[PATCH 013/118] drbd: Add interval tree data structure

Philipp Reisner
2011-08-25T15:37:09Z

From: Andreas Gruenbacher <agruen@linbit.com>

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
---
drivers/block/drbd/Makefile | 1 +
drivers/block/drbd/drbd_interval.c | 156 ++++++++++++++++++++++++++++++++++++
drivers/block/drbd/drbd_interval.h | 31 +++++++
3 files changed, 188 insertions(+), 0 deletions(-)
create mode 100644 drivers/block/drbd/drbd_interval.c
create mode 100644 drivers/block/drbd/drbd_interval.h

diff --git a/drivers/block/drbd/Makefile b/drivers/block/drbd/Makefile
index 0d3f337..cacbb04 100644
--- a/drivers/block/drbd/Makefile
+++ b/drivers/block/drbd/Makefile
@@ -1,5 +1,6 @@
drbd-y := drbd_bitmap.o drbd_proc.o
drbd-y += drbd_worker.o drbd_receiver.o drbd_req.o drbd_actlog.o
drbd-y += drbd_main.o drbd_strings.o drbd_nl.o
+drbd-y += drbd_interval.o

obj-$(CONFIG_BLK_DEV_DRBD) += drbd.o
diff --git a/drivers/block/drbd/drbd_interval.c b/drivers/block/drbd/drbd_interval.c
new file mode 100644
index 0000000..2511dd9
--- /dev/null
+++ b/drivers/block/drbd/drbd_interval.c
@@ -0,0 +1,156 @@
+#include "drbd_interval.h"
+
+/**
+ * interval_end - return end of @node
+ */
+static inline
+sector_t interval_end(struct rb_node *node)
+{
+ struct drbd_interval *this = rb_entry(node, struct drbd_interval, rb);
+ return this->end;
+}
+
+/**
+ * update_interval_end - recompute end of @node
+ *
+ * The end of an interval is the highest (start + (size >> 9)) value of this
+ * node and of its children. Called for @node and its parents whenever the end
+ * may have changed.
+ */
+static void
+update_interval_end(struct rb_node *node, void *__unused)
+{
+ struct drbd_interval *this = rb_entry(node, struct drbd_interval, rb);
+ sector_t end;
+
+ end = this->sector + (this->size >> 9);
+ if (node->rb_left) {
+ sector_t left = interval_end(node->rb_left);
+ if (left > end)
+ end = left;
+ }
+ if (node->rb_right) {
+ sector_t right = interval_end(node->rb_right);
+ if (right > end)
+ end = right;
+ }
+ this->end = end;
+}
+
+/**
+ * drbd_insert_interval - insert a new interval into a tree
+ */
+bool
+drbd_insert_interval(struct rb_root *root, struct drbd_interval *this)
+{
+ struct rb_node **new = &root->rb_node, *parent = NULL;
+
+ BUG_ON(!IS_ALIGNED(this->size, 512));
+
+ while (*new) {
+ struct drbd_interval *here =
+ rb_entry(*new, struct drbd_interval, rb);
+
+ parent = *new;
+ if (this->sector < here->sector)
+ new = &(*new)->rb_left;
+ else if (this->sector > here->sector)
+ new = &(*new)->rb_right;
+ else if (this < here)
+ new = &(*new)->rb_left;
+ else if (this->sector > here->sector)
+ new = &(*new)->rb_right;
+ return false;
+ }
+
+ rb_link_node(&this->rb, parent, new);
+ rb_insert_color(&this->rb, root);
+ rb_augment_insert(&this->rb, update_interval_end, NULL);
+ return true;
+}
+
+/**
+ * drbd_contains_interval - check if a tree contains a given interval
+ * @sector: start sector of @interval
+ * @interval: may not be a valid pointer
+ *
+ * Returns if the tree contains the node @interval with start sector @start.
+ * Does not dereference @interval until @interval is known to be a valid object
