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  * $FreeBSD: src/sys/kern/kern_physio.c,v 1.46.2.4 2003/11/14 09:51:47 simokawa Exp $
  20  * $DragonFly: src/sys/kern/kern_physio.c,v 1.12 2005/08/04 21:08:35 hmp Exp $
  21  */
  22
  23 #include <sys/param.h>
  24 #include <sys/systm.h>
  25 #include <sys/buf.h>
  26 #include <sys/conf.h>
  27 #include <sys/proc.h>
  28 #include <sys/uio.h>
  29 #include <sys/device.h>
  30 #include <sys/thread2.h>
  31
  32 #include <vm/vm.h>
  33 #include <vm/vm_extern.h>
  34
  35 static void
  36 physwakeup(struct buf *bp)
  37 {
  38         wakeup((caddr_t) bp);
  39 }
  40
  41 int
  42 physio(dev_t dev, struct uio *uio, int ioflag)
  43 {
  44         int i;
  45         int error;
  46         int chk_blockno;
  47         caddr_t sa;
  48         off_t blockno;
  49         u_int iolen;
  50         struct buf *bp;
  51
  52         /*
  53          * NOTE: we no longer have to PHOLD() the process, because the
  54          * kernel stack / uarea cannot be swapped, and when it can be in
  55          * the future it will only happen if the process is sleeping on
  56          * a particular address.
  57          */
  58         bp = getpbuf(NULL);
  59         sa = bp->b_data;
  60         error = 0;
  61
  62         /* XXX: sanity check */
  63         if(dev->si_iosize_max < PAGE_SIZE) {
  64                 printf("WARNING: %s si_iosize_max=%d, using DFLTPHYS.\n",
  65                     devtoname(dev), dev->si_iosize_max);
  66                 dev->si_iosize_max = DFLTPHYS;
  67         }
  68
  69         /* Don't check block number overflow for D_MEM */
  70         if ((dev_dflags(dev) & D_TYPEMASK) == D_MEM)
  71                 chk_blockno = 0;
  72         else
  73                 chk_blockno = 1;
  74
  75         for (i = 0; i < uio->uio_iovcnt; i++) {
  76                 while (uio->uio_iov[i].iov_len) {
  77                         if (uio->uio_rw == UIO_READ)
  78                                 bp->b_flags = B_PHYS | B_READ;
  79                         else
  80                                 bp->b_flags = B_PHYS | B_WRITE;
  81                         bp->b_dev = dev;
  82                         bp->b_iodone = physwakeup;
  83                         bp->b_data = uio->uio_iov[i].iov_base;
  84                         bp->b_bcount = uio->uio_iov[i].iov_len;
  85                         bp->b_offset = uio->uio_offset;
  86                         bp->b_saveaddr = sa;
  87
  88                         /* Don't exceed drivers iosize limit */
  89                         if (bp->b_bcount > dev->si_iosize_max)
  90                                 bp->b_bcount = dev->si_iosize_max;
  91
  92                         /*
  93                          * Make sure the pbuf can map the request
  94                          * XXX: The pbuf has kvasize = MAXPHYS so a request
  95                          * XXX: larger than MAXPHYS - PAGE_SIZE must be
  96                          * XXX: page aligned or it will be fragmented.
  97                          */
  98                         iolen = ((vm_offset_t) bp->b_data) & PAGE_MASK;
  99                         if ((bp->b_bcount + iolen) > bp->b_kvasize) {
 100                                 bp->b_bcount = bp->b_kvasize;
 101                                 if (iolen != 0)
 102                                         bp->b_bcount -= PAGE_SIZE;
 103                         }
 104                         bp->b_bufsize = bp->b_bcount;
 105
 106                         blockno = bp->b_offset >> DEV_BSHIFT;
 107                         if (chk_blockno && (daddr_t)blockno != blockno) {
 108                                 error = EINVAL; /* blockno overflow */
 109                                 goto doerror;
 110                         }
 111                         bp->b_blkno = blockno;
 112
 113                         if (uio->uio_segflg == UIO_USERSPACE)
 114                                 if (vmapbuf(bp) < 0) {
 115                                         error = EFAULT;
 116                                         goto doerror;
 117                                 }
 118
 119                         BUF_STRATEGY(bp, 0);
 120                         crit_enter();
 121                         while ((bp->b_flags & B_DONE) == 0)
 122                                 tsleep((caddr_t)bp, 0, "physstr", 0);
 123                         crit_exit();
 124
 125                         if (uio->uio_segflg == UIO_USERSPACE)
 126                                 vunmapbuf(bp);
 127                         iolen = bp->b_bcount - bp->b_resid;
 128                         if (iolen == 0 && !(bp->b_flags & B_ERROR))
 129                                 goto doerror;   /* EOF */
 130                         uio->uio_iov[i].iov_len -= iolen;
 131                         uio->uio_iov[i].iov_base += iolen;
 132                         uio->uio_resid -= iolen;
 133                         uio->uio_offset += iolen;
 134                         if( bp->b_flags & B_ERROR) {
 135                                 error = bp->b_error;
 136                                 goto doerror;
 137                         }
 138                 }
 139         }
 140 doerror:
 141         bp->b_data = sa;
 142         relpbuf(bp, NULL);
 143         return (error);
 144 }