sys/kern/kern_physio.c

   1 /*-
   2  * Copyright (c) 1994 John S. Dyson
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice immediately at the beginning of the file, without modification,
  10  *    this list of conditions, and the following disclaimer.
  11  * 2. Redistributions in binary form must reproduce the above copyright
  12  *    notice, this list of conditions and the following disclaimer in the
  13  *    documentation and/or other materials provided with the distribution.
  14  * 3. Absolutely no warranty of function or purpose is made by the author
  15  *    John S. Dyson.
  16  * 4. Modifications may be freely made to this file if the above conditions
  17  *    are met.
  18  */
  19
  20 #include <sys/cdefs.h>
  21 __FBSDID("$FreeBSD$");
  22
  23 #include <sys/param.h>
  24 #include <sys/systm.h>
  25 #include <sys/bio.h>
  26 #include <sys/buf.h>
  27 #include <sys/conf.h>
  28 #include <sys/proc.h>
  29 #include <sys/uio.h>
  30
  31 #include <vm/vm.h>
  32 #include <vm/vm_extern.h>
  33
  34 int
  35 physio(struct cdev *dev, struct uio *uio, int ioflag)
  36 {
  37         int i;
  38         int error;
  39         caddr_t sa;
  40         u_int iolen;
  41         struct buf *bp;
  42
  43         /* Keep the process UPAGES from being swapped. XXX: why ? */
  44         PHOLD(curproc);
  45
  46         bp = getpbuf(NULL);
  47         sa = bp->b_data;
  48         error = 0;
  49
  50         /* XXX: sanity check */
  51         if(dev->si_iosize_max < PAGE_SIZE) {
  52                 printf("WARNING: %s si_iosize_max=%d, using DFLTPHYS.\n",
  53                     devtoname(dev), dev->si_iosize_max);
  54                 dev->si_iosize_max = DFLTPHYS;
  55         }
  56
  57         for (i = 0; i < uio->uio_iovcnt; i++) {
  58                 while (uio->uio_iov[i].iov_len) {
  59                         bp->b_flags = 0;
  60                         if (uio->uio_rw == UIO_READ)
  61                                 bp->b_iocmd = BIO_READ;
  62                         else
  63                                 bp->b_iocmd = BIO_WRITE;
  64                         bp->b_iodone = bdone;
  65                         bp->b_data = uio->uio_iov[i].iov_base;
  66                         bp->b_bcount = uio->uio_iov[i].iov_len;
  67                         bp->b_offset = uio->uio_offset;
  68                         bp->b_iooffset = uio->uio_offset;
  69                         bp->b_saveaddr = sa;
  70
  71                         /* Don't exceed drivers iosize limit */
  72                         if (bp->b_bcount > dev->si_iosize_max)
  73                                 bp->b_bcount = dev->si_iosize_max;
  74
  75                         /*
  76                          * Make sure the pbuf can map the request
  77                          * XXX: The pbuf has kvasize = MAXPHYS so a request
  78                          * XXX: larger than MAXPHYS - PAGE_SIZE must be
  79                          * XXX: page aligned or it will be fragmented.
  80                          */
  81                         iolen = ((vm_offset_t) bp->b_data) & PAGE_MASK;
  82                         if ((bp->b_bcount + iolen) > bp->b_kvasize) {
  83                                 bp->b_bcount = bp->b_kvasize;
  84                                 if (iolen != 0)
  85                                         bp->b_bcount -= PAGE_SIZE;
  86                         }
  87                         bp->b_bufsize = bp->b_bcount;
  88
  89                         bp->b_blkno = btodb(bp->b_offset);
  90
  91                         if (uio->uio_segflg == UIO_USERSPACE)
  92                                 if (vmapbuf(bp) < 0) {
  93                                         error = EFAULT;
  94                                         goto doerror;
  95                                 }
  96
  97                         dev_strategy(dev, bp);
  98                         if (uio->uio_rw == UIO_READ)
  99                                 bwait(bp, PRIBIO, "physrd");
 100                         else
 101                                 bwait(bp, PRIBIO, "physwr");
 102
 103                         if (uio->uio_segflg == UIO_USERSPACE)
 104                                 vunmapbuf(bp);
 105                         iolen = bp->b_bcount - bp->b_resid;
 106                         if (iolen == 0 && !(bp->b_ioflags & BIO_ERROR))
 107                                 goto doerror;   /* EOF */
 108                         uio->uio_iov[i].iov_len -= iolen;
 109                         uio->uio_iov[i].iov_base =
 110                             (char *)uio->uio_iov[i].iov_base + iolen;
 111                         uio->uio_resid -= iolen;
 112                         uio->uio_offset += iolen;
 113                         if( bp->b_ioflags & BIO_ERROR) {
 114                                 error = bp->b_error;
 115                                 goto doerror;
 116                         }
 117                 }
 118         }
 119 doerror:
 120         relpbuf(bp, NULL);
 121         PRELE(curproc);
 122         return (error);
 123 }