+ * in @tree. Returns %false if @interval is in the tree but with a different
+ * sector number.
+ */
+bool
+drbd_contains_interval(struct rb_root *root, sector_t sector,
+ struct drbd_interval *interval)
+{
+ struct rb_node *node = root->rb_node;
+
+ while (node) {
+ struct drbd_interval *here =
+ rb_entry(node, struct drbd_interval, rb);
+
+ if (sector < here->sector)
+ node = node->rb_left;
+ else if (sector > here->sector)
+ node = node->rb_right;
+ else if (interval < here)
+ node = node->rb_left;
+ else if (interval > here)
+ node = node->rb_right;
+ else
+ return interval->sector == sector;
+ }
+ return false;
+}
+
+/**
+ * drbd_remove_interval - remove an interval from a tree
+ */
+void
+drbd_remove_interval(struct rb_root *root, struct drbd_interval *this)
+{
+ struct rb_node *deepest;
+
+ deepest = rb_augment_erase_begin(&this->rb);
+ rb_erase(&this->rb, root);
+ rb_augment_erase_end(deepest, update_interval_end, NULL);
+}
+
+/**
+ * drbd_find_overlap - search for an interval overlapping with [sector, sector + size)
+ * @sector: start sector
+ * @size: size, aligned to 512 bytes
+ *
+ * Returns the interval overlapping with [sector, sector + size), or NULL.
+ * When there is more than one overlapping interval in the tree, the interval
+ * with the lowest start sector is returned.
+ */
+struct drbd_interval *
+drbd_find_overlap(struct rb_root *root, sector_t sector, unsigned int size)
+{
+ struct rb_node *node = root->rb_node;
+ struct drbd_interval *overlap = NULL;
+ sector_t end = sector + (size >> 9);
+
+ BUG_ON(!IS_ALIGNED(size, 512));
+
+ while (node) {
+ struct drbd_interval *here =
+ rb_entry(node, struct drbd_interval, rb);
+
+ if (node->rb_left &&
+ sector < interval_end(node->rb_left)) {
+ /* Overlap if any must be on left side */
+ node = node->rb_left;
+ } else if (here->sector < end &&
+ sector < here->sector + (here->size >> 9)) {
+ overlap = here;
+ break;
+ } else if (sector >= here->sector) {
+ /* Overlap if any must be on right side */
+ node = node->rb_right;
+ } else
+ break;
+ }
+ return overlap;
+}
diff --git a/drivers/block/drbd/drbd_interval.h b/drivers/block/drbd/drbd_interval.h
new file mode 100644
index 0000000..bf8dcf7
--- /dev/null
+++ b/drivers/block/drbd/drbd_interval.h
@@ -0,0 +1,31 @@
+#ifndef __DRBD_INTERVAL_H
+#define __DRBD_INTERVAL_H
+
+#include <linux/types.h>
+#include <linux/rbtree.h>
+
+struct drbd_interval {
+ struct rb_node rb;
+ sector_t sector; /* start sector of the interval */
+ unsigned int size; /* size in bytes */
+ sector_t end; /* highest interval end in subtree */
+};
+
+static inline void drbd_clear_interval(struct drbd_interval *i)
+{
+ RB_CLEAR_NODE(&i->rb);
+}
+
+static inline bool drbd_interval_empty(struct drbd_interval *i)
+{
+ return RB_EMPTY_NODE(&i->rb);
+}
+
+bool drbd_insert_interval(struct rb_root *, struct drbd_interval *);
+struct drbd_interval *drbd_find_interval(struct rb_root *, sector_t,
+ struct drbd_interval *);
+void drbd_remove_interval(struct rb_root *, struct drbd_interval *);
+struct drbd_interval *drbd_find_overlap(struct rb_root *, sector_t,
+ unsigned int);
+
+#endif /* __DRBD_INTERVAL_H */
--
1.7.4.1