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

[Tobias Waldekranz <tobias@waldekranz.com>]

On fre, sep 05, 2025 at 18:54, Ahmad Fatoum <a.fatoum@pengutronix.de> wrote:
> 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.

Wow, nice! I will have to look into this more.

>> +		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/.

Right, yes I will read up on this in the future.

Thanks for reviewing!

> 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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