diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index e2287c7c10bebbbb6dc68f0c4aed056a97bdaafe..07f47a5d0d6f4e031f24b3711395b726d26aeedf 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -5373,27 +5373,33 @@ static void update_global_block_rsv(struct btrfs_fs_info *fs_info)
 
 	block_rsv->size = min_t(u64, num_bytes, SZ_512M);
 
-	num_bytes = sinfo->bytes_used + sinfo->bytes_pinned +
-		    sinfo->bytes_reserved + sinfo->bytes_readonly +
-		    sinfo->bytes_may_use;
-
-	if (sinfo->total_bytes > num_bytes) {
-		num_bytes = sinfo->total_bytes - num_bytes;
-		block_rsv->reserved += num_bytes;
-		sinfo->bytes_may_use += num_bytes;
-		trace_btrfs_space_reservation(fs_info, "space_info",
-				      sinfo->flags, num_bytes, 1);
-	}
-
-	if (block_rsv->reserved >= block_rsv->size) {
+	if (block_rsv->reserved < block_rsv->size) {
+		num_bytes = sinfo->bytes_used + sinfo->bytes_pinned +
+			sinfo->bytes_reserved + sinfo->bytes_readonly +
+			sinfo->bytes_may_use;
+		if (sinfo->total_bytes > num_bytes) {
+			num_bytes = sinfo->total_bytes - num_bytes;
+			num_bytes = min(num_bytes,
+					block_rsv->size - block_rsv->reserved);
+			block_rsv->reserved += num_bytes;
+			sinfo->bytes_may_use += num_bytes;
+			trace_btrfs_space_reservation(fs_info, "space_info",
+						      sinfo->flags, num_bytes,
+						      1);
+		}
+	} else if (block_rsv->reserved > block_rsv->size) {
 		num_bytes = block_rsv->reserved - block_rsv->size;
 		sinfo->bytes_may_use -= num_bytes;
 		trace_btrfs_space_reservation(fs_info, "space_info",
 				      sinfo->flags, num_bytes, 0);
 		block_rsv->reserved = block_rsv->size;
-		block_rsv->full = 1;
 	}
 
+	if (block_rsv->reserved == block_rsv->size)
+		block_rsv->full = 1;
+	else
+		block_rsv->full = 0;
+
 	spin_unlock(&block_rsv->lock);
 	spin_unlock(&sinfo->lock);
 }