*/
#include "qemu-common.h"
-#include "block_int.h"
+#include "block/block_int.h"
#include "block/qcow2.h"
-typedef struct QEMU_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 qcow2_free_snapshots(BlockDriverState *bs)
{
BDRVQcowState *s = bs->opaque;
{
BDRVQcowState *s = bs->opaque;
QCowSnapshotHeader h;
+ QCowSnapshotExtraData extra;
QCowSnapshot *sn;
int i, id_str_size, name_size;
int64_t offset;
}
offset = s->snapshots_offset;
- s->snapshots = g_malloc0(s->nb_snapshots * sizeof(QCowSnapshot));
+ s->snapshots = g_new0(QCowSnapshot, s->nb_snapshots);
for(i = 0; i < s->nb_snapshots; i++) {
/* Read statically sized part of the snapshot header */
id_str_size = be16_to_cpu(h.id_str_size);
name_size = be16_to_cpu(h.name_size);
- /* Skip extra data */
+ /* Read extra data */
+ ret = bdrv_pread(bs->file, offset, &extra,
+ MIN(sizeof(extra), extra_data_size));
+ if (ret < 0) {
+ goto fail;
+ }
offset += extra_data_size;
+ if (extra_data_size >= 8) {
+ sn->vm_state_size = be64_to_cpu(extra.vm_state_size_large);
+ }
+
+ if (extra_data_size >= 16) {
+ sn->disk_size = be64_to_cpu(extra.disk_size);
+ } else {
+ sn->disk_size = bs->total_sectors * BDRV_SECTOR_SIZE;
+ }
+
/* Read snapshot ID */
sn->id_str = g_malloc(id_str_size + 1);
ret = bdrv_pread(bs->file, offset, sn->id_str, id_str_size);
}
offset += name_size;
sn->name[name_size] = '\0';
+
+ if (offset - s->snapshots_offset > QCOW_MAX_SNAPSHOTS_SIZE) {
+ ret = -EFBIG;
+ goto fail;
+ }
}
+ assert(offset - s->snapshots_offset <= INT_MAX);
s->snapshots_size = offset - s->snapshots_offset;
return 0;
BDRVQcowState *s = bs->opaque;
QCowSnapshot *sn;
QCowSnapshotHeader h;
+ QCowSnapshotExtraData extra;
int i, name_size, id_str_size, snapshots_size;
struct {
uint32_t nb_snapshots;
uint64_t snapshots_offset;
} QEMU_PACKED header_data;
- int64_t offset, snapshots_offset;
+ int64_t offset, snapshots_offset = 0;
int ret;
/* compute the size of the snapshots */
sn = s->snapshots + i;
offset = align_offset(offset, 8);
offset += sizeof(h);
+ offset += sizeof(extra);
offset += strlen(sn->id_str);
offset += strlen(sn->name);
+
+ if (offset > QCOW_MAX_SNAPSHOTS_SIZE) {
+ ret = -EFBIG;
+ goto fail;
+ }
}
+
+ assert(offset <= INT_MAX);
snapshots_size = offset;
/* Allocate space for the new snapshot list */
snapshots_offset = qcow2_alloc_clusters(bs, snapshots_size);
- bdrv_flush(bs->file);
offset = snapshots_offset;
if (offset < 0) {
- return offset;
+ ret = offset;
+ goto fail;
+ }
+ ret = bdrv_flush(bs);
+ if (ret < 0) {
+ goto fail;
}
+ /* The snapshot list position has not yet been updated, so these clusters
+ * must indeed be completely free */
+ ret = qcow2_pre_write_overlap_check(bs, 0, offset, snapshots_size);
+ if (ret < 0) {
+ goto fail;
+ }
+
+
/* Write all snapshots to the new list */
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);
+ /* If it doesn't fit in 32 bit, older implementations should treat it
+ * as a disk-only snapshot rather than truncate the VM state */
+ if (sn->vm_state_size <= 0xffffffff) {
+ 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);
+ h.extra_data_size = cpu_to_be32(sizeof(extra));
