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1.1 root 1: /*
2: * linux/fs/truncate.c
3: *
4: * (C) 1991 Linus Torvalds
5: */
6:
1.1.1.5 ! root 7: #include <errno.h>
! 8:
1.1 root 9: #include <linux/sched.h>
10: #include <linux/minix_fs.h>
11: #include <linux/tty.h>
1.1.1.4 root 12: #include <linux/stat.h>
1.1.1.5 ! root 13: #include <linux/fcntl.h>
1.1 root 14:
1.1.1.3 root 15: /*
16: * Truncate has the most races in the whole filesystem: coding it is
17: * a pain in the a**. Especially as I don't do any locking...
18: *
19: * The code may look a bit weird, but that's just because I've tried to
20: * handle things like file-size changes in a somewhat graceful manner.
21: * Anyway, truncating a file at the same time somebody else writes to it
22: * is likely to result in pretty weird behaviour...
23: *
24: * The new code handles normal truncates (size = 0) as well as the more
25: * general case (size = XXX). I hope.
26: */
27:
28: static int trunc_direct(struct inode * inode)
1.1 root 29: {
30: int i;
1.1.1.3 root 31: int result = 0;
32: #define DIRECT_BLOCK ((inode->i_size + 1023) >> 10)
1.1 root 33:
1.1.1.3 root 34: repeat:
35: for (i = DIRECT_BLOCK ; i < 7 ; i++) {
36: if (i < DIRECT_BLOCK)
37: goto repeat;
38: if (!inode->i_data[i])
39: continue;
40: result = 1;
41: if (minix_free_block(inode->i_dev,inode->i_data[i]))
42: inode->i_data[i] = 0;
1.1 root 43: }
1.1.1.3 root 44: return result;
1.1 root 45: }
46:
1.1.1.3 root 47: static int trunc_indirect(struct inode * inode, int offset, unsigned short * p)
1.1 root 48: {
49: int i;
1.1.1.3 root 50: struct buffer_head * bh = NULL;
51: unsigned short * ind;
52: int result = 0;
53: #define INDIRECT_BLOCK (DIRECT_BLOCK-offset)
54:
55: if (*p)
56: bh = bread(inode->i_dev,*p);
57: if (!bh)
58: return 0;
59: repeat:
60: for (i = INDIRECT_BLOCK ; i < 512 ; i++) {
61: if (i < 0)
62: i = 0;
63: if (i < INDIRECT_BLOCK)
64: goto repeat;
65: ind = i+(unsigned short *) bh->b_data;
66: if (!*ind)
67: continue;
68: result = 1;
69: if (minix_free_block(inode->i_dev,*ind))
70: *ind = 0;
1.1 root 71: }
1.1.1.3 root 72: ind = (unsigned short *) bh->b_data;
73: for (i = 0; i < 512; i++)
74: if (*(ind++))
75: break;
76: brelse(bh);
77: if (i >= 512) {
78: result = 1;
79: if (minix_free_block(inode->i_dev,*p))
80: *p = 0;
81: }
82: return result;
83: }
84:
85: static int trunc_dindirect(struct inode * inode)
86: {
87: int i;
88: struct buffer_head * bh = NULL;
89: unsigned short * dind;
90: int result = 0;
91: #define DINDIRECT_BLOCK ((DIRECT_BLOCK-(512+7))>>9)
92:
93: if (inode->i_data[8])
94: bh = bread(inode->i_dev,inode->i_data[8]);
95: if (!bh)
1.1 root 96: return 0;
1.1.1.3 root 97: repeat:
98: for (i = DINDIRECT_BLOCK ; i < 512 ; i ++) {
99: if (i < 0)
100: i = 0;
101: if (i < DINDIRECT_BLOCK)
102: goto repeat;
103: dind = i+(unsigned short *) bh->b_data;
104: if (!*dind)
105: continue;
106: result |= trunc_indirect(inode,7+512+(i<<9),dind);
107: }
108: dind = (unsigned short *) bh->b_data;
109: for (i = 0; i < 512; i++)
110: if (*(dind++))
111: break;
112: brelse(bh);
113: if (i >= 512) {
114: result = 1;
115: if (minix_free_block(inode->i_dev,inode->i_data[8]))
116: inode->i_data[8] = 0;
117: }
118: return result;
1.1 root 119: }
1.1.1.3 root 120:
1.1 root 121: void minix_truncate(struct inode * inode)
122: {
1.1.1.3 root 123: int flag;
1.1 root 124:
125: if (!(S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||
126: S_ISLNK(inode->i_mode)))
127: return;
1.1.1.3 root 128: if (inode->i_data[7] & 0xffff0000)
129: printk("BAD! minix inode has 16 high bits set\n");
130: while (1) {
131: flag = trunc_direct(inode);
132: flag |= trunc_indirect(inode,7,(unsigned short *)&inode->i_data[7]);
133: flag |= trunc_dindirect(inode);
134: if (!flag)
135: break;
1.1 root 136: current->counter = 0;
137: schedule();
138: }
139: inode->i_mtime = inode->i_ctime = CURRENT_TIME;
1.1.1.3 root 140: inode->i_dirt = 1;
1.1 root 141: }
142:
143: /*
144: * Called when a inode is released. Note that this is different
145: * from minix_open: open gets called at every open, but release
146: * gets called only when /all/ the files are closed.
147: */
148: void minix_release(struct inode * inode, struct file * filp)
149: {
150: printk("minix_release not implemented\n");
151: }
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