[dm-devel] why does dm-cache use dm_deferred_entry_inc?

倪源江 niyuanjiang at ict.ac.cn
Sat Nov 15 08:49:52 UTC 2014


I'm reading the dm-cache code.I notice that before a bio is remapped and sent to the "real" device.the function "dm_deferred_entry_inc" will be invoked.And when a migration initiated ,the function "dm_deferred_set_add_work"  will be invoked to determine whether start the migration immediately.I guess those operation are used to ensure some sort of synchronization.But i'm not sure which kind of synchronization it can ensure and why.

Or my understanding is completely wrong . they are not at all used for synchronization?

Can anyone help me about this question?Thanks,

Yuanjiang Ni


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