*/
#include "qemu-common.h"
-#include "block_int.h"
+#include "block/block_int.h"
#include "block/qcow2.h"
-typedef struct __attribute__((packed)) QCowSnapshotHeader {
+typedef struct QEMU_PACKED QCowSnapshotHeader {
/* header is 8 byte aligned */
uint64_t l1_table_offset;
/* name follows */
} QCowSnapshotHeader;
+typedef struct QEMU_PACKED QCowSnapshotExtraData {
+ uint64_t vm_state_size_large;
+ uint64_t disk_size;
+} QCowSnapshotExtraData;
+
void qcow2_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);
+ g_free(s->snapshots[i].name);
+ g_free(s->snapshots[i].id_str);
}
- qemu_free(s->snapshots);
+ g_free(s->snapshots);
s->snapshots = NULL;
s->nb_snapshots = 0;
}
{
BDRVQcowState *s = bs->opaque;
QCowSnapshotHeader h;
+ QCowSnapshotExtraData extra;
QCowSnapshot *sn;
int i, id_str_size, name_size;
int64_t offset;
uint32_t extra_data_size;
+ int ret;
if (!s->nb_snapshots) {
s->snapshots = NULL;
}
offset = s->snapshots_offset;
- s->snapshots = qemu_mallocz(s->nb_snapshots * sizeof(QCowSnapshot));
+ s->snapshots = g_malloc0(s->nb_snapshots * sizeof(QCowSnapshot));
+
for(i = 0; i < s->nb_snapshots; i++) {
+ /* Read statically sized part of the snapshot header */
offset = align_offset(offset, 8);
- if (bdrv_pread(bs->file, offset, &h, sizeof(h)) != sizeof(h))
+ ret = bdrv_pread(bs->file, offset, &h, sizeof(h));
+ if (ret < 0) {
goto fail;
+ }
+
offset += sizeof(h);
sn = s->snapshots + i;
sn->l1_table_offset = be64_to_cpu(h.l1_table_offset);
id_str_size = be16_to_cpu(h.id_str_size);
name_size = be16_to_cpu(h.name_size);
+ /* 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;
- sn->id_str = qemu_malloc(id_str_size + 1);
- if (bdrv_pread(bs->file, offset, sn->id_str, id_str_size) != id_str_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);
+ if (ret < 0) {
goto fail;
+ }
offset += id_str_size;
sn->id_str[id_str_size] = '\0';
- sn->name = qemu_malloc(name_size + 1);
- if (bdrv_pread(bs->file, offset, sn->name, name_size) != name_size)
+ /* Read snapshot name */
+ sn->name = g_malloc(name_size + 1);
+ ret = bdrv_pread(bs->file, offset, sn->name, name_size);
+ if (ret < 0) {
goto fail;
+ }
offset += name_size;
sn->name[name_size] = '\0';
}
+
s->snapshots_size = offset - s->snapshots_offset;
return 0;
- fail:
+
+fail:
qcow2_free_snapshots(bs);
- return -1;
+ return ret;
}
/* add at the end of the file a new list of snapshots */
-static int qcow_write_snapshots(BlockDriverState *bs)
+static int qcow2_write_snapshots(BlockDriverState *bs)
{
BDRVQcowState *s = bs->opaque;
QCowSnapshot *sn;
QCowSnapshotHeader h;
+ QCowSnapshotExtraData extra;
int i, name_size, id_str_size, snapshots_size;
- uint64_t data64;
- uint32_t data32;
+ struct {
+ uint32_t nb_snapshots;
+ uint64_t snapshots_offset;
+ } QEMU_PACKED header_data;
int64_t offset, snapshots_offset;
+ int ret;
/* compute the size of the snapshots */
offset = 0;
sn = s->snapshots + i;
offset = align_offset(offset, 8);
offset += sizeof(h);
+ offset += sizeof(extra);
offset += strlen(sn->id_str);
offset += strlen(sn->name);
}
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;
return offset;
}
+ /* 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);
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_sync(bs->file, offset, &h, sizeof(h)) < 0)
+
+ ret = bdrv_pwrite(bs->file, offset, &h, sizeof(h));
+ if (ret < 0) {
goto fail;
+ }
offset += sizeof(h);
- if (bdrv_pwrite_sync(bs->file, offset, sn->id_str, id_str_size) < 0)
+
+ 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;
+ }
offset += id_str_size;
- if (bdrv_pwrite_sync(bs->file, offset, sn->name, name_size) < 0)
+
+ ret = bdrv_pwrite(bs->file, offset, sn->name, name_size);
+ if (ret < 0) {
goto fail;
+ }
offset += name_size;
}
- /* update the various header fields */
- data64 = cpu_to_be64(snapshots_offset);
- if (bdrv_pwrite_sync(bs->file, offsetof(QCowHeader, snapshots_offset),
- &data64, sizeof(data64)) < 0)
+ /*
+ * Update the header to point to the new snapshot table. This requires the
+ * new table and its refcounts to be stable on disk.
