From: Kevin Wolf Date: Fri, 24 Oct 2025 12:30:39 +0000 (+0200) Subject: qemu-img info: Optionally show block limits X-Git-Tag: v10.2.0-rc1~38^2~1 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=5b4b3bfdfc28d2398f34194d260d6eef9a9048b4;p=thirdparty%2Fqemu.git qemu-img info: Optionally show block limits 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 Reviewed-by: Eric Blake Reviewed-by: Hanna Czenczek Message-ID: <20251024123041.51254-4-kwolf@redhat.com> Signed-off-by: Kevin Wolf --- diff --git a/block/qapi.c b/block/qapi.c index 54521d0a68b..9f5771e0195 100644 --- a/block/qapi.c +++ b/block/qapi.c @@ -417,6 +417,7 @@ fail: */ void bdrv_query_block_graph_info(BlockDriverState *bs, BlockGraphInfo **p_info, + bool limits, Error **errp) { ERRP_GUARD(); @@ -425,7 +426,7 @@ void bdrv_query_block_graph_info(BlockDriverState *bs, BdrvChild *c; info = g_new0(BlockGraphInfo, 1); - bdrv_do_query_node_info(bs, qapi_BlockGraphInfo_base(info), false, errp); + bdrv_do_query_node_info(bs, qapi_BlockGraphInfo_base(info), limits, errp); if (*errp) { goto fail; } @@ -439,7 +440,7 @@ void bdrv_query_block_graph_info(BlockDriverState *bs, QAPI_LIST_APPEND(children_list_tail, c_info); c_info->name = g_strdup(c->name); - bdrv_query_block_graph_info(c->bs, &c_info->info, errp); + bdrv_query_block_graph_info(c->bs, &c_info->info, limits, errp); if (*errp) { goto fail; } @@ -936,6 +937,29 @@ void bdrv_image_info_specific_dump(ImageInfoSpecific *info_spec, visit_free(v); } +/** + * Dumps the given BlockLimitsInfo object in a human-readable form, + * prepending an optional prefix if the dump is not empty. + */ +static void bdrv_image_info_limits_dump(BlockLimitsInfo *limits, + const char *prefix, + int indentation) +{ + QObject *obj; + Visitor *v = qobject_output_visitor_new(&obj); + + visit_type_BlockLimitsInfo(v, NULL, &limits, &error_abort); + visit_complete(v, &obj); + if (!qobject_is_empty_dump(obj)) { + if (prefix) { + qemu_printf("%*s%s", indentation * 4, "", prefix); + } + dump_qobject(indentation + 1, obj); + } + qobject_unref(obj); + visit_free(v); +} + /** * Print the given @info object in human-readable form. Every field is indented * using the given @indentation (four spaces per indentation level). @@ -1011,6 +1035,12 @@ void bdrv_node_info_dump(BlockNodeInfo *info, int indentation, bool protocol) } } + if (info->limits) { + bdrv_image_info_limits_dump(info->limits, + "Block limits:\n", + indentation); + } + if (info->has_snapshots) { SnapshotInfoList *elem; diff --git a/docs/tools/qemu-img.rst b/docs/tools/qemu-img.rst index 5e7b85079d9..fdc9ea9cf27 100644 --- a/docs/tools/qemu-img.rst +++ b/docs/tools/qemu-img.rst @@ -503,7 +503,7 @@ Command description: The size syntax is similar to :manpage:`dd(1)`'s size syntax. -.. option:: info [--object OBJECTDEF] [--image-opts] [-f FMT] [--output=OFMT] [--backing-chain] [-U] FILENAME +.. option:: info [--object OBJECTDEF] [--image-opts] [-f FMT] [--output=OFMT] [--backing-chain] [--limits] [-U] FILENAME Give information about the disk image *FILENAME*. Use it in particular to know the size reserved on disk which can be different @@ -571,6 +571,10 @@ Command description: ``ImageInfoSpecific*`` QAPI object (e.g. ``ImageInfoSpecificQCow2`` for qcow2 images). + *Block limits* + The block limits for I/O that QEMU detected for the image. + This information is only shown if the ``--limits`` option was specified. + .. option:: map [--object OBJECTDEF] [--image-opts] [-f FMT] [--start-offset=OFFSET] [--max-length=LEN] [--output=OFMT] [-U] FILENAME Dump the metadata of image *FILENAME* and its backing file chain. diff --git a/include/block/qapi.h b/include/block/qapi.h index 54c48de26a3..be554e53dca 100644 --- a/include/block/qapi.h +++ b/include/block/qapi.h @@ -42,7 +42,7 @@ bdrv_query_image_info(BlockDriverState *bs, ImageInfo **p_info, bool flat, bool skip_implicit_filters, Error **errp); void GRAPH_RDLOCK bdrv_query_block_graph_info(BlockDriverState *bs, BlockGraphInfo **p_info, - Error **errp); + bool limits, Error **errp); void bdrv_snapshot_dump(QEMUSnapshotInfo *sn); void bdrv_image_info_specific_dump(ImageInfoSpecific *info_spec, diff --git a/qemu-img-cmds.hx b/qemu-img-cmds.hx index 2c5a8a28f9d..74b66f9d423 100644 --- a/qemu-img-cmds.hx +++ b/qemu-img-cmds.hx @@ -66,9 +66,9 @@ SRST ERST DEF("info", img_info, - "info [--object objectdef] [--image-opts] [-f fmt] [--output=ofmt] [--backing-chain] [-U] filename") + "info [--object objectdef] [--image-opts] [-f fmt] [--output=ofmt] [--backing-chain] [--limits] [-U] filename") SRST -.. option:: info [--object OBJECTDEF] [--image-opts] [-f FMT] [--output=OFMT] [--backing-chain] [-U] FILENAME +.. option:: info [--object OBJECTDEF] [--image-opts] [-f FMT] [--output=OFMT] [--backing-chain] [--limits] [-U] FILENAME ERST DEF("map", img_map, diff --git a/qemu-img.c b/qemu-img.c index 7a162fdc08d..5cdbeda9699 100644 --- a/qemu-img.c +++ b/qemu-img.c @@ -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; }