minix/servers/vfs/main.c

/*
 * a loop that gets messages requesting work, carries out the work, and sends
 * replies.
 *
 * The entry points into this file are:
 *   main:	main program of the Virtual File System
 *   reply:	send a reply to a process after the requested work is done
 *
 * Changes for VFS:
 *   Jul 2006 (Balazs Gerofi)
 */

#include "fs.h"
#include <fcntl.h>
#include <string.h>
#include <stdio.h>
#include <signal.h>
#include <assert.h>
#include <stdlib.h>
#include <sys/ioc_memory.h>
#include <sys/svrctl.h>
#include <sys/select.h>
#include <minix/callnr.h>
#include <minix/com.h>
#include <minix/keymap.h>
#include <minix/const.h>
#include <minix/endpoint.h>
#include <minix/safecopies.h>
#include "file.h"
#include "fproc.h"
#include "param.h"

#include <minix/vfsif.h>
#include "vmnt.h"
#include "vnode.h"

#if ENABLE_SYSCALL_STATS
EXTERN unsigned long calls_stats[NCALLS];
#endif

FORWARD _PROTOTYPE( void fs_init, (void)				);
FORWARD _PROTOTYPE( void get_work, (void)				);
FORWARD _PROTOTYPE( void init_root, (void)				);
FORWARD _PROTOTYPE( void service_pm, (void)				);


/*===========================================================================*
 *				main					     *
 *===========================================================================*/
PUBLIC int main()
{
/* This is the main program of the file system.  The main loop consists of
 * three major activities: getting new work, processing the work, and sending
 * the reply.  This loop never terminates as long as the file system runs.
 */
  int error;

  fs_init();

  /* This is the main loop that gets work, processes it, and sends replies. */
  while (TRUE) {
	get_work();		/* sets who and call_nr */

	if (who_e == PM_PROC_NR && call_nr != PROC_EVENT)
		printf("FS: strange, got message %d from PM\n", call_nr);

	if (call_nr == DEV_REVIVE)
	{
		endpoint_t endpt;

		endpt = m_in.REP_ENDPT;
		if(endpt == FS_PROC_NR) {
			endpt = suspended_ep(m_in.m_source, m_in.REP_IO_GRANT);
			if(endpt == NONE) {
				printf("FS: proc with "
			"grant %d from %d not found (revive)\n",
					m_in.REP_IO_GRANT, m_in.m_source);
				continue;
			}
		}
		revive(endpt, m_in.REP_STATUS);
		continue;
	}
	if (call_nr == DEV_REOPEN_REPL)
	{
		reopen_reply();
		continue;
	}
	if (call_nr == DEV_CLOSE_REPL)
	{
		close_reply();
		continue;
	}
	if (call_nr == DEV_SEL_REPL1)
	{
		select_reply1();
		continue;
	}
	if (call_nr == DEV_SEL_REPL2)
	{
		select_reply2();
		continue;
	}

 	/* Check for special control messages first. */
        if ((call_nr & NOTIFY_MESSAGE)) {
		if (call_nr == PROC_EVENT && who_e == PM_PROC_NR)
		{
			/* PM tries to get FS to do something */
			service_pm();
		}
		else if (call_nr == SYN_ALARM && who_e == CLOCK)
		{
			/* Alarm timer expired. Used only for select().
			 * Check it.
			 */
			fs_expire_timers(m_in.NOTIFY_TIMESTAMP);
		}
		else
		{
			/* Device notifies us of an event. */
			dev_status(&m_in);
		}
#if 0
		if (!check_vrefs())
		{
			printf("after call %d from %d/%d\n",
				call_nr, who_p, who_e);
			panic(__FILE__, "check_vrefs failed at line", __LINE__);
		}
#endif
		continue;
	}

	/* We only expect notify()s from tasks. */
	if(who_p < 0) {
    		printf("FS: ignoring message from %d (%d)\n",
			who_e, m_in.m_type);
		continue;
	}

	/* Now it's safe to set and check fp. */
	fp = &fproc[who_p];	/* pointer to proc table struct */
	super_user = (fp->fp_effuid == SU_UID ? TRUE : FALSE);   /* su? */

	/* Calls from VM. */
	if(who_e == VM_PROC_NR) {
	    int caught = 1;
	    switch(call_nr)
	    {
		case VM_VFS_OPEN:
			error = do_vm_open();
			break;
		case VM_VFS_CLOSE:
			error = do_vm_close();
			break;
		case VM_VFS_MMAP:
			error = do_vm_mmap();
			break;
		default:
			caught = 0;
			break;
	   }
	   if(caught) {
		reply(who_e, error);
		continue;
	   }
	}

