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("$FreeBSD$"); 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/racct.h> 31 #include <sys/uio.h> 32 #include <geom/geom.h> 33 34 #include <vm/vm.h> 35 #include <vm/vm_page.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 /* check if character device is being destroyed */ 53 if (csw == NULL) 54 return (ENXIO); 55 56 /* XXX: sanity check */ 57 if(dev->si_iosize_max < PAGE_SIZE) { 58 printf("WARNING: %s si_iosize_max=%d, using DFLTPHYS.\n", 59 devtoname(dev), dev->si_iosize_max); 60 dev->si_iosize_max = DFLTPHYS; 61 } 62 63 /* 64 * If the driver does not want I/O to be split, that means that we 65 * need to reject any requests that will not fit into one buffer. 66 */ 67 if (dev->si_flags & SI_NOSPLIT && 68 (uio->uio_resid > dev->si_iosize_max || uio->uio_resid > MAXPHYS || 69 uio->uio_iovcnt > 1)) { 70 /* 71 * Tell the user why his I/O was rejected. 72 */ 73 if (uio->uio_resid > dev->si_iosize_max) 74 uprintf("%s: request size=%zd > si_iosize_max=%d; " 75 "cannot split request\n", devtoname(dev), 76 uio->uio_resid, dev->si_iosize_max); 77 if (uio->uio_resid > MAXPHYS) 78 uprintf("%s: request size=%zd > MAXPHYS=%d; " 79 "cannot split request\n", devtoname(dev), 80 uio->uio_resid, MAXPHYS); 81 if (uio->uio_iovcnt > 1) 82 uprintf("%s: request vectors=%d > 1; " 83 "cannot split request\n", devtoname(dev), 84 uio->uio_iovcnt); 85 return (EFBIG); 86 } 87 88 /* 89 * Keep the process UPAGES from being swapped. Processes swapped 90 * out while holding pbufs, used by swapper, may lead to deadlock. 91 */ 92 PHOLD(curproc); 93 94 bp = g_alloc_bio(); 95 if (uio->uio_segflg != UIO_USERSPACE) { 96 pbuf = NULL; 97 pages = NULL; 98 } else if ((dev->si_flags & SI_UNMAPPED) && unmapped_buf_allowed) { 99 pbuf = NULL; 100 maxpages = btoc(MIN(uio->uio_resid, MAXPHYS)) + 1; 101 pages = malloc(sizeof(*pages) * maxpages, M_DEVBUF, M_WAITOK); 102 } else { 103 pbuf = getpbuf(NULL); 104 sa = pbuf->b_data; 105 maxpages = btoc(MAXPHYS); 106 pages = pbuf->b_pages; 107 } 108 prot = VM_PROT_READ; 109 if (uio->uio_rw == UIO_READ) 110 prot |= VM_PROT_WRITE; /* Less backwards than it looks */ 111 error = 0; 112 for (i = 0; i < uio->uio_iovcnt; i++) { 113 #ifdef RACCT 114 if (racct_enable) { 115 PROC_LOCK(curproc); 116 if (uio->uio_rw == UIO_READ) { 117 racct_add_force(curproc, RACCT_READBPS, 118 uio->uio_iov[i].iov_len); 119 racct_add_force(curproc, RACCT_READIOPS, 1); 120 } else { 121 racct_add_force(curproc, RACCT_WRITEBPS, 122 uio->uio_iov[i].iov_len); 123 racct_add_force(curproc, RACCT_WRITEIOPS, 1); 124 } 125 PROC_UNLOCK(curproc); 126 } 127 #endif /* RACCT */ 128 129 while (uio->uio_iov[i].iov_len) { 130 g_reset_bio(bp); 131 if (uio->uio_rw == UIO_READ) { 132 bp->bio_cmd = BIO_READ; 133 curthread->td_ru.ru_inblock++; 134 } else { 135 bp->bio_cmd = BIO_WRITE; 136 curthread->td_ru.ru_oublock++; 137 } 138 bp->bio_offset = uio->uio_offset; 139 base = uio->uio_iov[i].iov_base; 140 bp->bio_length = uio->uio_iov[i].iov_len; 141 if (bp->bio_length > dev->si_iosize_max) 142 bp->bio_length = dev->si_iosize_max; 143 if (bp->bio_length > MAXPHYS) 144 bp->bio_length = MAXPHYS; 145 146 /* 147 * Make sure the pbuf can map the request. 148 * The pbuf has kvasize = MAXPHYS, so a request 149 * larger than MAXPHYS - PAGE_SIZE must be 150 * page aligned or it will be fragmented. 151 */ 152 poff = (vm_offset_t)base & PAGE_MASK; 153 if (pbuf && bp->bio_length + poff > pbuf->b_kvasize) { 154 if (dev->si_flags & SI_NOSPLIT) { 155 uprintf("%s: request ptr %p is not " 156 "on a page boundary; cannot split " 157 "request\n", devtoname(dev), 158 base); 159 error = EFBIG; 160 goto doerror; 161 } 162 bp->bio_length = pbuf->b_kvasize; 163 if (poff != 0) 164 bp->bio_length -= PAGE_SIZE; 165 } 166 167 bp->bio_bcount = bp->bio_length; 168 bp->bio_dev = dev; 169 170 if (pages) { 171 if ((npages = vm_fault_quick_hold_pages( 172 &curproc->p_vmspace->vm_map, 173 (vm_offset_t)base, bp->bio_length, 174 prot, pages, maxpages)) < 0) { 175 error = EFAULT; 176 goto doerror; 177 } 178 if (pbuf) { 179 pmap_qenter((vm_offset_t)sa, 180 pages, npages); 181 bp->bio_data = sa + poff; 182 } else { 183 bp->bio_ma = pages; 184 bp->bio_ma_n = npages; 185 bp->bio_ma_offset = poff; 186 bp->bio_data = unmapped_buf; 187 bp->bio_flags |= BIO_UNMAPPED; 188 } 189 } else 190 bp->bio_data = base; 191 192 csw->d_strategy(bp); 193 if (uio->uio_rw == UIO_READ) 194 biowait(bp, "physrd"); 195 else 196 biowait(bp, "physwr"); 197 198 if (pages) { 199 if (pbuf) 200 pmap_qremove((vm_offset_t)sa, npages); 201 vm_page_unhold_pages(pages, npages); 202 } 203 204 iolen = bp->bio_length - bp->bio_resid; 205 if (iolen == 0 && !(bp->bio_flags & BIO_ERROR)) 206 goto doerror; /* EOF */ 207 uio->uio_iov[i].iov_len -= iolen; 208 uio->uio_iov[i].iov_base = 209 (char *)uio->uio_iov[i].iov_base + iolen; 210 uio->uio_resid -= iolen; 211 uio->uio_offset += iolen; 212 if (bp->bio_flags & BIO_ERROR) { 213 error = bp->bio_error; 214 goto doerror; 215 } 216 } 217 } 218 doerror: 219 if (pbuf) 220 relpbuf(pbuf, NULL); 221 else if (pages) 222 free(pages, M_DEVBUF); 223 g_destroy_bio(bp); 224 PRELE(curproc); 225 return (error); 226 }
Cache object: f65e331b090a474d18e4317840bfbf90
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