KernelBlockDevices: libblockdev Reference Manual

KernelBlockDevices

KernelBlockDevices — plugin for operations with kernel block devices

Functions

gboolean	bd_kbd_bcache_attach ()
gboolean	bd_kbd_bcache_create ()
gboolean	bd_kbd_bcache_destroy ()
gboolean	bd_kbd_bcache_detach ()
gchar *	bd_kbd_bcache_get_backing_device ()
gchar *	bd_kbd_bcache_get_cache_device ()
BDKBDBcacheMode	bd_kbd_bcache_get_mode ()
BDKBDBcacheMode	bd_kbd_bcache_get_mode_from_str ()
const gchar *	bd_kbd_bcache_get_mode_str ()
gboolean	bd_kbd_bcache_set_mode ()
BDKBDBcacheStats *	bd_kbd_bcache_stats_copy ()
void	bd_kbd_bcache_stats_free ()
BDKBDBcacheStats *	bd_kbd_bcache_status ()
GQuark	bd_kbd_error_quark ()
gboolean	bd_kbd_zram_create_devices ()
gboolean	bd_kbd_zram_destroy_devices ()
BDKBDZramStats *	bd_kbd_zram_get_stats ()
BDKBDZramStats *	bd_kbd_zram_stats_copy ()
void	bd_kbd_zram_stats_free ()

Types and Values

enum	BDKBDBcacheMode
	BDKBDBcacheStats
enum	BDKBDError
	BDKBDZramStats
#define	BD_KBD_ERROR

Includes

#include <kbd.h>

Description

A plugin for operations with kernel block devices.

Functions

bd_kbd_bcache_attach ()

gboolean
bd_kbd_bcache_attach (gchar *c_set_uuid,
                      gchar *bcache_device,
                      GError **error);

Parameters

c_set_uuid	cache set UUID of the cache to attach
bcache_device	bcache device to attach `c_set_uuid` cache to
error	place to store error (if any).	[out]

Returns

whether the c_set_uuid cache was successfully attached to bcache_device or not

bd_kbd_bcache_create ()

gboolean
bd_kbd_bcache_create (gchar *backing_device,
                      gchar *cache_device,
                      gchar **bcache_device,
                      GError **error);

Parameters

backing_device	backing (slow) device of the cache
cache_device	cache (fast) device of the cache
bcache_device	place to store the name of the new bcache device (if any).	[out][allow-none]
error	place to store error (if any).	[out]

Returns

whether the bcache device was successfully created or not

bd_kbd_bcache_destroy ()

gboolean
bd_kbd_bcache_destroy (gchar *bcache_device,
                       GError **error);

Parameters

bcache_device	bcache device to destroy
error	place to store error (if any).	[out]

Returns

whether the bcache device bcache_device was successfully destroyed or not

bd_kbd_bcache_detach ()

gboolean
bd_kbd_bcache_detach (gchar *bcache_device,
                      gchar **c_set_uuid,
                      GError **error);

Parameters

bcache_device	bcache device to detach the cache from
c_set_uuid	cache set UUID of the detached cache.	[out][allow-none][transfer full]
error	place to store error (if any).	[out]

Returns

whether the bcache device bcache_device was successfully destroyed or not

Note: Flushes the cache first.

bd_kbd_bcache_get_backing_device ()

gchar *
bd_kbd_bcache_get_backing_device (gchar *bcache_device,
                                  GError **error);

Parameters

bcache_device	Bcache device to get the backing device for
error	place to store error (if any).	[out]

Returns

name of the backing device of the bcache_device or NULL if failed to determine (error is populated).

[transfer full]

bd_kbd_bcache_get_cache_device ()

gchar *
bd_kbd_bcache_get_cache_device (gchar *bcache_device,
                                GError **error);

Parameters

bcache_device	Bcache device to get the cache device for
error	place to store error (if any).	[out]

Returns

name of the cache device of the bcache_device or NULL if failed to determine (error is populated)

Note: returns the name of the first cache device of bcache_device (in case there are more).

[transfer full]

bd_kbd_bcache_get_mode ()

BDKBDBcacheMode
bd_kbd_bcache_get_mode (gchar *bcache_device,
                        GError **error);

Parameters

bcache_device	device to get mode of
error	place to store error (if any).	[out]

Returns

current mode of the bcache_device

bd_kbd_bcache_get_mode_from_str ()

BDKBDBcacheMode
bd_kbd_bcache_get_mode_from_str (gchar *mode_str,
                                 GError **error);

Parameters

mode_str	string representation of mode
error	place to store error (if any).	[out]

Returns

mode matching the mode_str given or BD_KBD_MODE_UNKNOWN in case of no match

bd_kbd_bcache_get_mode_str ()

const gchar *
bd_kbd_bcache_get_mode_str (BDKBDBcacheMode mode,
                            GError **error);

Parameters

mode	mode to get string representation of
error	place to store error (if any).	[out]

Returns

string representation of mode or NULL in case of error.

