Cant mount previously working dataset - high CPU

[niksfirefly]

System information

Type	Version/Name
Distribution Name	Ubuntu
Distribution Version	18.04
Linux Kernel	4.15.0-23-generic #25-Ubuntu SMP Wed May 23 18:02:16 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux
ZFS Version	0.7.5-1ubuntu15
SPL Version	0.7.5-1ubuntu1

Problem

I cant mount previously working dataset.
I observe high CPU and kern.log errors instantly which leads host to become unresponsive.
How can i debug and restore data from this dataset?
Zpool scrub was done without errors.

How to reproduce the problem

zfs mount pool/lxd/containers/dev-firewalld
or
lxc start dev-firewalld

kern.log

kernel: [  787.291341] Call Trace:
kernel: [  787.291348]  dump_stack+0x63/0x8b
kernel: [  787.291355]  spl_dumpstack+0x42/0x50 [spl]
kernel: [  787.291360]  spl_panic+0xc8/0x110 [spl]
kernel: [  787.291364]  ? __update_load_avg_se.isra.38+0x1c0/0x1d0
kernel: [  787.291366]  ? __update_load_avg_se.isra.38+0x1c0/0x1d0
kernel: [  787.291368]  ? update_load_avg+0x57f/0x6e0
kernel: [  787.291371]  ? update_curr+0xf5/0x1d0
kernel: [  787.291373]  ? select_idle_sibling+0x383/0x410
kernel: [  787.291375]  ? __enqueue_entity+0x5c/0x60
kernel: [  787.291377]  ? enqueue_entity+0x10e/0x6b0
kernel: [  787.291379]  ? wakeup_preempt_entity.isra.69+0x41/0x50
kernel: [  787.291381]  ? wakeup_preempt_entity.isra.69+0x41/0x50
kernel: [  787.291436]  range_tree_add+0x90/0x300 [zfs]
kernel: [  787.291469]  metaslab_free_dva+0x12b/0x400 [zfs]
kernel: [  787.291499]  metaslab_free+0xdd/0xf0 [zfs]
kernel: [  787.291534]  zio_dva_free+0x1c/0x30 [zfs]
kernel: [  787.291567]  zio_wait+0xb2/0x1b0 [zfs]
kernel: [  787.291599]  zio_free+0x9a/0xe0 [zfs]
kernel: [  787.291628]  dsl_free+0x11/0x20 [zfs]
kernel: [  787.291652]  dsl_dataset_block_kill+0x27e/0x460 [zfs]
kernel: [  787.291673]  dbuf_write_done+0x182/0x1b0 [zfs]
kernel: [  787.291691]  arc_write_done+0x86/0x3f0 [zfs]
kernel: [  787.291723]  zio_done+0x449/0xdf0 [zfs]
kernel: [  787.291756]  zio_execute+0x90/0xf0 [zfs]
kernel: [  787.291762]  taskq_thread+0x2ab/0x4e0 [spl]
kernel: [  787.291764]  ? wake_up_q+0x80/0x80
kernel: [  787.291797]  ? zio_reexecute+0x390/0x390 [zfs]
kernel: [  787.291800]  kthread+0x121/0x140
kernel: [  787.291805]  ? taskq_thread_should_stop+0x70/0x70 [spl]
kernel: [  787.291808]  ? kthread_create_worker_on_cpu+0x70/0x70
kernel: [  787.291811]  ret_from_fork+0x35/0x40
kernel: [  967.742944] INFO: task z_wr_int_6:19627 blocked for more than 120 seconds.
kernel: [  967.742948]       Tainted: P           OE    4.15.0-23-generic #25-Ubuntu
kernel: [  967.742951] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
kernel: [  967.742954] z_wr_int_6      D    0 19627      2 0x80000000
kernel: [  967.742958] Call Trace:
kernel: [  967.742965]  __schedule+0x297/0x8b0
kernel: [  967.742971]  ? select_idle_sibling+0x383/0x410
kernel: [  967.742977]  schedule+0x2c/0x80
kernel: [  967.742983]  schedule_preempt_disabled+0xe/0x10
kernel: [  967.742986]  __mutex_lock.isra.2+0x18c/0x4d0
kernel: [  967.742995]  ? spl_kmem_cache_alloc+0x64/0x140 [spl]
kernel: [  967.742999]  __mutex_lock_slowpath+0x13/0x20
kernel: [  967.743003]  ? __mutex_lock_slowpath+0x13/0x20
kernel: [  967.743006]  mutex_lock+0x2f/0x40
kernel: [  967.743072]  metaslab_free_dva+0xce/0x400 [zfs]
kernel: [  967.743138]  metaslab_free+0xdd/0xf0 [zfs]
kernel: [  967.743210]  zio_dva_free+0x1c/0x30 [zfs]
kernel: [  967.743278]  zio_wait+0xb2/0x1b0 [zfs]
kernel: [  967.743341]  zio_free+0x9a/0xe0 [zfs]
kernel: [  967.743405]  dsl_free+0x11/0x20 [zfs]
kernel: [  967.743463]  dsl_dataset_block_kill+0x27e/0x460 [zfs]
kernel: [  967.743509]  dbuf_write_done+0x182/0x1b0 [zfs]
kernel: [  967.743550]  arc_write_done+0x86/0x3f0 [zfs]
kernel: [  967.743619]  zio_done+0x449/0xdf0 [zfs]
kernel: [  967.743689]  zio_execute+0x90/0xf0 [zfs]
kernel: [  967.743699]  taskq_thread+0x2ab/0x4e0 [spl]
kernel: [  967.743704]  ? wake_up_q+0x80/0x80
kernel: [  967.743772]  ? zio_reexecute+0x390/0x390 [zfs]
kernel: [  967.743779]  kthread+0x121/0x140
kernel: [  967.743789]  ? taskq_thread_should_stop+0x70/0x70 [spl]
kernel: [  967.743795]  ? kthread_create_worker_on_cpu+0x70/0x70
kernel: [  967.743801]  ret_from_fork+0x35/0x40

[stale]

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