1 /*- 2 * SPDX-License-Identifier: BSD-4-Clause 3 * 4 * Copyright (c) 1994 John S. Dyson 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice immediately at the beginning of the file, without modification, 12 * this list of conditions, and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. Absolutely no warranty of function or purpose is made by the author 17 * John S. Dyson. 18 * 4. Modifications may be freely made to this file if the above conditions 19 * are met. 20 */ 21 22 #include <sys/cdefs.h> 23 __FBSDID("$FreeBSD$"); 24 25 #include <sys/param.h> 26 #include <sys/systm.h> 27 #include <sys/bio.h> 28 #include <sys/buf.h> 29 #include <sys/conf.h> 30 #include <sys/malloc.h> 31 #include <sys/proc.h> 32 #include <sys/racct.h> 33 #include <sys/uio.h> 34 #include <geom/geom.h> 35 36 #include <vm/vm.h> 37 #include <vm/vm_page.h> 38 #include <vm/vm_extern.h> 39 #include <vm/vm_map.h> 40 41 int 42 physio(struct cdev *dev, struct uio *uio, int ioflag) 43 { 44 struct cdevsw *csw; 45 struct buf *pbuf; 46 struct bio *bp; 47 struct vm_page **pages; 48 char *base, *sa; 49 u_int iolen, poff; 50 int error, i, npages, maxpages; 51 vm_prot_t prot; 52 53 csw = dev->si_devsw; 54 npages = 0; 55 sa = NULL; 56 /* check if character device is being destroyed */ 57 if (csw == NULL) 58 return (ENXIO); 59 60 /* XXX: sanity check */ 61 if(dev->si_iosize_max < PAGE_SIZE) { 62 printf("WARNING: %s si_iosize_max=%d, using DFLTPHYS.\n", 63 devtoname(dev), dev->si_iosize_max); 64 dev->si_iosize_max = DFLTPHYS; 65 } 66 67 /* 68 * If the driver does not want I/O to be split, that means that we 69 * need to reject any requests that will not fit into one buffer. 70 */ 71 if (dev->si_flags & SI_NOSPLIT && 72 (uio->uio_resid > dev->si_iosize_max || uio->uio_resid > maxphys || 73 uio->uio_iovcnt > 1)) { 74 /* 75 * Tell the user why his I/O was rejected. 76 */ 77 if (uio->uio_resid > dev->si_iosize_max) 78 uprintf("%s: request size=%zd > si_iosize_max=%d; " 79 "cannot split request\n", devtoname(dev), 80 uio->uio_resid, dev->si_iosize_max); 81 if (uio->uio_resid > maxphys) 82 uprintf("%s: request size=%zd > maxphys=%lu; " 83 "cannot split request\n", devtoname(dev), 84 uio->uio_resid, maxphys); 85 if (uio->uio_iovcnt > 1) 86 uprintf("%s: request vectors=%d > 1; " 87 "cannot split request\n", devtoname(dev), 88 uio->uio_iovcnt); 89 return (EFBIG); 90 } 91 92 /* 93 * Keep the process UPAGES from being swapped. Processes swapped 94 * out while holding pbufs, used by swapper, may lead to deadlock. 95 */ 96 PHOLD(curproc); 97 98 bp = g_alloc_bio(); 99 if (uio->uio_segflg != UIO_USERSPACE) { 100 pbuf = NULL; 101 pages = NULL; 102 } else if ((dev->si_flags & SI_UNMAPPED) && unmapped_buf_allowed) { 103 pbuf = NULL; 104 maxpages = btoc(MIN(uio->uio_resid, maxphys)) + 1; 105 pages = malloc(sizeof(*pages) * maxpages, M_DEVBUF, M_WAITOK); 106 } else { 107 pbuf = uma_zalloc(pbuf_zone, M_WAITOK); 108 MPASS((pbuf->b_flags & B_MAXPHYS) != 0); 109 sa = pbuf->b_data; 110 maxpages = btoc(maxphys); 111 pages = pbuf->b_pages; 112 } 113 prot = VM_PROT_READ; 114 if (uio->uio_rw == UIO_READ) 