	  /* Other calls. */
	  switch(call_nr)
	  {
	      case DEVCTL:
		error= do_devctl();
		if (error != SUSPEND) reply(who_e, error);
		break;

	      case MAPDRIVER:
		error= do_mapdriver();
		if (error != SUSPEND) reply(who_e, error);
		break;

	      default:
		/* Call the internal function that does the work. */
		if (call_nr < 0 || call_nr >= NCALLS) { 
			error = SUSPEND;
			/* Not supposed to happen. */
			printf("VFS: illegal %d system call by %d\n",
				call_nr, who_e);
		} else if (fp->fp_pid == PID_FREE) {
			error = ENOSYS;
			printf(
		"FS, bad process, who = %d, call_nr = %d, endpt1 = %d\n",
				 who_e, call_nr, m_in.endpt1);
		} else {
#if ENABLE_SYSCALL_STATS
			calls_stats[call_nr]++;
#endif
			error = (*call_vec[call_nr])();
		}

		/* Copy the results back to the user and send reply. */
		if (error != SUSPEND) { reply(who_e, error); }
	}
#if 0
	if (!check_vrefs())
	{
		printf("after call %d from %d/%d\n", call_nr, who_p, who_e);
		panic(__FILE__, "check_vrefs failed at line", __LINE__);
	}
#endif
	
	
  }
  return(OK);				/* shouldn't come here */
}

/*===========================================================================*
 *				get_work				     *
 *===========================================================================*/
PRIVATE void get_work()
{  
  /* Normally wait for new input.  However, if 'reviving' is
   * nonzero, a suspended process must be awakened.
   */
  int r, found_one, fd_nr;
  struct filp *f;
  register struct fproc *rp;

  while (reviving != 0) {
	found_one= FALSE;

	/* Revive a suspended process. */
	for (rp = &fproc[0]; rp < &fproc[NR_PROCS]; rp++) 
		if (rp->fp_pid != PID_FREE && rp->fp_revived == REVIVING) {
			found_one= TRUE;
			who_p = (int)(rp - fproc);
			who_e = rp->fp_endpoint;
			call_nr = rp->fp_fd & BYTE;

			m_in.fd = (rp->fp_fd >>8) & BYTE;
			m_in.buffer = rp->fp_buffer;
			m_in.nbytes = rp->fp_nbytes;
			rp->fp_suspended = NOT_SUSPENDED; /*no longer hanging*/
			rp->fp_revived = NOT_REVIVING;
			reviving--;
			/* This should be a pipe I/O, not a device I/O.
			 * If it is, it'll 'leak' grants.
			 */
			assert(!GRANT_VALID(rp->fp_grant));

			if (rp->fp_task == -XPIPE)
			{
				fp= rp;
				fd_nr= (rp->fp_fd >> 8);
				f= get_filp(fd_nr);
				assert(f != NULL);
				r= rw_pipe((call_nr == READ) ? READING :
					WRITING, who_e, fd_nr, f,
					rp->fp_buffer, rp->fp_nbytes);
				if (r != SUSPEND)
					reply(who_e, r);
				continue;
			}

			return;
		}
	if (!found_one)
		panic(__FILE__,"get_work couldn't revive anyone", NO_NUM);
  }

  for(;;) {
    int r;
    /* Normal case.  No one to revive. */
    if ((r=receive(ANY, &m_in)) != OK)
	panic(__FILE__,"fs receive error", r);
    who_e = m_in.m_source;
    who_p = _ENDPOINT_P(who_e);

    if(who_p < -NR_TASKS || who_p >= NR_PROCS)
     	panic(__FILE__,"receive process out of range", who_p);
    if(who_p >= 0 && fproc[who_p].fp_endpoint == NONE) {
    	printf("FS: ignoring request from %d, endpointless slot %d (%d)\n",
		m_in.m_source, who_p, m_in.m_type);
	continue;
    }
    if(who_p >= 0 && fproc[who_p].fp_endpoint != who_e) {
    	printf("FS: receive endpoint inconsistent (%d, %d, %d).\n",
		who_e, fproc[who_p].fp_endpoint, who_e);
	panic(__FILE__, "FS: inconsistent endpoint ", NO_NUM);
	continue;
    }
    call_nr = m_in.m_type;
    return;
  }
}


/*===========================================================================*
 *				reply					     *
 *===========================================================================*/
PUBLIC void reply(whom, result)
int whom;			/* process to reply to */
int result;			/* result of the call (usually OK or error #) */
{
/* Send a reply to a user process.  If the send fails, just ignore it. */
  int s;

#if 0
  if (call_nr == SYMLINK)
	printf("vfs:reply: replying %d for call %d\n", result, call_nr);
#endif

  m_out.reply_type = result;
  s = sendnb(whom, &m_out);
  if (s != OK) printf("VFS: couldn't send reply %d to %d: %d\n",
	result, whom, s);
}

