From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752574AbcFFOaJ (ORCPT ); Mon, 6 Jun 2016 10:30:09 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:58836 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752317AbcFFOaD (ORCPT ); Mon, 6 Jun 2016 10:30:03 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Liu Bo , David Sterba Subject: [PATCH 4.5 109/128] Btrfs: do not create empty block group if we have allocated data Date: Sun, 5 Jun 2016 15:24:24 -0700 Message-Id: <20160605222324.695332712@linuxfoundation.org> X-Mailer: git-send-email 2.8.3 In-Reply-To: <20160605222321.183131188@linuxfoundation.org> References: <20160605222321.183131188@linuxfoundation.org> User-Agent: quilt/0.64 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.5-stable review patch. If anyone has any objections, please let me know. ------------------ From: Liu Bo commit cf25ce518e8ef9d59b292e51193bed2b023a32da upstream. Now we force to create empty block group to keep data profile alive, however, in the below example, we eventually get an empty block group while we're trying to get more space for other types (metadata/system), - Before, block group "A": size=2G, used=1.2G block group "B": size=2G, used=512M - After "btrfs balance start -dusage=50 mount_point", block group "A": size=2G, used=(1.2+0.5)G block group "C": size=2G, used=0 Since there is no data in block group C, it won't be deleted automatically and we have to get the unused 2G until the next mount. Balance itself just moves data and doesn't remove data, so it's safe to not create such a empty block group if we already have data allocated in other block groups. Signed-off-by: Liu Bo Signed-off-by: David Sterba Signed-off-by: Greg Kroah-Hartman --- fs/btrfs/volumes.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -3401,6 +3401,7 @@ static int __btrfs_balance(struct btrfs_ u32 count_meta = 0; u32 count_sys = 0; int chunk_reserved = 0; + u64 bytes_used = 0; /* step one make some room on all the devices */ devices = &fs_info->fs_devices->devices; @@ -3539,7 +3540,13 @@ again: goto loop; } - if ((chunk_type & BTRFS_BLOCK_GROUP_DATA) && !chunk_reserved) { + ASSERT(fs_info->data_sinfo); + spin_lock(&fs_info->data_sinfo->lock); + bytes_used = fs_info->data_sinfo->bytes_used; + spin_unlock(&fs_info->data_sinfo->lock); + + if ((chunk_type & BTRFS_BLOCK_GROUP_DATA) && + !chunk_reserved && !bytes_used) { trans = btrfs_start_transaction(chunk_root, 0); if (IS_ERR(trans)) { mutex_unlock(&fs_info->delete_unused_bgs_mutex);