On Sat, Oct 13, 2012 at 12:46 AM, Kashyap Chamarthy
<kashyap...@gmail.com> wrote:
> 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]$Attached a documentation patch for the '--backing-chain' option. /kashyap
0001-Add-documentation-for-qemu-img-info-backing-chain.patch
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