On 07/27/2016 08:52 AM, Benjamin Marzinski wrote:
if you look in drivers/md/dm-ioctl.c at do_resume(), device mapper internally does a suspend when you call resume with a new table loaded. That's when these suspends are happening. In the userspace tools, this happens in the DM_DEVICE_RESUME calls after dm_addmap_reload(), which loads the new table. These all happen in the domap() function.
Thanks Ben for chiming in. As far as I can see md->map is only used in the I/O submission path but not in the I/O completion path. So why to suspend and resume I/O before activating the new map? Do you think it would be safe to activate the new map without suspending and resuming I/O?
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