Distribution is Arch, up to date @ 14/07/13, 11:20 UTC, load was < 1 (4 cores in system) when measurement were taken. # uname -a Linux horus 3.10.6-2-ARCH #1 SMP PREEMPT Tue Aug 13 09:47:01 CEST 2013 x86_64 GNU/Linux Archiv is mounted from fstab at boot. # mount | grep Archiv /dev/sdd1 on /mnt/Archiv type btrfs (rw,relatime,compress=zlib,space_cache) # sync && time umount -v /mnt/Archiv umount: /mnt/Archiv (/dev/sdd1) unmounted umount -v /mnt/Archiv 0,01s user 0,52s system 1% cpu 46,591 total # time mount -v /mnt/Archiv mount: /dev/sde1 mounted on /mnt/Archiv. mount -v /mnt/Archiv 0,00s user 0,18s system 1% cpu 11,008 total During the unmount I triggered Sysrq + w (echo w > /proc/sysrq-trigger). The journal output of this command is attached. I will be happy to provide any further input.
Created attachment 107201 [details] journalctl output of sysrq+w during unmount.
# btrfs filesystem show failed to open /dev/sr0: No medium found Label: 'Archiv' uuid: b2504193-efeb-4ef3-8797-a8d73536a416 Total devices 2 FS bytes used 2.19TB devid 2 size 2.73TB used 1.10TB path /dev/sde1 devid 1 size 2.73TB used 1.10TB path /dev/sdd1 Btrfs v0.20-rc1-253-g7854c8b
Could you post your btrfs fi df as well?
# btrfs filesystem df /mnt/Archiv Data, RAID0: total=2.19TB, used=2.19TB Data: total=8.00MB, used=7.99MB System, RAID1: total=8.00MB, used=160.00KB System: total=4.00MB, used=0.00 Metadata, RAID1: total=5.00GB, used=4.09GB Metadata: total=8.00MB, used=0.00
: SysRq : Show Blocked State : task PC stack pid father : umount D ffff88037c28b750 0 3707 2488 0x00000000 : ffff88037c28b6c0 0000000000000082 0000000000014340 ffff88037c28bfd8 : ffff88037c28bfd8 0000000000014340 ffff88040ef50870 0000000000000008 : ffff88037c28b650 ffffffff8124d3d3 ffff8802ae79b688 0000000000000002 : Call Trace: : [<ffffffff8124d3d3>] ? submit_bio+0x73/0x160 : [<ffffffffa101f316>] ? btrfs_map_bio+0x2e6/0x560 [btrfs] : [<ffffffff8101a909>] ? read_tsc+0x9/0x20 : [<ffffffff81121d80>] ? filemap_fdatawait+0x30/0x30 : [<ffffffff814c6909>] schedule+0x29/0x70 : [<ffffffff814c6baf>] io_schedule+0x8f/0xe0 : [<ffffffff81121d8e>] sleep_on_page+0xe/0x20 : [<ffffffff814c43a0>] __wait_on_bit+0x60/0x90 : [<ffffffff81121b3f>] wait_on_page_bit+0x7f/0x90 : [<ffffffff8107b490>] ? autoremove_wake_function+0x40/0x40 : [<ffffffffa10165ca>] read_extent_buffer_pages+0x2ba/0x2f0 [btrfs] : [<ffffffff81122a8a>] ? find_or_create_page+0x5a/0x90 : [<ffffffffa0fed810>] ? free_root_pointers+0x150/0x150 [btrfs] : [<ffffffffa0fef703>] btree_read_extent_buffer_pages.constprop.54+0xb3/0x120 [btrfs] : [<ffffffffa0ff0f56>] read_tree_block+0x46/0x50 [btrfs] : [<ffffffffa0fd2933>] read_block_for_search.isra.38+0x123/0x3d0 [btrfs] : [<ffffffffa0fcd619>] ? unlock_up+0x149/0x160 [btrfs] : [<ffffffffa0fd4b5a>] btrfs_search_slot+0x42a/0x950 [btrfs] : [<ffffffffa0fda27f>] lookup_inline_extent_backref+0xef/0x5d0 [btrfs] : [<ffffffffa10113d9>] ? set_extent_dirty+0x29/0x30 [btrfs] : [<ffffffffa0fdd0c6>] __btrfs_free_extent+0xe6/0xa00 [btrfs] : [<ffffffffa103a234>] ? btrfs_merge_delayed_refs+0x1f4/0x3d0 [btrfs] : [<ffffffffa0fe1725>] run_clustered_refs+0x715/0xda0 [btrfs] : [<ffffffffa0fe6020>] btrfs_run_delayed_refs+0xd0/0x500 [btrfs] : [<ffffffffa0fd0db6>] ? btrfs_cow_block+0x116/0x1f0 [btrfs] : [<ffffffffa100ff29>] ? release_extent_buffer+0xa9/0xd0 [btrfs] : [<ffffffffa0ff4618>] commit_cowonly_roots+0xa8/0x260 [btrfs] : [<ffffffffa0ff65ad>] btrfs_commit_transaction+0x5bd/0xaf0 [btrfs] : [<ffffffff8107b450>] ? wake_up_bit+0x30/0x30 : [<ffffffffa0ff1501>] btrfs_commit_super+0x91/0x110 [btrfs] : [<ffffffffa0ff1748>] close_ctree+0x1c8/0x270 [btrfs] : [<ffffffff811a580c>] ? evict_inodes+0x11c/0x130 : [<ffffffffa0fcb179>] btrfs_put_super+0x19/0x20 [btrfs] : [<ffffffff8118d436>] generic_shutdown_super+0x56/0xe0 : [<ffffffff8118d682>] kill_anon_super+0x12/0x20 : [<ffffffffa0fcaf26>] btrfs_kill_super+0x16/0x90 [btrfs] : [<ffffffff8118da5d>] deactivate_locked_super+0x3d/0x60 : [<ffffffff8118e046>] deactivate_super+0x46/0x60 : [<ffffffff811a914f>] mntput_no_expire+0xef/0x150 : [<ffffffff811aa351>] SyS_umount+0x91/0x3b0 : [<ffffffff814cf81d>] system_call_fastpath+0x1a/0x1f Seems like sync does not sync enough and there's lots of work left for umount.