Btrfs: Bring back find_free_extent CPU usage optimizations

Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 12 insertions, 8 deletions

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 15082b1087be..5e392804ab15 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -182,9 +182,9 @@ static int noinline find_search_start(struct btrfs_root *root,
         int ret;
         struct btrfs_block_group_cache *cache = *cache_ret;
         struct extent_io_tree *free_space_cache;
+        struct extent_state *state;
         u64 last;
         u64 start = 0;
-        u64 end = 0;
         u64 cache_miss = 0;
         u64 total_fs_bytes;
         u64 search_start = *start_ret;
@@ -205,30 +205,34 @@ again:
                 goto new_group;
         }
 
+        spin_lock_irq(&free_space_cache->lock);
+        state = find_first_extent_bit_state(free_space_cache, last, EXTENT_DIRTY);
         while(1) {
-                ret = find_first_extent_bit(&root->fs_info->free_space_cache,
-                                            last, &start, &end, EXTENT_DIRTY);
-                if (ret) {
+                if (!state) {
                         if (!cache_miss)
                                 cache_miss = last;
+                        spin_unlock_irq(&free_space_cache->lock);
                         goto new_group;
                 }
 
-                start = max(last, start);
-                last = end + 1;
+                start = max(last, state->start);
+                last = state->end + 1;
                 if (last - start < num) {
                         if (last == cache->key.objectid + cache->key.offset)
                                 cache_miss = start;
+                        do {
+                                state = extent_state_next(state);
+                        } while(state && !(state->state & EXTENT_DIRTY));
                         continue;
                 }
+                spin_unlock_irq(&free_space_cache->lock);
                 if (start + num > cache->key.objectid + cache->key.offset)
                         goto new_group;
                 if (start + num  > total_fs_bytes)
                         goto new_group;
                 *start_ret = start;
                 return 0;
-        }
-out:
+        } out:
         cache = btrfs_lookup_block_group(root->fs_info, search_start);
         if (!cache) {
                 printk("Unable to find block group for %Lu\n", search_start);