unable to mount a btrfs file system kernel 3.19.2

Hello everyone,

I have an issue with my ssd where a btrfs partition is located. I have a /dev/sdb1 in ext4 for the /boot, and the rest of the ssd is /dev/sdb2 which is the root of my Archlinux. When I boot, it hangs up after loading the kernel. So I tried with an Archlinux liveboot, and I have the same behavior with the following trace in logs when I try to mount the btrfs partition :

Apr 11 16:25:56 archiso kernel: INFO: task mount:573 blocked for more than 120 seconds.
Apr 11 16:25:56 archiso kernel:       Not tainted 3.19.2-1-ARCH #1
Apr 11 16:25:56 archiso kernel: "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
Apr 11 16:25:56 archiso kernel: mount           D ffff8807f1c937f8     0   573    524 0x00000004
Apr 11 16:25:56 archiso kernel:  ffff8807f1c937f8 ffff8807f7d6ed50 0000000000013f00 ffff8807f1c93fd8
Apr 11 16:25:56 archiso kernel:  0000000000013f00 ffff8807f98109f0 ffff8807f7d6ed50 ffff8807ecce5ea0
Apr 11 16:25:56 archiso kernel:  0000000000000004 ffff8807f1c93758 ffffffffa048ec91 ffff8807ecce5ea0
Apr 11 16:25:56 archiso kernel: Call Trace:
Apr 11 16:25:56 archiso kernel:  [<ffffffffa048ec91>] ? set_extent_buffer_dirty+0x71/0xc0 [btrfs]
Apr 11 16:25:56 archiso kernel:  [<ffffffffa0464796>] ? btrfs_buffer_uptodate+0x56/0x80 [btrfs]
Apr 11 16:25:56 archiso kernel:  [<ffffffff8155e999>] schedule+0x29/0x70
Apr 11 16:25:56 archiso kernel:  [<ffffffffa04a6745>] btrfs_tree_lock+0x65/0x200 [btrfs]
Apr 11 16:25:56 archiso kernel:  [<ffffffff810b4380>] ? wait_woken+0x90/0x90
Apr 11 16:25:56 archiso kernel:  [<ffffffffa0444cd9>] btrfs_search_slot+0x799/0xaa0 [btrfs]
Apr 11 16:25:56 archiso kernel:  [<ffffffff810b43c0>] ? autoremove_wake_function+0x40/0x40
Apr 11 16:25:56 archiso kernel:  [<ffffffffa04469f5>] btrfs_insert_empty_items+0x75/0xd0 [btrfs]
Apr 11 16:25:56 archiso kernel:  [<ffffffffa04a6a37>] btrfs_insert_orphan_item+0x67/0xa0 [btrfs]
Apr 11 16:25:56 archiso kernel:  [<ffffffffa04a912e>] insert_orphan_item+0x5e/0x90 [btrfs]
Apr 11 16:25:56 archiso kernel:  [<ffffffffa04ab531>] replay_one_buffer+0x361/0x380 [btrfs]
Apr 11 16:25:56 archiso kernel:  [<ffffffffa048e244>] ? alloc_extent_buffer+0x34/0x370 [btrfs]
Apr 11 16:25:56 archiso kernel:  [<ffffffffa04a78f3>] walk_down_log_tree+0x1d3/0x410 [btrfs]
Apr 11 16:25:56 archiso kernel:  [<ffffffffa04a7bfb>] walk_log_tree+0xcb/0x1d0 [btrfs]
Apr 11 16:25:56 archiso kernel:  [<ffffffffa04af7f7>] btrfs_recover_log_trees+0x1e7/0x490 [btrfs]
Apr 11 16:25:56 archiso kernel:  [<ffffffffa04ab1d0>] ? replay_one_dir_item+0xf0/0xf0 [btrfs]
Apr 11 16:25:56 archiso kernel:  [<ffffffffa0467b3e>] open_ctree+0x17ae/0x2030 [btrfs]
Apr 11 16:25:56 archiso kernel:  [<ffffffffa043c633>] btrfs_mount+0x843/0x920 [btrfs]
Apr 11 16:25:56 archiso kernel:  [<ffffffff8117b7aa>] ? pcpu_alloc+0x35a/0x680
Apr 11 16:25:56 archiso kernel:  [<ffffffff811d5d68>] mount_fs+0x38/0x1c0
Apr 11 16:25:56 archiso kernel:  [<ffffffff8117bb05>] ? __alloc_percpu+0x15/0x20
Apr 11 16:25:56 archiso kernel:  [<ffffffff811f116b>] vfs_kern_mount+0x6b/0x120
Apr 11 16:25:56 archiso kernel:  [<ffffffff811f4184>] do_mount+0x224/0xb40
Apr 11 16:25:56 archiso kernel:  [<ffffffff811f4dae>] SyS_mount+0x7e/0xe0
Apr 11 16:25:56 archiso kernel:  [<ffffffff81562809>] system_call_fastpath+0x12/0x17
Apr 11 16:25:56 archiso kernel: INFO: task btrfs-transacti:596 blocked for more than 120 seconds.
Apr 11 16:25:56 archiso kernel:       Not tainted 3.19.2-1-ARCH #1
Apr 11 16:25:56 archiso kernel: "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
Apr 11 16:25:56 archiso kernel: btrfs-transacti D ffff8807e8937d98     0   596      2 0x00000000
Apr 11 16:25:56 archiso kernel:  ffff8807e8937d98 ffff8807f2e7bba0 0000000000013f00 ffff8807e8937fd8
Apr 11 16:25:56 archiso kernel:  0000000000013f00 ffff8807f9e76d50 ffff8807f2e7bba0 ffff8807eccb90c8
Apr 11 16:25:56 archiso kernel:  ffff8807ecc79000 ffff880000000000 ffff8807ecc79000 ffff880700000033
Apr 11 16:25:56 archiso kernel: Call Trace:
Apr 11 16:25:56 archiso kernel:  [<ffffffff811b5d1a>] ? kmem_cache_alloc+0x16a/0x180
Apr 11 16:25:56 archiso kernel:  [<ffffffffa043f7ca>] ? btrfs_free_path+0x2a/0x40 [btrfs]
Apr 11 16:25:56 archiso kernel:  [<ffffffffa04c3213>] ? __btrfs_run_delayed_items+0xf3/0x1d0 [btrfs]
Apr 11 16:25:56 archiso kernel:  [<ffffffff8155e999>] schedule+0x29/0x70
Apr 11 16:25:56 archiso kernel:  [<ffffffffa046a555>] btrfs_commit_transaction+0x2a5/0xbe0 [btrfs]
Apr 11 16:25:56 archiso kernel:  [<ffffffff810b4380>] ? wait_woken+0x90/0x90
Apr 11 16:25:56 archiso kernel:  [<ffffffffa0465fc5>] transaction_kthread+0x1d5/0x240 [btrfs]
Apr 11 16:25:56 archiso kernel:  [<ffffffffa0465df0>] ? btrfs_cleanup_transaction+0x5a0/0x5a0 [btrfs]
Apr 11 16:25:56 archiso kernel:  [<ffffffff81091748>] kthread+0xd8/0xf0
Apr 11 16:25:56 archiso kernel:  [<ffffffff81091670>] ? kthread_create_on_node+0x1c0/0x1c0
Apr 11 16:25:56 archiso kernel:  [<ffffffff81562758>] ret_from_fork+0x58/0x90
Apr 11 16:25:56 archiso kernel:  [<ffffffff81091670>] ? kthread_create_on_node+0x1c0/0x1c0

