Release SCL_STATE in map_write_done()

The config lock must be held for the duration of the MMP write.
Since the I/Os are executed via map_nowait(), the done function
is the only place where we know the write has completed.

Since SCL_STATE is taken as reader, overlapping I/Os do not
create a deadlock.  The refcount is simply increased when new
I/Os are queued and decreased when I/Os complete.

Test case added which exercises the probe IO call path to
verify the fix and prevent a regression.

Reviewed-by: Brian Behlendorf <[email protected]>
Signed-off-by: Olaf Faaland <[email protected]>
Closes #6394

0 files changed, 0 insertions, 0 deletions