btrfs: replace stripe extents

Update stripe extents in case a write to an already existing address
incoming.

Signed-off-by: Johannes Thumshirn <[email protected]>
Reviewed-by: Qu Wenruo <[email protected]>

fs/btrfs/raid-stripe-tree.c

@@ -73,6 +73,36 @@ int btrfs_delete_raid_extent(struct btrfs_trans_handle *trans, u64 start, u64 le
 	return ret;
 }
 
+static int update_raid_extent_item(struct btrfs_trans_handle *trans,
+				   struct btrfs_key *key,
+				   struct btrfs_stripe_extent *stripe_extent,
+				   const size_t item_size)
+{
+	struct btrfs_path *path;
+	struct extent_buffer *leaf;
+	int ret;
+	int slot;
+
+	path = btrfs_alloc_path();
+	if (!path)
+		return -ENOMEM;
+
+	ret = btrfs_search_slot(trans, trans->fs_info->stripe_root, key, path,
+				0, 1);
+	if (ret)
+		return ret == 1 ? ret : -EINVAL;
+
+	leaf = path->nodes[0];
+	slot = path->slots[0];
+
+	write_extent_buffer(leaf, stripe_extent,
+			    btrfs_item_ptr_offset(leaf, slot), item_size);
+	btrfs_mark_buffer_dirty(trans, leaf);
+	btrfs_free_path(path);
+
+	return ret;
+}
+
 static int btrfs_insert_one_raid_extent(struct btrfs_trans_handle *trans,
 					struct btrfs_io_context *bioc)
 {
@@ -112,6 +142,9 @@ static int btrfs_insert_one_raid_extent(struct btrfs_trans_handle *trans,
 
 	ret = btrfs_insert_item(trans, stripe_root, &stripe_key, stripe_extent,
 				item_size);
+	if (ret == -EEXIST)
+		ret = update_raid_extent_item(trans, &stripe_key, stripe_extent,
+					      item_size);
 	if (ret)
 		btrfs_abort_transaction(trans, ret);