From patchwork Sat Jul 2 12:30:17 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Filipe Manana X-Patchwork-Id: 9223361 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id B556660572 for ; Mon, 11 Jul 2016 11:16:04 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id A53F32787D for ; Mon, 11 Jul 2016 11:16:04 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 9878627C14; Mon, 11 Jul 2016 11:16:04 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.5 required=2.0 tests=BAYES_00, DATE_IN_PAST_96_XX, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 14F6E2787D for ; Mon, 11 Jul 2016 11:16:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933717AbcGKLPw (ORCPT ); Mon, 11 Jul 2016 07:15:52 -0400 Received: from mail.kernel.org ([198.145.29.136]:35352 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932178AbcGKLPv (ORCPT ); Mon, 11 Jul 2016 07:15:51 -0400 Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 2BBC820204 for ; Mon, 11 Jul 2016 11:15:47 +0000 (UTC) Received: from debian3.lan (bl12-226-64.dsl.telepac.pt [85.245.226.64]) (using TLSv1.2 with cipher AES128-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id EEFE5201F4 for ; Mon, 11 Jul 2016 11:15:45 +0000 (UTC) From: fdmanana@kernel.org To: linux-btrfs@vger.kernel.org Subject: [PATCH 4/7] Btrfs: incremental send, fix premature rmdir operations Date: Sat, 2 Jul 2016 13:30:17 +0100 Message-Id: <1467462617-14293-1-git-send-email-fdmanana@kernel.org> X-Mailer: git-send-email 2.7.0.rc3 X-Virus-Scanned: ClamAV using ClamSMTP Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Robbie Ko Under certain situations, an incremental send operation can contain a rmdir operation that will make the receiving end fail when attempting to execute it, because the target directory is not yet empty. Consider the following example: Parent snapshot: . (ino 256) |--- a/ (ino 257) | |--- c/ (ino 260) | |--- del/ (ino 259) |--- tmp/ (ino 258) |--- x/ (ino 261) Send snapshot: . (ino 256) |--- a/ (ino 257) | |--- x/ (ino 261) | |--- c/ (ino 260) |--- tmp/ (ino 258) 1) When processing inode 258, we delay its rename operation because inode 260 is its new parent in the send snapshot and it was not yet renamed (since 260 > 258, that is, beyond the current progress); 2) When processing inode 259, we realize we can not yet send an rmdir operation (against inode 259) because inode 258 was still not yet renamed/moved away from inode 259. Therefore we update data structures so that after inode 258 is renamed, we try again to see if we can finally send an rmdir operation for inode 259; 3) When we process inode 260, we send a rename operation for it followed by a rename operation for inode 258. Once we send the rename operation for inode 258 we then check if we can finally issue an rmdir for its previous parent, inode 259, by calling the can_rmdir() function with a value of sctx->cur_ino + 1 (260 + 1 = 261) for its "progress" argument. This makes can_rmdir() return true (value 1) because even though there's still a child inode of inode 259 that was not yet renamed/moved, which is inode 261, the given value of progress (261) is not lower then 261 (that is, not lower than the inode number of some child of inode 259). So we end up sending a rmdir operation for inode 259 before its child inode 261 is processed and renamed. So fix this by passing the correct progress value to the call to can_rmdir() from within apply_dir_move() (where we issue delayed rename operations), which should match stcx->cur_ino (the number of the inode currently being processed) and not sctx->cur_ino + 1. A test case for fstests follows soon. Signed-off-by: Robbie Ko Signed-off-by: Filipe Manana [Rewrote change log to be more detailed, clear and well formatted] Signed-off-by: Filipe Manana --- fs/btrfs/send.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/btrfs/send.c b/fs/btrfs/send.c index 3d6a4dd..4115aba 100644 --- a/fs/btrfs/send.c +++ b/fs/btrfs/send.c @@ -3236,7 +3236,7 @@ static int apply_dir_move(struct send_ctx *sctx, struct pending_dir_move *pm) /* already deleted */ goto finish; } - ret = can_rmdir(sctx, rmdir_ino, odi->gen, sctx->cur_ino + 1); + ret = can_rmdir(sctx, rmdir_ino, odi->gen, sctx->cur_ino); if (ret < 0) goto out; if (!ret)