1 files changed, 18 insertions, 30 deletions

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 1b10c2fe7c7d..3abb03b5ab22 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -2839,40 +2839,28 @@ u64 btrfs_csum_bytes_to_leaves(struct btrfs_fs_info *fs_info, u64 csum_bytes)
 	return num_csums;
 }
 
-int btrfs_check_space_for_delayed_refs(struct btrfs_trans_handle *trans)
+bool btrfs_check_space_for_delayed_refs(struct btrfs_fs_info *fs_info)
 {
-	struct btrfs_fs_info *fs_info = trans->fs_info;
-	struct btrfs_block_rsv *global_rsv;
-	u64 num_heads = trans->transaction->delayed_refs.num_heads_ready;
-	u64 csum_bytes = trans->transaction->delayed_refs.pending_csums;
-	unsigned int num_dirty_bgs = trans->transaction->num_dirty_bgs;
-	u64 num_bytes, num_dirty_bgs_bytes;
-	int ret = 0;
+	struct btrfs_block_rsv *delayed_refs_rsv = &fs_info->delayed_refs_rsv;
+	struct btrfs_block_rsv *global_rsv = &fs_info->global_block_rsv;
+	bool ret = false;
+	u64 reserved;
 
-	num_bytes = btrfs_calc_trans_metadata_size(fs_info, 1);
-	num_heads = heads_to_leaves(fs_info, num_heads);
-	if (num_heads > 1)
-		num_bytes += (num_heads - 1) * fs_info->nodesize;
-	num_bytes <<= 1;
-	num_bytes += btrfs_csum_bytes_to_leaves(fs_info, csum_bytes) *
-							fs_info->nodesize;
-	num_dirty_bgs_bytes = btrfs_calc_trans_metadata_size(fs_info,
-							     num_dirty_bgs);
-	global_rsv = &fs_info->global_block_rsv;
+	spin_lock(&global_rsv->lock);
+	reserved = global_rsv->reserved;
+	spin_unlock(&global_rsv->lock);
 
 	/*
-	 * If we can't allocate any more chunks lets make sure we have _lots_ of
-	 * wiggle room since running delayed refs can create more delayed refs.
+	 * Since the global reserve is just kind of magic we don't really want
+	 * to rely on it to save our bacon, so if our size is more than the
+	 * delayed_refs_rsv and the global rsv then it's time to think about
+	 * bailing.
 	 */
-	if (global_rsv->space_info->full) {
-		num_dirty_bgs_bytes <<= 1;
-		num_bytes <<= 1;
-	}
-
-	spin_lock(&global_rsv->lock);
-	if (global_rsv->reserved <= num_bytes + num_dirty_bgs_bytes)
-		ret = 1;
-	spin_unlock(&global_rsv->lock);
+	spin_lock(&delayed_refs_rsv->lock);
+	reserved += delayed_refs_rsv->reserved;
+	if (delayed_refs_rsv->size >= reserved)
+		ret = true;
+	spin_unlock(&delayed_refs_rsv->lock);
 	return ret;
 }
 
@@ -2891,7 +2879,7 @@ int btrfs_should_throttle_delayed_refs(struct btrfs_trans_handle *trans)
 	if (val >= NSEC_PER_SEC / 2)
 		return 2;
 
-	return btrfs_check_space_for_delayed_refs(trans);
+	return btrfs_check_space_for_delayed_refs(trans->fs_info);
 }
 
 struct async_delayed_refs {