1 files changed, 130 insertions, 0 deletions
diff --git a/fs/btrfs/bit-radix.c b/fs/btrfs/bit-radix.c
new file mode 100644
index 00000000000..e8bf876db39
--- /dev/null
+++ b/fs/btrfs/bit-radix.c
@@ -0,0 +1,130 @@
+/*
+ * Copyright (C) 2007 Oracle.  All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License v2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 021110-1307, USA.
+ */
+
+#include "bit-radix.h"
+
+#define BIT_ARRAY_BYTES 256
+#define BIT_RADIX_BITS_PER_ARRAY ((BIT_ARRAY_BYTES - sizeof(unsigned long)) * 8)
+
+extern struct kmem_cache *btrfs_bit_radix_cachep;
+int set_radix_bit(struct radix_tree_root *radix, unsigned long bit)
+{
+	unsigned long *bits;
+	unsigned long slot;
+	int bit_slot;
+	int ret;
+
+	slot = bit / BIT_RADIX_BITS_PER_ARRAY;
+	bit_slot = bit % BIT_RADIX_BITS_PER_ARRAY;
+
+	bits = radix_tree_lookup(radix, slot);
+	if (!bits) {
+		bits = kmem_cache_alloc(btrfs_bit_radix_cachep, GFP_NOFS);
+		if (!bits)
+			return -ENOMEM;
+		memset(bits + 1, 0, BIT_ARRAY_BYTES - sizeof(unsigned long));
+		bits[0] = slot;
+		ret = radix_tree_insert(radix, slot, bits);
+		if (ret)
+			return ret;
+	}
+	ret = test_and_set_bit(bit_slot, bits + 1);
+	if (ret < 0)
+		ret = 1;
+	return ret;
+}
+
+int test_radix_bit(struct radix_tree_root *radix, unsigned long bit)
+{
+	unsigned long *bits;
+	unsigned long slot;
+	int bit_slot;
+
+	slot = bit / BIT_RADIX_BITS_PER_ARRAY;
+	bit_slot = bit % BIT_RADIX_BITS_PER_ARRAY;
+
+	bits = radix_tree_lookup(radix, slot);
+	if (!bits)
+		return 0;
+	return test_bit(bit_slot, bits + 1);
+}
+
+int clear_radix_bit(struct radix_tree_root *radix, unsigned long bit)
+{
+	unsigned long *bits;
+	unsigned long slot;
+	int bit_slot;
+	int i;
+	int empty = 1;
+
+	slot = bit / BIT_RADIX_BITS_PER_ARRAY;
+	bit_slot = bit % BIT_RADIX_BITS_PER_ARRAY;
+
+	bits = radix_tree_lookup(radix, slot);
+	if (!bits)
+		return 0;
+	clear_bit(bit_slot, bits + 1);
+	for (i = 1; i < BIT_ARRAY_BYTES / sizeof(unsigned long); i++) {
+		if (bits[i]) {
+			empty = 0;
+			break;
+		}
+	}
+	if (empty) {
+		bits = radix_tree_delete(radix, slot);
+		BUG_ON(!bits);
+		kmem_cache_free(btrfs_bit_radix_cachep, bits);
+	}
+	return 0;
+}
+
+int find_first_radix_bit(struct radix_tree_root *radix, unsigned long *retbits,
+			 unsigned long start, int nr)
+{
+	unsigned long *bits;
+	unsigned long *gang[4];
+	int found;
+	int ret;
+	int i;
+	int total_found = 0;
+	unsigned long slot;
+
+	slot = start / BIT_RADIX_BITS_PER_ARRAY;
+	ret = radix_tree_gang_lookup(radix, (void **)gang, slot,
+				     ARRAY_SIZE(gang));
+	found = start % BIT_RADIX_BITS_PER_ARRAY;
+	for (i = 0; i < ret && nr > 0; i++) {
+		bits = gang[i];
+		while(nr > 0) {
+			found = find_next_bit(bits + 1,
+					      BIT_RADIX_BITS_PER_ARRAY,
+					      found);
+			if (found < BIT_RADIX_BITS_PER_ARRAY) {
+				*retbits = bits[0] *
+					BIT_RADIX_BITS_PER_ARRAY + found;
+				retbits++;
+				nr--;
+				total_found++;
+				found++;
+			} else
+				break;
+		}
+		found = 0;
+	}
+	return total_found;
+}