[transfer none]

bd_kbd_bcache_set_mode ()

gboolean
bd_kbd_bcache_set_mode (gchar *bcache_device,
                        BDKBDBcacheMode mode,
                        GError **error);

Parameters

bcache_device	bcache device to set mode of
mode	mode to set
error	place to store error (if any).	[out]

Returns

whether the mode was successfully set or not

bd_kbd_bcache_stats_copy ()

BDKBDBcacheStats *
bd_kbd_bcache_stats_copy (BDKBDBcacheStats *data);

Creates a new copy of data .

[skip]

bd_kbd_bcache_stats_free ()

void
bd_kbd_bcache_stats_free (BDKBDBcacheStats *data);

Frees data .

[skip]

bd_kbd_bcache_status ()

BDKBDBcacheStats *
bd_kbd_bcache_status (gchar *bcache_device,
                      GError **error);

Parameters

bcache_device	bcache device to get status for
error	place to store error (if any).	[out]

Returns

status of the bcache_device or NULL in case of error (error is set).

[transfer full]

bd_kbd_error_quark ()

GQuark
bd_kbd_error_quark (void);

[skip]

bd_kbd_zram_create_devices ()

gboolean
bd_kbd_zram_create_devices (guint64 num_devices,
                            guint64 *sizes,
                            guint64 *nstreams,
                            GError **error);

Parameters

num_devices	number of devices to create
sizes	requested sizes (in bytes) for created zRAM devices.	[array zero-terminated=1]
nstreams	numbers of streams for created zRAM devices.	[allow-none][array zero-terminated=1]
error	place to store error (if any).	[out]

Returns

whether num_devices zRAM devices were successfully created or not

**Lengths of size and nstreams (if given) have to be >= num_devices !**

bd_kbd_zram_destroy_devices ()

gboolean
bd_kbd_zram_destroy_devices (GError **error);

Parameters

error

place to store error (if any).

[out]

Returns

whether zRAM devices were successfully destroyed or not

The only way how to destroy zRAM device right now is to unload the 'zram' module and thus destroy all of them. That's why this function doesn't allow specification of which devices should be destroyed.

bd_kbd_zram_get_stats ()

BDKBDZramStats *
bd_kbd_zram_get_stats (gchar *device,
                       GError **error);

Parameters

device	zRAM device to get stats for
error	place to store error (if any).	[out]

Returns

statistics for the zRAM device.

[transfer full]

bd_kbd_zram_stats_copy ()

BDKBDZramStats *
bd_kbd_zram_stats_copy (BDKBDZramStats *data);

Creates a new copy of data .

[skip]

bd_kbd_zram_stats_free ()

void
bd_kbd_zram_stats_free (BDKBDZramStats *data);

Frees data .

[skip]

Types and Values

enum BDKBDBcacheMode

Members

BD_KBD_MODE_WRITETHROUGH
BD_KBD_MODE_WRITEBACK
BD_KBD_MODE_WRITEAROUND
BD_KBD_MODE_NONE
BD_KBD_MODE_UNKNOWN

BDKBDBcacheStats

typedef struct {
    gchar *state;
    guint64 block_size;
    guint64 cache_size;
    guint64 cache_used;
    guint64 hits;
    guint64 misses;
    guint64 bypass_hits;
    guint64 bypass_misses;
} BDKBDBcacheStats;

Members

gchar *`state`;	state of the cache
guint64 `block_size`;	block size used by the cache
guint64 `cache_size`;	size of the cache
guint64 `cache_used`;	size of the used space in the cache
guint64 `hits`;	number of hits
guint64 `misses`;	number of misses
guint64 `bypass_hits`;	number of bypass hits
guint64 `bypass_misses`;	number of bypass misses

enum BDKBDError

Members

BD_KBD_ERROR_INVAL
BD_KBD_ERROR_KMOD_INIT_FAIL
BD_KBD_ERROR_MODULE_FAIL
BD_KBD_ERROR_MODULE_NOEXIST
BD_KBD_ERROR_ZRAM_NOEXIST
BD_KBD_ERROR_ZRAM_INVAL
BD_KBD_ERROR_BCACHE_PARSE
BD_KBD_ERROR_BCACHE_SETUP_FAIL
BD_KBD_ERROR_BCACHE_DETACH_FAIL
BD_KBD_ERROR_BCACHE_NOT_ATTACHED
BD_KBD_ERROR_BCACHE_UUID
BD_KBD_ERROR_BCACHE_MODE_FAIL
BD_KBD_ERROR_BCACHE_MODE_INVAL
BD_KBD_ERROR_BCACHE_NOEXIST
BD_KBD_ERROR_BCACHE_INVAL

BDKBDZramStats

typedef struct {
    guint64 disksize;
    guint64 num_reads;
    guint64 num_writes;
    guint64 invalid_io;
    guint64 zero_pages;
    guint64 max_comp_streams;
    gchar* comp_algorithm;
    guint64 orig_data_size;
    guint64 compr_data_size;
    guint64 mem_used_total;
} BDKBDZramStats;

see zRAM kernel documentation for details (https://www.kernel.org/doc/Documentation/blockdev/zram.txt)

BD_KBD_ERROR

#define             BD_KBD_ERROR