From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.kernel.org ([198.145.29.136]:42761 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755686AbcETPIx (ORCPT ); Fri, 20 May 2016 11:08:53 -0400 Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id CD01B20374 for ; Fri, 20 May 2016 15:08:51 +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 3100C20364 for ; Fri, 20 May 2016 15:08:50 +0000 (UTC) From: fdmanana@kernel.org To: linux-btrfs@vger.kernel.org Subject: [PATCH 5/6] Btrfs: fix race setting block group back to RW mode during device replace Date: Fri, 20 May 2016 05:45:10 +0100 Message-Id: <1463719510-3014-1-git-send-email-fdmanana@kernel.org> Sender: linux-btrfs-owner@vger.kernel.org List-ID: From: Filipe Manana After it finishes processing a device extent, the device replace code sets back the block group to RW mode and then after that it sets the left cursor to match the logical end address of the block group, so that future writes into extents belonging to the block group go both the source (old) and target (new) devices. However from the moment we turn the block group back to RW mode we have a short time window, that lasts until we update the left cursor's value, where extents can be allocated from the block group and written to, in which case they will not be copied/written to the target (new) device. Fix this by updating the left cursor's value before turning the block group back to RW mode. Signed-off-by: Filipe Manana --- fs/btrfs/scrub.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c index a58e0ae..c4c09a8 100644 --- a/fs/btrfs/scrub.c +++ b/fs/btrfs/scrub.c @@ -3680,6 +3680,11 @@ int scrub_enumerate_chunks(struct scrub_ctx *sctx, scrub_pause_off(fs_info); + btrfs_dev_replace_lock(&fs_info->dev_replace, 1); + dev_replace->cursor_left = dev_replace->cursor_right; + dev_replace->item_needs_writeback = 1; + btrfs_dev_replace_unlock(&fs_info->dev_replace, 1); + if (ro_set) btrfs_dec_block_group_ro(root, cache); @@ -3717,11 +3722,6 @@ int scrub_enumerate_chunks(struct scrub_ctx *sctx, ret = -ENOMEM; break; } - - btrfs_dev_replace_lock(&fs_info->dev_replace, 1); - dev_replace->cursor_left = dev_replace->cursor_right; - dev_replace->item_needs_writeback = 1; - btrfs_dev_replace_unlock(&fs_info->dev_replace, 1); skip: key.offset = found_key.offset + length; btrfs_release_path(path); -- 2.7.0.rc3