Re: [PATCH 5/5] commands: dmsetup: Basic command set for dm device management

[Ahmad Fatoum <a.fatoum@pengutronix.de>]

On 8/28/25 5:05 PM, Tobias Waldekranz wrote:
> Modeled on dmsetup(8) from LVM2.
> 
> This lets the user create/remove arbitrary dm devices using the same
> table file format used in Linux, and dump information about currently
> configured devices.
> 
> Signed-off-by: Tobias Waldekranz <tobias@waldekranz.com>
> ---
>  commands/Kconfig   |  14 +++++
>  commands/Makefile  |   1 +
>  commands/dmsetup.c | 145 +++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 160 insertions(+)
>  create mode 100644 commands/dmsetup.c
> 
> diff --git a/commands/Kconfig b/commands/Kconfig
> index 1626912c30..219f626c3e 100644
> --- a/commands/Kconfig
> +++ b/commands/Kconfig
> @@ -732,6 +732,20 @@ config CMD_PARTED
>  	         unit <unit>     change display/input units
>  	         refresh         refresh a partition table
>  
> +config CMD_DMSETUP
> +	tristate
> +	depends on DM_BLK
> +	prompt "dmsetup"
> +	help
> +	  dmsetup - low level interface to the device mapper
> +
> +	  Compose virtual block devices from a table of mappings from
> +	  logical block addresses to various data sources, such as
> +	  linear ranges from other existing devices.
> +
> +	  commands:
> +	        create <name> <table-file>
> +
>  config CMD_UBI
>  	tristate
>  	default y if MTD_UBI
> diff --git a/commands/Makefile b/commands/Makefile
> index d9403b18d5..6b010fe30c 100644
> --- a/commands/Makefile
> +++ b/commands/Makefile
> @@ -166,4 +166,5 @@ obj-$(CONFIG_CMD_STACKSMASH)	+= stacksmash.o
>  obj-$(CONFIG_CMD_PARTED)	+= parted.o
>  obj-$(CONFIG_CMD_EFI_HANDLE_DUMP)	+= efi_handle_dump.o
>  obj-$(CONFIG_CMD_HOST)		+= host.o
> +obj-$(CONFIG_CMD_DMSETUP)	+= dmsetup.o
>  UBSAN_SANITIZE_ubsan.o := y
> diff --git a/commands/dmsetup.c b/commands/dmsetup.c
> new file mode 100644
> index 0000000000..722aa6cbf0
> --- /dev/null
> +++ b/commands/dmsetup.c
> @@ -0,0 +1,145 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +// SPDX-FileCopyrightText: © 2025 Tobias Waldekranz <tobias@waldekranz.com>, Wires
> +
> +#include <command.h>
> +#include <common.h>
> +#include <dm.h>
> +#include <libfile.h>
> +
> +static struct dm_device *dmsetup_find(const char *name)
> +{
> +	struct dm_device *dm;
> +
> +	dm = dm_find_by_name(name);
> +	if (IS_ERR_OR_NULL(dm)) {
> +		pr_err("Found no device named \"%s\"\n", name);

pr_/dev_ is logged, so will also be shared with Linux if pstore/ramoops
is enabled. For commands, just use printf.

> +		return NULL;
> +	}
> +
> +	return dm;
> +}

> +	dm = dm_create(argv[0], table);
> +	free(table);
> +	if (IS_ERR_OR_NULL(dm)) {
> +		pr_err("Failed to create %s: %s\n",
> +		       argv[0], strerror(-PTR_ERR(dm)));

%pe and pass dm directly.

> +		return COMMAND_ERROR;
> +	}
> +
> +	pr_info("Created %s\n", argv[0]);
> +	return COMMAND_SUCCESS;
> +}
> +
> +static int do_dmsetup(int argc, char *argv[])
> +{
> +	const char *cmd;
> +
> +	if (argc < 2)
> +		return COMMAND_ERROR_USAGE;
> +
> +	cmd = argv[1];
> +	argc -= 2;
> +	argv += 2;
> +
> +	if (!strcmp(cmd, "create"))
> +		return dmsetup_create(argc, argv);
> +	else if (!strcmp(cmd, "info"))
> +		return dmsetup_info(argc, argv);
> +	else if (!strcmp(cmd, "remove"))
> +		return dmsetup_remove(argc, argv);
> +
> +	printf("Unknown command: %s\n", cmd);
> +	return -EINVAL;
> +}
> +
> +BAREBOX_CMD_HELP_START(dmsetup)
> +BAREBOX_CMD_HELP_TEXT("dmsetup - low level interface to the device mapper")
> +BAREBOX_CMD_HELP_TEXT("")
> +BAREBOX_CMD_HELP_TEXT("Compose virtual block devices from a table of mappings from")
> +BAREBOX_CMD_HELP_TEXT("logical block addresses to various data sources, such as")
> +BAREBOX_CMD_HELP_TEXT("linear ranges from other existing devices.")
> +BAREBOX_CMD_HELP_TEXT("")
> +BAREBOX_CMD_HELP_TEXT("commands:")
> +BAREBOX_CMD_HELP_OPT("create <name> <table-file>", "Create new device")
> +BAREBOX_CMD_HELP_OPT("info [<name>]", "Show device information")
> +BAREBOX_CMD_HELP_OPT("remove <name>", "Remove device")
> +BAREBOX_CMD_HELP_END

Nice. FYI, if selftest is too cumbersome once you start adding more
targets, you can also add tests that exercise commands via pytest. See
test/py/.

Cheers,
Ahmad

> +
> +BAREBOX_CMD_START(dmsetup)
> +	.cmd = do_dmsetup,
> +	BAREBOX_CMD_DESC("low level interface to the device mapper")
> +	BAREBOX_CMD_OPTS("<command> [args...]")
> +	BAREBOX_CMD_GROUP(CMD_GRP_PART)
> +	BAREBOX_CMD_HELP(cmd_dmsetup_help)
> +BAREBOX_CMD_END

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