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>
---
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);
}
--
1.6.6.2
