From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from cn.fujitsu.com ([59.151.112.132]:49144 "EHLO heian.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1754921AbbIPKPe convert rfc822-to-8bit (ORCPT ); Wed, 16 Sep 2015 06:15:34 -0400 From: Zhao Lei To: "'sam tygier'" , References: In-Reply-To: Subject: RE: [PATCH] Btrfs: Check metadata redundancy on balance Date: Wed, 16 Sep 2015 18:15:31 +0800 Message-ID: <001001d0f068$9e44d300$dace7900$@cn.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Sender: linux-btrfs-owner@vger.kernel.org List-ID: Hi, sam tygier > -----Original Message----- > From: linux-btrfs-owner@vger.kernel.org > [mailto:linux-btrfs-owner@vger.kernel.org] On Behalf Of sam tygier > Sent: Wednesday, September 16, 2015 4:42 PM > To: linux-btrfs@vger.kernel.org > Subject: [PATCH] Btrfs: Check metadata redundancy on balance > > It was recommended that I resend after the merge window. No changes since > last version. > > Currently BTRFS allows you to make bad choices of data and metadata levels. > For example -d raid1 -m raid0 means you can only use half your total disk space, > but will loose everything if 1 disk fails. It should give a warning in these cases. > > This patch is a follow up to > [PATCH v2] btrfs-progs: check metadata redundancy in order to cover the case > of using balance to convert to such a set of raid levels. > Can we check and show warning of balance operation in btrfs-progs, just like above patch? > A simple example to hit this is to create a single device fs, which will default to > single:dup, then to add a second device and attempt to convert to raid1 with > the command btrfs balance start -dconvert=raid1 /mnt this will result in a > filesystem with raid1:dup, which will not survive the loss of one drive. I > personally don't see why the tools should allow this, but in the previous thread > a warning was considered sufficient. > > Signed-off-by: Sam Tygier > > From: Sam Tygier > Date: Sat, 13 Jun 2015 18:13:06 +0100 > Subject: [PATCH] Btrfs: Check metadata redundancy on balance > > When converting a filesystem via balance check that metadata mode is at least > as redundant as the data mode. For example give warning > when: > -dconvert=raid1 -mconvert=single > --- > fs/btrfs/volumes.c | 24 ++++++++++++++++++++++++ > 1 file changed, 24 insertions(+) > > diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index fbe7c10..a0ce1f7 > 100644 > --- a/fs/btrfs/volumes.c > +++ b/fs/btrfs/volumes.c > @@ -3454,6 +3454,24 @@ static void __cancel_balance(struct btrfs_fs_info > *fs_info) > atomic_set(&fs_info->mutually_exclusive_operation_running, 0); } > > +static int group_profile_max_safe_loss(u64 flag) { > + switch (flag & BTRFS_BLOCK_GROUP_PROFILE_MASK) { > + case 0: /* single */ > + case BTRFS_BLOCK_GROUP_DUP: > + case BTRFS_BLOCK_GROUP_RAID0: > + return 0; > + case BTRFS_BLOCK_GROUP_RAID1: > + case BTRFS_BLOCK_GROUP_RAID5: > + case BTRFS_BLOCK_GROUP_RAID10: > + return 1; > + case BTRFS_BLOCK_GROUP_RAID6: > + return 2; > + default: > + return -1; > + } > +} > + Maybe btrfs_get_num_tolerated_disk_barrier_failures() fits above request, better to use existence function if possible. Thanks Zhaolei > /* > * Should be called with both balance and volume mutexes held > */ > @@ -3572,6 +3590,12 @@ int btrfs_balance(struct btrfs_balance_control > *bctl, > } > } while (read_seqretry(&fs_info->profiles_lock, seq)); > > + if (group_profile_max_safe_loss(bctl->meta.target) < > + group_profile_max_safe_loss(bctl->data.target)){ > + btrfs_info(fs_info, > + "Warning: metatdata has lower redundancy than data\n"); > + } > + > if (bctl->sys.flags & BTRFS_BALANCE_ARGS_CONVERT) { > int num_tolerated_disk_barrier_failures; > u64 target = bctl->sys.target; > -- > 2.4.3 > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html