Hi, I'm back.
I looked at current internal suspend code in 3.19.
One thing that seems strange is this:
static void __dm_internal_suspend(struct mapped_device *md, unsigned suspend_flags)
{
struct dm_table *map = NULL;
if (dm_suspended_internally_md(md))
return; /* nested internal suspend */
....
static void __dm_internal_resume(struct mapped_device *md)
{
if (!dm_suspended_internally_md(md))
return; /* resume from nested internal suspend */
- the comments imply that the code supports nested internal suspend, while
in fact it doesn't. If the caller calls:
* dm_internal_suspend_noflush
* dm_internal_suspend_noflush
* dm_internal_resume
the device is not suspended while it should be.
The "if" branch in __dm_internal_resume has nothing to do with nested
suspend, it's called if the caller calls dm_internal_resume without
dm_internal_suspend_noflush - that shouldn't happen, so there should be
WARN or BUG.
If you want to support multiple internal suspends (which is needed if one
table can have multiple dm-thin targets), you need a counter that counts
how many times the device was suspended - the counter doesn't have to be
atomic because the code already holds md->suspend_lock. If you don't want
to support multiple internal suspends, there should be at least WARN when
the caller attempts to do it.
Mikulas
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