> +}
>> +
>> +BlockDriverState* bdrv_get_backing_bdrv(BlockDriverState *bs)
>> +{
>> + return bs->backing_hd;
>> +}
>> +
>> int bdrv_write_compressed(BlockDriverState *bs, int64_t sector_num,
>> const uint8_t *buf, int nb_sectors)
>> {
>> diff --git a/block.h b/block.h
>> index edf5704..1d04322 100644
>> --- a/block.h
>> +++ b/block.h
>> @@ -179,6 +179,8 @@ int bdrv_get_info(BlockDriverState *bs,
>> BlockDriverInfo *bdi);
>> const char *bdrv_get_encrypted_filename(BlockDriverState *bs);
>> void bdrv_get_backing_filename(BlockDriverState *bs,
>> char *filename, int filename_size);
>> +const char *bdrv_get_filename(BlockDriverState *bs);
>> +BlockDriverState* bdrv_get_backing_bdrv(BlockDriverState *bs);
>> int bdrv_snapshot_create(BlockDriverState *bs,
>> QEMUSnapshotInfo *sn_info);
>> int bdrv_snapshot_goto(BlockDriverState *bs,
>> diff --git a/block/qcow2-snapshot.c b/block/qcow2-snapshot.c
>> index 8ddaea2..ca06fcf 100644
>> --- a/block/qcow2-snapshot.c
>> +++ b/block/qcow2-snapshot.c
>> @@ -191,16 +191,23 @@ static int qcow_write_snapshots(BlockDriverState
>> *bs)
>> 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;
>> + int id_max = 0;
>> +
>> + assert(bs);
>> +
>> + do {
>> + BDRVQcowState *s = bs->opaque;
>> + QCowSnapshot *sn;
>> + int i, id;
>> +
>> + 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;
>> + }
>> + } while ((bs = bdrv_get_backing_bdrv(bs)));
>>
>> - 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);
>> }
>>
>> @@ -316,41 +323,88 @@ int qcow2_snapshot_goto(BlockDriverState *bs,
>> const char *snapshot_id)
>> {
>> BDRVQcowState *s = bs->opaque;
>> QCowSnapshot *sn;
>> - int i, snapshot_index, l1_size2;
>> + int i, snapshot_index, l1_size2, ret;
>>
>> snapshot_index = find_snapshot_by_id_or_name(bs, snapshot_id);
>> - if (snapshot_index< 0)
>> - return -ENOENT;
>> +
>> + if (snapshot_index< 0) {
>> + /* if there is a backing file, use it. In this case, the
>> + * current image needs to be reset to be consistent
>> + */
>> + if (bs->backing_hd) {
>> + ret = bdrv_snapshot_goto(bs->backing_hd, snapshot_id);
>> + if (ret< 0) {
>> + return ret;
>> + }
>> + /* reset the sectors of the current image (Note: there can
>> + * still be snapshots, so the refcounts must be kept
>> + * consistent)
>> + */
>> + if (qcow2_update_snapshot_refcount(bs, s->l1_table_offset,
>> + s->l1_size, -1)< 0) {
>> + return -EIO;
>> + }
>> + l1_size2 = s->l1_size * sizeof(uint64_t);
>> + memset(s->l1_table, 0, l1_size2);
>> + if (bdrv_pwrite(s->hd, s->l1_table_offset,
>> + s->l1_table, l1_size2) != l1_size2) {
>> + return -EIO;
>> + }
>> + return 0;
>> + } else {
>> + return -ENOENT;
>> + }
>> + }
>> +
>> + assert(0<= snapshot_index);
>> +
>> sn =&s->snapshots[snapshot_index];
>>
>> - if (qcow2_update_snapshot_refcount(bs, s->l1_table_offset,
>> s->l1_size, -1)< 0)
>> - goto fail;
>> + /* if the file is read-only, all can be done by updating the
>> + * in-memory L1 table. Otherwise, we'll need to do some writes.
