kern_physio.c revision 137186 
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: head/sys/kern/kern_physio.c 137186 2004-11-04 07:59:57Z phk $");
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/proc.h>
29#include <sys/uio.h>
30
31#include <vm/vm.h>
32#include <vm/vm_extern.h>
33
34int
35physio(struct cdev *dev, struct uio *uio, int ioflag)
36{
37	int i;
38	int error;
39	caddr_t sa;
40	u_int iolen;
41	struct buf *bp;
42
43	/* Keep the process UPAGES from being swapped. XXX: why ? */
44	PHOLD(curproc);
45
46	bp = getpbuf(NULL);
47	sa = bp->b_data;
48	error = 0;
49
50	/* XXX: sanity check */
51	if(dev->si_iosize_max < PAGE_SIZE) {
52		printf("WARNING: %s si_iosize_max=%d, using DFLTPHYS.\n",
53		    devtoname(dev), dev->si_iosize_max);
54		dev->si_iosize_max = DFLTPHYS;
55	}
56
57	for (i = 0; i < uio->uio_iovcnt; i++) {
58		while (uio->uio_iov[i].iov_len) {
59			bp->b_flags = 0;
60			if (uio->uio_rw == UIO_READ)
61				bp->b_iocmd = BIO_READ;
62			else
63				bp->b_iocmd = BIO_WRITE;
64			bp->b_iodone = bdone;
65			bp->b_data = uio->uio_iov[i].iov_base;
66			bp->b_bcount = uio->uio_iov[i].iov_len;
67			bp->b_offset = uio->uio_offset;
68			bp->b_iooffset = uio->uio_offset;
69			bp->b_saveaddr = sa;
70
71			/* Don't exceed drivers iosize limit */
72			if (bp->b_bcount > dev->si_iosize_max)
73				bp->b_bcount = dev->si_iosize_max;
74
75			/*
76			 * Make sure the pbuf can map the request
77			 * XXX: The pbuf has kvasize = MAXPHYS so a request
78			 * XXX: larger than MAXPHYS - PAGE_SIZE must be
79			 * XXX: page aligned or it will be fragmented.
80			 */
81			iolen = ((vm_offset_t) bp->b_data) & PAGE_MASK;
82			if ((bp->b_bcount + iolen) > bp->b_kvasize) {
83				bp->b_bcount = bp->b_kvasize;
84				if (iolen != 0)
85					bp->b_bcount -= PAGE_SIZE;
86			}
87			bp->b_bufsize = bp->b_bcount;
88
89			bp->b_blkno = btodb(bp->b_offset);
90
91			if (uio->uio_segflg == UIO_USERSPACE)
92				if (vmapbuf(bp) < 0) {
93					error = EFAULT;
94					goto doerror;
95				}
96
97			dev_strategy(dev, bp);
98			if (uio->uio_rw == UIO_READ)
99				bwait(bp, PRIBIO, "physrd");
100			else
101				bwait(bp, PRIBIO, "physwr");
102
103			if (uio->uio_segflg == UIO_USERSPACE)
104				vunmapbuf(bp);
105			iolen = bp->b_bcount - bp->b_resid;
106			if (iolen == 0 && !(bp->b_ioflags & BIO_ERROR))
107				goto doerror;	/* EOF */
108			uio->uio_iov[i].iov_len -= iolen;
109			uio->uio_iov[i].iov_base =
110			    (char *)uio->uio_iov[i].iov_base + iolen;
111			uio->uio_resid -= iolen;
112			uio->uio_offset += iolen;
113			if( bp->b_ioflags & BIO_ERROR) {
114				error = bp->b_error;
115				goto doerror;
116			}
117		}
118	}
119doerror:
120	relpbuf(bp, NULL);
121	PRELE(curproc);
122	return (error);
123}
124