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 1.24 2006/12/23 01:35:04 swildner 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 bio *bio)
  37 {
  38         bio->bio_buf->b_cmd = BUF_CMD_DONE;
  39         wakeup(bio);
  40 }
  41
  42 static int
  43 physio(cdev_t dev, struct uio *uio, int ioflag)
  44 {
  45         int i;
  46         int error;
  47         int chk_blockno;
  48         int saflags;
  49         int iolen;
  50         int bcount;
  51         struct buf *bp;
  52
  53         bp = getpbuf(NULL);
  54         saflags = bp->b_flags;
  55         error = 0;
  56
  57         /* XXX: sanity check */
  58         if(dev->si_iosize_max < PAGE_SIZE) {
  59                 kprintf("WARNING: %s si_iosize_max=%d, using DFLTPHYS.\n",
  60                     devtoname(dev), dev->si_iosize_max);
  61                 dev->si_iosize_max = DFLTPHYS;
  62         }
  63
  64         /* Don't check block number overflow for D_MEM */
  65         if ((dev_dflags(dev) & D_TYPEMASK) == D_MEM)
  66                 chk_blockno = 0;
  67         else
  68                 chk_blockno = 1;
  69
  70         for (i = 0; i < uio->uio_iovcnt; i++) {
  71                 while (uio->uio_iov[i].iov_len) {
  72                         if (uio->uio_rw == UIO_READ)
  73                                 bp->b_cmd = BUF_CMD_READ;
  74                         else
  75                                 bp->b_cmd = BUF_CMD_WRITE;
  76                         bp->b_flags = saflags;
  77                         bcount = uio->uio_iov[i].iov_len;
  78
  79                         reinitbufbio(bp);       /* clear translation cache */
  80                         bp->b_bio1.bio_offset = uio->uio_offset;
  81                         bp->b_bio1.bio_done = physwakeup;
  82
  83                         /* Don't exceed drivers iosize limit */
  84                         if (bcount > dev->si_iosize_max)
  85                                 bcount = dev->si_iosize_max;
  86
  87                         /*
  88                          * Make sure the pbuf can map the request
  89                          * XXX: The pbuf has kvasize = MAXPHYS so a request
  90                          * XXX: larger than MAXPHYS - PAGE_SIZE must be
  91                          * XXX: page aligned or it will be fragmented.
  92                          */
  93                         iolen = ((vm_offset_t) uio->uio_iov[i].iov_base) &
  94                                 PAGE_MASK;
  95                         if ((bcount + iolen) > bp->b_kvasize) {
  96                                 bcount = bp->b_kvasize;
  97                                 if (iolen != 0)
  98                                         bcount -= PAGE_SIZE;
  99                         }
 100                         if (uio->uio_segflg == UIO_USERSPACE) {
 101                                 if (vmapbuf(bp, uio->uio_iov[i].iov_base, bcount) < 0) {
 102                                         error = EFAULT;
 103                                         goto doerror;
 104                                 }
 105                         } else {
 106                                 bp->b_data = uio->uio_iov[i].iov_base;
 107                                 bp->b_bcount = bcount;
 108                         }
 109                         dev_dstrategy(dev, &bp->b_bio1);
 110                         crit_enter();
 111                         while (bp->b_cmd != BUF_CMD_DONE)
 112                                 tsleep(&bp->b_bio1, 0, "physstr", 0);
 113                         crit_exit();
 114
 115                         if (uio->uio_segflg == UIO_USERSPACE)
 116                                 vunmapbuf(bp);
 117                         iolen = bp->b_bcount - bp->b_resid;
 118                         if (iolen == 0 && !(bp->b_flags & B_ERROR))
 119                                 goto doerror;   /* EOF */
 120                         uio->uio_iov[i].iov_len -= iolen;
 121                         uio->uio_iov[i].iov_base += iolen;
 122                         uio->uio_resid -= iolen;
 123                         uio->uio_offset += iolen;
 124                         if( bp->b_flags & B_ERROR) {
 125                                 error = bp->b_error;
 126                                 goto doerror;
 127                         }
 128                 }
 129         }
 130 doerror:
 131         relpbuf(bp, NULL);
 132         return (error);
 133 }
 134
 135 int
 136 physread(struct dev_read_args *ap)
 137 {
 138         return(physio(ap->a_head.a_dev, ap->a_uio, ap->a_ioflag));
 139 }
 140
 141 int
 142 physwrite(struct dev_write_args *ap)
 143 {
 144         return(physio(ap->a_head.a_dev, ap->a_uio, ap->a_ioflag));
 145 }
 146