minix/servers/mfs/device.c

#include "fs.h"
#include <fcntl.h>
#include <assert.h>
#include <minix/callnr.h>
#include <minix/com.h>
#include <minix/endpoint.h>
#include <minix/ioctl.h>
#include <minix/safecopies.h>
#include <minix/u64.h>
#include <string.h>
#include "inode.h"
#include "super.h"
#include "const.h"
#include "drivers.h"

#include <minix/vfsif.h>

PRIVATE int dummyproc;

FORWARD _PROTOTYPE( int safe_io_conversion, (endpoint_t,
  cp_grant_id_t *, int *, cp_grant_id_t *, int, endpoint_t *,
  void **, int *, vir_bytes));
FORWARD _PROTOTYPE( void safe_io_cleanup, (cp_grant_id_t, cp_grant_id_t *,
	int));
FORWARD _PROTOTYPE( int gen_opcl, (endpoint_t driver_e, int op,
				Dev_t dev, int proc_e, int flags)	);
FORWARD _PROTOTYPE( int gen_io, (endpoint_t task_nr, message *mess_ptr)	);


/*===========================================================================*
 *				fs_new_driver   			     *
 *===========================================================================*/
PUBLIC int fs_new_driver(void)
{
 /* New driver endpoint for this device */
  driver_endpoints[(fs_m_in.REQ_DEV >> MAJOR) & BYTE].driver_e =
	  fs_m_in.REQ_DRIVER_E;
  return(OK);
}


/*===========================================================================*
 *				safe_io_conversion			     *
 *===========================================================================*/
PRIVATE int safe_io_conversion(driver, gid, op, gids, gids_size,
	io_ept, buf, vec_grants, bytes)
endpoint_t driver;
cp_grant_id_t *gid;
int *op;
cp_grant_id_t *gids;
int gids_size;
endpoint_t *io_ept;
void **buf;
int *vec_grants;
vir_bytes bytes;
{
  int j;
  iovec_t *v;
  static iovec_t *new_iovec;

  STATICINIT(new_iovec, NR_IOREQS);
  
  /* Number of grants allocated in vector I/O. */
  *vec_grants = 0;

  /* Driver can handle it - change request to a safe one. */
  
  *gid = GRANT_INVALID;
  
  switch(*op) {
	case MFS_DEV_READ:
	case MFS_DEV_WRITE:
	  /* Change to safe op. */
	  *op = *op == MFS_DEV_READ ? DEV_READ_S : DEV_WRITE_S;
	  
	  if((*gid=cpf_grant_direct(driver, (vir_bytes) *buf, bytes,
				    *op == DEV_READ_S?CPF_WRITE:CPF_READ))<0) {
		panic("cpf_grant_magic of buffer failed");
	  }

	  break;
	case MFS_DEV_GATHER:
	case MFS_DEV_SCATTER:
	  /* Change to safe op. */
	  *op = *op == MFS_DEV_GATHER ? DEV_GATHER_S : DEV_SCATTER_S;

	  /* Grant access to my new i/o vector. */
	  if((*gid = cpf_grant_direct(driver, (vir_bytes) new_iovec,
				      bytes * sizeof(iovec_t),
				      CPF_READ | CPF_WRITE)) < 0) {
		panic("cpf_grant_direct of vector failed");
	  }
	  v = (iovec_t *) *buf;
	  /* Grant access to i/o buffers. */
	  for(j = 0; j < bytes; j++) {
		if(j >= NR_IOREQS) 
			panic("vec too big: %d", bytes);
		new_iovec[j].iov_addr = gids[j] =
		  cpf_grant_direct(driver, (vir_bytes) v[j].iov_addr,
				   v[j].iov_size,
				   *op == DEV_GATHER_S ? CPF_WRITE : CPF_READ);
		if(!GRANT_VALID(gids[j])) {
			panic("mfs: grant to iovec buf failed");
		}
		new_iovec[j].iov_size = v[j].iov_size;
		(*vec_grants)++;
	  }

