kern_physio.c revision 60041 
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 * $FreeBSD: head/sys/kern/kern_physio.c 60041 2000-05-05 09:59:14Z phk $
20 */
21
22#include <sys/param.h>
23#include <sys/systm.h>
24#include <sys/bio.h>
25#include <sys/buf.h>
26#include <sys/conf.h>
27#include <sys/proc.h>
28#include <sys/uio.h>
29
30#include <vm/vm.h>
31#include <vm/vm_extern.h>
32
33static void
34physwakeup(struct buf *bp)
35{
36	wakeup((caddr_t) bp);
37}
38
39int
40physio(dev_t dev, struct uio *uio, int ioflag)
41{
42	int i;
43	int error;
44	int spl;
45	caddr_t sa;
46	off_t blockno;
47	u_int iolen;
48	struct buf *bp;
49
50	/* Keep the process UPAGES from being swapped. XXX: why ? */
51	PHOLD(curproc);
52
53	bp = getpbuf(NULL);
54	sa = bp->b_data;
55	error = bp->b_error = 0;
56
57	/* XXX: sanity check */
58	if(dev->si_iosize_max < PAGE_SIZE) {
59		printf("WARNING: %s si_iosize_max=%d, using DFLTPHYS.\n",
60		    devtoname(dev), dev->si_iosize_max);
61		dev->si_iosize_max = DFLTPHYS;
62	}
63
64	for (i = 0; i < uio->uio_iovcnt; i++) {
65		while (uio->uio_iov[i].iov_len) {
66			bp->b_flags = B_PHYS;
67			if (uio->uio_rw == UIO_READ)
68				bp->b_iocmd = BIO_READ;
69			else
70				bp->b_iocmd = BIO_WRITE;
71			bp->b_dev = dev;
72			bp->b_iodone = physwakeup;
73			bp->b_data = uio->uio_iov[i].iov_base;
74			bp->b_bcount = uio->uio_iov[i].iov_len;
75			bp->b_offset = uio->uio_offset;
76			bp->b_saveaddr = sa;
77
78			/* Don't exceed drivers iosize limit */
79			if (bp->b_bcount > dev->si_iosize_max)
80				bp->b_bcount = dev->si_iosize_max;
81
82			/*
83			 * Make sure the pbuf can map the request
84			 * XXX: The pbuf has kvasize = MAXPHYS so a request
85			 * XXX: larger than MAXPHYS - PAGE_SIZE must be
86			 * XXX: page aligned or it will be fragmented.
87			 */
88			iolen = ((vm_offset_t) bp->b_data) & PAGE_MASK;
89			if ((bp->b_bcount + iolen) > bp->b_kvasize) {
90				bp->b_bcount = bp->b_kvasize;
91				if (iolen != 0)
92					bp->b_bcount -= PAGE_SIZE;
93			}
94			bp->b_bufsize = bp->b_bcount;
95
96			blockno = bp->b_offset >> DEV_BSHIFT;
97			if ((daddr_t)blockno != blockno) {
98				error = EINVAL; /* blockno overflow */
99				goto doerror;
100			}
101			bp->b_blkno = blockno;
102
103			if (uio->uio_segflg == UIO_USERSPACE) {
104				if (!useracc(bp->b_data, bp->b_bufsize,
105				    bp->b_iocmd == BIO_READ ?
106				    VM_PROT_WRITE : VM_PROT_READ)) {
107					error = EFAULT;
108					goto doerror;
109				}
110				vmapbuf(bp);
111			}
112
113			DEV_STRATEGY(bp, 0);
114			spl = splbio();
115			while ((bp->b_flags & B_DONE) == 0)
116				tsleep((caddr_t)bp, PRIBIO, "physstr", 0);
117			splx(spl);
118
119			if (uio->uio_segflg == UIO_USERSPACE)
120				vunmapbuf(bp);
121			iolen = bp->b_bcount - bp->b_resid;
122			if (iolen == 0 && !(bp->b_ioflags & BIO_ERROR))
123				goto doerror;	/* EOF */
124			uio->uio_iov[i].iov_len -= iolen;
125			uio->uio_iov[i].iov_base += iolen;
126			uio->uio_resid -= iolen;
127			uio->uio_offset += iolen;
128			if( bp->b_ioflags & BIO_ERROR) {
129				error = bp->b_error;
130				goto doerror;
131			}
132		}
133	}
134doerror:
135	relpbuf(bp, NULL);
136	PRELE(curproc);
137	return (error);
138}
139