[LU-7616] creation of LVM snapshot on ldiskfs based MDT hangs until MDT activity/use is halted

• Type: Bug
• Resolution: Unresolved
• Priority: Major
• Affects Version/s: Lustre 2.7.0

Environment

CentOS release 6.5 (Final)

2.6.32-504.8.1.el6_lustre.x86_64 #1 SMP Thu Feb 26 22:39:27 PST 2015 x86_64 x86_64 x86_64 GNU/Linux

lustre: 2.7.0
kernel: patchless_client
build: 2.7.0-RC4--PRISTINE-2.6.32-504.8.1.el6_lustre.x86_64

• Severity: 3
• Assignee: WC Triage
• Reporter: tom crowe

Description

trying to create a MDT snapshot via LVM (for backups) with the following command:

lvcreate --size 20G --snapshot --name lv-mdt0_snap /dev/vg-3015/lv-mdt0

immediately following, errors are logged like this:

Dec 28 09:24:32 mds01 kernel: ------------[ cut here ]------------
Dec 28 09:24:32 mds01 kernel: WARNING: at /var/lib/jenkins/workspace/lustre-b2_7/arch/x86_64/build_type/server/distro/el6.6/ib_stack/inkernel/BUILD/BUILD/lustre-2.7.0/ldiskfs/super.c:280 ldiskfs_journal_start_sb+0xce/0xe0 [ldiskfs]() (Tainted: P        W  ---------------   )
Dec 28 09:24:32 mds01 kernel: Hardware name: ProLiant DL380p Gen8
Dec 28 09:24:32 mds01 kernel: Modules linked in: ext2 osp(U) mdd(U) lod(U) mdt(U) lfsck(U) mgs(U) mgc(U) osd_ldiskfs(U) lquota(U) ldiskfs(U) lustre(U) lov(U) mdc(U) fid(U) lmv(U) fld(U) ksocklnd(U) ptlrpc(U) obdclass(U) lnet(U) sha512_generic crc32c_intel libcfs(U) ip6table_filter ip6_tables ebtable_nat ebtables bridge stp llc ipt_REJECT ipt_LOG xt_limit nf_conntrack_ipv4 nf_defrag_ipv4 xt_state nf_conntrack iptable_filter ip_tables ib_ipoib rdma_ucm ib_ucm ib_uverbs ib_umad rdma_cm ib_cm iw_cm zfs(P)(U) zcommon(P)(U) znvpair(P)(U) zavl(P)(U) zunicode(P)(U) spl(U) zlib_deflate dm_snapshot dm_bufio dm_round_robin dm_multipath vhost_net macvtap macvlan tun kvm_intel kvm iTCO_wdt iTCO_vendor_support microcode hpilo hpwdt power_meter acpi_ipmi ipmi_si ipmi_msghandler tg3 sg serio_raw lpc_ich mfd_core shpchp ext4 jbd2 mbcache sd_mod crc_t10dif mlx4_ib ib_sa ib_mad ib_core ib_addr ipv6 mlx4_en ptp pps_core mlx4_core hpsa(U) qla2xxx scsi_transport_fc scsi_tgt pata_acpi ata_generic ata_piix dm_mirror dm_region_hash dm_
Dec 28 09:24:32 mds01 kernel: log dm_mod [last unloaded: scsi_wait_scan]
Dec 28 09:24:32 mds01 kernel: Pid: 5300, comm: mdt00_005 Tainted: P        W  ---------------    2.6.32-504.8.1.el6_lustre.x86_64 #1
Dec 28 09:24:32 mds01 kernel: Call Trace:
Dec 28 09:24:32 mds01 kernel: [<ffffffff81074df7>] ? warn_slowpath_common+0x87/0xc0
Dec 28 09:24:32 mds01 kernel: [<ffffffff81074e4a>] ? warn_slowpath_null+0x1a/0x20
Dec 28 09:24:32 mds01 kernel: [<ffffffffa0e9234e>] ? ldiskfs_journal_start_sb+0xce/0xe0 [ldiskfs]
Dec 28 09:24:32 mds01 kernel: [<ffffffffa0e6c23a>] ? ldiskfs_dirty_inode+0x2a/0x60 [ldiskfs]
Dec 28 09:24:32 mds01 kernel: [<ffffffffa1050966>] ? osd_attr_set+0x166/0x460 [osd_ldiskfs]
Dec 28 09:25:03 mds01 kernel: ------------[ cut here ]------------

The lvcreate command does return if the MDT activity is halted (unmount clients).

Issue Links

• is related to: LU-8071 lvcreate --snapshot of MDT hangs in ldiskfs_journal_start_sb