1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
|
#include "job.h"
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <pthread.h>
#define DEV_STRLEN 12 // INCLUDING NULLCHAR (increase to 13 if you need more than 100 (0-99) devices)
#define MAX_NUM_DEVICES_TO_CHECK 100
#ifndef FALSE
#define FALSE (0)
#endif
#ifndef TRUE
#define TRUE (!FALSE)
#endif
typedef struct
{
char available;
char name[DEV_STRLEN];
} device_t;
// "/dev/dnbdXX" == 11 bytes per device + nullchar = 12
static device_t *devices = NULL;
static int num_devices = 0;
static char keep_running = TRUE;
static char* get_free_device();
void* dnbd3_job_thread(void *data)
{
int i, j;
// Determine number of available dnbd3 devices, which are needed for proxy mode
char dev[DEV_STRLEN];
for (i = 0; i < MAX_NUM_DEVICES_TO_CHECK; ++i)
{
sprintf(dev, "/dev/dnbd%d", i);
if (access(dev, W_OK | R_OK)) // Need RW access to device to read and do ioctl
continue;
++num_devices;
}
if (num_devices > 0)
{
devices = calloc(num_devices, sizeof(*devices));
for (i = 0, j = 0; i < MAX_NUM_DEVICES_TO_CHECK; ++i)
{
memset(dev, 0, DEV_STRLEN);
sprintf(dev, "/dev/dnbd%d", i);
if (access(dev, W_OK | R_OK))
continue;
if (j >= num_devices) // More available devices during second iteration? :-(
break;
memcpy(devices[j].name, dev, DEV_STRLEN);
devices[j].available = TRUE;
++j;
}
}
//
// Job/Watchdog mainloop
while (keep_running)
{
// TODO: Update image atime
// TODO: Handle image deletion
// TODO: Replicate proxied images (limited bandwidth)
// TODO: Query other servers for new images/status/...
// TODO: Switch server of dnbd device based on more sophisticated inputs than just rtt
}
//
free(devices);
devices = NULL;
pthread_exit(NULL);
return NULL;
}
void dnbd3_job_shutdown()
{
keep_running = FALSE;
}
/**
* Get full name of an available dnbd3 device, eg. /dev/dnbd4
* Returned buffer is owned by this module, do not modify or free!
*/
static char* get_free_device()
{
if (devices == NULL)
return NULL;
int i;
for (i = 0; i < num_devices; ++i)
{
if (!devices[i].available)
continue;
// TODO: Check sysfs if device is maybe already connected
return devices[i].name;
}
return NULL;
}
|