+
+ memset(&extra, 0, sizeof(extra));
+ extra.vm_state_size_large = cpu_to_be64(sn->vm_state_size);
+ extra.disk_size = cpu_to_be64(sn->disk_size);
id_str_size = strlen(sn->id_str);
name_size = strlen(sn->name);
+ assert(id_str_size <= UINT16_MAX && name_size <= UINT16_MAX);
h.id_str_size = cpu_to_be16(id_str_size);
h.name_size = cpu_to_be16(name_size);
offset = align_offset(offset, 8);
}
offset += sizeof(h);
+ ret = bdrv_pwrite(bs->file, offset, &extra, sizeof(extra));
+ if (ret < 0) {
+ goto fail;
+ }
+ offset += sizeof(extra);
+
ret = bdrv_pwrite(bs->file, offset, sn->id_str, id_str_size);
if (ret < 0) {
goto fail;
}
/* free the old snapshot table */
- qcow2_free_clusters(bs, s->snapshots_offset, s->snapshots_size);
+ qcow2_free_clusters(bs, s->snapshots_offset, s->snapshots_size,
+ QCOW2_DISCARD_SNAPSHOT);
s->snapshots_offset = snapshots_offset;
s->snapshots_size = snapshots_size;
return 0;
fail:
+ if (snapshots_offset > 0) {
+ qcow2_free_clusters(bs, snapshots_offset, snapshots_size,
+ QCOW2_DISCARD_ALWAYS);
+ }
return ret;
}
{
BDRVQcowState *s = bs->opaque;
QCowSnapshot *sn;
- int i, id, id_max = 0;
+ int i;
+ unsigned long id, id_max = 0;
for(i = 0; i < s->nb_snapshots; i++) {
sn = s->snapshots + i;
if (id > id_max)
id_max = id;
}
- snprintf(id_str, id_str_size, "%d", id_max + 1);
+ snprintf(id_str, id_str_size, "%lu", id_max + 1);
}
-static int find_snapshot_by_id(BlockDriverState *bs, const char *id_str)
+static int find_snapshot_by_id_and_name(BlockDriverState *bs,
+ const char *id,
+ const char *name)
{
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;
+ if (id && name) {
+ for (i = 0; i < s->nb_snapshots; i++) {
+ if (!strcmp(s->snapshots[i].id_str, id) &&
+ !strcmp(s->snapshots[i].name, name)) {
+ return i;
+ }
+ }
+ } else if (id) {
+ for (i = 0; i < s->nb_snapshots; i++) {
+ if (!strcmp(s->snapshots[i].id_str, id)) {
+ return i;
+ }
+ }
+ } else if (name) {
+ for (i = 0; i < s->nb_snapshots; i++) {
+ if (!strcmp(s->snapshots[i].name, name)) {
+ return i;
+ }
+ }
}
+
return -1;
}
-static int find_snapshot_by_id_or_name(BlockDriverState *bs, const char *name)
+static int find_snapshot_by_id_or_name(BlockDriverState *bs,
+ const char *id_or_name)
{
- BDRVQcowState *s = bs->opaque;
- int i, ret;
+ int ret;
- ret = find_snapshot_by_id(bs, name);
- if (ret >= 0)
+ ret = find_snapshot_by_id_and_name(bs, id_or_name, NULL);
+ if (ret >= 0) {
return ret;
- for(i = 0; i < s->nb_snapshots; i++) {
- if (!strcmp(s->snapshots[i].name, name))
- return i;
}
- return -1;
+ return find_snapshot_by_id_and_name(bs, NULL, id_or_name);
}
/* if no id is provided, a new one is constructed */
uint64_t *l1_table = NULL;
int64_t l1_table_offset;
+ if (s->nb_snapshots >= QCOW_MAX_SNAPSHOTS) {
+ return -EFBIG;
+ }
+
memset(sn, 0, sizeof(*sn));
/* Generate an ID if it wasn't passed */
}
/* Check that the ID is unique */
- if (find_snapshot_by_id(bs, sn_info->id_str) >= 0) {
- return -ENOENT;
+ if (find_snapshot_by_id_and_name(bs, sn_info->id_str, NULL) >= 0) {
+ return -EEXIST;
}
/* Populate sn with passed data */
sn->id_str = g_strdup(sn_info->id_str);
