DM(3) | Library Functions Manual | DM(3) |
dm
—
#include <dm.h>
void
libdm_iter_destroy
(libdm_iter_t
libdm_iter);
int
libdm_task_run
(libdm_task_t
*libdm_task);
libdm_task_t
libdm_task_create
(const
char *command);
void
libdm_task_destroy
(libdm_task_t
libdm_task);
int
libdm_task_set_name
(const
char *name, libdm_task_t
libdm_task);
char *
libdm_task_get_name
(libdm_task_t
libdm_task);
int
libdm_task_set_uuid
(const
char *uuid, libdm_task_t
libdm_task);
char *
libdm_task_get_uuid
(libdm_task_t
libdm_task);
char *
libdm_task_get_command
(libdm_task_t
libdm_task);
int32_t
libdm_task_get_cmd_version
(libdm_task_t
libdm_task, uint32_t
*ver, size_t
size);
int
libdm_task_set_minor
(uint32_t
minor, libdm_task_t
libdm_task);
uint32_t
libdm_task_get_minor
(libdm_task_t
libdm_task);
int
libdm_task_set_flags
(uint32_t
flags, libdm_task_t
libdm_task);
uint32_t
libdm_task_get_flags
(libdm_task_t
libdm_task);
uint32_t
libdm_task_get_target_num
(libdm_task_t
libdm_task);
int32_t
libdm_task_get_open_num
(libdm_task_t
libdm_task);
uint32_t
libdm_task_get_event_num
(libdm_task_t
libdm_task);
int
libdm_task_set_cmd
(libdm_cmd_t
libdm_cmd, libdm_task_t
libdm_task);
libdm_cmd_t
libdm_task_get_cmd
(libdm_task_t
libdm_task);
libdm_cmd_t
libdm_cmd_create
(void);
void
libdm_cmd_destroy
(libdm_cmd_t
libdm_cmd);
libdm_iter_t
libdm_cmd_iter_create
(libdm_cmd_t
libdm_cmd);
int
libdm_cmd_set_table
(libdm_table_t
libdm_table, libdm_cmd_t
libdm_cmd);
libdm_table_t
libdm_cmd_get_table
(libdm_iter_t
iter);
libdm_target_t
libdm_cmd_get_target
(libdm_iter_t
iter);
libdm_dev_t
libdm_cmd_get_dev
(libdm_iter_t
iter);
uint64_t
libdm_cmd_get_deps
(libdm_iter_t
libdm_iter);
libdm_table_t
libdm_table_create
(void);
void
libdm_table_destroy
(libdm_table_t
libdm_table);
int
libdm_table_set_start
(uint64_t
start, libdm_table_t
libdm_table);
uint64_t
libdm_table_get_start
(libdm_table_t
libdm_table);
int
libdm_table_set_length
(uint64_t
length, libdm_table_t
libdm_table);
uint64_t
libdm_table_get_length
(libdm_table_t
libdm_table);
int
libdm_table_set_target
(const
char *name, libdm_table_t
libdm_table);
char *
libdm_table_get_target
(libdm_table_t
libdm_table);
int
libdm_table_set_params
(const
char *params,
libdm_table_t
libdm_table);
char *
libdm_table_get_params
(libdm_table_t
libdm_table);
int32_t
libdm_table_get_status
(libdm_table_t
libdm_table);
void
libdm_target_destroy
(libdm_target_t
libdm_target);
char *
libdm_target_get_name
(libdm_target_t
libdm_target);
int32_t
libdm_target_get_version
(libdm_target_t
libdm_target, uint32_t
*ver, size_t
size);
void
libdm_dev_destroy
(libdm_dev_t
libdm_dev);
char *
libdm_dev_get_name
(libdm_dev_t
libdm_dev);
uint32_t
libdm_dev_get_minor
(libdm_dev_t
libdm_dev);
int
libdm_dev_set_newname
(const
char *newname,
libdm_cmd_t
libdm_cmd);
Except libdm_dev_t which is received from kernel as list of physical devices on which the logical device depends. libdm_target_t which is received from kernel as list of available targets to use. libdm_iter_t which is used as iteration counter for array entries in the task structure.
Every object attribute in libdm can be set and gotten by appropriate routines, therefore there always are set and get routines.
libdm_task_create
() function creates a libdm task
dictionary with command string set to command. If
command is NULL
, libdm_task_t is
not created and the function returns NULL
.
libdm_task_destroy
() free all memory
allocated to libdm_task by
libdm_task_create
().
libdm_task_run
() Sends created
libdm_task to kernel and receives new one as
reply.
