drivers/staging/cowloop/cowloop.h

   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
  13 struct 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
  41 struct 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
  50 struct 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)