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qemu-img info: Optionally show block limits

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Add a new --limits option to 'qemu-img info' that displays the block
limits for the image and all of its children, making the information
more accessible for human users than in QMP. This option is not enabled
by default because it can be a lot of output that isn't usually relevant
if you're not specifically trying to diagnose some I/O problem.

This makes the same information automatically also available in HMP
'info block -v'.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Hanna Czenczek <hreitz@redhat.com>
Message-ID: <20251024123041.51254-4-kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Kevin Wolf 2025-10-24 14:30:39 +02:00
parent d2634e1828
commit 5b4b3bfdfc
5 changed files with 52 additions and 9 deletions
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15
qemu-img.c
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@ -86,6 +86,7 @@ enum {
OPTION_BITMAPS = 275,
OPTION_FORCE = 276,
OPTION_SKIP_BROKEN = 277,
OPTION_LIMITS = 278,
};
typedef enum OutputFormat {
@ -3002,7 +3003,8 @@ static gboolean str_equal_func(gconstpointer a, gconstpointer b)
static BlockGraphInfoList *collect_image_info_list(bool image_opts,
const char *filename,
const char *fmt,
bool chain, bool force_share)
bool chain, bool limits,
bool force_share)
{
BlockGraphInfoList *head = NULL;
BlockGraphInfoList **tail = &head;
@ -3039,7 +3041,7 @@ static BlockGraphInfoList *collect_image_info_list(bool image_opts,
* the chain manually here.
*/
bdrv_graph_rdlock_main_loop();
bdrv_query_block_graph_info(bs, &info, &err);
bdrv_query_block_graph_info(bs, &info, limits, &err);
bdrv_graph_rdunlock_main_loop();
if (err) {
@ -3088,6 +3090,7 @@ static int img_info(const img_cmd_t *ccmd, int argc, char **argv)
BlockGraphInfoList *list;
bool image_opts = false;
bool force_share = false;
bool limits = false;
fmt = NULL;
for(;;) {
@ -3097,6 +3100,7 @@ static int img_info(const img_cmd_t *ccmd, int argc, char **argv)
{"image-opts", no_argument, 0, OPTION_IMAGE_OPTS},
{"backing-chain", no_argument, 0, OPTION_BACKING_CHAIN},
{"force-share", no_argument, 0, 'U'},
{"limits", no_argument, 0, OPTION_LIMITS},
{"output", required_argument, 0, OPTION_OUTPUT},
{"object", required_argument, 0, OPTION_OBJECT},
{0, 0, 0, 0}
@ -3119,6 +3123,8 @@ static int img_info(const img_cmd_t *ccmd, int argc, char **argv)
" display information about the backing chain for copy-on-write overlays\n"
" -U, --force-share\n"
" open image in shared mode for concurrent access\n"
" --limits\n"
" show detected block limits (may depend on options, e.g. cache mode)\n"
" --output human|json\n"
" specify output format (default: human)\n"
" --object OBJDEF\n"
@ -3140,6 +3146,9 @@ static int img_info(const img_cmd_t *ccmd, int argc, char **argv)
case 'U':
force_share = true;
break;
case OPTION_LIMITS:
limits = true;
break;
case OPTION_OUTPUT:
output_format = parse_output_format(argv[0], optarg);
break;
@ -3156,7 +3165,7 @@ static int img_info(const img_cmd_t *ccmd, int argc, char **argv)
filename = argv[optind++];
list = collect_image_info_list(image_opts, filename, fmt, chain,
force_share);
limits, force_share);
if (!list) {
return 1;
}