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/*
** DO NOT MODIFY THESE VALUES (would make old cowfiles unusable)
*/
#define MAPUNIT 1024 /* blocksize for bit in bitmap */
#define MUSHIFT 10 /* bitshift for bit in bitmap */
#define MUMASK 0x3ff /* bitmask for bit in bitmap */
#define COWMAGIC 0x574f437f /* byte-swapped '7f C O W' */
#define COWDIRTY 0x01
#define COWPACKED 0x02
#define COWVERSION 1
struct cowhead
{
int magic; /* identifies a cowfile */
short version; /* version of cowhead */
short flags; /* flags indicating status */
unsigned long mapunit; /* blocksize per bit in bitmap */
unsigned long mapsize; /* total size of bitmap (bytes) */
unsigned long doffset; /* start-offset datablocks in cow */
unsigned long rdoblocks; /* size of related read-only file */
unsigned long rdofingerprint; /* fingerprint of read-only file */
unsigned long cowused; /* number of datablocks used in cow */
};
#define COWDEVDIR "/dev/cow/"
#define COWDEVICE COWDEVDIR "%ld"
#define COWCONTROL COWDEVDIR "ctl"
#define MAXCOWS 1024
#define COWCTL (MAXCOWS-1) /* minor number of /dev/cow/ctl */
#define COWPROCDIR "/proc/cow/"
#define COWPROCFILE COWPROCDIR "%d"
/*
** ioctl related stuff
*/
#define ANYDEV ((unsigned long)-1)
struct cowpair
{
unsigned char *rdofile; /* pathname of the rdofile */
unsigned char *cowfile; /* pathname of the cowfile */
unsigned short rdoflen; /* length of rdofile pathname */
unsigned short cowflen; /* length of cowfile pathname */
unsigned long device; /* requested/returned device number */
};
struct cowwatch
{
int flags; /* request flags */
unsigned long device; /* requested device number */
unsigned long threshold; /* continue if free Kb < threshold */
unsigned long totalkb; /* ret: total filesystem size (Kb) */
unsigned long availkb; /* ret: free filesystem size (Kb) */
};
#define WATCHWAIT 0x01 /* block until threshold reached */
#define COWSYNC _IO ('C', 1)
#define COWMKPAIR _IOW ('C', 2, struct cowpair)
#define COWRMPAIR _IOW ('C', 3, unsigned long)
#define COWWATCH _IOW ('C', 4, struct cowwatch)
#define COWCLOSE _IOW ('C', 5, unsigned long)
#define COWRDOPEN _IOW ('C', 6, unsigned long)
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