/*===========================================================================*
 *				fs_init					     *
 *===========================================================================*/
PRIVATE void fs_init()
{
/* Initialize global variables, tables, etc. */
  int s;
  register struct fproc *rfp;
  struct vmnt *vmp;
  struct vnode *root_vp;
  message mess;

  /* Clear endpoint field */
  last_login_fs_e = NONE;
  mount_m_in.m1_p3 = (char *) NONE;

  /* Initialize the process table with help of the process manager messages. 
   * Expect one message for each system process with its slot number and pid. 
   * When no more processes follow, the magic process number NONE is sent. 
   * Then, stop and synchronize with the PM.
   */
  do {
  	if (OK != (s=receive(PM_PROC_NR, &mess)))
  		panic(__FILE__,"FS couldn't receive from PM", s);
  	if (NONE == mess.PR_ENDPT) break; 

	rfp = &fproc[mess.PR_SLOT];
	rfp->fp_pid = mess.PR_PID;
	rfp->fp_endpoint = mess.PR_ENDPT;
	rfp->fp_realuid = (uid_t) SYS_UID;
	rfp->fp_effuid = (uid_t) SYS_UID;
	rfp->fp_realgid = (gid_t) SYS_GID;
	rfp->fp_effgid = (gid_t) SYS_GID;
	rfp->fp_umask = ~0;
	rfp->fp_grant = GRANT_INVALID;
   
  } while (TRUE);			/* continue until process NONE */
  mess.m_type = OK;			/* tell PM that we succeeded */
  s = send(PM_PROC_NR, &mess);		/* send synchronization message */

  /* All process table entries have been set. Continue with FS initialization.
   * Certain relations must hold for the file system to work at all. Some 
   * extra block_size requirements are checked at super-block-read-in time.
   */
  if (OPEN_MAX > 127) panic(__FILE__,"OPEN_MAX > 127", NO_NUM);
  
  /* The following initializations are needed to let dev_opcl succeed .*/
  fp = (struct fproc *) NULL;
  who_e = who_p = FS_PROC_NR;

  build_dmap();			/* build device table and map boot driver */
  init_root();			/* init root device and load super block */
  init_select();		/* init select() structures */


  vmp = &vmnt[0];		/* Should be the root filesystem */
  if (vmp->m_dev == NO_DEV)
	panic(__FILE__, "vfs:fs_init: no root filesystem", NO_NUM);
  root_vp= vmp->m_root_node;

  /* The root device can now be accessed; set process directories. */
  for (rfp=&fproc[0]; rfp < &fproc[NR_PROCS]; rfp++) {
	FD_ZERO(&(rfp->fp_filp_inuse));
  	if (rfp->fp_pid != PID_FREE) {
                
		dup_vnode(root_vp);
                rfp->fp_rd = root_vp;
		dup_vnode(root_vp);
                rfp->fp_wd = root_vp;
		
  	} else  rfp->fp_endpoint = NONE;
  }

  system_hz = sys_hz();
}

/*===========================================================================*
 *				init_root				     *
 *===========================================================================*/
PRIVATE void init_root()
{
  int r = OK;
  struct vmnt *vmp;
  struct vnode *root_node;
  struct dmap *dp;
  char *label;
  message m;
  struct node_details resX;
  
  /* Open the root device. */
  root_dev = DEV_IMGRD;
  ROOT_FS_E = MFS_PROC_NR;
  
  /* Wait FS login message */
  if (last_login_fs_e != ROOT_FS_E) {
	  /* Wait FS login message */
	  if (receive(ROOT_FS_E, &m) != OK) {
		  printf("VFS: Error receiving login request from FS_e %d\n", 
				  ROOT_FS_E);
		  panic(__FILE__, "Error receiving login request from root filesystem\n", ROOT_FS_E);
	  }
	  if (m.m_type != FS_READY) {
		  printf("VFS: Invalid login request from FS_e %d\n", 
				  ROOT_FS_E);
		  panic(__FILE__, "Error receiving login request from root filesystem\n", ROOT_FS_E);
	  }
  }
  last_login_fs_e = NONE;
  
  /* Initialize vmnt table */
  for (vmp = &vmnt[0]; vmp < &vmnt[NR_MNTS]; ++vmp)
      vmp->m_dev = NO_DEV;
  
  vmp = &vmnt[0];
 
  /* We'll need a vnode for the root inode, check whether there is one */
  if ((root_node = get_free_vnode(__FILE__, __LINE__)) == NIL_VNODE) {
	panic(__FILE__,"Cannot get free vnode", r);
  }
  