sn->name = g_strdup(sn_info->name);
+ sn->disk_size = bs->total_sectors * BDRV_SECTOR_SIZE;
sn->vm_state_size = sn_info->vm_state_size;
sn->date_sec = sn_info->date_sec;
sn->date_nsec = sn_info->date_nsec;
sn->l1_table_offset = l1_table_offset;
sn->l1_size = s->l1_size;
- l1_table = g_malloc(s->l1_size * sizeof(uint64_t));
+ l1_table = g_try_new(uint64_t, s->l1_size);
+ if (s->l1_size && l1_table == NULL) {
+ ret = -ENOMEM;
+ goto fail;
+ }
+
for(i = 0; i < s->l1_size; i++) {
l1_table[i] = cpu_to_be64(s->l1_table[i]);
}
+ ret = qcow2_pre_write_overlap_check(bs, 0, sn->l1_table_offset,
+ s->l1_size * sizeof(uint64_t));
+ if (ret < 0) {
+ goto fail;
+ }
+
ret = bdrv_pwrite(bs->file, sn->l1_table_offset, l1_table,
s->l1_size * sizeof(uint64_t));
if (ret < 0) {
goto fail;
}
- ret = bdrv_flush(bs);
- if (ret < 0) {
- goto fail;
- }
-
/* Append the new snapshot to the snapshot list */
- new_snapshot_list = g_malloc((s->nb_snapshots + 1) * sizeof(QCowSnapshot));
+ new_snapshot_list = g_new(QCowSnapshot, s->nb_snapshots + 1);
if (s->snapshots) {
memcpy(new_snapshot_list, s->snapshots,
s->nb_snapshots * sizeof(QCowSnapshot));
if (ret < 0) {
g_free(s->snapshots);
s->snapshots = old_snapshot_list;
+ s->nb_snapshots--;
goto fail;
}
g_free(old_snapshot_list);
+ /* The VM state isn't needed any more in the active L1 table; in fact, it
+ * hurts by causing expensive COW for the next snapshot. */
+ qcow2_discard_clusters(bs, qcow2_vm_state_offset(s),
+ align_offset(sn->vm_state_size, s->cluster_size)
+ >> BDRV_SECTOR_BITS,
+ QCOW2_DISCARD_NEVER);
+
#ifdef DEBUG_ALLOC
{
BdrvCheckResult result = {0};
- qcow2_check_refcounts(bs, &result);
+ qcow2_check_refcounts(bs, &result, 0);
}
#endif
return 0;
QCowSnapshot *sn;
int i, snapshot_index;
int cur_l1_bytes, sn_l1_bytes;
+ int ret;
+ uint64_t *sn_l1_table = NULL;
+ /* Search the snapshot */
snapshot_index = find_snapshot_by_id_or_name(bs, snapshot_id);
- if (snapshot_index < 0)
+ if (snapshot_index < 0) {
return -ENOENT;
+ }
sn = &s->snapshots[snapshot_index];
- if (qcow2_update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size, -1) < 0)
+ if (sn->disk_size != bs->total_sectors * BDRV_SECTOR_SIZE) {
+ error_report("qcow2: Loading snapshots with different disk "
+ "size is not implemented");
+ ret = -ENOTSUP;
goto fail;
+ }
- if (qcow2_grow_l1_table(bs, sn->l1_size, true) < 0)
+ /*
+ * Make sure that the current L1 table is big enough to contain the whole
+ * L1 table of the snapshot. If the snapshot L1 table is smaller, the
+ * current one must be padded with zeros.
+ */
+ ret = qcow2_grow_l1_table(bs, sn->l1_size, true);
+ if (ret < 0) {
goto fail;
+ }
cur_l1_bytes = s->l1_size * sizeof(uint64_t);
sn_l1_bytes = sn->l1_size * sizeof(uint64_t);
- if (cur_l1_bytes > sn_l1_bytes) {
- memset(s->l1_table + sn->l1_size, 0, cur_l1_bytes - sn_l1_bytes);
+ /*
+ * Copy the snapshot L1 table to the current L1 table.
+ *
+ * Before overwriting the old current L1 table on disk, make sure to
+ * increase all refcounts for the clusters referenced by the new one.
+ * Decrease the refcount referenced by the old one only when the L1
+ * table is overwritten.
