kern_physio.c revision 121223 
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 121223 2003-10-18 19:48:21Z 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(dev_t dev, struct uio *uio, int ioflag)
36{
37	int i;
38	int error;
39	int spl;
40	caddr_t sa;
41	u_int iolen;
42	struct buf *bp;
43
44	/* We cannot trust the device driver to hold Giant for us */
45	mtx_lock(&Giant);
46	/* Keep the process UPAGES from being swapped. XXX: why ? */
47	PHOLD(curproc);
48
49	bp = getpbuf(NULL);
50	sa = bp->b_data;
51	error = 0;
52
53	/* XXX: sanity check */
54	if(dev->si_iosize_max < PAGE_SIZE) {
55		printf("WARNING: %s si_iosize_max=%d, using DFLTPHYS.\n",
56		    devtoname(dev), dev->si_iosize_max);
57		dev->si_iosize_max = DFLTPHYS;
58	}
59
60	for (i = 0; i < uio->uio_iovcnt; i++) {
61		while (uio->uio_iov[i].iov_len) {
62			bp->b_flags = B_PHYS;
63			if (uio->uio_rw == UIO_READ)
64				bp->b_iocmd = BIO_READ;
65			else
66				bp->b_iocmd = BIO_WRITE;
67			bp->b_dev = dev;
68			bp->b_iodone = bdone;
69			bp->b_data = uio->uio_iov[i].iov_base;
70			bp->b_bcount = uio->uio_iov[i].iov_len;
71			bp->b_offset = uio->uio_offset;
72			bp->b_iooffset = uio->uio_offset;
73			bp->b_saveaddr = sa;
74
75			/* Don't exceed drivers iosize limit */
76			if (bp->b_bcount > dev->si_iosize_max)
77				bp->b_bcount = dev->si_iosize_max;
78
79			/*
80			 * Make sure the pbuf can map the request
81			 * XXX: The pbuf has kvasize = MAXPHYS so a request
82			 * XXX: larger than MAXPHYS - PAGE_SIZE must be
83			 * XXX: page aligned or it will be fragmented.
84			 */
85			iolen = ((vm_offset_t) bp->b_data) & PAGE_MASK;
86			if ((bp->b_bcount + iolen) > bp->b_kvasize) {
87				bp->b_bcount = bp->b_kvasize;
88				if (iolen != 0)
89					bp->b_bcount -= PAGE_SIZE;
90			}
91			bp->b_bufsize = bp->b_bcount;
92
93			bp->b_blkno = btodb(bp->b_offset);
94
95			if (uio->uio_segflg == UIO_USERSPACE)
96				if (vmapbuf(bp) < 0) {
97					error = EFAULT;
98					goto doerror;
99				}
100
101			DEV_STRATEGY(bp);
102			spl = splbio();
103			if (uio->uio_rw == UIO_READ)
104				bwait(bp, PRIBIO, "physrd");
105			else
106				bwait(bp, PRIBIO, "physwr");
107			splx(spl);
108
109			if (uio->uio_segflg == UIO_USERSPACE)
110				vunmapbuf(bp);
111			iolen = bp->b_bcount - bp->b_resid;
112			if (iolen == 0 && !(bp->b_ioflags & BIO_ERROR))
113				goto doerror;	/* EOF */
114			uio->uio_iov[i].iov_len -= iolen;
115			uio->uio_iov[i].iov_base =
116			    (char *)uio->uio_iov[i].iov_base + iolen;
117			uio->uio_resid -= iolen;
118			uio->uio_offset += iolen;
119			if( bp->b_ioflags & BIO_ERROR) {
120				error = bp->b_error;
121				goto doerror;
122			}
123		}
124	}
125doerror:
126	relpbuf(bp, NULL);
127	PRELE(curproc);
128	mtx_unlock(&Giant);
129	return (error);
130}
131