Import of Linus's Linux 1.1.68

1 files changed, 184 insertions, 0 deletions

diff --git a/fs/minix/truncate.c b/fs/minix/truncate.c
new file mode 100644
index 000000000..0b127b9b8
--- /dev/null
+++ b/fs/minix/truncate.c
@@ -0,0 +1,184 @@
+/*
+ *  linux/fs/truncate.c
+ *
+ *  Copyright (C) 1991, 1992  Linus Torvalds
+ */
+
+#include <linux/errno.h>
+#include <linux/sched.h>
+#include <linux/minix_fs.h>
+#include <linux/stat.h>
+#include <linux/fcntl.h>
+
+/*
+ * Truncate has the most races in the whole filesystem: coding it is
+ * a pain in the a**. Especially as I don't do any locking...
+ *
+ * The code may look a bit weird, but that's just because I've tried to
+ * handle things like file-size changes in a somewhat graceful manner.
+ * Anyway, truncating a file at the same time somebody else writes to it
+ * is likely to result in pretty weird behaviour...
+ *
+ * The new code handles normal truncates (size = 0) as well as the more
+ * general case (size = XXX). I hope.
+ */
+
+static int trunc_direct(struct inode * inode)
+{
+	unsigned short * p;
+	struct buffer_head * bh;
+	int i, tmp;
+	int retry = 0;
+#define DIRECT_BLOCK ((inode->i_size + 1023) >> 10)
+
+repeat:
+	for (i = DIRECT_BLOCK ; i < 7 ; i++) {
+		p = i + inode->u.minix_i.i_data;
+		if (!(tmp = *p))
+			continue;
+		bh = get_hash_table(inode->i_dev,tmp,BLOCK_SIZE);
+		if (i < DIRECT_BLOCK) {
+			brelse(bh);
+			goto repeat;
+		}
+		if ((bh && bh->b_count != 1) || tmp != *p) {
+			retry = 1;
+			brelse(bh);
+			continue;
+		}
+		*p = 0;
+		inode->i_dirt = 1;
+		brelse(bh);
+		minix_free_block(inode->i_sb,tmp);
+	}
+	return retry;
+}
+
+static int trunc_indirect(struct inode * inode, int offset, unsigned short * p)
+{
+	struct buffer_head * bh;
+	int i, tmp;
+	struct buffer_head * ind_bh;
+	unsigned short * ind;
+	int retry = 0;
+#define INDIRECT_BLOCK (DIRECT_BLOCK-offset)
+
+	tmp = *p;
+	if (!tmp)
+		return 0;
+	ind_bh = bread(inode->i_dev, tmp, BLOCK_SIZE);
+	if (tmp != *p) {
+		brelse(ind_bh);
+		return 1;
+	}
+	if (!ind_bh) {
+		*p = 0;
+		return 0;
+	}
+repeat:
+	for (i = INDIRECT_BLOCK ; i < 512 ; i++) {
+		if (i < 0)
+			i = 0;
+		if (i < INDIRECT_BLOCK)
+			goto repeat;
+		ind = i+(unsigned short *) ind_bh->b_data;
+		tmp = *ind;
+		if (!tmp)
+			continue;
+		bh = get_hash_table(inode->i_dev,tmp,BLOCK_SIZE);
+		if (i < INDIRECT_BLOCK) {
+			brelse(bh);
+			goto repeat;
+		}
+		if ((bh && bh->b_count != 1) || tmp != *ind) {
+			retry = 1;
+			brelse(bh);
+			continue;
+		}
+		*ind = 0;
+		mark_buffer_dirty(ind_bh, 1);
+		brelse(bh);
+		minix_free_block(inode->i_sb,tmp);
+	}
+	ind = (unsigned short *) ind_bh->b_data;
+	for (i = 0; i < 512; i++)
+		if (*(ind++))
+			break;
+	if (i >= 512)
+		if (ind_bh->b_count != 1)
+			retry = 1;
+		else {
+			tmp = *p;
+			*p = 0;
+			minix_free_block(inode->i_sb,tmp);
+		}
+	brelse(ind_bh);
+	return retry;
+}
+		
+static int trunc_dindirect(struct inode * inode)
+{
+	int i, tmp;
+	struct buffer_head * dind_bh;
+	unsigned short * dind, * p;
+	int retry = 0;
+#define DINDIRECT_BLOCK ((DIRECT_BLOCK-(512+7))>>9)
+
+	p = 8 + inode->u.minix_i.i_data;
+	if (!(tmp = *p))
+		return 0;
+	dind_bh = bread(inode->i_dev, tmp, BLOCK_SIZE);
+	if (tmp != *p) {
+		brelse(dind_bh);
+		return 1;
+	}
+	if (!dind_bh) {
+		*p = 0;
+		return 0;
+	}
+repeat:
+	for (i = DINDIRECT_BLOCK ; i < 512 ; i ++) {
+		if (i < 0)
+			i = 0;
+		if (i < DINDIRECT_BLOCK)
+			goto repeat;
+		dind = i+(unsigned short *) dind_bh->b_data;
+		retry |= trunc_indirect(inode,7+512+(i<<9),dind);
+		mark_buffer_dirty(dind_bh, 1);
+	}
+	dind = (unsigned short *) dind_bh->b_data;
+	for (i = 0; i < 512; i++)
+		if (*(dind++))
+			break;
+	if (i >= 512)
+		if (dind_bh->b_count != 1)
+			retry = 1;
+		else {
+			tmp = *p;
+			*p = 0;
+			inode->i_dirt = 1;
+			minix_free_block(inode->i_sb,tmp);
+		}
+	brelse(dind_bh);
+	return retry;
+}
+		
+void minix_truncate(struct inode * inode)
+{
+	int retry;
+
+	if (!(S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||
+	     S_ISLNK(inode->i_mode)))
+		return;
+	while (1) {
+		retry = trunc_direct(inode);
+		retry |= trunc_indirect(inode,7,inode->u.minix_i.i_data+7);
+		retry |= trunc_dindirect(inode);
+		if (!retry)
+			break;
+		current->counter = 0;
+		schedule();
+	}
+	inode->i_mtime = inode->i_ctime = CURRENT_TIME;
+	inode->i_dirt = 1;
+}