minix/servers/vm/vfs.c

   1
   2 /* Sending requests to VFS and handling the replies.  */
   3
   4 #define _SYSTEM 1
   5
   6 #include <minix/callnr.h>
   7 #include <minix/com.h>
   8 #include <minix/config.h>
   9 #include <minix/const.h>
  10 #include <minix/ds.h>
  11 #include <minix/endpoint.h>
  12 #include <minix/minlib.h>
  13 #include <minix/type.h>
  14 #include <minix/ipc.h>
  15 #include <minix/sysutil.h>
  16 #include <minix/syslib.h>
  17 #include <minix/type.h>
  18 #include <minix/bitmap.h>
  19 #include <string.h>
  20 #include <errno.h>
  21 #include <unistd.h>
  22 #include <assert.h>
  23 #include <sys/param.h>
  24
  25 #include "proto.h"
  26 #include "glo.h"
  27 #include "util.h"
  28 #include "region.h"
  29 #include "sanitycheck.h"
  30
  31 #define STATELEN 70
  32
  33 static struct vfs_request_node {
  34         message                 reqmsg;
  35         char                    reqstate[STATELEN];
  36         void                    *opaque;
  37         endpoint_t              who;
  38         int                     req_id;
  39         vfs_callback_t          callback;
  40         struct vfs_request_node *next;
  41 } *first_queued, *active;
  42
  43 static void activate(void)
  44 {
  45         assert(!active);
  46         assert(first_queued);
  47
  48         active = first_queued;
  49         first_queued = first_queued->next;
  50
  51         if(asynsend3(VFS_PROC_NR, &active->reqmsg, AMF_NOREPLY) != OK)
  52                 panic("VM: asynsend to VFS failed");
  53 }
  54
  55 #define ID_MAX LONG_MAX
  56
  57 /*===========================================================================*
  58  *                              vfs_request                                 *
  59  *===========================================================================*/
  60 int vfs_request(int reqno, int fd, struct vmproc *vmp, u64_t offset, u32_t len,
  61         vfs_callback_t reply_callback, void *cbarg, void *state, int statelen)
  62 {
  63 /* Perform an asynchronous request to VFS.
  64  * We send a message of type VFS_VMCALL to VFS. VFS will respond
  65  * with message type VM_VFS_REPLY. We send the request asynchronously
  66  * and then handle the reply as it if were a VM_VFS_REPLY request.
  67  */
  68         message *m;
  69         static int reqid = 0;
  70         struct vfs_request_node *reqnode;
  71
  72         reqid++;
  73
  74         assert(statelen <= STATELEN);
  75
  76         if(!SLABALLOC(reqnode)) {
  77                 printf("vfs_request: no memory for request node\n");
  78                 return ENOMEM;
  79         }
  80
  81         m = &reqnode->reqmsg;
  82         memset(m, 0, sizeof(*m));
  83         m->m_type = VFS_VMCALL;
  84         m->VFS_VMCALL_REQ = reqno;
  85         m->VFS_VMCALL_FD = fd;
  86         m->VFS_VMCALL_REQID = reqid;
  87         m->VFS_VMCALL_ENDPOINT = vmp->vm_endpoint;
  88         m->VFS_VMCALL_OFFSET = offset;
  89         m->VFS_VMCALL_LENGTH = len;
  90
  91         reqnode->who = vmp->vm_endpoint;
  92         reqnode->req_id = reqid;
  93         reqnode->next = first_queued;
  94         reqnode->callback = reply_callback;
  95         reqnode->opaque = cbarg;
  96         if(state) memcpy(reqnode->reqstate, state, statelen);
  97         first_queued = reqnode;
  98
  99         /* Send the request message if none pending. */
 100         if(!active)
 101                 activate();
 102
 103         return OK;
 104 }
 105
 106 /*===========================================================================*
 107  *                              do_vfs_reply                                 *
 108  *===========================================================================*/
 109 int do_vfs_reply(message *m)
 110 {
 111 /* VFS has handled a VM request and VFS has replied. It must be the
 112  * active request.
 113  */
 114         struct vfs_request_node *orignode = active;
 115         vfs_callback_t req_callback;
 116         void *cbarg;
 117         int n;
 118         struct vmproc *vmp;
 119
 120         assert(active);
 121         assert(active->req_id == m->VMV_REQID);
 122
 123         /* the endpoint may have exited */
 124         if(vm_isokendpt(m->VMV_ENDPOINT, &n) != OK)
 125                 vmp = NULL;
 126         else    vmp = &vmproc[n];
 127
 128         req_callback = active->callback;
 129         cbarg = active->opaque;
 130         active = NULL;
 131
 132         /* Invoke requested reply-callback within VM. */
 133         if(req_callback) req_callback(vmp, m, cbarg, orignode->reqstate);
 134
 135         SLABFREE(orignode);
 136
 137         /* Send the next request message if any and not re-activated. */
 138         if(first_queued && !active)
 139                 activate();
 140
 141         return SUSPEND; /* don't reply to the reply */
 142 }
 143