+ */
+ ret = bdrv_flush(bs);
+ if (ret < 0) {
goto fail;
- data32 = cpu_to_be32(s->nb_snapshots);
- if (bdrv_pwrite_sync(bs->file, offsetof(QCowHeader, nb_snapshots),
- &data32, sizeof(data32)) < 0)
+ }
+
+ QEMU_BUILD_BUG_ON(offsetof(QCowHeader, snapshots_offset) !=
+ offsetof(QCowHeader, nb_snapshots) + sizeof(header_data.nb_snapshots));
+
+ header_data.nb_snapshots = cpu_to_be32(s->nb_snapshots);
+ header_data.snapshots_offset = cpu_to_be64(snapshots_offset);
+
+ ret = bdrv_pwrite_sync(bs->file, offsetof(QCowHeader, nb_snapshots),
+ &header_data, sizeof(header_data));
+ if (ret < 0) {
goto fail;
+ }
/* free the old snapshot table */
qcow2_free_clusters(bs, s->snapshots_offset, s->snapshots_size);
s->snapshots_offset = snapshots_offset;
s->snapshots_size = snapshots_size;
return 0;
- fail:
- return -1;
+
+fail:
+ return ret;
}
static void find_new_snapshot_id(BlockDriverState *bs,
int qcow2_snapshot_create(BlockDriverState *bs, QEMUSnapshotInfo *sn_info)
{
BDRVQcowState *s = bs->opaque;
- QCowSnapshot *snapshots1, sn1, *sn = &sn1;
+ QCowSnapshot *new_snapshot_list = NULL;
+ QCowSnapshot *old_snapshot_list = NULL;
+ QCowSnapshot sn1, *sn = &sn1;
int i, ret;
uint64_t *l1_table = NULL;
int64_t l1_table_offset;
memset(sn, 0, sizeof(*sn));
+ /* Generate an ID if it wasn't passed */
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;
+ /* Check that the ID is unique */
+ if (find_snapshot_by_id(bs, sn_info->id_str) >= 0) {
+ return -EEXIST;
+ }
- 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;
+ /* 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->vm_clock_nsec = sn_info->vm_clock_nsec;
- ret = qcow2_update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size, 1);
- if (ret < 0)
- goto fail;
-
- /* create the L1 table of the snapshot */
+ /* Allocate the L1 table of the snapshot and copy the current one there. */
l1_table_offset = qcow2_alloc_clusters(bs, s->l1_size * sizeof(uint64_t));
if (l1_table_offset < 0) {
+ ret = l1_table_offset;
goto fail;
}
- bdrv_flush(bs->file);
sn->l1_table_offset = l1_table_offset;
sn->l1_size = s->l1_size;
- if (s->l1_size != 0) {
- l1_table = qemu_malloc(s->l1_size * sizeof(uint64_t));
- } else {
- l1_table = NULL;
- }
-
+ l1_table = g_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_sync(bs->file, sn->l1_table_offset,
- l1_table, s->l1_size * sizeof(uint64_t)) < 0)
+
+ ret = bdrv_pwrite(bs->file, sn->l1_table_offset, l1_table,
+ s->l1_size * sizeof(uint64_t));
+ if (ret < 0) {
goto fail;
- qemu_free(l1_table);
+ }
+
+ g_free(l1_table);
l1_table = NULL;
- snapshots1 = qemu_malloc((s->nb_snapshots + 1) * sizeof(QCowSnapshot));
+ /*
+ * Increase the refcounts of all clusters and make sure everything is
+ * stable on disk before updating the snapshot table to contain a pointer
+ * to the new L1 table.
