From 97658cdd3af7d01461874c93b89afa4a2465e7c6 Mon Sep 17 00:00:00 2001 From: NeilBrown Date: Mon, 18 Apr 2011 18:25:42 +1000 Subject: md: provide generic support for handling unplug callbacks. When an md device adds a request to a queue, it can call mddev_check_plugged. If this succeeds then we know that the md thread will be woken up shortly, and ->plug_cnt will be non-zero until then, so some processing can be delayed. If it fails, then no unplug callback is expected and the make_request function needs to do whatever is required to make the request happen. Signed-off-by: NeilBrown --- drivers/md/md.h | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'drivers/md/md.h') diff --git a/drivers/md/md.h b/drivers/md/md.h index fad90228672f..0b1fd3f1d85b 100644 --- a/drivers/md/md.h +++ b/drivers/md/md.h @@ -179,6 +179,9 @@ struct mddev_s int delta_disks, new_level, new_layout; int new_chunk_sectors; + atomic_t plug_cnt; /* If device is expecting + * more bios soon. + */ struct mdk_thread_s *thread; /* management thread */ struct mdk_thread_s *sync_thread; /* doing resync or reconstruct */ sector_t curr_resync; /* last block scheduled */ @@ -508,4 +511,5 @@ extern struct bio *bio_clone_mddev(struct bio *bio, gfp_t gfp_mask, mddev_t *mddev); extern struct bio *bio_alloc_mddev(gfp_t gfp_mask, int nr_iovecs, mddev_t *mddev); +extern int mddev_check_plugged(mddev_t *mddev); #endif /* _MD_MD_H */ -- cgit v1.2.1