lib/libbdev/minor.c

   1 /* libbdev - tracking and reopening of opened minor devices */
   2
   3 #include <minix/drivers.h>
   4 #include <minix/bdev.h>
   5 #include <assert.h>
   6
   7 #include "const.h"
   8 #include "type.h"
   9 #include "proto.h"
  10
  11 static struct {
  12   dev_t dev;
  13   int count;
  14   int access;
  15 } open_dev[NR_OPEN_DEVS] = { { NO_DEV, 0, 0 } };
  16
  17 int bdev_minor_reopen(dev_t dev)
  18 {
  19 /* Reopen all minor devices on a major device. This function duplicates some
  20  * code from elsewhere, because in this case we must avoid performing recovery.
  21  * FIXME: if reopening fails with a non-IPC error, we should attempt to close
  22  * all minors that we did manage to reopen so far, or they might stay open
  23  * forever.
  24  */
  25   endpoint_t endpt;
  26   message m;
  27   int i, j, r, major;
  28
  29   major = major(dev);
  30   endpt = bdev_driver_get(dev);
  31
  32   assert(endpt != NONE);
  33
  34   for (i = 0; i < NR_OPEN_DEVS; i++) {
  35         if (major(open_dev[i].dev) != major)
  36                 continue;
  37
  38         /* Each minor device may have been opened multiple times. Send an open
  39          * request for each time that it was opened before. We could reopen it
  40          * just once, but then we'd have to keep a shadow open count as well.
  41          */
  42         for (j = 0; j < open_dev[i].count; j++) {
  43                 memset(&m, 0, sizeof(m));
  44                 m.m_type = BDEV_OPEN;
  45                 m.BDEV_MINOR = minor(open_dev[i].dev);
  46                 m.BDEV_ACCESS = open_dev[i].access;
  47                 m.BDEV_ID = NO_ID;
  48
  49                 if ((r = sendrec(endpt, &m)) != OK) {
  50                         printf("bdev: IPC to driver (%d) failed (%d)\n",
  51                                 endpt, r);
  52                         return r;
  53                 }
  54
  55                 if (m.m_type != BDEV_REPLY) {
  56                         printf("bdev: driver (%d) sent weird response (%d)\n",
  57                                 endpt, m.m_type);
  58                         return EINVAL;
  59                 }
  60
  61                 if (m.BDEV_ID != NO_ID) {
  62                         printf("bdev: driver (%d) sent invalid ID (%ld)\n",
  63                                 endpt, m.BDEV_ID);
  64                         return EINVAL;
  65                 }
  66
  67                 if ((r = m.BDEV_STATUS) != OK) {
  68                         printf("bdev: driver (%d) failed device reopen (%d)\n",
  69                                 endpt, r);
  70                         return r;
  71                 }
  72         }
  73   }
  74
  75   return OK;
  76 }
  77
  78 void bdev_minor_add(dev_t dev, int access)
  79 {
  80 /* Increase the reference count of the given minor device.
  81  */
  82   int i, free = -1;
  83
  84   for (i = 0; i < NR_OPEN_DEVS; i++) {
  85         if (open_dev[i].dev == dev) {
  86                 open_dev[i].count++;
  87                 open_dev[i].access |= access;
  88
  89                 return;
  90         }
  91
  92         if (free < 0 && open_dev[i].dev == NO_DEV)
  93                 free = i;
  94   }
  95
  96   if (free < 0) {
  97         printf("bdev: too many open devices, increase NR_OPEN_DEVS\n");
  98         return;
  99   }
 100
 101   open_dev[free].dev = dev;
 102   open_dev[free].count = 1;
 103   open_dev[free].access = access;
 104 }
 105
 106 void bdev_minor_del(dev_t dev)
 107 {
 108 /* Decrease the reference count of the given minor device, if present.
 109  */
 110   int i;
 111
 112   for (i = 0; i < NR_OPEN_DEVS; i++) {
 113         if (open_dev[i].dev == dev) {
 114                 if (!--open_dev[i].count)
 115                         open_dev[i].dev = NO_DEV;
 116
 117                 break;
 118         }
 119   }
 120 }