Stack overflow when destroying deeply nested clones
Destroy operations on deeply nested chains of clones can overflow
the stack:
Depth Size Location (221 entries)
----- ---- --------
0) 15664 48 mutex_lock+0x5/0x30
1) 15616 8 mutex_lock+0x5/0x30...
- 13576 72 dsl_dataset_remove_clones_key.isra.4+0x124/0x1e0 [zfs]
- 13504 72 dsl_dataset_remove_clones_key.isra.4+0x18a/0x1e0 [zfs]
- 13432 72 dsl_dataset_remove_clones_key.isra.4+0x18a/0x1e0 [zfs]
...
- 2128 72 dsl_dataset_remove_clones_key.isra.4+0x18a/0x1e0 [zfs]
- 2056 72 dsl_dataset_remove_clones_key.isra.4+0x18a/0x1e0 [zfs]
- 1984 72 dsl_dataset_remove_clones_key.isra.4+0x18a/0x1e0 [zfs]
- 1912 136 dsl_destroy_snapshot_sync_impl+0x4e0/0x1090 [zfs]
- 1776 16 dsl_destroy_snapshot_check+0x0/0x90 [zfs]
...
- 304 128 kthread+0xdf/0x100
- 176 48 ret_from_fork+0x22/0x40
- 128 128 kthread+0x0/0x100
Fix this issue by converting dsl_dataset_remove_clones_key() from
recursive to iterative.
Reviewed-by: Paul Zuchowski <pzuchowski@datto.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: loli10K <ezomori.nozomu@gmail.com>
Closes #7279
Closes #7810