On Fri, Oct 12, 2012 at 7:39 PM, Stefan Hajnoczi <stefa...@redhat.com> wrote:
> The qemu-img info --backing-chain option enumerates the backing file
> chain. For example, for base.qcow2 <- snap1.qcow2 <- snap2.qcow2 the
> output becomes:
>
> $ qemu-img info --backing-chain snap2.qcow2
> image: snap2.qcow2
> file format: qcow2
> virtual size: 100M (104857600 bytes)
> disk size: 196K
> cluster_size: 65536
> backing file: snap1.qcow2
> backing file format: qcow2
>
> image: snap1.qcow2
> file format: qcow2
> virtual size: 100M (104857600 bytes)
> disk size: 196K
> cluster_size: 65536
> backing file: base.qcow2
> backing file format: qcow2
>
> image: base.qcow2
> file format: qcow2
> virtual size: 100M (104857600 bytes)
> disk size: 136K
> cluster_size: 65536
>
> Signed-off-by: Stefan Hajnoczi <stefa...@redhat.com>
> ---
> qemu-img.c | 98
> ++++++++++++++++++++++++++++++++++++++++++++++++--------------
> 1 file changed, 76 insertions(+), 22 deletions(-)
>
> diff --git a/qemu-img.c b/qemu-img.c
> index f17f187..c717f3e 100644
> --- a/qemu-img.c
> +++ b/qemu-img.c
> @@ -1249,7 +1249,10 @@ static void dump_human_image_info(ImageInfo *info)
> }
> }
>
> -enum {OPTION_OUTPUT = 256};
> +enum {
> + OPTION_OUTPUT = 256,
> + OPTION_BACKING_CHAIN = 257,
> +};
>
> typedef enum OutputFormat {
> OFORMAT_JSON,
> @@ -1260,7 +1263,9 @@ static int img_info(int argc, char **argv)
> {
> int c;
> OutputFormat output_format = OFORMAT_HUMAN;
> - const char *filename, *fmt, *output;
> + bool chain = false;
> + const char *output;
> + char *filename, *fmt;
> BlockDriverState *bs;
> ImageInfo *info;
>
> @@ -1272,6 +1277,7 @@ static int img_info(int argc, char **argv)
> {"help", no_argument, 0, 'h'},
> {"format", required_argument, 0, 'f'},
> {"output", required_argument, 0, OPTION_OUTPUT},
> + {"backing-chain", no_argument, 0, OPTION_BACKING_CHAIN},
> {0, 0, 0, 0}
> };
> c = getopt_long(argc, argv, "f:h",
> @@ -1285,17 +1291,20 @@ static int img_info(int argc, char **argv)
> help();
> break;
> case 'f':
> - fmt = optarg;
> + fmt = g_strdup(optarg);
> break;
> case OPTION_OUTPUT:
> output = optarg;
> break;
> + case OPTION_BACKING_CHAIN:
> + chain = true;
> + break;
> }
> }
> if (optind >= argc) {
> help();
> }
> - filename = argv[optind++];
> + filename = g_strdup(argv[optind++]);
>
> if (output && !strcmp(output, "json")) {
> output_format = OFORMAT_JSON;
> @@ -1303,31 +1312,76 @@ static int img_info(int argc, char **argv)
> output_format = OFORMAT_HUMAN;
> } else if (output) {
> error_report("--output must be used with human or json as
> argument.");
> - return 1;
> + goto err;
> }
>
> - bs = bdrv_new_open(filename, fmt, BDRV_O_FLAGS | BDRV_O_NO_BACKING,
> false);
> - if (!bs) {
> - return 1;
> + if (chain && output_format == OFORMAT_JSON) {
> + printf("[\n");
> }
>
> - info = g_new0(ImageInfo, 1);
> - collect_image_info(bs, info, filename, fmt);
> + do {
> + bs = bdrv_new_open(filename, fmt, BDRV_O_FLAGS | BDRV_O_NO_BACKING,
> + false);
> + if (!bs) {
> + goto err;
> + }
>
> - switch (output_format) {
> - case OFORMAT_HUMAN:
> - dump_human_image_info(info);
> - dump_snapshots(bs);
> - break;
> - case OFORMAT_JSON:
> - collect_snapshots(bs, info);
> - dump_json_image_info(info);
> - break;
> - }
> + info = g_new0(ImageInfo, 1);
> + collect_image_info(bs, info, filename, fmt);
>
> - qapi_free_ImageInfo(info);
> - bdrv_delete(bs);
> + switch (output_format) {
> + case OFORMAT_HUMAN:
> + dump_human_image_info(info);
> + dump_snapshots(bs);
> + break;
> + case OFORMAT_JSON:
> + collect_snapshots(bs, info);
> + dump_json_image_info(info);
> + break;
> + }
> +
> + g_free(filename);
> + g_free(fmt);
> + filename = NULL;
> + fmt = NULL;
> +
> + if (chain) {
> + if (info->has_full_backing_filename) {
> + filename = g_strdup(info->full_backing_filename);
> + } else if (info->has_backing_filename) {
> + filename = g_strdup(info->backing_filename);
> + }
> +
> + if (filename && info->has_backing_filename_format) {
> + fmt = g_strdup(info->backing_filename_format);
> + }
> +
> + /* Print delimiters between items */
> + if (filename) {
> + switch (output_format) {
> + case OFORMAT_HUMAN:
> + printf("\n");
> + break;
> + case OFORMAT_JSON:
> + printf(",\n");
> + break;
> + }
> + }
> + }
> +
> + qapi_free_ImageInfo(info);
> + bdrv_delete(bs);
> + } while (filename);
> +
> + if (chain && output_format == OFORMAT_JSON) {
> + printf("]\n");
> + }
> return 0;
> +
> +err:
> + g_free(filename);
> + g_free(fmt);
> + return 1;
> }
>
> #define SNAPSHOT_LIST 1
> --
> 1.7.11.4
>
Thanks a lot Stefan for making this. Just tested this with latest qemu
git. Works like a charm:
[kashyap@moon qemu]$ ./qemu-img info --backing-chain
/var/lib/libvirt/images/snap4-of-test-f17base.qcow2
image: /var/lib/libvirt/images/snap4-of-test-f17base.qcow2
file format: qcow2
virtual size: 1.0G (1073741824 bytes)
disk size: 3.6M
cluster_size: 65536
backing file: /var/lib/libvirt/images/snap1-of-test-f17base.qcow2
backing file format: qcow2
image: /var/lib/libvirt/images/snap1-of-test-f17base.qcow2
file format: qcow2
virtual size: 1.0G (1073741824 bytes)
disk size: 968K
cluster_size: 65536
backing file: /export/vmimgs2/test-f17base.img
backing file format: raw
image: /export/vmimgs2/test-f17base.img
file format: raw
virtual size: 1.0G (1073741824 bytes)
disk size: 607M
[kashyap@moon qemu]$
