tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1/*
2** DO NOT MODIFY THESE VALUES (would make old cowfiles unusable)
3*/
4#define MAPUNIT 1024 /* blocksize for bit in bitmap */
5#define MUSHIFT 10 /* bitshift for bit in bitmap */
6#define MUMASK 0x3ff /* bitmask for bit in bitmap */
7
8#define COWMAGIC 0x574f437f /* byte-swapped '7f C O W' */
9#define COWDIRTY 0x01
10#define COWPACKED 0x02
11#define COWVERSION 1
12
13struct cowhead
14{
15 int magic; /* identifies a cowfile */
16 short version; /* version of cowhead */
17 short flags; /* flags indicating status */
18 unsigned long mapunit; /* blocksize per bit in bitmap */
19 unsigned long mapsize; /* total size of bitmap (bytes) */
20 unsigned long doffset; /* start-offset datablocks in cow */
21 unsigned long rdoblocks; /* size of related read-only file */
22 unsigned long rdofingerprint; /* fingerprint of read-only file */
23 unsigned long cowused; /* number of datablocks used in cow */
24};
25
26#define COWDEVDIR "/dev/cow/"
27#define COWDEVICE COWDEVDIR "%ld"
28#define COWCONTROL COWDEVDIR "ctl"
29
30#define MAXCOWS 1024
31#define COWCTL (MAXCOWS-1) /* minor number of /dev/cow/ctl */
32
33#define COWPROCDIR "/proc/cow/"
34#define COWPROCFILE COWPROCDIR "%d"
35
36/*
37** ioctl related stuff
38*/
39#define ANYDEV ((unsigned long)-1)
40
41struct cowpair
42{
43 unsigned char *rdofile; /* pathname of the rdofile */
44 unsigned char *cowfile; /* pathname of the cowfile */
45 unsigned short rdoflen; /* length of rdofile pathname */
46 unsigned short cowflen; /* length of cowfile pathname */
47 unsigned long device; /* requested/returned device number */
48};
49
50struct cowwatch
51{
52 int flags; /* request flags */
53 unsigned long device; /* requested device number */
54 unsigned long threshold; /* continue if free Kb < threshold */
55 unsigned long totalkb; /* ret: total filesystem size (Kb) */
56 unsigned long availkb; /* ret: free filesystem size (Kb) */
57};
58
59#define WATCHWAIT 0x01 /* block until threshold reached */
60
61#define COWSYNC _IO ('C', 1)
62#define COWMKPAIR _IOW ('C', 2, struct cowpair)
63#define COWRMPAIR _IOW ('C', 3, unsigned long)
64#define COWWATCH _IOW ('C', 4, struct cowwatch)
65#define COWCLOSE _IOW ('C', 5, unsigned long)
66#define COWRDOPEN _IOW ('C', 6, unsigned long)