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
physio(struct cdev * dev,struct uio * uio,int ioflag)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 switch (uio->uio_rw) {
120 case UIO_READ:
121 racct_add_force(curproc, RACCT_READBPS,
122 uio->uio_iov[i].iov_len);
123 racct_add_force(curproc, RACCT_READIOPS, 1);
124 break;
125 case UIO_WRITE:
126 racct_add_force(curproc, RACCT_WRITEBPS,
127 uio->uio_iov[i].iov_len);
128 racct_add_force(curproc, RACCT_WRITEIOPS, 1);
129 break;
130 }
131 PROC_UNLOCK(curproc);
132 }
133 #endif /* RACCT */
134
135 while (uio->uio_iov[i].iov_len) {
136 g_reset_bio(bp);
137 switch (uio->uio_rw) {
138 case UIO_READ:
139 bp->bio_cmd = BIO_READ;
140 curthread->td_ru.ru_inblock++;
141 break;
142 case UIO_WRITE:
143 bp->bio_cmd = BIO_WRITE;
144 curthread->td_ru.ru_oublock++;
145 break;
146 }
147 bp->bio_offset = uio->uio_offset;
148 base = uio->uio_iov[i].iov_base;
149 bp->bio_length = uio->uio_iov[i].iov_len;
150 if (bp->bio_length > dev->si_iosize_max)
151 bp->bio_length = dev->si_iosize_max;
152 if (bp->bio_length > maxphys)
153 bp->bio_length = maxphys;
154 bp->bio_bcount = bp->bio_length;
155 bp->bio_dev = dev;
156
157 if (pages) {
158 if ((npages = vm_fault_quick_hold_pages(
159 &curproc->p_vmspace->vm_map,
160 (vm_offset_t)base, bp->bio_length,
161 prot, pages, maxpages)) < 0) {
162 error = EFAULT;
163 goto doerror;
164 }
165 poff = (vm_offset_t)base & PAGE_MASK;
166 if (pbuf && sa) {
167 pmap_qenter((vm_offset_t)sa,
168 pages, npages);
169 bp->bio_data = sa + poff;
170 } else {
171 bp->bio_ma = pages;
172 bp->bio_ma_n = npages;
173 bp->bio_ma_offset = poff;
174 bp->bio_data = unmapped_buf;
175 bp->bio_flags |= BIO_UNMAPPED;
176 }
177 } else
178 bp->bio_data = base;
179
180 csw->d_strategy(bp);
181 if (uio->uio_rw == UIO_READ)
182 biowait(bp, "physrd");
183 else
184 biowait(bp, "physwr");
185
186 if (pages) {
187 if (pbuf)
188 pmap_qremove((vm_offset_t)sa, npages);
189 vm_page_unhold_pages(pages, npages);
190 }
191
192 iolen = bp->bio_length - bp->bio_resid;
193 if (iolen == 0 && !(bp->bio_flags & BIO_ERROR))
194 goto doerror; /* EOF */
195 uio->uio_iov[i].iov_len -= iolen;
196 uio->uio_iov[i].iov_base =
197 (char *)uio->uio_iov[i].iov_base + iolen;
198 uio->uio_resid -= iolen;
199 uio->uio_offset += iolen;
200 if (bp->bio_flags & BIO_ERROR) {
201 error = bp->bio_error;
202 goto doerror;
203 }
204 }
205 }
206 doerror:
207 if (pbuf)
208 uma_zfree(pbuf_zone, pbuf);
209 else if (pages)
210 free(pages, M_DEVBUF);
211 g_destroy_bio(bp);
212 PRELE(curproc);
213 return (error);
214 }
215