minix/servers/vfs/tll.h

   1 #ifndef __VFS_TLL_H__
   2 #define __VFS_TLL_H__
   3
   4 /* Three-level-lock. Allows read-only, read-serialized, and write-only locks */
   5
   6 typedef enum { TLL_NONE, TLL_READ, TLL_READSER, TLL_WRITE } tll_access_t;
   7 typedef enum { TLL_DFLT = 0x0, TLL_UPGR = 0x1, TLL_PEND = 0x2 } tll_status_t;
   8
   9 typedef struct {
  10   tll_access_t t_current;       /* Current type of access to lock */
  11   struct worker_thread *t_owner;/* Owner of non-read-only lock */
  12   signed int t_readonly;        /* No. of current read-only access */
  13   tll_status_t t_status;        /* Lock status; nothing, pending upgrade, or
  14                                  * pending upgrade of read-serialized to
  15                                  * write-only */
  16   struct worker_thread *t_write;/* Write/read-only access requestors queue */
  17   struct worker_thread *t_serial;/* Read-serialized access requestors queue */
  18 } tll_t;
  19
  20 #endif