Brian Behlendorf 8a02d01e85 Fix zvol_open() lock inversion ... When restructuring the zvol_open() logic for the Linux 5.13 kernel a lock inversion was accidentally introduced. In the updated code the spa_namespace_lock is now taken before the zv_suspend_lock allowing the following scenario to occur: down_read <=== waiting for zv_suspend_lock zvol_open <=== holds spa_namespace_lock __blkdev_get blkdev_get_by_dev blkdev_open ... mutex_lock <== waiting for spa_namespace_lock spa_open_common spa_open dsl_pool_hold dmu_objset_hold_flags dmu_objset_hold dsl_prop_get dsl_prop_get_integer zvol_create_minor dmu_recv_end zfs_ioc_recv_impl <=== holds zv_suspend_lock via zvol_suspend() zfs_ioc_recv ... This commit resolves the issue by moving the acquisition of the spa_namespace_lock back to after the zv_suspend_lock which restores the original ordering. Additionally, as part of this change the error exit paths were simplified where possible. Reviewed-by: Tony Hutter <hutter2@llnl.gov> Reviewed-by: Rich Ercolani <rincebrain@gmail.com> Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov> Closes #12863		2021-12-17 09:52:13 -08:00
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spl	Add notes to system_taskq	2021-11-19 10:02:45 -07:00
zfs	Fix zvol_open() lock inversion	2021-12-17 09:52:13 -08:00