  /* Get driver process' endpoint */  
  dp = &dmap[(root_dev >> MAJOR) & BYTE];
  if (dp->dmap_driver == NONE) {
	panic(__FILE__,"No driver for root device", r);
  }

  label= dp->dmap_label;
  if (strlen(label) == 0)
  {
	panic(__FILE__, "vfs:init_root: no label for major", root_dev >> MAJOR);
  }

  /* Issue request */
  r = req_readsuper(ROOT_FS_E, label, root_dev, 0 /*!readonly*/,
	1 /*isroot*/, &resX);
  if (r != OK) {
      panic(__FILE__,"Cannot read superblock from root", r);
  }
  
  /* Fill in root node's fields */
  root_node->v_fs_e = resX.fs_e;
  root_node->v_inode_nr = resX.inode_nr;
  root_node->v_mode = resX.fmode;
  root_node->v_size = resX.fsize;
  root_node->v_sdev = NO_DEV;
  root_node->v_fs_count = 1;
  root_node->v_ref_count = 1;

  /* Fill in max file size and blocksize for the vmnt */
  vmp->m_fs_e = resX.fs_e;
  vmp->m_dev = root_dev;
  vmp->m_flags = 0;
  
  /* Root node is indeed on the partition */
  root_node->v_vmnt = vmp;
  root_node->v_dev = vmp->m_dev;

  /* Root directory is not mounted on a vnode. */
  vmp->m_mounted_on = NULL;
  vmp->m_root_node = root_node;
}

/*===========================================================================*
 *				service_pm				     *
 *===========================================================================*/
PRIVATE void service_pm()
{
	int r, call;
        struct vmnt *vmp;
	message m;

	/* Ask PM for work until there is nothing left to do */
	for (;;)
	{
		m.m_type= PM_GET_WORK;
		r= sendrec(PM_PROC_NR, &m);
		if (r != OK)
		{
			panic("VFS", "service_pm: sendrec failed", r);
		}
		if (m.m_type == PM_IDLE) {
			break;
		}
		call= m.m_type;
		switch(call)
		{
		case PM_SETSID:
			pm_setsid(m.PM_SETSID_PROC);

			/* No need to report status to PM */
			break;

		case PM_SETGID:
			pm_setgid(m.PM_SETGID_PROC, m.PM_SETGID_EGID,
				m.PM_SETGID_RGID);

			/* No need to report status to PM */
			break;

		case PM_SETUID:
			pm_setuid(m.PM_SETUID_PROC, m.PM_SETUID_EGID,
				m.PM_SETUID_RGID);

			/* No need to report status to PM */
			break;

		case PM_FORK:
			pm_fork(m.PM_FORK_PPROC, m.PM_FORK_CPROC,
				m.PM_FORK_CPID);

			/* No need to report status to PM */
			break;

		case PM_EXIT:
		case PM_EXIT_TR:
			pm_exit(m.PM_EXIT_PROC);

			/* Reply dummy status to PM for synchronization */
			m.m_type= (call == PM_EXIT_TR ? PM_EXIT_REPLY_TR :
				PM_EXIT_REPLY);
			/* Keep m.PM_EXIT_PROC */

			r= send(PM_PROC_NR, &m);
			if (r != OK)
				panic(__FILE__, "service_pm: send failed", r);
			break;

		case PM_UNPAUSE:
		case PM_UNPAUSE_TR:
			unpause(m.PM_UNPAUSE_PROC);

			/* No need to report status to PM */
			break;

		case PM_REBOOT:
			pm_reboot();

			/* Reply dummy status to PM for synchronization */
			m.m_type= PM_REBOOT_REPLY;
			r= send(PM_PROC_NR, &m);
			if (r != OK)
				panic(__FILE__, "service_pm: send failed", r);
			break;

		case PM_EXEC:
			r= pm_exec(m.PM_EXEC_PROC, m.PM_EXEC_PATH,
				m.PM_EXEC_PATH_LEN, m.PM_EXEC_FRAME, 
				m.PM_EXEC_FRAME_LEN);

			/* Reply status to PM */
			m.m_type= PM_EXEC_REPLY;
			/* Keep m.PM_EXEC_PROC */
			m.PM_EXEC_STATUS= r;
			
			r= send(PM_PROC_NR, &m);
			if (r != OK)
				panic(__FILE__, "service_pm: send failed", r);
			break;

		case PM_DUMPCORE:
			r= pm_dumpcore(m.PM_CORE_PROC,
				(struct mem_map *)m.PM_CORE_SEGPTR);

			/* Reply status to PM */
			m.m_type= PM_CORE_REPLY;
			/* Keep m.PM_CORE_PROC */
			m.PM_CORE_STATUS= r;
			
			r= send(PM_PROC_NR, &m);
			if (r != OK)
				panic(__FILE__, "service_pm: send failed", r);
			break;

		default:
			panic("VFS", "service_pm: unknown call", m.m_type);
		}
	}
}