Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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FreeBSD/Linux Kernel Cross Reference
sys/kern/kern_physio.c
Version:
- FREEBSD - FREEBSD-13-STABLE - FREEBSD-13-0 - FREEBSD-12-STABLE - FREEBSD-12-0 - FREEBSD-11-STABLE - FREEBSD-11-0 - FREEBSD-10-STABLE - FREEBSD-10-0 - FREEBSD-9-STABLE - FREEBSD-9-0 - FREEBSD-8-STABLE - FREEBSD-8-0 - FREEBSD-7-STABLE - FREEBSD-7-0 - FREEBSD-6-STABLE - FREEBSD-6-0 - FREEBSD-5-STABLE - FREEBSD-5-0 - FREEBSD-4-STABLE - FREEBSD-3-STABLE - FREEBSD22 - l41 - OPENBSD - linux-2.6 - MK84 - PLAN9 - xnu-8792
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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: releng/10.4/sys/kern/kern_physio.c 290705 2015-11-12 08:47:10Z hselasky $"); 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/malloc.h> 29 #include <sys/proc.h> 30 #include <sys/uio.h> 31 #include <geom/geom.h> 32 33 #include <vm/vm.h> 34 #include <vm/vm_page.h> 35 #include <vm/vm_extern.h> 36 #include <vm/vm_map.h> 37 38 int 39 physio(struct cdev *dev, struct uio *uio, int ioflag) 40 { 41 struct cdevsw *csw; 42 struct buf *pbuf; 43 struct bio *bp; 44 struct vm_page **pages; 45 caddr_t sa; 46 u_int iolen, poff; 47 int error, i, npages, maxpages; 48 vm_prot_t prot; 49 50 csw = dev->si_devsw; 51 /* check if character device is being destroyed */ 52 if (csw == NULL) 53 return (ENXIO); 54 55 /* XXX: sanity check */ 56 if(dev->si_iosize_max < PAGE_SIZE) { 57 printf("WARNING: %s si_iosize_max=%d, using DFLTPHYS.\n", 58 devtoname(dev), dev->si_iosize_max); 59 dev->si_iosize_max = DFLTPHYS; 60 } 61 62 /* 63 * If the driver does not want I/O to be split, that means that we 64 * need to reject any requests that will not fit into one buffer. 65 */ 66 if (dev->si_flags & SI_NOSPLIT && 67 (uio->uio_resid > dev->si_iosize_max || uio->uio_resid > MAXPHYS || 68 uio->uio_iovcnt > 1)) { 69 /* 70 * Tell the user why his I/O was rejected. 71 */ 72 if (uio->uio_resid > dev->si_iosize_max) 73 uprintf("%s: request size=%zd > si_iosize_max=%d; " 74 "cannot split request\n", devtoname(dev), 75 uio->uio_resid, dev->si_iosize_max); 76 if (uio->uio_resid > MAXPHYS) 77 uprintf("%s: request size=%zd > MAXPHYS=%d; " 78 "cannot split request\n", devtoname(dev), 79 uio->uio_resid, MAXPHYS); 80 if (uio->uio_iovcnt > 1) 81 uprintf("%s: request vectors=%d > 1; " 82 "cannot split request\n", devtoname(dev), 83 uio->uio_iovcnt); 84 return (EFBIG); 85 } 86 87 /* 88 * Keep the process UPAGES from being swapped. Processes swapped 89 * out while holding pbufs, used by swapper, may lead to deadlock. 