initial version

Book-Lite/linux-0.12/fs/truncate.c

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+/*
+ *  linux/fs/truncate.c
+ *
+ *  (C) 1991  Linus Torvalds
+ */
+
+#include <linux/sched.h>
+
+#include <sys/stat.h>
+
+static int free_ind(int dev,int block)
+{
+	struct buffer_head * bh;
+	unsigned short * p;
+	int i;
+	int block_busy;
+
+	if (!block)
+		return 1;
+	block_busy = 0;
+	if (bh=bread(dev,block)) {
+		p = (unsigned short *) bh->b_data;
+		for (i=0;i<512;i++,p++)
+			if (*p)
+				if (free_block(dev,*p)) {
+					*p = 0;
+					bh->b_dirt = 1;
+				} else
+					block_busy = 1;
+		brelse(bh);
+	}
+	if (block_busy)
+		return 0;
+	else
+		return free_block(dev,block);
+}
+
+static int free_dind(int dev,int block)
+{
+	struct buffer_head * bh;
+	unsigned short * p;
+	int i;
+	int block_busy;
+
+	if (!block)
+		return 1;
+	block_busy = 0;
+	if (bh=bread(dev,block)) {
+		p = (unsigned short *) bh->b_data;
+		for (i=0;i<512;i++,p++)
+			if (*p)
+				if (free_ind(dev,*p)) {
+					*p = 0;
+					bh->b_dirt = 1;
+				} else
+					block_busy = 1;
+		brelse(bh);
+	}
+	if (block_busy)
+		return 0;
+	else
+		return free_block(dev,block);
+}
+
+void truncate(struct m_inode * inode)
+{
+	int i;
+	int block_busy;
+
+	if (!(S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||
+	     S_ISLNK(inode->i_mode)))
+		return;
+repeat:
+	block_busy = 0;
+	for (i=0;i<7;i++)
+		if (inode->i_zone[i]) {
+			if (free_block(inode->i_dev,inode->i_zone[i]))
+				inode->i_zone[i]=0;
+			else
+				block_busy = 1;
+		}
+	if (free_ind(inode->i_dev,inode->i_zone[7]))
+		inode->i_zone[7] = 0;
+	else
+		block_busy = 1;
+	if (free_dind(inode->i_dev,inode->i_zone[8]))
+		inode->i_zone[8] = 0;
+	else
+		block_busy = 1;
+	inode->i_dirt = 1;
+	if (block_busy) {
+		current->counter = 0;
+		schedule();
+		goto repeat;
+	}
+	inode->i_size = 0;
+	inode->i_mtime = inode->i_ctime = CURRENT_TIME;
+}
+