+ */
+ sn_l1_table = g_try_malloc0(cur_l1_bytes);
+ if (cur_l1_bytes && sn_l1_table == NULL) {
+ ret = -ENOMEM;
+ goto fail;
}
- /* copy the snapshot l1 table to the current l1 table */
- if (bdrv_pread(bs->file, sn->l1_table_offset,
- s->l1_table, sn_l1_bytes) < 0)
+ ret = bdrv_pread(bs->file, sn->l1_table_offset, sn_l1_table, sn_l1_bytes);
+ if (ret < 0) {
goto fail;
- if (bdrv_pwrite_sync(bs->file, s->l1_table_offset,
- s->l1_table, cur_l1_bytes) < 0)
+ }
+
+ ret = qcow2_update_snapshot_refcount(bs, sn->l1_table_offset,
+ sn->l1_size, 1);
+ if (ret < 0) {
+ goto fail;
+ }
+
+ ret = qcow2_pre_write_overlap_check(bs, QCOW2_OL_ACTIVE_L1,
+ s->l1_table_offset, cur_l1_bytes);
+ if (ret < 0) {
goto fail;
+ }
+
+ ret = bdrv_pwrite_sync(bs->file, s->l1_table_offset, sn_l1_table,
+ cur_l1_bytes);
+ if (ret < 0) {
+ goto fail;
+ }
+
+ /*
+ * Decrease refcount of clusters of current L1 table.
+ *
+ * At this point, the in-memory s->l1_table points to the old L1 table,
+ * whereas on disk we already have the new one.
+ *
+ * qcow2_update_snapshot_refcount special cases the current L1 table to use
+ * the in-memory data instead of really using the offset to load a new one,
+ * which is why this works.
+ */
+ ret = qcow2_update_snapshot_refcount(bs, s->l1_table_offset,
+ s->l1_size, -1);
+
+ /*
+ * Now update the in-memory L1 table to be in sync with the on-disk one. We
+ * need to do this even if updating refcounts failed.
+ */
for(i = 0;i < s->l1_size; i++) {
- be64_to_cpus(&s->l1_table[i]);
+ s->l1_table[i] = be64_to_cpu(sn_l1_table[i]);
}
- if (qcow2_update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size, 1) < 0)
+ if (ret < 0) {
+ goto fail;
+ }
+
+ g_free(sn_l1_table);
+ sn_l1_table = NULL;
+
+ /*
+ * Update QCOW_OFLAG_COPIED in the active L1 table (it may have changed
+ * when we decreased the refcount of the old snapshot.
+ */
+ ret = qcow2_update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size, 0);
+ if (ret < 0) {
goto fail;
+ }
#ifdef DEBUG_ALLOC
{
BdrvCheckResult result = {0};
- qcow2_check_refcounts(bs, &result);
+ qcow2_check_refcounts(bs, &result, 0);
}
#endif
return 0;
- fail:
- return -EIO;
+
+fail:
+ g_free(sn_l1_table);
+ return ret;
}
-int qcow2_snapshot_delete(BlockDriverState *bs, const char *snapshot_id)
+int qcow2_snapshot_delete(BlockDriverState *bs,
+ const char *snapshot_id,
+ const char *name,
+ Error **errp)
{
BDRVQcowState *s = bs->opaque;
- QCowSnapshot *sn;
+ QCowSnapshot sn;
int snapshot_index, ret;
- snapshot_index = find_snapshot_by_id_or_name(bs, snapshot_id);
- if (snapshot_index < 0)
+ /* Search the snapshot */
+ snapshot_index = find_snapshot_by_id_and_name(bs, snapshot_id, name);
+ if (snapshot_index < 0) {
+ error_setg(errp, "Can't find the snapshot");
return -ENOENT;
- sn = &s->snapshots[snapshot_index];
+ }
+ sn = s->snapshots[snapshot_index];
- ret = qcow2_update_snapshot_refcount(bs, sn->l1_table_offset, sn->l1_size, -1);
- if (ret < 0)
+ /* Remove it from the snapshot list */
+ memmove(s->snapshots + snapshot_index,
+ s->snapshots + snapshot_index + 1,
+ (s->nb_snapshots - snapshot_index - 1) * sizeof(sn));
+ s->nb_snapshots--;
+ ret = qcow2_write_snapshots(bs);
+ if (ret < 0) {
+ error_setg_errno(errp, -ret,
+ "Failed to remove snapshot from snapshot list");
return ret;
- /* must update the copied flag on the current cluster offsets */
- ret = qcow2_update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size, 0);
- if (ret < 0)
+ }
+
+ /*
+ * The snapshot is now unused, clean up. If we fail after this point, we
+ * won't recover but just leak clusters.
+ */
+ g_free(sn.id_str);
+ g_free(sn.name);
+
+ /*
+ * Now decrease the refcounts of clusters referenced by the snapshot and
+ * free the L1 table.