Additional information :

Label: none uuid: aa6b1bae-3c28-482d-a446-c31875f21cf0

	Total devices 1 FS bytes used 64.63GiB
	devid    1 size 111.29GiB used 111.02GiB path /dev/sda2

btrfs-progs v3.19

Linux archiso 3.19.2-1-ARCH #1 SMP PREEMPT Wed Mar 18 16:21:02 CET 2015 x86_64 GNU/Linux

And the full output from journald is available there :
http://sprunge.us/jPMG

Is it a known bug? Or does someone have an idea about how I could fix this issue?

Thank you in advance.

Olivier.

[snip]

See the first issue here: https://btrfs.wiki.kernel.org/index.php/Gotchas

Hugo.

Hugo Mills             | Do not meddle in the affairs of system
hugo@... carfax.org.uk | administrators, for they are subtle, and quick to
http://carfax.org.uk/  | anger.
PGP: E2AB1DE4          |

Oh, I didn't see there were similar link in the wiki, my bad. Thank you for your prompt answer :)

Olivier.

Hi Hugo, looking at the page again, I see
"bcache + btrfs does not seem to be stable yet" linking to a thread more than 2 years old and btrfs kernels that wouldn't be stable without bcache anyway.

I've seen others mention they switched to bcache recently and not seen new "it's broken" reports.

So, is it ok
1) to assume bcache and btrfs play ok together now?
2) remove the warning from that gotchas page?

Thanks,
Marc

"A mouse is a device used to point at the xterm you want to type in" - A.S.R.
Microsoft is to operating systems ....
                                      .... what McDonalds is to gourmet cooking
Home page: http://marc.merlins.org/                         | PGP 1024R/763BE901

I'm one of those that used to have problems with btrfs on top of bcache. After some corruptions, I gave up this setup.

Recently (from February, I think) I gave it another shot, and I have had no problems since.
I use bcache in writeback mode, with very good performance. I'm feeling btrfs very stable in this setup.

Best Regards,

Fabio Pfeifer

2015-04-20 11:49 GMT-03:00 Marc MERLIN <[email protected]>:

[..snip]

This hang on mount was caused by a backported fix to -stable, which you probably caught after an update to 3.19.2.

The fix is in 3.19.5: commit 0187ad2b69a51a23924cd41f730e2d923535db80 in
https://kernel.org/pub/linux/kernel/v3.x/ChangeLog-3.19.5

So just get a fresh 3.19.5 (or directly 4.0) and it should mount again.

-h