List of attributes avaialable in libdm_task_t:
Attribute | Description | Mode |
DM_IOCTL_OPEN |
Device open-count | Read-Only |
DM_IOCTL_MINOR |
Device minor number | Read-Write |
DM_IOCTL_NAME |
Device name | Read-Write |
DM_IOCTL_UUID |
Device uuid | Read-Write |
DM_IOCTL_TARGET_COUNT |
Number of table entries | Read-Only |
DM_IOCTL_FLAGS |
Device status flags | Read-Write |
libdm_task_set_name
() and
libdm_task_get_name
() Set name of the device for
commands which need to have a dm device identifier. The device-mapper later
uses the device name to look up the device from the list of all devices. The
get routine will fetch the device name from the task dictionary.
libdm_task_set_uuid
() and
libdm_task_get_uuid
() Set uuid of device for
commands which need to have a dm device identifier. The device-mapper later
uses the device uuid to look up the device from the list of all devices. The
get routine will fetch the device uuid from the task dictionary.
libdm_task_set_minor
() and
libdm_task_get_minor
() Set minor device number of
device for commands which need to have a dm device identifier. The
device-mapper later uses the device minor number to look up the device from
the list of all devices. The get routine will fetch the device minor number
from the task dictionary.
libdm_task_set_flags
() and
libdm_task_get_flags
() Set/fetch device status flags
from the task dictionary.
libdm_task_get_open_num
() Fetch number of
opened devices from the kernel and return them as count.
libdm_task_get_target_num
() Fetch number
of opened devices from the kernel and return them as count.
libdm_task_get_cmd_version
() Get the
version of the dm driver in the kernel as array uint32_t
*ver of size size.
libdm_task_set_cmd
() and
libdm_task_get_cmd
() Add and fetch cmd structure
from libdm_task_t. libdm_cmd_t
is the container used to carry information specific for the particular
command. cmd is usually set before libdm_task_run is used and is taken from
the task structure after the task run was called.
libdm_cmd_create
() function will allocate a cmd
structure which can later be put in to the task.
libdm_cmd_destroy
() will deallocate a
previously allocated cmd structure.
libdm_cmd_set_table
() Will load and fetch
the device mapping table from the dm device. The table is usually loaded to
the device during initial device creation or device resizing.
Because libdm_cmd is an array of structures, all _get routines
need an iterator to work. For every entry we can have more than one.
libdm_cmd_get_table
() When the user creates a task
with the "status" command, the kernel sends cmd with a table in
it.
libdm_cmd_get_target
() Get mapping target
description from cmd. Target contains target_name and target_version.
libdm_cmd_get_dev
() When user creates a
task with the "info" command, the kernel sends cmd with
information about dm device to user.
libdm_cmd_get_deps
() When user creates a
task with the "deps" command, the kernel sends cmd with an array
of physical devices attached to the dm device.
Usually the device has more than one table entry in the device
command. Therefore cmd iterators are needed for
libdm_cmd_t; they can be created by the
libdm_cmd_iter_create
() function.
Example device table entry
0 1024 linear /dev/wd1a
384
Attribute | Description |
DM_TABLE_TYPE |
Used device mapper target |
DM_TABLE_START |
Device Logical start block |
DM_TABLE_STAT |
Is 1 if this is current active table |
DM_TABLE_LENGTH |
Logical length described by table |
DM_TABLE_PARAMS |
Params passed down to target |
libdm_table_set_start
() and
libdm_table_get_start
() Set start table from
start value to libdm_table
argument. Get routine will get the table start from kernel as
libdm_table.
libdm_table_set_length
() and
libdm_table_get_length
() Set table length from
length value to libdm_table
argument. Get routine will get the table length from kernel as
libdm_table.
libdm_table_set_target
() and
libdm_table_get_target
() Set target name from
target value to libdm_table
argument. The target must be actually present in the kernel, otherwise
libdm_task_run
() will fail. Get routine will get the
table entry target from kernel as libdm_table.
libdm_table_set_params
() and
libdm_table_get_params
() Set table target parameter
string from params argument to
libdm_table. This is later in the kernel passed to the
target init routine. Get routine will get the table parameter string from
kernel as libdm_table.
libdm_table_get_status
() Get table status
which can be Active/Inactive. This tells if this table is actually used or
not.
libdm_target_destroy
() Destroy target received from
libdm_cmd with libdm_cmd_iter iterator.
libdm_target_get_name
() returns pointer to
a string with available target name.
lobdm_target_get_version
() Sets argument
ver[3] to a in-kernel loaded target version.
libdm_dev_destroy
() Destroy device received from
libdm_cmd with libdm_cmd_iter iterator.
libdm_dev_get_name
() Return pointer to a
string with underlying device name from
libdm_dev_t
libdm_dev_get_minor
() Return underlying
device minor number.
libdm_dev_set_newname
() This routine will set new dm
device name attribute to newname. User must then called
libdm_task_run on this task to change the device name.
NULL
pointer. Otherwise, an error number will be
returned to indicate the error.
dm
was written and contributed to
NetBSD by Adam Hamsik and
first appeared in NetBSD 6.0.
January 22, 2016 | NetBSD 9.0 |