Mercurial > hg > Members > innparusu > xv6_rpi_port

annotate source/log.c @ 11:0157781eb6c2 default tip

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add entry point
author mir3636
date Tue, 25 Dec 2018 19:06:09 +0900
parents c450faca55f4
children
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
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0
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
1 #include "types.h"
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
2 #include "defs.h"
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
3 #include "param.h"
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
4 #include "spinlock.h"
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
5 #include "fs.h"
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
6 #include "buf.h"
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
7
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
8 // Simple logging. Each system call that might write the file system
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
9 // should be surrounded with begin_trans() and commit_trans() calls.
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
10 //
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
11 // The log holds at most one transaction at a time. Commit forces
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
12 // the log (with commit record) to disk, then installs the affected
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
13 // blocks to disk, then erases the log. begin_trans() ensures that
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
14 // only one system call can be in a transaction; others must wait.
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
15 //
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
16 // Allowing only one transaction at a time means that the file
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
17 // system code doesn't have to worry about the possibility of
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
18 // one transaction reading a block that another one has modified,
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
19 // for example an i-node block.
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
20 //
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
21 // Read-only system calls don't need to use transactions, though
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
22 // this means that they may observe uncommitted data. I-node and
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
23 // buffer locks prevent read-only calls from seeing inconsistent data.
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
24 //
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
25 // The log is a physical re-do log containing disk blocks.
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
26 // The on-disk log format:
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
27 // header block, containing sector #s for block A, B, C, ...
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
28 // block A
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
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29 // block B
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
30 // block C
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
31 // ...
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
32 // Log appends are synchronous.
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
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33
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
34 // Contents of the header block, used for both the on-disk header block
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
35 // and to keep track in memory of logged sector #s before commit.
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
36 struct logheader {
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
37 int n;
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
38 int sector[LOGSIZE];
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
39 };
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
40
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
41 struct log {
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
42 struct spinlock lock;
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
43 int start;
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
44 int size;
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
45 int busy; // a transaction is active
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
46 int dev;
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
47 struct logheader lh;
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
48 };
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
49 struct log log;
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
50
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
51 static void recover_from_log(void);
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
52
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
53 void
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
54 initlog(void)
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
55 {
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
56 if (sizeof(struct logheader) >= BSIZE)
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
57 panic("initlog: too big logheader");
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
58
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
59 struct superblock sb;
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
60 memset(&log, 0, sizeof(log));
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
61 initlock(&log.lock, "log");
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
62 readsb(ROOTDEV, &sb);
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
63 log.start = sb.size - sb.nlog;
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
64 log.size = sb.nlog;
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
65 log.dev = ROOTDEV;
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
66 recover_from_log();
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
67 }
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
68
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
69 // Copy committed blocks from log to their home location
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
70 static void
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
71 install_trans(void)
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
72 {
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
73 int tail;
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
74
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
75 for (tail = 0; tail < log.lh.n; tail++) {
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
76 struct buf *lbuf = bread(log.dev, log.start+tail+1); // read log block
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
77 struct buf *dbuf = bread(log.dev, log.lh.sector[tail]); // read dst
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
78 memmove(dbuf->data, lbuf->data, BSIZE); // copy block to dst
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
79 bwrite(dbuf); // write dst to disk
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
80 brelse(lbuf);
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
81 brelse(dbuf);
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
82 }
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
83 }
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
84
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
85 // Read the log header from disk into the in-memory log header
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
86 static void
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
87 read_head(void)
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
88 {
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
89 struct buf *buf = bread(log.dev, log.start);
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
90 struct logheader *lh = (struct logheader *) (buf->data);
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
91 int i;
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
92 log.lh.n = lh->n;
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
93 for (i = 0; i < log.lh.n; i++) {
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
94 log.lh.sector[i] = lh->sector[i];
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
95 }
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
96 brelse(buf);
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
97 }
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
98
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
99 // Write in-memory log header to disk.
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
100 // This is the true point at which the
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
101 // current transaction commits.
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
102 static void
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
103 write_head(void)
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
104 {
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
105 struct buf *buf = bread(log.dev, log.start);
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
106 struct logheader *hb = (struct logheader *) (buf->data);
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
107 int i;
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
108 hb->n = log.lh.n;
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
109 for (i = 0; i < log.lh.n; i++) {
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
110 hb->sector[i] = log.lh.sector[i];
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
111 }
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
112 bwrite(buf);
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
113 brelse(buf);
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
114 }
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
115
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
116 static void
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
117 recover_from_log(void)
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
118 {
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
119 read_head();
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
120 install_trans(); // if committed, copy from log to disk
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
121 log.lh.n = 0;
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
122 write_head(); // clear the log
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
123 }
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
124
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
125 void
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
126 begin_trans(void)
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
127 {
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
128 acquire(&log.lock);
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
129 while (log.busy) {
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
130 sleep(&log, &log.lock);
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
131 }
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
132 log.busy = 1;
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
133 release(&log.lock);
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
134 }
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
135
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
136 void
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
137 commit_trans(void)
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
138 {
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
139 if (log.lh.n > 0) {
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
140 write_head(); // Write header to disk -- the real commit
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
141 install_trans(); // Now install writes to home locations
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
142 log.lh.n = 0;
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
143 write_head(); // Erase the transaction from the log
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
144 }
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
145
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
146 acquire(&log.lock);
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
147 log.busy = 0;
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
148 wakeup(&log);
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
149 release(&log.lock);
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
150 }
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
151
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
152 // Caller has modified b->data and is done with the buffer.
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
153 // Append the block to the log and record the block number,
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
154 // but don't write the log header (which would commit the write).
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
155 // log_write() replaces bwrite(); a typical use is:
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
156 // bp = bread(...)
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
157 // modify bp->data[]
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
158 // log_write(bp)
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
159 // brelse(bp)
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
160 void
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
161 log_write(struct buf *b)
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
162 {
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
163 int i;
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
164
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
165 if (log.lh.n >= LOGSIZE || log.lh.n >= log.size - 1)
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
166 panic("too big a transaction");
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
167 if (!log.busy)
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
168 panic("write outside of trans");
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
169
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
170 for (i = 0; i < log.lh.n; i++) {
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
171 if (log.lh.sector[i] == b->sector) // log absorbtion?
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
172 break;
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
173 }
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
diff changeset
174 log.lh.sector[i] = b->sector;
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
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175 struct buf *lbuf = bread(b->dev, log.start+i+1);
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
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176 memmove(lbuf->data, b->data, BSIZE);
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
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177 bwrite(lbuf);
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
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178 brelse(lbuf);
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
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179 if (i == log.lh.n)
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
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180 log.lh.n++;
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
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181 b->flags |= B_DIRTY; // XXX prevent eviction
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
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182 }
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
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183
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
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184 //PAGEBREAK!
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
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185 // Blank page.
Tatsuki IHA <innparusu@cr.ie.u-ryukyu.ac.jp>
parents:
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186