90 */ 91 PHOLD(curproc); 92 93 bp = g_alloc_bio(); 94 if (uio->uio_segflg != UIO_USERSPACE) { 95 pbuf = NULL; 96 pages = NULL; 97 } else if ((dev->si_flags & SI_UNMAPPED) && unmapped_buf_allowed) { 98 pbuf = NULL; 99 maxpages = btoc(MIN(uio->uio_resid, MAXPHYS)) + 1; 100 pages = malloc(sizeof(*pages) * maxpages, M_DEVBUF, M_WAITOK); 101 } else { 102 pbuf = getpbuf(NULL); 103 sa = pbuf->b_data; 104 maxpages = btoc(MAXPHYS); 105 pages = pbuf->b_pages; 106 } 107 prot = VM_PROT_READ; 108 if (uio->uio_rw == UIO_READ) 109 prot |= VM_PROT_WRITE; /* Less backwards than it looks */ 110 error = 0; 111 for (i = 0; i < uio->uio_iovcnt; i++) { 112 while (uio->uio_iov[i].iov_len) { 113 bzero(bp, sizeof(*bp)); 114 if (uio->uio_rw == UIO_READ) { 115 bp->bio_cmd = BIO_READ; 116 curthread->td_ru.ru_inblock++; 117 } else { 118 bp->bio_cmd = BIO_WRITE; 119 curthread->td_ru.ru_oublock++; 120 } 121 bp->bio_offset = uio->uio_offset; 122 bp->bio_data = uio->uio_iov[i].iov_base; 123 bp->bio_length = uio->uio_iov[i].iov_len; 124 if (bp->bio_length > dev->si_iosize_max) 125 bp->bio_length = dev->si_iosize_max; 126 if (bp->bio_length > MAXPHYS) 127 bp->bio_length = MAXPHYS; 128 129 /* 130 * Make sure the pbuf can map the request. 131 * The pbuf has kvasize = MAXPHYS, so a request 132 * larger than MAXPHYS - PAGE_SIZE must be 133 * page aligned or it will be fragmented. 134 */ 135 poff = (vm_offset_t)bp->bio_data & PAGE_MASK; 136 if (pbuf && bp->bio_length + poff > pbuf->b_kvasize) { 137 if (dev->si_flags & SI_NOSPLIT) { 138 uprintf("%s: request ptr %p is not " 139 "on a page boundary; cannot split " 140 "request\n", devtoname(dev), 141 bp->bio_data); 142 error = EFBIG; 143 goto doerror; 144 } 145 bp->bio_length = pbuf->b_kvasize; 146 if (poff != 0) 147 bp->bio_length -= PAGE_SIZE; 148 } 149 150 bp->bio_bcount = bp->bio_length; 151 bp->bio_dev = dev; 152 153 if (pages) { 154 if ((npages = vm_fault_quick_hold_pages( 155 &curproc->p_vmspace->vm_map, 156 (vm_offset_t)bp->bio_data, bp->bio_length, 157 prot, pages, maxpages)) < 0) { 158 error = EFAULT; 159 goto doerror; 160 } 161 if (pbuf) { 162 pmap_qenter((vm_offset_t)sa, 163 pages, npages); 164 bp->bio_data = sa + poff; 165 } else { 166 bp->bio_ma = pages; 167 bp->bio_ma_n = npages; 168 bp->bio_ma_offset = poff; 169 bp->bio_data = unmapped_buf; 170 bp->bio_flags |= BIO_UNMAPPED; 171 } 172 } 173 174 csw->d_strategy(bp); 175 if (uio->uio_rw == UIO_READ) 176 biowait(bp, "physrd"); 177 else 178 biowait(bp, "physwr"); 179 180 if (pages) { 181 if (pbuf) 182 pmap_qremove((vm_offset_t)sa, npages); 183 vm_page_unhold_pages(pages, npages); 184 } 185 186 iolen = bp->bio_length - bp->bio_resid; 187 if (iolen == 0 && !(bp->bio_flags & BIO_ERROR)) 188 goto doerror; /* EOF */ 189 uio->uio_iov[i].iov_len -= iolen; 190 uio->uio_iov[i].iov_base = 191 (char *)uio->uio_iov[i].iov_base + iolen; 192 uio->uio_resid -= iolen; 193 uio->uio_offset += iolen; 194 if (bp->bio_flags & BIO_ERROR) { 195 error = bp->bio_error; 196 goto doerror; 197 } 198 } 199 } 200 doerror: 201 if (pbuf) 202 relpbuf(pbuf, NULL); 203 else if (pages) 204 free(pages, M_DEVBUF); 205 g_destroy_bio(bp); 206 PRELE(curproc); 207 return (error); 208 }
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