Struct devicemapper::DM

pub struct DM {
    // some fields omitted
}

Context needed for communicating with devicemapper.

Methods

impl DM

fn new() -> Result<DM>

Create a new context for communicating with DM.

fn version(&self) -> Result<(u32, u32, u32)>

Devicemapper version information: Major, Minor, and patchlevel versions.

fn remove_all(&self, flags: DmFlags) -> Result<()>

Remove all DM devices and tables. Use discouraged other than for debugging.

If DM_DEFERRED_REMOVE is set, the request will succeed for in-use devices, and they will be removed when released.

Valid flags: DM_DEFERRED_REMOVE

fn list_devices(&self) -> Result<Vec<(String, Device)>>

Returns a list of tuples containing DM device names and a Device, which holds their major and minor device numbers.

fn device_create(&self, name: &str, uuid: Option<&str>, flags: DmFlags) -> Result<DeviceInfo>

Create a DM device. It starts out in a "suspended" state.

Valid flags: DM_READONLY, DM_PERSISTENT_DEV

Example

use devicemapper::{DM, DmFlags};
let dm = DM::new().unwrap();

// Setting a uuid is optional
let dev = dm.device_create("example-dev", None, DmFlags::empty()).unwrap();

fn device_remove(&self, name: &DevId, flags: DmFlags) -> Result<DeviceInfo>

Remove a DM device and its mapping tables.

If DM_DEFERRED_REMOVE is set, the request for an in-use devices will succeed, and it will be removed when no longer used.

Valid flags: DM_DEFERRED_REMOVE

fn device_rename(&self, old_name: &str, new_name: &str, flags: DmFlags) -> Result<DeviceInfo>

Change a DM device's name.

If DM_UUID is set, change the UUID instead.

Valid flags: DM_UUID

fn device_suspend(&self, name: &DevId, flags: DmFlags) -> Result<DeviceInfo>

Suspend or resume a DM device, depending on if DM_SUSPEND flag is set or not.

Resuming a DM device moves a table loaded into the "inactive" slot by table_load() into the "active" slot.

Will block until pending I/O is completed unless DM_NOFLUSH flag is given. Will freeze filesystem unless DM_SKIP_LOCKFS flags is given. Additional I/O to a suspended device will be held until it is resumed.

Valid flags: DM_SUSPEND, DM_NOFLUSH, DM_SKIP_LOCKFS

Example

use devicemapper::{DM, DmFlags, DM_SUSPEND, DevId};
let dm = DM::new().unwrap();

dm.device_suspend(&DevId::Name("example-dev"), DM_SUSPEND).unwrap();

fn device_status(&self, name: &DevId) -> Result<DeviceInfo>

Get DeviceInfo for a device. This is also returned by other methods, but if just the DeviceInfo is desired then this just gets it.

fn device_wait(&self, name: &DevId, flags: DmFlags) -> Result<(DeviceInfo, Vec<TargetLine>)>

Wait for a device to report an event.

Once an event occurs, this function behaves just like table_status, see that function for more details.

This interface is not very friendly to monitoring multiple devices. Events are also exported via uevents, that method may be preferable.

fn table_load<T1, T2>(&self, name: &DevId, targets: &[(u64, u64, T1, T2)]) -> Result<DeviceInfo> where T1: Borrow<str>, T2: Borrow<str>

Load targets for a device into its inactive table slot.

targets is an array of (sector_start, sector_length, type, params).

params are target-specific, please see Linux kernel documentation for more.

Example

use devicemapper::{DM, DmFlags, DevId};
let dm = DM::new().unwrap();

// Create a 16MiB device (32768 512-byte sectors) that maps to /dev/sdb1
// starting 1MiB into sdb1
let table = vec![(0, 32768, "linear", "/dev/sdb1 2048")];

dm.table_load(&DevId::Name("example-dev"), &table).unwrap();

fn table_clear(&self, name: &DevId) -> Result<DeviceInfo>

Clear the "inactive" table for a device.

fn table_deps(&self, dev: Device, flags: DmFlags) -> Result<Vec<Device>>

Query DM for which devices are referenced by the "active" table for this device.

If DM_QUERY_INACTIVE_TABLE is set, instead return for the inactive table.

Valid flags: DM_QUERY_INACTIVE_TABLE

fn table_status(&self, name: &DevId, flags: DmFlags) -> Result<(DeviceInfo, Vec<TargetLine>)>

Return the status of all targets for a device's "active" table.

Returns DeviceInfo and a Vec of (sector_start, sector_length, type, params).

If DM_STATUS_TABLE flag is set, returns the current table value. Otherwise returns target-specific status information.

If DM_NOFLUSH is set, retrieving the target-specific status information for targets with metadata will not cause a metadata write.

If DM_QUERY_INACTIVE_TABLE is set, instead return the status of the inactive table.

Valid flags: DM_NOFLUSH, DM_STATUS_TABLE, DM_QUERY_INACTIVE_TABLE

Example

use devicemapper::{DM, DmFlags, DM_STATUS_TABLE, DevId};
let dm = DM::new().unwrap();

let res = dm.table_status(&DevId::Name("example-dev"), DM_STATUS_TABLE).unwrap();
println!("{} {:?}", res.0.name(), res.1);

fn list_versions(&self) -> Result<Vec<(String, u32, u32, u32)>>

Returns a list of each loaded target type with its name, and version broken into major, minor, and patchlevel.

fn target_msg(&self, name: &DevId, sector: u64, msg: &str) -> Result<(DeviceInfo, Option<String>)>

Send a message to the target at a given sector. If sector is not needed use 0. DM-wide messages start with '@', and may return a string; targets do not.

fn device_set_geometry(&self, _flags: DmFlags)

Unimplemented.

fn depends_on(&self, dev: Device, dm_majors: &BTreeSet<u32>) -> bool

Recursively walk DM deps to see if dev might be its own dependency.