From 90b277593df873d3a2480f002e2eb5fe1f8e5277 Mon Sep 17 00:00:00 2001 From: Kevin Wolf Date: Wed, 11 Apr 2012 16:33:50 +0200 Subject: qcow2: Save disk size in snapshot header This allows that different snapshots of an image can have different sizes, which is a requirement for enabling image resizing even with images that have internal snapshots. We don't do the actual support for it now, but make sure that the additional field is present and not completely ignored in all version 3 images. When trying to load a snapshot of different size, it returns an error. Signed-off-by: Kevin Wolf --- block/qcow2-snapshot.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) (limited to 'block/qcow2-snapshot.c') diff --git a/block/qcow2-snapshot.c b/block/qcow2-snapshot.c index 7d3fde5a8a..42f971b590 100644 --- a/block/qcow2-snapshot.c +++ b/block/qcow2-snapshot.c @@ -48,6 +48,7 @@ typedef struct QEMU_PACKED QCowSnapshotHeader { typedef struct QEMU_PACKED QCowSnapshotExtraData { uint64_t vm_state_size_large; + uint64_t disk_size; } QCowSnapshotExtraData; void qcow2_free_snapshots(BlockDriverState *bs) @@ -117,6 +118,12 @@ int qcow2_read_snapshots(BlockDriverState *bs) 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); @@ -197,6 +204,7 @@ static int qcow2_write_snapshots(BlockDriverState *bs) 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); @@ -330,6 +338,7 @@ int qcow2_snapshot_create(BlockDriverState *bs, QEMUSnapshotInfo *sn_info) 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; @@ -426,6 +435,13 @@ int qcow2_snapshot_goto(BlockDriverState *bs, const char *snapshot_id) } sn = &s->snapshots[snapshot_index]; + 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; + } + /* * 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 -- cgit v1.2.1