+ */
+ ret = qcow2_update_snapshot_refcount(bs, sn.l1_table_offset,
+ sn.l1_size, -1);
+ if (ret < 0) {
+ error_setg_errno(errp, -ret, "Failed to free the cluster and L1 table");
return ret;
- qcow2_free_clusters(bs, sn->l1_table_offset, sn->l1_size * sizeof(uint64_t));
+ }
+ qcow2_free_clusters(bs, sn.l1_table_offset, sn.l1_size * sizeof(uint64_t),
+ QCOW2_DISCARD_SNAPSHOT);
- g_free(sn->id_str);
- g_free(sn->name);
- memmove(sn, sn + 1, (s->nb_snapshots - snapshot_index - 1) * sizeof(*sn));
- s->nb_snapshots--;
- ret = qcow2_write_snapshots(bs);
+ /* must update the copied flag on the current cluster offsets */
+ ret = qcow2_update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size, 0);
if (ret < 0) {
- /* XXX: restore snapshot if error ? */
+ error_setg_errno(errp, -ret,
+ "Failed to update snapshot status in disk");
return ret;
}
+
#ifdef DEBUG_ALLOC
{
BdrvCheckResult result = {0};
- qcow2_check_refcounts(bs, &result);
+ qcow2_check_refcounts(bs, &result, 0);
}
#endif
return 0;
return s->nb_snapshots;
}
- sn_tab = g_malloc0(s->nb_snapshots * sizeof(QEMUSnapshotInfo));
+ sn_tab = g_new0(QEMUSnapshotInfo, s->nb_snapshots);
for(i = 0; i < s->nb_snapshots; i++) {
sn_info = sn_tab + i;
sn = s->snapshots + i;
return s->nb_snapshots;
}
-int qcow2_snapshot_load_tmp(BlockDriverState *bs, const char *snapshot_name)
+int qcow2_snapshot_load_tmp(BlockDriverState *bs,
+ const char *snapshot_id,
+ const char *name,
+ Error **errp)
{
- int i, snapshot_index, l1_size2;
+ int i, snapshot_index;
BDRVQcowState *s = bs->opaque;
QCowSnapshot *sn;
+ uint64_t *new_l1_table;
+ int new_l1_bytes;
+ int ret;
+
+ assert(bs->read_only);
- snapshot_index = find_snapshot_by_id_or_name(bs, snapshot_name);
+ /* Search the snapshot */
+ snapshot_index = find_snapshot_by_id_and_name(bs, snapshot_id, name);
if (snapshot_index < 0) {
+ error_setg(errp,
+ "Can't find snapshot");
return -ENOENT;
}
-
sn = &s->snapshots[snapshot_index];
- s->l1_size = sn->l1_size;
- l1_size2 = s->l1_size * sizeof(uint64_t);
- if (s->l1_table != NULL) {
- g_free(s->l1_table);
- }
- s->l1_table_offset = sn->l1_table_offset;
- s->l1_table = g_malloc0(align_offset(l1_size2, 512));
+ /* Allocate and read in the snapshot's L1 table */
+ if (sn->l1_size > QCOW_MAX_L1_SIZE) {
+ error_setg(errp, "Snapshot L1 table too large");
+ return -EFBIG;
+ }
+ new_l1_bytes = sn->l1_size * sizeof(uint64_t);
+ new_l1_table = qemu_try_blockalign(bs->file,
+ align_offset(new_l1_bytes, 512));
+ if (new_l1_table == NULL) {
+ return -ENOMEM;
+ }
- if (bdrv_pread(bs->file, sn->l1_table_offset,
- s->l1_table, l1_size2) != l1_size2) {
- return -1;
+ ret = bdrv_pread(bs->file, sn->l1_table_offset, new_l1_table, new_l1_bytes);
+ if (ret < 0) {
+ error_setg(errp, "Failed to read l1 table for snapshot");
+ qemu_vfree(new_l1_table);
+ return ret;
}
+ /* Switch the L1 table */
+ qemu_vfree(s->l1_table);
+
+ s->l1_size = sn->l1_size;
+ s->l1_table_offset = sn->l1_table_offset;
+ s->l1_table = new_l1_table;
+
for(i = 0;i < s->l1_size; i++) {
be64_to_cpus(&s->l1_table[i]);
}
+
return 0;
}
projects / mirror_qemu.git / blobdiff