1 files changed, 24 insertions, 9 deletions

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index cfb3cf711b34..2f03181b777f 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -6117,10 +6117,13 @@ enum btrfs_loop_type {
 /*
  * walks the btree of allocated extents and find a hole of a given size.
  * The key ins is changed to record the hole:
- * ins->objectid == block start
+ * ins->objectid == start position
  * ins->flags = BTRFS_EXTENT_ITEM_KEY
- * ins->offset == number of blocks
+ * ins->offset == the size of the hole.
  * Any available blocks before search_start are skipped.
+ *
+ * If there is no suitable free space, we will record the max size of
+ * the free space extent currently.
  */
 static noinline int find_free_extent(struct btrfs_root *orig_root,
 				     u64 num_bytes, u64 empty_size,
@@ -6133,6 +6136,7 @@ static noinline int find_free_extent(struct btrfs_root *orig_root,
 	struct btrfs_block_group_cache *block_group = NULL;
 	struct btrfs_block_group_cache *used_block_group;
 	u64 search_start = 0;
+	u64 max_extent_size = 0;
 	int empty_cluster = 2 * 1024 * 1024;
 	struct btrfs_space_info *space_info;
 	int loop = 0;
@@ -6292,7 +6296,10 @@ have_block_group:
 				btrfs_get_block_group(used_block_group);
 
 			offset = btrfs_alloc_from_cluster(used_block_group,
-			  last_ptr, num_bytes, used_block_group->key.objectid);
+						last_ptr,
+						num_bytes,
+						used_block_group->key.objectid,
+						&max_extent_size);
 			if (offset) {
 				/* we have a block, we're done */
 				spin_unlock(&last_ptr->refill_lock);
@@ -6355,8 +6362,10 @@ refill_cluster:
 				 * cluster
 				 */
 				offset = btrfs_alloc_from_cluster(block_group,
-						  last_ptr, num_bytes,
-						  search_start);
+							last_ptr,
+							num_bytes,
+							search_start,
+							&max_extent_size);
 				if (offset) {
 					/* we found one, proceed */
 					spin_unlock(&last_ptr->refill_lock);
@@ -6391,13 +6400,18 @@ unclustered_alloc:
 		if (cached &&
 		    block_group->free_space_ctl->free_space <
 		    num_bytes + empty_cluster + empty_size) {
+			if (block_group->free_space_ctl->free_space >
+			    max_extent_size)
+				max_extent_size =
+					block_group->free_space_ctl->free_space;
 			spin_unlock(&block_group->free_space_ctl->tree_lock);
 			goto loop;
 		}
 		spin_unlock(&block_group->free_space_ctl->tree_lock);
 
 		offset = btrfs_find_space_for_alloc(block_group, search_start,
-						    num_bytes, empty_size);
+						    num_bytes, empty_size,
+						    &max_extent_size);
 		/*
 		 * If we didn't find a chunk, and we haven't failed on this
 		 * block group before, and this block group is in the middle of
@@ -6515,7 +6529,8 @@ loop:
 		ret = 0;
 	}
 out:
-
+	if (ret == -ENOSPC)
+		ins->offset = max_extent_size;
 	return ret;
 }
 
@@ -6573,8 +6588,8 @@ again:
 			       flags);
 
 	if (ret == -ENOSPC) {
-		if (!final_tried) {
-			num_bytes = num_bytes >> 1;
+		if (!final_tried && ins->offset) {
+			num_bytes = min(num_bytes >> 1, ins->offset);
 			num_bytes = round_down(num_bytes, root->sectorsize);
 			num_bytes = max(num_bytes, min_alloc_size);
 			if (num_bytes == min_alloc_size)