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WebSVN – planix.SVN – Blame – /os/branches/feature_fixcpp/sys/src/cmd/disk/kfs/iobuf.c – Rev 2

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2 - 1 
#include	"all.h"
2 
 
3 
#define	DEBUG	0
4 
 
5 
long	niob;
6 
long	nhiob;
7 
Hiob	*hiob;
8 
 
9 
Iobuf*
10 
getbuf(Device dev, long addr, int flag)
11 
{
12 
	Iobuf *p, *s;
13 
	Hiob *hp;
14 
	long h;
15 
 
16 
	if(DEBUG)
17 
		print("getbuf %D(%ld) f=%x\n", dev, addr, flag);
18 
	h = addr +
19 
		dev.type*1009L +
20 
		dev.ctrl*10007L +
21 
		dev.unit*100003L +
22 
		dev.part*1000003L;
23 
	if(h < 0)
24 
		h = ~h;
25 
	h %= nhiob;
26 
	hp = &hiob[h];
27 
 
28 
loop:
29 
	lock(hp);
30 
 
31 
/*
32 
 * look for it in the active list
33 
 */
34 
	s = hp->link;
35 
	for(p=s;;) {
36 
		if(p->addr == addr && !devcmp(p->dev, dev)) {
37 
			if(p != s) {
38 
				p->back->fore = p->fore;
39 
				p->fore->back = p->back;
40 
				p->fore = s;
41 
				p->back = s->back;
42 
				s->back = p;
43 
				p->back->fore = p;
44 
				hp->link = p;
45 
			}
46 
			unlock(hp);
47 
			qlock(p);
48 
			if(p->addr != addr || devcmp(p->dev, dev)) {
49 
				qunlock(p);
50 
				goto loop;
51 
			}
52 
			p->flags |= flag;
53 
			cons.bhit.count++;
54 
			p->iobuf = p->xiobuf;
55 
			return p;
56 
		}
57 
		p = p->fore;
58 
		if(p == s)
59 
			break;
60 
	}
61 
	if(flag & Bprobe) {
62 
		unlock(hp);
63 
		return 0;
64 
	}
65 
 
66 
/*
67 
 * not found
68 
 * take oldest unlocked entry in this queue
69 
 */
70 
xloop:
71 
	p = s->back;
72 
	if(!canqlock(p)) {
73 
		if(p == hp->link) {
74 
			unlock(hp);
75 
			print("iobuf all locked\n");
76 
			goto loop;
77 
		}
78 
		s = p;
79 
		goto xloop;
80 
	}
81 
	/*
82 
	 * its dangerous to flush the pseudo
83 
	 * devices since they recursively call
84 
	 * getbuf/putbuf. deadlock!
85 
	 */
86 
	if(p->flags & Bres) {
87 
		qunlock(p);
88 
		if(p == hp->link) {
89 
			unlock(hp);
90 
			print("iobuf all resed\n");
91 
			goto loop;
92 
		}
93 
		s = p;
94 
		goto xloop;
95 
	}
96 
	if(p->flags & Bmod) {
97 
		unlock(hp);
98 
		if(!devwrite(p->dev, p->addr, p->xiobuf))
99 
			p->flags &= ~(Bimm|Bmod);
100 
		qunlock(p);
101 
		goto loop;
102 
	}
103 
	hp->link = p;
104 
	p->addr = addr;
105 
	p->dev = dev;
106 
	p->flags = flag;
107 
	unlock(hp);
108 
	p->iobuf = p->xiobuf;
109 
	if(flag & Bread) {
110 
		if(devread(p->dev, p->addr, p->iobuf)) {
111 
			p->flags = 0;
112 
			p->dev = devnone;
113 
			p->addr = -1;
114 
			p->iobuf = (char*)-1;
115 
			qunlock(p);
116 
			return 0;
117 
		}
118 
		cons.bread.count++;
119 
		return p;
120 
	}
121 
	cons.binit.count++;
122 
	return p;
123 
}
124 
 
125 
/*
126 
 * syncblock tries to put out a block per hashline
127 
 * returns 0 all done,
128 
 * returns 1 if it missed something
129 
 */
130 
int
131 
syncblock(void)
132 
{
133 
	Iobuf *p, *s, *q;
134 
	Hiob *hp;
135 
	long h;
136 
	int flag;
137 
 
138 
	flag = 0;
139 
	for(h=0; h<nhiob; h++) {
140 
		q = 0;
141 
		hp = &hiob[h];
142 
		lock(hp);
143 
		s = hp->link;
144 
		for(p=s;;) {
145 
			if(p->flags & Bmod) {
146 
				if(q)
147 
					flag = 1;	/* more than 1 mod/line */
148 
				q = p;
149 
			}
150 
			p = p->fore;
151 
			if(p == s)
152 
				break;
153 
		}
154 
		unlock(hp);
155 
		if(q) {
156 
			if(!canqlock(q)) {
157 
				flag = 1;		/* missed -- was locked */
158 
				continue;
159 
			}
160 
			if(!(q->flags & Bmod)) {
161 
				qunlock(q);
162 
				continue;
163 
			}
164 
			if(!devwrite(q->dev, q->addr, q->xiobuf))
165 
				q->flags &= ~(Bmod|Bimm);
166 
			qunlock(q);
167 
		}
168 
	}
169 
	return flag;
170 
}
171 
 
172 
void
173 
sync(char *reason)
174 
{
175 
	long i;
176 
 
177 
	print("sync: %s\n", reason);
178 
	for(i=10*nhiob; i>0; i--)
179 
		if(!syncblock())
180 
			return;
181 
	print("sync shorted\n");
182 
}
183 
 
184 
void
185 
putbuf(Iobuf *p)
186 
{
187 
	if(canqlock(p))
188 
		print("buffer not locked %D(%ld)\n", p->dev, p->addr);
189 
	if(p->flags & Bimm) {
190 
		if(!(p->flags & Bmod))
191 
			print("imm and no mod %D(%ld)\n", p->dev, p->addr);
192 
		if(!devwrite(p->dev, p->addr, p->iobuf))
193 
			p->flags &= ~(Bmod|Bimm);
194 
	}
195 
	p->iobuf = (char*)-1;
196 
	qunlock(p);
197 
}
198 
 
199 
int
200 
checktag(Iobuf *p, int tag, long qpath)
201 
{
202 
	Tag *t;
203 
 
204 
	t = (Tag*)(p->iobuf+BUFSIZE);
205 
	if(t->tag != tag) {
206 
		if(1 || CHAT(0))
207 
			print("	tag = %G; expected %G; addr = %lud\n",
208 
				t->tag, tag, p->addr);
209 
		return 2;
210 
	}
211 
	if(qpath != QPNONE) {
212 
		qpath &= ~QPDIR;
213 
		if(qpath != t->path) {
214 
			if(qpath == (t->path&~QPDIR))	/* old bug */
215 
				return 0;
216 
			if(1 || CHAT(0))
217 
				print("	tag/path = %lux; expected %G/%lux\n",
218 
					t->path, tag, qpath);
219 
			return 1;
220 
		}
221 
	}
222 
	return 0;
223 
}
224 
 
225 
void
226 
settag(Iobuf *p, int tag, long qpath)
227 
{
228 
	Tag *t;
229 
 
230 
	t = (Tag*)(p->iobuf+BUFSIZE);
231 
	t->tag = tag;
232 
	if(qpath != QPNONE)
233 
		t->path = qpath & ~QPDIR;
234 
	p->flags |= Bmod;
235 
}