Btrfs: Bring back find_free_extent CPU usage optimizations

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

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 15082b1087beb553c43ed2605a4e2ab529b53e33..5e392804ab15eec31925c4314f91d5db0c34a0e0 100644 (file)
--- 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);