	  /* Set user's vector to the new one. */
	  *buf = new_iovec;
	  break;
  }

  /* If we have converted to a safe operation, I/O
   * endpoint becomes FS if it wasn't already.
   */
  if(GRANT_VALID(*gid)) {
	*io_ept = SELF_E;
	return 1;
  }

  /* Not converted to a safe operation (because there is no
   * copying involved in this operation).
   */
  return 0;
}

/*===========================================================================*
 *			safe_io_cleanup					     *
 *===========================================================================*/
PRIVATE void safe_io_cleanup(gid, gids, gids_size)
cp_grant_id_t gid;
cp_grant_id_t *gids;
int gids_size;
{
/* Free resources (specifically, grants) allocated by safe_io_conversion(). */
  int j;

  cpf_revoke(gid);

  for(j = 0; j < gids_size; j++)
	cpf_revoke(gids[j]);

  return;
}

/*===========================================================================*
 *			block_dev_io					     *
 *===========================================================================*/
PUBLIC int block_dev_io(op, dev, proc_e, buf, pos, bytes, flags)
int op;				/* MFS_DEV_READ, MFS_DEV_WRITE, etc. */
dev_t dev;			/* major-minor device number */
int proc_e;			/* in whose address space is buf? */
void *buf;			/* virtual address of the buffer */
u64_t pos;			/* byte position */
int bytes;			/* how many bytes to transfer */
int flags;			/* special flags, like O_NONBLOCK */
{
/* Read or write from a device.  The parameter 'dev' tells which one. */
  int r, safe;
  message m;
  cp_grant_id_t gid = GRANT_INVALID;
  int vec_grants;
  int op_used;
  void *buf_used;
  static cp_grant_id_t *gids;
  endpoint_t driver_e;

  STATICINIT(gids, NR_IOREQS);

  /* Determine driver endpoint for this device */
  driver_e = driver_endpoints[(dev >> MAJOR) & BYTE].driver_e;
  
  /* See if driver is roughly valid. */
  if (driver_e == NONE) {
      printf("MFS(%d) block_dev_io: no driver for dev %x\n", SELF_E, dev);
      return(EDEADSRCDST);
  }
  
  /* The io vector copying relies on this I/O being for FS itself. */
  if(proc_e != SELF_E) {
      printf("MFS(%d) doing block_dev_io for non-self %d\n", SELF_E, proc_e);
      panic("doing block_dev_io for non-self: %d", proc_e);
  }
  
  /* By default, these are right. */
  m.IO_ENDPT = proc_e;
  m.ADDRESS  = buf;
  buf_used = buf;

  /* Convert parameters to 'safe mode'. */
  op_used = op;
  safe = safe_io_conversion(driver_e, &gid,
          &op_used, gids, NR_IOREQS, &m.IO_ENDPT, &buf_used,
          &vec_grants, bytes);

  /* Set up rest of the message. */
  if (safe) m.IO_GRANT = (char *) gid;

  m.m_type   = op_used;
  m.DEVICE   = (dev >> MINOR) & BYTE;
  m.POSITION = ex64lo(pos);
  m.COUNT    = bytes;
  m.HIGHPOS  = ex64hi(pos);

  /* Call the task. */
  r = sendrec(driver_e, &m);
  if(r == OK && m.REP_STATUS == ERESTART) r = EDEADSRCDST;

  /* As block I/O never SUSPENDs, safe cleanup must be done whether
   * the I/O succeeded or not. */
  if (safe) safe_io_cleanup(gid, gids, vec_grants);
  
  /* RECOVERY:
   * - send back dead driver number
   * - VFS unmaps it, waits for new driver
   * - VFS sends the new driver endp for the FS proc and the request again 
   */
  if (r != OK) {
      if (r == EDEADSRCDST) {
          printf("MFS(%d) dead driver %d\n", SELF_E, driver_e);
          driver_endpoints[(dev >> MAJOR) & BYTE].driver_e = NONE;
          return r;
          /*dmap_unmap_by_endpt(task_nr);    <- in the VFS proc...  */
      }
      else if (r == ELOCKED) {
          printf("MFS(%d) ELOCKED talking to %d\n", SELF_E, driver_e);
          return r;
      }
      else 
          panic("call_task: can't send/receive: %d", r);
  } 
  else {
      /* Did the process we did the sendrec() for get a result? */
      if (m.REP_ENDPT != proc_e) {
          printf("MFS(%d) strange device reply from %d, type = %d, proc = %d (not %d) (2) ignored\n", SELF_E, m.m_source, m.m_type, proc_e, m.REP_ENDPT);
          r = EIO;
      }
  }

