Add the rt linux 4.1.3-rt3 as base

[kvmfornfv.git] / kernel / drivers / block / drbd / drbd_interval.c

diff --git a/kernel/drivers/block/drbd/drbd_interval.c b/kernel/drivers/block/drbd/drbd_interval.c
new file mode 100644 (file)
index 0000000..51b25ad
--- /dev/null
+++ b/kernel/drivers/block/drbd/drbd_interval.c
@@ -0,0 +1,179 @@
+#include <asm/bug.h>
+#include <linux/rbtree_augmented.h>
+#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;
+}
+
+/**
+ * compute_subtree_last  -  compute 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 inline sector_t
+compute_subtree_last(struct drbd_interval *node)
+{
+       sector_t max = node->sector + (node->size >> 9);
+
+       if (node->rb.rb_left) {
+               sector_t left = interval_end(node->rb.rb_left);
+               if (left > max)
+                       max = left;
+       }
+       if (node->rb.rb_right) {
+               sector_t right = interval_end(node->rb.rb_right);
+               if (right > max)
+                       max = right;
+       }
+       return max;
+}
+
+RB_DECLARE_CALLBACKS(static, augment_callbacks, struct drbd_interval, rb,
+                    sector_t, end, compute_subtree_last);
+
+/**
+ * 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;
+       sector_t this_end = this->sector + (this->size >> 9);
+
+       BUG_ON(!IS_ALIGNED(this->size, 512));
+
+       while (*new) {
+               struct drbd_interval *here =
+                       rb_entry(*new, struct drbd_interval, rb);
+
+               parent = *new;
+               if (here->end < this_end)
+                       here->end = this_end;
+               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 > here)
+                       new = &(*new)->rb_right;
+               else
+                       return false;
+       }
+
+       this->end = this_end;
+       rb_link_node(&this->rb, parent, new);
+       rb_insert_augmented(&this->rb, root, &augment_callbacks);
+       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 true;
+       }
+       return false;
+}
+
+/**
+ * drbd_remove_interval  -  remove an interval from a tree
+ */
+void
+drbd_remove_interval(struct rb_root *root, struct drbd_interval *this)
+{
+       rb_erase_augmented(&this->rb, root, &augment_callbacks);
+}
+
+/**
+ * drbd_find_overlap  - search for an interval overlapping with [sector, sector + size)
+ * @sector:    start sector
+ * @size:      size, aligned to 512 bytes
+ *
+ * Returns an interval overlapping with [sector, sector + size), or NULL if
+ * there is none.  When there is more than one overlapping interval in the
+ * tree, the interval with the lowest start sector is returned, and all other
+ * overlapping intervals will be on the right side of the tree, reachable with
+ * rb_next().
+ */
+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;
+}
+
+struct drbd_interval *
+drbd_next_overlap(struct drbd_interval *i, sector_t sector, unsigned int size)
+{
+       sector_t end = sector + (size >> 9);
+       struct rb_node *node;
+
+       for (;;) {
+               node = rb_next(&i->rb);
+               if (!node)
+                       return NULL;
+               i = rb_entry(node, struct drbd_interval, rb);
+               if (i->sector >= end)
+                       return NULL;
+               if (sector < i->sector + (i->size >> 9))
+                       return i;
+       }
+}