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x-vs=clean score=-100 state=0 X-ME-VSCategory: clean X-CM-Envelope: MS4wfEcwe/wZn3X7vaFpQR+MnTKH0qeQln/QWX2BjRX8a3x3ToTeliWbBRc+KVaBcdCHC96UTPdTjIy4pu87u5DfoYRfq1c8la0NrgwXElXDM3MiJoHM4yql tNYWvWFZnliFOZjcKNsE05eh2qWoUI0PFPqlRYhiA8N1yaj9/hiwr2hLPLvj9USnbjEZKOLhLCT7JIOK9ISoUFBsK2wzu7345fy58cajntvneQG8pfYSJFmp X-CM-Analysis: v=2.3 cv=Tq3Iegfh c=1 sm=1 tr=0 a=UK1r566ZdBxH71SXbqIOeA==:117 a=UK1r566ZdBxH71SXbqIOeA==:17 a=IkcTkHD0fZMA:10 a=VUJBJC2UJ8kA:10 a=yPCof4ZbAAAA:8 a=VwQbUJbxAAAA:8 a=iox4zFpeAAAA:8 a=ag1SF4gXAAAA:8 a=lUoSDrnz3zN8yKeRpAYA:9 a=QEXdDO2ut3YA:10 a=AjGcO6oz07-iQ99wixmX:22 a=WzC6qhA0u3u7Ye7llzcV:22 a=Yupwre4RP9_Eg_Bd0iYG:22 X-ME-CMScore: 0 X-ME-CMCategory: none Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S966587AbeEXL5S (ORCPT ); Thu, 24 May 2018 07:57:18 -0400 Received: from mail.kernel.org ([198.145.29.99]:56828 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S966813AbeEXJpl (ORCPT ); Thu, 24 May 2018 05:45:41 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Anand Jain , David Sterba Subject: [PATCH 4.4 69/92] btrfs: fix crash when trying to resume balance without the resume flag Date: Thu, 24 May 2018 11:38:46 +0200 Message-Id: <20180524093205.984977330@linuxfoundation.org> X-Mailer: git-send-email 2.17.0 In-Reply-To: <20180524093159.286472249@linuxfoundation.org> References: <20180524093159.286472249@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Content-Type: text/plain; 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If anyone has any objections, please let me know. ------------------ From: Anand Jain commit 02ee654d3a04563c67bfe658a05384548b9bb105 upstream. We set the BTRFS_BALANCE_RESUME flag in the btrfs_recover_balance() only, which isn't called during the remount. So when resuming from the paused balance we hit the bug: kernel: kernel BUG at fs/btrfs/volumes.c:3890! :: kernel: balance_kthread+0x51/0x60 [btrfs] kernel: kthread+0x111/0x130 :: kernel: RIP: btrfs_balance+0x12e1/0x1570 [btrfs] RSP: ffffba7d0090bde8 Reproducer: On a mounted filesystem: btrfs balance start --full-balance /btrfs btrfs balance pause /btrfs mount -o remount,ro /dev/sdb /btrfs mount -o remount,rw /dev/sdb /btrfs To fix this set the BTRFS_BALANCE_RESUME flag in btrfs_resume_balance_async(). CC: stable@vger.kernel.org # 4.4+ Signed-off-by: Anand Jain Reviewed-by: David Sterba Signed-off-by: David Sterba Signed-off-by: Greg Kroah-Hartman --- fs/btrfs/volumes.c | 9 +++++++++ 1 file changed, 9 insertions(+) --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -3850,6 +3850,15 @@ int btrfs_resume_balance_async(struct bt return 0; } + /* + * A ro->rw remount sequence should continue with the paused balance + * regardless of who pauses it, system or the user as of now, so set + * the resume flag. + */ + spin_lock(&fs_info->balance_lock); + fs_info->balance_ctl->flags |= BTRFS_BALANCE_RESUME; + spin_unlock(&fs_info->balance_lock); + tsk = kthread_run(balance_kthread, fs_info, "btrfs-balance"); return PTR_ERR_OR_ZERO(tsk); }