Btrfs: switch extent_map to a rw lock
There are two main users of the extent_map tree. The
first is regular file inodes, where it is evenly spread
between readers and writers.
The second is the chunk allocation tree, which maps blocks from
logical addresses to phyiscal ones, and it is 99.99% reads.
The mapping tree is a point of lock contention during heavy IO
workloads, so this commit switches things to a rw lock.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
diff --git a/fs/btrfs/extent_map.c b/fs/btrfs/extent_map.c
index 30c9365..72e9fa3 100644
--- a/fs/btrfs/extent_map.c
+++ b/fs/btrfs/extent_map.c
@@ -36,7 +36,7 @@
void extent_map_tree_init(struct extent_map_tree *tree, gfp_t mask)
{
tree->map.rb_node = NULL;
- spin_lock_init(&tree->lock);
+ rwlock_init(&tree->lock);
}
/**
@@ -222,7 +222,6 @@
ret = -EEXIST;
goto out;
}
- assert_spin_locked(&tree->lock);
rb = tree_insert(&tree->map, em->start, &em->rb_node);
if (rb) {
ret = -EEXIST;
@@ -285,7 +284,6 @@
struct rb_node *next = NULL;
u64 end = range_end(start, len);
- assert_spin_locked(&tree->lock);
rb_node = __tree_search(&tree->map, start, &prev, &next);
if (!rb_node && prev) {
em = rb_entry(prev, struct extent_map, rb_node);
@@ -331,7 +329,6 @@
int ret = 0;
WARN_ON(test_bit(EXTENT_FLAG_PINNED, &em->flags));
- assert_spin_locked(&tree->lock);
rb_erase(&em->rb_node, &tree->map);
em->in_tree = 0;
return ret;