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 1.9 2004/12/31 22:30:19 dillon 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
  31 #include <vm/vm.h>
  32 #include <vm/vm_extern.h>
  33
  34 #include <machine/physio_proc.h>
  35
  36 /* I have no idea what this is used for */
  37 struct physio_proc_head physio_proc_freet, physio_proc_busyt;
  38
  39 static void
  40 physwakeup(struct buf *bp)
  41 {
  42         wakeup((caddr_t) bp);
  43 }
  44
  45 int
  46 physio(dev_t dev, struct uio *uio, int ioflag)
  47 {
  48         int i;
  49         int error;
  50         int spl;
  51         int chk_blockno;
  52         caddr_t sa;
  53         off_t blockno;
  54         u_int iolen;
  55         struct buf *bp;
  56
  57         /*
  58          * NOTE: we no longer have to PHOLD() the process, because the
  59          * kernel stack / uarea cannot be swapped, and when it can be in
  60          * the future it will only happen if the process is sleeping on
  61          * a particular address.
  62          */
  63         bp = getpbuf(NULL);
  64         sa = bp->b_data;
  65         error = 0;
  66
  67         /* XXX: sanity check */
  68         if(dev->si_iosize_max < PAGE_SIZE) {
  69                 printf("WARNING: %s si_iosize_max=%d, using DFLTPHYS.\n",
  70                     devtoname(dev), dev->si_iosize_max);
  71                 dev->si_iosize_max = DFLTPHYS;
  72         }
  73
  74         /* Don't check block number overflow for D_MEM */
  75         if ((dev_dflags(dev) & D_TYPEMASK) == D_MEM)
  76                 chk_blockno = 0;
  77         else
  78                 chk_blockno = 1;
  79
  80         for (i = 0; i < uio->uio_iovcnt; i++) {
  81                 while (uio->uio_iov[i].iov_len) {
  82                         if (uio->uio_rw == UIO_READ)
  83                                 bp->b_flags = B_PHYS | B_CALL | B_READ;
  84                         else
  85                                 bp->b_flags = B_PHYS | B_CALL | B_WRITE;
  86                         bp->b_dev = dev;
  87                         bp->b_iodone = physwakeup;
  88                         bp->b_data = uio->uio_iov[i].iov_base;
  89                         bp->b_bcount = uio->uio_iov[i].iov_len;
  90                         bp->b_offset = uio->uio_offset;
  91                         bp->b_saveaddr = sa;
  92
  93                         /* Don't exceed drivers iosize limit */
  94                         if (bp->b_bcount > dev->si_iosize_max)
  95                                 bp->b_bcount = dev->si_iosize_max;
  96
  97                         /*
  98                          * Make sure the pbuf can map the request
  99                          * XXX: The pbuf has kvasize = MAXPHYS so a request
 100                          * XXX: larger than MAXPHYS - PAGE_SIZE must be
 101                          * XXX: page aligned or it will be fragmented.
 102                          */
 103                         iolen = ((vm_offset_t) bp->b_data) & PAGE_MASK;
 104                         if ((bp->b_bcount + iolen) > bp->b_kvasize) {
 105                                 bp->b_bcount = bp->b_kvasize;
 106                                 if (iolen != 0)
 107                                         bp->b_bcount -= PAGE_SIZE;
 108                         }
 109                         bp->b_bufsize = bp->b_bcount;
 110
 111                         blockno = bp->b_offset >> DEV_BSHIFT;
 112                         if (chk_blockno && (daddr_t)blockno != blockno) {
 113                                 error = EINVAL; /* blockno overflow */
 114                                 goto doerror;
 115                         }
 116                         bp->b_blkno = blockno;
 117
 118                         if (uio->uio_segflg == UIO_USERSPACE)
 119                                 if (vmapbuf(bp) < 0) {
 120                                         error = EFAULT;
 121                                         goto doerror;
 122                                 }
 123
 124                         BUF_STRATEGY(bp, 0);
 125                         spl = splbio();
 126                         while ((bp->b_flags & B_DONE) == 0)
 127                                 tsleep((caddr_t)bp, 0, "physstr", 0);
 128                         splx(spl);
 129
 130                         if (uio->uio_segflg == UIO_USERSPACE)
 131                                 vunmapbuf(bp);
 132                         iolen = bp->b_bcount - bp->b_resid;
 133                         if (iolen == 0 && !(bp->b_flags & B_ERROR))
 134                                 goto doerror;   /* EOF */
 135                         uio->uio_iov[i].iov_len -= iolen;
 136                         uio->uio_iov[i].iov_base += iolen;
 137                         uio->uio_resid -= iolen;
 138                         uio->uio_offset += iolen;
 139                         if( bp->b_flags & B_ERROR) {
 140                                 error = bp->b_error;
 141                                 goto doerror;
 142                         }
 143                 }
 144         }
 145 doerror:
 146         bp->b_data = sa;
 147         relpbuf(bp, NULL);
 148         return (error);
 149 }