115 prot |= VM_PROT_WRITE; /* Less backwards than it looks */ 116 error = 0; 117 for (i = 0; i < uio->uio_iovcnt; i++) { 118 #ifdef RACCT 119 if (racct_enable) { 120 PROC_LOCK(curproc); 121 if (uio->uio_rw == UIO_READ) { 122 racct_add_force(curproc, RACCT_READBPS, 123 uio->uio_iov[i].iov_len); 124 racct_add_force(curproc, RACCT_READIOPS, 1); 125 } else { 126 racct_add_force(curproc, RACCT_WRITEBPS, 127 uio->uio_iov[i].iov_len); 128 racct_add_force(curproc, RACCT_WRITEIOPS, 1); 129 } 130 PROC_UNLOCK(curproc); 131 } 132 #endif /* RACCT */ 133 134 while (uio->uio_iov[i].iov_len) { 135 g_reset_bio(bp); 136 if (uio->uio_rw == UIO_READ) { 137 bp->bio_cmd = BIO_READ; 138 curthread->td_ru.ru_inblock++; 139 } else { 140 bp->bio_cmd = BIO_WRITE; 141 curthread->td_ru.ru_oublock++; 142 } 143 bp->bio_offset = uio->uio_offset; 144 base = uio->uio_iov[i].iov_base; 145 bp->bio_length = uio->uio_iov[i].iov_len; 146 if (bp->bio_length > dev->si_iosize_max) 147 bp->bio_length = dev->si_iosize_max; 148 if (bp->bio_length > maxphys) 149 bp->bio_length = maxphys; 150 151 /* 152 * Make sure the pbuf can map the request. 153 * The pbuf has kvasize = maxphys, so a request 154 * larger than maxphys - PAGE_SIZE must be 155 * page aligned or it will be fragmented. 156 */ 157 poff = (vm_offset_t)base & PAGE_MASK; 158 if (pbuf && bp->bio_length + poff > pbuf->b_kvasize) { 159 if (dev->si_flags & SI_NOSPLIT) { 160 uprintf("%s: request ptr %p is not " 161 "on a page boundary; cannot split " 162 "request\n", devtoname(dev), 163 base); 164 error = EFBIG; 165 goto doerror; 166 } 167 bp->bio_length = pbuf->b_kvasize; 168 if (poff != 0) 169 bp->bio_length -= PAGE_SIZE; 170 } 171 172 bp->bio_bcount = bp->bio_length; 173 bp->bio_dev = dev; 174 175 if (pages) { 176 if ((npages = vm_fault_quick_hold_pages( 177 &curproc->p_vmspace->vm_map, 178 (vm_offset_t)base, bp->bio_length, 179 prot, pages, maxpages)) < 0) { 180 error = EFAULT; 181 goto doerror; 182 } 183 if (pbuf && sa) { 184 pmap_qenter((vm_offset_t)sa, 185 pages, npages); 186 bp->bio_data = sa + poff; 187 } else { 188 bp->bio_ma = pages; 189 bp->bio_ma_n = npages; 190 bp->bio_ma_offset = poff; 191 bp->bio_data = unmapped_buf; 192 bp->bio_flags |= BIO_UNMAPPED; 193 } 194 } else 195 bp->bio_data = base; 196 197 csw->d_strategy(bp); 198 if (uio->uio_rw == UIO_READ) 199 biowait(bp, "physrd"); 200 else 201 biowait(bp, "physwr"); 202 203 if (pages) { 204 if (pbuf) 205 pmap_qremove((vm_offset_t)sa, npages); 206 vm_page_unhold_pages(pages, npages); 207 } 208 209 iolen = bp->bio_length - bp->bio_resid; 210 if (iolen == 0 && !(bp->bio_flags & BIO_ERROR)) 211 goto doerror; /* EOF */ 212 uio->uio_iov[i].iov_len -= iolen; 213 uio->uio_iov[i].iov_base = 214 (char *)uio->uio_iov[i].iov_base + iolen; 215 uio->uio_resid -= iolen; 216 uio->uio_offset += iolen; 217 if (bp->bio_flags & BIO_ERROR) { 218 error = bp->bio_error; 219 goto doerror; 220 } 221 } 222 } 223 doerror: 224 if (pbuf) 225 uma_zfree(pbuf_zone, pbuf); 226 else if (pages) 227 free(pages, M_DEVBUF); 228 g_destroy_bio(bp); 229 PRELE(curproc); 230 return (error); 231 } 232