From 2d759a46b4d65e1392843cf9df7101897af87008 Mon Sep 17 00:00:00 2001 From: Joe Thornber Date: Fri, 10 Oct 2014 15:27:16 +0100 Subject: dm thin: remap the bios in a cell immediately This use of direct submission in process_prepared_mapping() reduces latency for submitting bios in a cell by avoiding adding those bios to the deferred list and waiting for the next iteration of the worker. But this direct submission exposes the potential for a race between releasing a cell and incrementing deferred set. Fix this by introducing dm_cell_visit_release() and refactoring inc_remap_and_issue_cell() accordingly. Signed-off-by: Joe Thornber Signed-off-by: Mike Snitzer --- drivers/md/dm-bio-prison.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) (limited to 'drivers/md/dm-bio-prison.c') diff --git a/drivers/md/dm-bio-prison.c b/drivers/md/dm-bio-prison.c index 90a5662..bbe22a5 100644 --- a/drivers/md/dm-bio-prison.c +++ b/drivers/md/dm-bio-prison.c @@ -241,6 +241,20 @@ void dm_cell_error(struct dm_bio_prison *prison, } EXPORT_SYMBOL_GPL(dm_cell_error); +void dm_cell_visit_release(struct dm_bio_prison *prison, + void (*visit_fn)(void *, struct dm_bio_prison_cell *), + void *context, + struct dm_bio_prison_cell *cell) +{ + unsigned long flags; + + spin_lock_irqsave(&prison->lock, flags); + visit_fn(context, cell); + rb_erase(&cell->node, &prison->cells); + spin_unlock_irqrestore(&prison->lock, flags); +} +EXPORT_SYMBOL_GPL(dm_cell_visit_release); + /*----------------------------------------------------------------*/ #define DEFERRED_SET_SIZE 64 -- cgit v1.1