kern_physio.c revision 116182
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: head/sys/kern/kern_physio.c 116182 2003-06-11 00:56:59Z obrien $"); 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 34int 35physio(dev_t dev, struct uio *uio, int ioflag) 36{ 37 int i; 38 int error; 39 int spl; 40 caddr_t sa; 41 u_int iolen; 42 struct buf *bp; 43 44 /* Keep the process UPAGES from being swapped. XXX: why ? */ 45 PHOLD(curproc); 46 47 bp = getpbuf(NULL); 48 sa = bp->b_data; 49 error = 0; 50 51 /* XXX: sanity check */ 52 if(dev->si_iosize_max < PAGE_SIZE) { 53 printf("WARNING: %s si_iosize_max=%d, using DFLTPHYS.\n", 54 devtoname(dev), dev->si_iosize_max); 55 dev->si_iosize_max = DFLTPHYS; 56 } 57 58 for (i = 0; i < uio->uio_iovcnt; i++) { 59 while (uio->uio_iov[i].iov_len) { 60 bp->b_flags = B_PHYS; 61 if (uio->uio_rw == UIO_READ) 62 bp->b_iocmd = BIO_READ; 63 else 64 bp->b_iocmd = BIO_WRITE; 65 bp->b_dev = dev; 66 bp->b_iodone = bdone; 67 bp->b_data = uio->uio_iov[i].iov_base; 68 bp->b_bcount = uio->uio_iov[i].iov_len; 69 bp->b_offset = uio->uio_offset; 70 bp->b_saveaddr = sa; 71 72 /* Don't exceed drivers iosize limit */ 73 if (bp->b_bcount > dev->si_iosize_max) 74 bp->b_bcount = dev->si_iosize_max; 75 76 /* 77 * Make sure the pbuf can map the request 78 * XXX: The pbuf has kvasize = MAXPHYS so a request 79 * XXX: larger than MAXPHYS - PAGE_SIZE must be 80 * XXX: page aligned or it will be fragmented. 81 */ 82 iolen = ((vm_offset_t) bp->b_data) & PAGE_MASK; 83 if ((bp->b_bcount + iolen) > bp->b_kvasize) { 84 bp->b_bcount = bp->b_kvasize; 85 if (iolen != 0) 86 bp->b_bcount -= PAGE_SIZE; 87 } 88 bp->b_bufsize = bp->b_bcount; 89 90 bp->b_blkno = btodb(bp->b_offset); 91 92 if (uio->uio_segflg == UIO_USERSPACE) 93 if (vmapbuf(bp) < 0) { 94 error = EFAULT; 95 goto doerror; 96 } 97 98 DEV_STRATEGY(bp); 99 spl = splbio(); 100 if (uio->uio_rw == UIO_READ) 101 bwait(bp, PRIBIO, "physrd"); 102 else 103 bwait(bp, PRIBIO, "physwr"); 104 splx(spl); 105 106 if (uio->uio_segflg == UIO_USERSPACE) 107 vunmapbuf(bp); 108 iolen = bp->b_bcount - bp->b_resid; 109 if (iolen == 0 && !(bp->b_ioflags & BIO_ERROR)) 110 goto doerror; /* EOF */ 111 uio->uio_iov[i].iov_len -= iolen; 112 uio->uio_iov[i].iov_base = 113 (char *)uio->uio_iov[i].iov_base + iolen; 114 uio->uio_resid -= iolen; 115 uio->uio_offset += iolen; 116 if( bp->b_ioflags & BIO_ERROR) { 117 error = bp->b_error; 118 goto doerror; 119 } 120 } 121 } 122doerror: 123 relpbuf(bp, NULL); 124 PRELE(curproc); 125 return (error); 126} 127