From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from victor.provo.novell.com ([137.65.250.26]:37666 "EHLO prv3-mh.provo.novell.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1754044AbbERSMM (ORCPT ); Mon, 18 May 2015 14:12:12 -0400 From: Filipe Manana To: linux-btrfs@vger.kernel.org Cc: stable@vger.kernel.org, Filipe Manana Subject: [PATCH] Btrfs: fix racy system chunk allocation when setting block group ro Date: Mon, 18 May 2015 19:11:40 +0100 Message-Id: <1431972715-16833-1-git-send-email-fdmanana@suse.com> Sender: linux-btrfs-owner@vger.kernel.org List-ID: If while setting a block group read-only we end up allocating a system chunk, through check_system_chunk(), we were not doing it while holding the chunk mutex which is a problem if a concurrent chunk allocation is happening, through do_chunk_alloc(), as it means both block groups can end up using the same logical addresses and physical regions in the device(s). So make sure we hold the chunk mutex. Cc: stable@vger.kernel.org # 4.0+ Fixes: 2f0810880f08 ("btrfs: delete chunk allocation attemp when setting block group ro") Signed-off-by: Filipe Manana --- fs/btrfs/extent-tree.c | 2 ++ fs/btrfs/volumes.c | 1 + 2 files changed, 3 insertions(+) diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c index 4bf489b..1d757d8 100644 --- a/fs/btrfs/extent-tree.c +++ b/fs/btrfs/extent-tree.c @@ -8846,7 +8846,9 @@ again: out: if (cache->flags & BTRFS_BLOCK_GROUP_SYSTEM) { alloc_flags = update_block_group_flags(root, cache->flags); + lock_chunks(root->fs_info->chunk_root); check_system_chunk(trans, root, alloc_flags); + unlock_chunks(root->fs_info->chunk_root); } mutex_unlock(&root->fs_info->ro_block_group_mutex); diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index 56b91ed..d2b276c 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -4641,6 +4641,7 @@ int btrfs_alloc_chunk(struct btrfs_trans_handle *trans, { u64 chunk_offset; + ASSERT(mutex_is_locked(&extent_root->fs_info->chunk_mutex)); chunk_offset = find_next_chunk(extent_root->fs_info); return __btrfs_alloc_chunk(trans, extent_root, chunk_offset, type); } -- 2.1.3