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/param.h> 21 #include <sys/systm.h> 22 #include <sys/bio.h> 23 #include <sys/buf.h> 24 #include <sys/conf.h> 25 #include <sys/malloc.h> 26 #include <sys/proc.h> 27 #include <sys/racct.h> 28 #include <sys/rwlock.h> 29 #include <sys/uio.h> 30 #include <geom/geom.h> 31 32 #include <vm/vm.h> 33 #include <vm/vm_object.h> 34 #include <vm/vm_page.h> 35 #include <vm/vm_pager.h> 36 #include <vm/vm_extern.h> 37 #include <vm/vm_map.h> 38 39 int 40 physio(struct cdev *dev, struct uio *uio, int ioflag) 41 { 42 struct cdevsw *csw; 43 struct buf *pbuf; 44 struct bio *bp; 45 struct vm_page **pages; 46 char *base, *sa; 47 u_int iolen, poff; 48 int error, i, npages, maxpages; 49 vm_prot_t prot; 50 51 csw = dev->si_devsw; 52 npages = 0; 53 sa = NULL; 54 /* check if character device is being destroyed */ 55 if (csw == NULL) 56 return (ENXIO); 57 58 /* XXX: sanity check */ 59 if (dev->si_iosize_max < PAGE_SIZE) { 60 printf("WARNING: %s si_iosize_max=%d, using DFLTPHYS.\n", 61 devtoname(dev), dev->si_iosize_max); 62 dev->si_iosize_max = DFLTPHYS; 63 } 64 65 /* 66 * If the driver does not want I/O to be split, that means that we 67 * need to reject any requests that will not fit into one buffer. 68 */ 69 if (dev->si_flags & SI_NOSPLIT && 70 (uio->uio_resid > dev->si_iosize_max || uio->uio_resid > maxphys || 71 uio->uio_iovcnt > 1)) { 72 /* 73 * Tell the user why his I/O was rejected. 74 */ 75 if (uio->uio_resid > dev->si_iosize_max) 76 uprintf("%s: request size=%zd > si_iosize_max=%d; " 77 "cannot split request\n", devtoname(dev), 78 uio->uio_resid, dev->si_iosize_max); 79 if (uio->uio_resid > maxphys) 80 uprintf("%s: request size=%zd > maxphys=%lu; " 81 "cannot split request\n", devtoname(dev), 82 uio->uio_resid, maxphys); 83 if (uio->uio_iovcnt > 1) 84 uprintf("%s: request vectors=%d > 1; " 85 "cannot split request\n", devtoname(dev), 86 uio->uio_iovcnt); 87 return (EFBIG); 88 } 89 90 /* 91 * Keep the process UPAGES from being swapped. Processes swapped 92 * out while holding pbufs, used by swapper, may lead to deadlock. 93 */ 94 PHOLD(curproc); 95 96 bp = g_alloc_bio(); 97 if (uio->uio_segflg != UIO_USERSPACE) { 98 pbuf = NULL; 99 pages = NULL; 100 } else if ((dev->si_flags & SI_UNMAPPED) && unmapped_buf_allowed) { 101 pbuf = NULL; 102 maxpages = btoc(MIN(uio->uio_resid, maxphys)) + 1; 103 pages = malloc(sizeof(*pages) * maxpages, M_DEVBUF, M_WAITOK); 104 } else { 105 pbuf = uma_zalloc(pbuf_zone, M_WAITOK); 106 MPASS((pbuf->b_flags & B_MAXPHYS) != 0); 107 sa = pbuf->b_data; 108 maxpages = PBUF_PAGES; 109 pages = pbuf->b_pages; 110 } 111 prot = VM_PROT_READ; 112 if (uio->uio_rw == UIO_READ) 113 prot |= VM_PROT_WRITE; /* Less backwards than it looks */ 114 error = 0; 115 for (i = 0; i < uio->uio_iovcnt; i++) { 116 #ifdef RACCT 117 if (racct_enable) { 118 PROC_LOCK(curproc); 119 if (uio->uio_rw == UIO_READ) { 120 racct_add_force(curproc, RACCT_READBPS, 121 uio->uio_iov[i].iov_len); 122 racct_add_force(curproc, RACCT_READIOPS, 1); 123 } else { 124 racct_add_force(curproc, RACCT_WRITEBPS, 125 uio->uio_iov[i].iov_len); 126 racct_add_force(curproc, RACCT_WRITEIOPS, 1); 127 } 128 PROC_UNLOCK(curproc); 129 } 130 #endif /* RACCT */ 131 132 while (uio->uio_iov[i].iov_len) { 133 g_reset_bio(bp); 134 if (uio->uio_rw == UIO_READ) { 135 bp->bio_cmd = BIO_READ; 136 curthread->td_ru.ru_inblock++; 137 } else { 138 bp->bio_cmd = BIO_WRITE; 139 curthread->td_ru.ru_oublock++; 140 } 141 bp->bio_offset = uio->uio_offset; 142 base = uio->uio_iov[i].iov_base; 143 bp->bio_length = uio->uio_iov[i].iov_len; 144 if (bp->bio_length > dev->si_iosize_max) 145 bp->bio_length = dev->si_iosize_max; 146 if (bp->bio_length > maxphys) 147 bp->bio_length = maxphys; 148 bp->bio_bcount = bp->bio_length; 149 bp->bio_dev = dev; 150 151 if (pages) { 152 if ((npages = vm_fault_quick_hold_pages( 153 &curproc->p_vmspace->vm_map, 154 (vm_offset_t)base, bp->bio_length, 155 prot, pages, maxpages)) < 0) { 156 error = EFAULT; 157 goto doerror; 158 } 159 poff = (vm_offset_t)base & PAGE_MASK; 160 if (pbuf && sa) { 161 pmap_qenter((vm_offset_t)sa, 162 pages, npages); 163 bp->bio_data = sa + poff; 164 } else { 165 bp->bio_ma = pages; 166 bp->bio_ma_n = npages; 167 bp->bio_ma_offset = poff; 168 bp->bio_data = unmapped_buf; 169 bp->bio_flags |= BIO_UNMAPPED; 170 } 171 } else 172 bp->bio_data = base; 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 uma_zfree(pbuf_zone, pbuf); 203 else if (pages) 204 free(pages, M_DEVBUF); 205 g_destroy_bio(bp); 206 PRELE(curproc); 207 return (error); 208 } 209