+ */
+ ret = qcow2_update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size, 1);
+ 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));
if (s->snapshots) {
- memcpy(snapshots1, s->snapshots, s->nb_snapshots * sizeof(QCowSnapshot));
- qemu_free(s->snapshots);
+ memcpy(new_snapshot_list, s->snapshots,
+ s->nb_snapshots * sizeof(QCowSnapshot));
+ old_snapshot_list = s->snapshots;
}
- s->snapshots = snapshots1;
+ s->snapshots = new_snapshot_list;
s->snapshots[s->nb_snapshots++] = *sn;
- if (qcow_write_snapshots(bs) < 0)
+ ret = qcow2_write_snapshots(bs);
+ if (ret < 0) {
+ g_free(s->snapshots);
+ s->snapshots = old_snapshot_list;
goto fail;
+ }
+
+ g_free(old_snapshot_list);
+
#ifdef DEBUG_ALLOC
- qcow2_check_refcounts(bs);
+ {
+ BdrvCheckResult result = {0};
+ qcow2_check_refcounts(bs, &result, 0);
+ }
#endif
return 0;
- fail:
- qemu_free(sn->name);
- qemu_free(l1_table);
- return -1;
+
+fail:
+ g_free(sn->id_str);
+ g_free(sn->name);
+ g_free(l1_table);
+
+ return ret;
}
/* copy the snapshot 'snapshot_name' into the current disk image */
{
BDRVQcowState *s = bs->opaque;
QCowSnapshot *sn;
- int i, snapshot_index, l1_size2;
+ 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) < 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;
+ }
- 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(bs->file, sn->l1_table_offset,
- s->l1_table, l1_size2) != l1_size2)
+ cur_l1_bytes = s->l1_size * sizeof(uint64_t);
+ sn_l1_bytes = sn->l1_size * sizeof(uint64_t);
+
+ /*
+ * 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_malloc0(cur_l1_bytes);
+
+ ret = bdrv_pread(bs->file, sn->l1_table_offset, sn_l1_table, sn_l1_bytes);
+ if (ret < 0) {
+ goto fail;
+ }
+
+ ret = qcow2_update_snapshot_refcount(bs, sn->l1_table_offset,
+ sn->l1_size, 1);
+ if (ret < 0) {
goto fail;
- if (bdrv_pwrite_sync(bs->file, s->l1_table_offset,
- s->l1_table, l1_size2) < 0)
+ }
+
+ 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
- qcow2_check_refcounts(bs);
+ {
+ BdrvCheckResult result = {0};
+ 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)
{
BDRVQcowState *s = bs->opaque;
- QCowSnapshot *sn;
+ QCowSnapshot sn;
int snapshot_index, ret;
+ /* 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];
+ }
+ 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) {
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) {
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));
- 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);
+ /* 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 ? */
return ret;
}
+
#ifdef DEBUG_ALLOC
- qcow2_check_refcounts(bs);
+ {
+ BdrvCheckResult result = {0};
+ qcow2_check_refcounts(bs, &result, 0);
+ }
#endif
return 0;
}
return s->nb_snapshots;
}
- sn_tab = qemu_mallocz(s->nb_snapshots * sizeof(QEMUSnapshotInfo));
+ sn_tab = g_malloc0(s->nb_snapshots * sizeof(QEMUSnapshotInfo));
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 i, snapshot_index;
+ BDRVQcowState *s = bs->opaque;
+ QCowSnapshot *sn;
+ uint64_t *new_l1_table;
+ int new_l1_bytes;
+ int ret;
+
+ assert(bs->read_only);
+
+ /* Search the snapshot */
+ snapshot_index = find_snapshot_by_id_or_name(bs, snapshot_name);
+ if (snapshot_index < 0) {
+ return -ENOENT;
+ }
+ sn = &s->snapshots[snapshot_index];
+
+ /* Allocate and read in the snapshot's L1 table */
+ new_l1_bytes = s->l1_size * sizeof(uint64_t);
+ new_l1_table = g_malloc0(align_offset(new_l1_bytes, 512));
+
+ ret = bdrv_pread(bs->file, sn->l1_table_offset, new_l1_table, new_l1_bytes);
+ if (ret < 0) {
+ g_free(new_l1_table);
+ return ret;
+ }
+
+ /* Switch the L1 table */
+ g_free(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 / qemu.git / blobdiff