>> + */
>>
>> - if (qcow2_grow_l1_table(bs, sn->l1_size)< 0)
>> - goto fail;
>> + if (!bs->read_only) {
>> + if (qcow2_update_snapshot_refcount(bs, s->l1_table_offset,
>> + s->l1_size, -1)
>> +< 0) {
>> + return -EIO;
>> + }
>> + }
>> +
>> + if (qcow2_grow_l1_table(bs, sn->l1_size)< 0) {
>> + return -EIO;
>> + }
>>
>> 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;
>> + s->l1_table, l1_size2) != l1_size2) {
>> + return -EIO;
>> + }
>> + if (!bs->read_only) {
>> + if (bdrv_pwrite(s->hd, s->l1_table_offset,
>> + s->l1_table, l1_size2) != l1_size2) {
>> + return -EIO;
>> + }
>> + }
>> for(i = 0;i< s->l1_size; i++) {
>> be64_to_cpus(&s->l1_table[i]);
>> }
>>
>> - if (qcow2_update_snapshot_refcount(bs, s->l1_table_offset,
>> s->l1_size, 1)< 0)
>> - goto fail;
>> + if (!bs->read_only) {
>> + if (qcow2_update_snapshot_refcount(bs, s->l1_table_offset,
>> + s->l1_size, 1)
>> +< 0) {
>> + return -EIO;
>> + }
>> + }
>>
>> #ifdef DEBUG_ALLOC
>> qcow2_check_refcounts(bs);
>> #endif
>> return 0;
>> - fail:
>> - return -EIO;
>> }
>>
>> int qcow2_snapshot_delete(BlockDriverState *bs, const char *snapshot_id)
>> @@ -416,4 +470,3 @@ int qcow2_snapshot_list(BlockDriverState *bs,
>> QEMUSnapshotInfo **psn_tab)
>> *psn_tab = sn_tab;
>> return s->nb_snapshots;
>> }
>> -
>> diff --git a/qemu-img.c b/qemu-img.c
>> index 0c9f2d4..345a768 100644
>> --- a/qemu-img.c
>> +++ b/qemu-img.c
>> @@ -873,16 +873,21 @@ static void dump_snapshots(BlockDriverState *bs)
>> int nb_sns, i;
>> char buf[256];
>>
>> - nb_sns = bdrv_snapshot_list(bs,&sn_tab);
>> - if (nb_sns<= 0)
>> - return;
>> - printf("Snapshot list:\n");
>> - printf("%s\n", bdrv_snapshot_dump(buf, sizeof(buf), NULL));
>> - for(i = 0; i< nb_sns; i++) {
>> - sn =&sn_tab[i];
>> - printf("%s\n", bdrv_snapshot_dump(buf, sizeof(buf), sn));
>> - }
>> - qemu_free(sn_tab);
>> + assert(bs);
>> +
>> + do {
>> + nb_sns = bdrv_snapshot_list(bs,&sn_tab);
>> + if (nb_sns<= 0)
>> + continue;
>> + printf("Snapshot list (from %s):\n",
>> + bdrv_get_filename(bs));
>> + printf("%s\n", bdrv_snapshot_dump(buf, sizeof(buf), NULL));
>> + for(i = 0; i< nb_sns; i++) {
>> + sn =&sn_tab[i];
>> + printf("%s\n", bdrv_snapshot_dump(buf, sizeof(buf), sn));
>> + }
>> + qemu_free(sn_tab);
>> + } while ((bs = bdrv_get_backing_bdrv(bs)));
>> }
>>
>> static int img_info(int argc, char **argv)
>> diff --git a/savevm.c b/savevm.c
>> index 2fd3de6..8a81c42 100644
>> --- a/savevm.c
>> +++ b/savevm.c
>> @@ -1616,25 +1616,53 @@ static BlockDriverState *get_bs_snapshots(void)
>> return bs;
>> }
>>
>> +/* Find a snapshot with the given name.
>> + * sn_bs is an out parameter: if NULL, only the current BlockDriverState
>> (bs)
>> + * is checked; otherwise, *sb_bs is set to point to the backing block
>> driver
>> + * state where the found snapshot resides.
>> + */
>> static int bdrv_snapshot_find(BlockDriverState *bs, QEMUSnapshotInfo
>> *sn_info,
>> - const char *name)
>> + const char *name, BlockDriverState **sn_bs)
>> {
>> QEMUSnapshotInfo *sn_tab, *sn;
>> int nb_sns, i, ret;
>>
>> + assert(bs);
>> +
>> ret = -ENOENT;
>> - nb_sns = bdrv_snapshot_list(bs,&sn_tab);
>> - if (nb_sns< 0)
>> - return ret;
>> - for(i = 0; i< nb_sns; i++) {
>> - sn =&sn_tab[i];
>> - if (!strcmp(sn->id_str, name) || !strcmp(sn->name, name)) {
>> - *sn_info = *sn;
>> - ret = 0;
>> + do {
>> + nb_sns = bdrv_snapshot_list(bs,&sn_tab);
>> + if (nb_sns< 0) {
>> + if (nb_sns == -ENOTSUP) {
>> + /* If this device does not support snapshots,
>> + * its backing file still might; continue on
>> + * to the backing file.