  /* Task has completed.  See if call completed. */
  if (m.REP_STATUS == SUSPEND) {
      panic("MFS block_dev_io: driver returned SUSPEND");
  }

  if(buf != buf_used && r == OK) {
      memcpy(buf, buf_used, bytes * sizeof(iovec_t));
  }

  return(m.REP_STATUS);
}

/*===========================================================================*
 *				dev_open				     *
 *===========================================================================*/
PUBLIC int dev_open(driver_e, dev, proc, flags)
endpoint_t driver_e;
dev_t dev;			/* device to open */
int proc;			/* process to open for */
int flags;			/* mode bits and flags */
{
  int major, r;

  /* Determine the major device number call the device class specific
   * open/close routine.  (This is the only routine that must check the
   * device number for being in range.  All others can trust this check.)
   */
  major = (dev >> MAJOR) & BYTE;
  if (major >= NR_DEVICES) major = 0;
  r = gen_opcl(driver_e, DEV_OPEN, dev, proc, flags);
  if (r == SUSPEND) panic("suspend on open from");
  return(r);
}


/*===========================================================================*
 *				dev_close				     *
 *===========================================================================*/
PUBLIC void dev_close(driver_e, dev)
endpoint_t driver_e;
dev_t dev;			/* device to close */
{
  (void) gen_opcl(driver_e, DEV_CLOSE, dev, 0, 0);
}


/*===========================================================================*
 *				gen_opcl				     *
 *===========================================================================*/
PRIVATE int gen_opcl(driver_e, op, dev, proc_e, flags)
endpoint_t driver_e;
int op;				/* operation, DEV_OPEN or DEV_CLOSE */
dev_t dev;			/* device to open or close */
int proc_e;			/* process to open/close for */
int flags;			/* mode bits and flags */
{
/* Called from the dmap struct in table.c on opens & closes of special files.*/
  message dev_mess;

  dev_mess.m_type   = op;
  dev_mess.DEVICE   = (dev >> MINOR) & BYTE;
  dev_mess.IO_ENDPT = proc_e;
  dev_mess.COUNT    = flags;

  /* Call the task. */
  gen_io(driver_e, &dev_mess);

  return(dev_mess.REP_STATUS);
}


/*===========================================================================*
 *				gen_io					     *
 *===========================================================================*/
PRIVATE int gen_io(
  endpoint_t task_nr,		/* which task to call */
  message *mess_ptr		/* pointer to message for task */
)
{
/* All file system I/O ultimately comes down to I/O on major/minor device
 * pairs.  These lead to calls on the following routines via the dmap table.
 */

  int r, proc_e;

  proc_e = mess_ptr->IO_ENDPT;

  r = sendrec(task_nr, mess_ptr);
  if(r == OK && mess_ptr->REP_STATUS == ERESTART) r = EDEADSRCDST;
	if (r != OK) {
		if (r == EDEADSRCDST) {
			printf("fs: dead driver %d\n", task_nr);
			panic("should handle crashed drivers");
			/* dmap_unmap_by_endpt(task_nr); */
			return r;
		}
		if (r == ELOCKED) {
			printf("fs: ELOCKED talking to %d\n", task_nr);
			return r;
		}
		panic("call_task: can't send/receive: %d", r);
	}

  	/* Did the process we did the sendrec() for get a result? */
  	if (mess_ptr->REP_ENDPT != proc_e) {
		printf(
		"fs: strange device reply from %d, type = %d, proc = %d (not %d) (2) ignored\n",
			mess_ptr->m_source,
			mess_ptr->m_type,
			proc_e,
			mess_ptr->REP_ENDPT);
		return(EIO);
	}

  return(OK);
}