Btrfs: Fix hole insertion corner cases
There were a few places that could cause duplicate extent insertion,
this adjusts the code that creates holes to avoid it.
lookup_extent_map is changed to correctly return all of the extents in a
range, even when there are none matching at the start of the range.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
diff --git a/fs/btrfs/extent_map.c b/fs/btrfs/extent_map.c
index 485cf07..010a287 100644
--- a/fs/btrfs/extent_map.c
+++ b/fs/btrfs/extent_map.c
@@ -204,10 +204,12 @@
}
static struct rb_node *__tree_search(struct rb_root *root, u64 offset,
- struct rb_node **prev_ret)
+ struct rb_node **prev_ret,
+ struct rb_node **next_ret)
{
struct rb_node * n = root->rb_node;
struct rb_node *prev = NULL;
+ struct rb_node *orig_prev = NULL;
struct tree_entry *entry;
struct tree_entry *prev_entry = NULL;
@@ -223,13 +225,25 @@
else
return n;
}
- if (!prev_ret)
- return NULL;
- while(prev && offset > prev_entry->end) {
- prev = rb_next(prev);
- prev_entry = rb_entry(prev, struct tree_entry, rb_node);
+
+ if (prev_ret) {
+ orig_prev = prev;
+ while(prev && offset > prev_entry->end) {
+ prev = rb_next(prev);
+ prev_entry = rb_entry(prev, struct tree_entry, rb_node);
+ }
+ *prev_ret = prev;
+ prev = orig_prev;
}
- *prev_ret = prev;
+
+ if (next_ret) {
+ prev_entry = rb_entry(prev, struct tree_entry, rb_node);
+ while(prev && offset < prev_entry->start) {
+ prev = rb_prev(prev);
+ prev_entry = rb_entry(prev, struct tree_entry, rb_node);
+ }
+ *next_ret = prev;
+ }
return NULL;
}
@@ -237,7 +251,7 @@
{
struct rb_node *prev;
struct rb_node *ret;
- ret = __tree_search(root, offset, &prev);
+ ret = __tree_search(root, offset, &prev, NULL);
if (!ret)
return prev;
return ret;
@@ -248,7 +262,7 @@
struct rb_node *node;
struct tree_entry *entry;
- node = __tree_search(root, offset, NULL);
+ node = __tree_search(root, offset, NULL, NULL);
if (!node)
return -ENOENT;
entry = rb_entry(node, struct tree_entry, rb_node);
@@ -314,9 +328,21 @@
{
struct extent_map *em;
struct rb_node *rb_node;
+ struct rb_node *prev = NULL;
+ struct rb_node *next = NULL;
read_lock_irq(&tree->lock);
- rb_node = tree_search(&tree->map, start);
+ rb_node = __tree_search(&tree->map, start, &prev, &next);
+ if (!rb_node && prev) {
+ em = rb_entry(prev, struct extent_map, rb_node);
+ if (em->start <= end && em->end >= start)
+ goto found;
+ }
+ if (!rb_node && next) {
+ em = rb_entry(next, struct extent_map, rb_node);
+ if (em->start <= end && em->end >= start)
+ goto found;
+ }
if (!rb_node) {
em = NULL;
goto out;
@@ -330,6 +356,7 @@
em = NULL;
goto out;
}
+found:
atomic_inc(&em->refs);
out:
read_unlock_irq(&tree->lock);