>> + */
>> + continue;
>> + } else {
>> + return ret;
>> + }
>> + }
>> + for (i = 0; i< nb_sns; i++) {
>> + sn =&sn_tab[i];
>> + if (!strcmp(sn->id_str, name) || !strcmp(sn->name, name)) {
>> + *sn_info = *sn;
>> + if (sn_bs != 0) {
>> + *sn_bs = bs;
>> + }
>> + ret = 0;
>> + break;
>> + }
>> + }
>> + qemu_free(sn_tab);
>> + if (ret == 0) {
>> break;
>> }
>> - }
>> - qemu_free(sn_tab);
>> + if (!sn_bs) {
>> + break;
>> + }
>> + } while ((bs = bdrv_get_backing_bdrv(bs)));
>> +
>> return ret;
>> }
>>
>> @@ -1651,7 +1679,7 @@ static int del_existing_snapshots(Monitor *mon,
>> const char *name)
>> QTAILQ_FOREACH(dinfo,&drives, next) {
>> bs = dinfo->bdrv;
>> if (bdrv_can_snapshot(bs)&&
>> - bdrv_snapshot_find(bs, snapshot, name)>= 0)
>> + bdrv_snapshot_find(bs, snapshot, name, NULL)>= 0)
>> {
>> ret = bdrv_snapshot_delete(bs, name);
>> if (ret< 0) {
>> @@ -1696,7 +1724,7 @@ void do_savevm(Monitor *mon, const QDict *qdict)
>>
>> memset(sn, 0, sizeof(*sn));
>> if (name) {
>> - ret = bdrv_snapshot_find(bs, old_sn, name);
>> + ret = bdrv_snapshot_find(bs, old_sn, name, NULL);
>> if (ret>= 0) {
>> pstrcpy(sn->name, sizeof(sn->name), old_sn->name);
>> pstrcpy(sn->id_str, sizeof(sn->id_str), old_sn->id_str);
>> @@ -1759,7 +1787,7 @@ void do_savevm(Monitor *mon, const QDict *qdict)
>> int load_vmstate(Monitor *mon, const char *name)
>> {
>> DriveInfo *dinfo;
>> - BlockDriverState *bs, *bs1;
>> + BlockDriverState *bs, *bs1, *sn_bs;
>> QEMUSnapshotInfo sn;
>> QEMUFile *f;
>> int ret;
>> @@ -1804,12 +1832,12 @@ int load_vmstate(Monitor *mon, const char *name)
>> }
>>
>> /* Don't even try to load empty VM states */
>> - ret = bdrv_snapshot_find(bs,&sn, name);
>> + ret = bdrv_snapshot_find(bs,&sn, name,&sn_bs);
>> if ((ret>= 0)&& (sn.vm_state_size == 0))
>> return -EINVAL;
>>
>> /* restore the VM state */
>> - f = qemu_fopen_bdrv(bs, 0);
>> + f = qemu_fopen_bdrv(sn_bs, 0);
>> if (!f) {
>> monitor_printf(mon, "Could not open VM state file\n");
>> return -EINVAL;
>> @@ -1876,17 +1904,25 @@ void do_info_snapshots(Monitor *mon)
>> }
>> monitor_printf(mon, "\n");
>>
>> - nb_sns = bdrv_snapshot_list(bs,&sn_tab);
>> - if (nb_sns< 0) {
>> - monitor_printf(mon, "bdrv_snapshot_list: error %d\n", nb_sns);
>> - return;
>> - }
>> - monitor_printf(mon, "Snapshot list (from %s):\n",
>> - bdrv_get_device_name(bs));
>> - monitor_printf(mon, "%s\n", bdrv_snapshot_dump(buf, sizeof(buf),
>> NULL));
>> - for(i = 0; i< nb_sns; i++) {
>> - sn =&sn_tab[i];
>> - monitor_printf(mon, "%s\n", bdrv_snapshot_dump(buf, sizeof(buf),
>> sn));
>> + for (; bs; bs = bdrv_get_backing_bdrv(bs)) {
>> + nb_sns = bdrv_snapshot_list(bs,&sn_tab);
>> + if (nb_sns< 0) {
>> + monitor_printf(mon, "bdrv_snapshot_list: error %d\n",
>> nb_sns);
>> + continue;
>> + }
>> + const char* device_name = bdrv_get_device_name(bs);
>> + if (device_name&& device_name[0]) {
>> + monitor_printf(mon, "Snapshot list (device %s, from %s):\n",
>> + device_name, bdrv_get_filename(bs));
>> + } else {
>> + monitor_printf(mon, "Snapshot list (from %s):\n",
>> + bdrv_get_filename(bs));
>> + }
>> + monitor_printf(mon, "%s\n", bdrv_snapshot_dump(buf,
>> sizeof(buf), NULL));
>> + for(i = 0; i< nb_sns; i++) {
>> + sn =&sn_tab[i];
>> + monitor_printf(mon, "%s\n", bdrv_snapshot_dump(buf,
>> sizeof(buf), sn));
>> + }
>> + qemu_free(sn_tab);
>> }
>> - qemu_free(sn_tab);
>> }
>>
>>
>
>
