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/11.0/sys/kern/kern_physio.c 297633 2016-04-07 04:23:25Z trasz $");
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 caddr_t 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 bp->bio_data = 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)bp->bio_data & 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 bp->bio_data);
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)bp->bio_data, 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 }
190
191 csw->d_strategy(bp);
192 if (uio->uio_rw == UIO_READ)
193 biowait(bp, "physrd");
194 else
195 biowait(bp, "physwr");
196
197 if (pages) {
198 if (pbuf)
199 pmap_qremove((vm_offset_t)sa, npages);
200 vm_page_unhold_pages(pages, npages);
201 }
202
203 iolen = bp->bio_length - bp->bio_resid;
204 if (iolen == 0 && !(bp->bio_flags & BIO_ERROR))
205 goto doerror; /* EOF */
206 uio->uio_iov[i].iov_len -= iolen;
207 uio->uio_iov[i].iov_base =
208 (char *)uio->uio_iov[i].iov_base + iolen;
209 uio->uio_resid -= iolen;
210 uio->uio_offset += iolen;
211 if (bp->bio_flags & BIO_ERROR) {
212 error = bp->bio_error;
213 goto doerror;
214 }
215 }
216 }
217 doerror:
218 if (pbuf)
219 relpbuf(pbuf, NULL);
220 else if (pages)
221 free(pages, M_DEVBUF);
222 g_destroy_bio(bp);
223 PRELE(curproc);
224 return (error);
225 }
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