kern_physio.c revision 58934 
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 58934 2000-04-02 15:24:56Z phk $
20 */
21
22#include <sys/param.h>
23#include <sys/systm.h>
24#include <sys/buf.h>
25#include <sys/conf.h>
26#include <sys/proc.h>
27#include <sys/uio.h>
28
29#include <vm/vm.h>
30#include <vm/vm_extern.h>
31
32static void
33physwakeup(struct buf *bp)
34{
35	wakeup((caddr_t) bp);
36}
37
38int
39physio(dev_t dev, struct uio *uio, int ioflag)
40{
41	int i;
42	int error;
43	int spl;
44	caddr_t sa;
45	off_t blockno;
46	u_int iolen;
47	struct buf *bp;
48
49	/* Keep the process UPAGES from being swapped. XXX: why ? */
50	PHOLD(curproc);
51
52	bp = getpbuf(NULL);
53	sa = bp->b_data;
54	error = bp->b_error = 0;
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	for (i = 0; i < uio->uio_iovcnt; i++) {
64		while (uio->uio_iov[i].iov_len) {
65			bp->b_flags = B_PHYS;
66			if (uio->uio_rw == UIO_READ)
67				bp->b_iocmd = BIO_READ;
68			else
69				bp->b_iocmd = BIO_WRITE;
70			bp->b_dev = dev;
71			bp->b_iodone = physwakeup;
72			bp->b_data = uio->uio_iov[i].iov_base;
73			bp->b_bcount = uio->uio_iov[i].iov_len;
74			bp->b_offset = uio->uio_offset;
75			bp->b_saveaddr = sa;
76
77			/* Don't exceed drivers iosize limit */
78			if (bp->b_bcount > dev->si_iosize_max)
79				bp->b_bcount = dev->si_iosize_max;
80
81			/*
82			 * Make sure the pbuf can map the request
83			 * XXX: The pbuf has kvasize = MAXPHYS so a request
84			 * XXX: larger than MAXPHYS - PAGE_SIZE must be
85			 * XXX: page aligned or it will be fragmented.
86			 */
87			iolen = ((vm_offset_t) bp->b_data) & PAGE_MASK;
88			if ((bp->b_bcount + iolen) > bp->b_kvasize) {
89				bp->b_bcount = bp->b_kvasize;
90				if (iolen != 0)
91					bp->b_bcount -= PAGE_SIZE;
92			}
93			bp->b_bufsize = bp->b_bcount;
94
95			blockno = bp->b_offset >> DEV_BSHIFT;
96			if ((daddr_t)blockno != blockno) {
97				error = EINVAL; /* blockno overflow */
98				goto doerror;
99			}
100			bp->b_blkno = blockno;
101
102			if (uio->uio_segflg == UIO_USERSPACE) {
103				if (!useracc(bp->b_data, bp->b_bufsize,
104				    bp->b_iocmd == BIO_READ ?
105				    VM_PROT_WRITE : VM_PROT_READ)) {
106					error = EFAULT;
107					goto doerror;
108				}
109				vmapbuf(bp);
110			}
111
112			DEV_STRATEGY(bp, 0);
113			spl = splbio();
114			while ((bp->b_flags & B_DONE) == 0)
115				tsleep((caddr_t)bp, PRIBIO, "physstr", 0);
116			splx(spl);
117
118			if (uio->uio_segflg == UIO_USERSPACE)
119				vunmapbuf(bp);
120			iolen = bp->b_bcount - bp->b_resid;
121			if (iolen == 0 && !(bp->b_ioflags & BIO_ERROR))
122				goto doerror;	/* EOF */
123			uio->uio_iov[i].iov_len -= iolen;
124			uio->uio_iov[i].iov_base += iolen;
125			uio->uio_resid -= iolen;
126			uio->uio_offset += iolen;
127			if( bp->b_ioflags & BIO_ERROR) {
128				error = bp->b_error;
129				goto doerror;
130			}
131		}
132	}
133doerror:
134	relpbuf(bp, NULL);
135	PRELE(curproc);
136	return (error);
137}
138