minix3/servers/vm/vfs.c

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2020-02-21 00:59:27 +05:30
/* Sending requests to VFS and handling the replies. */
#define _SYSTEM 1
#include <minix/callnr.h>
#include <minix/com.h>
#include <minix/config.h>
#include <minix/const.h>
#include <minix/ds.h>
#include <minix/endpoint.h>
#include <minix/minlib.h>
#include <minix/type.h>
#include <minix/ipc.h>
#include <minix/sysutil.h>
#include <minix/syslib.h>
#include <minix/type.h>
#include <minix/bitmap.h>
#include <string.h>
#include <errno.h>
#include <env.h>
#include <unistd.h>
#include <assert.h>
#include <sys/param.h>
#include "proto.h"
#include "glo.h"
#include "util.h"
#include "region.h"
#include "sanitycheck.h"
#define STATELEN 70
static struct vfs_request_node {
message reqmsg;
char reqstate[STATELEN];
void *opaque;
endpoint_t who;
int req_id;
vfs_callback_t callback;
struct vfs_request_node *next;
} *first_queued, *active;
static void activate(void)
{
assert(!active);
assert(first_queued);
active = first_queued;
first_queued = first_queued->next;
if(asynsend3(VFS_PROC_NR, &active->reqmsg, AMF_NOREPLY) != OK)
panic("VM: asynsend to VFS failed");
}
#define ID_MAX LONG_MAX
/*===========================================================================*
* vfs_request *
*===========================================================================*/
int vfs_request(int reqno, int fd, struct vmproc *vmp, u64_t offset, u32_t len,
vfs_callback_t reply_callback, void *cbarg, void *state, int statelen)
{
/* Perform an asynchronous request to VFS.
* We send a message of type VFS_VMCALL to VFS. VFS will respond
* with message type VM_VFS_REPLY. We send the request asynchronously
* and then handle the reply as it if were a VM_VFS_REPLY request.
*/
message *m;
static int reqid = 0;
struct vfs_request_node *reqnode;
reqid++;
assert(statelen <= STATELEN);
if(!SLABALLOC(reqnode)) {
printf("vfs_request: no memory for request node\n");
return ENOMEM;
}
m = &reqnode->reqmsg;
memset(m, 0, sizeof(*m));
m->m_type = VFS_VMCALL;
m->VFS_VMCALL_REQ = reqno;
m->VFS_VMCALL_FD = fd;
m->VFS_VMCALL_REQID = reqid;
m->VFS_VMCALL_ENDPOINT = vmp->vm_endpoint;
m->VFS_VMCALL_OFFSET = offset;
m->VFS_VMCALL_LENGTH = len;
reqnode->who = vmp->vm_endpoint;
reqnode->req_id = reqid;
reqnode->next = first_queued;
reqnode->callback = reply_callback;
reqnode->opaque = cbarg;
if(state) memcpy(reqnode->reqstate, state, statelen);
first_queued = reqnode;
/* Send the request message if none pending. */
if(!active)
activate();
return OK;
}
/*===========================================================================*
* do_vfs_reply *
*===========================================================================*/
int do_vfs_reply(message *m)
{
/* VFS has handled a VM request and VFS has replied. It must be the
* active request.
*/
struct vfs_request_node *orignode = active;
vfs_callback_t req_callback;
void *cbarg;
int n;
struct vmproc *vmp;
assert(active);
assert(active->req_id == m->VMV_REQID);
/* the endpoint may have exited */
if(vm_isokendpt(m->VMV_ENDPOINT, &n) != OK)
vmp = NULL;
else vmp = &vmproc[n];
req_callback = active->callback;
cbarg = active->opaque;
active = NULL;
/* Invoke requested reply-callback within VM. */
if(req_callback) req_callback(vmp, m, cbarg, orignode->reqstate);
SLABFREE(orignode);
/* Send the next request message if any and not re-activated. */
if(first_queued && !active)
activate();
return SUSPEND; /* don't reply to the reply */
}