Now that we've got code for raid5/6 stripe awareness, bcache just needs
to know about the stripes and when writing partial stripes is expensive
- we probably don't want to enable this optimization for raid1 or 10,
even though they have stripes. So add a flag to queue_limits.
Signed-off-by: Kent Overstreet <kmo@xxxxxxxxxxxxx>
---
This is in my pile of bcache stuff queued up for 3.14 - if no one objects it'll
be in my bcache pull request:
drivers/md/bcache/super.c | 6 ++++++
drivers/md/raid5.c | 1 +
include/linux/blkdev.h | 1 +
3 files changed, 8 insertions(+)
diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
index 63ebef78df..e363efcf2b 100644
--- a/drivers/md/bcache/super.c
+++ b/drivers/md/bcache/super.c
@@ -1134,6 +1134,12 @@ static int cached_dev_init(struct cached_dev *dc, unsigned block_size)
hlist_add_head(&io->hash, dc->io_hash + RECENT_IO);
}
+ dc->disk.stripe_size = q->limits.io_opt >> 9;
+
+ if (dc->disk.stripe_size)
+ dc->partial_stripes_expensive =
+ q->limits.raid_partial_stripes_expensive;
+
ret = bcache_device_init(&dc->disk, block_size,
dc->bdev->bd_part->nr_sects - dc->sb.data_offset);
if (ret)
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index bef353c51c..4b5035f286 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -6104,6 +6104,7 @@ static int run(struct mddev *mddev)
blk_queue_io_min(mddev->queue, chunk_size);
blk_queue_io_opt(mddev->queue, chunk_size *
(conf->raid_disks - conf->max_degraded));
+ mddev->queue->limits.raid_partial_stripes_expensive = 1;
/*
* We can only discard a whole stripe. It doesn't make sense to
* discard data disk but write parity disk
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 02cb6f0ea7..0375654adb 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -291,6 +291,7 @@ struct queue_limits {
unsigned char discard_misaligned;
unsigned char cluster;
unsigned char discard_zeroes_data;
+ unsigned char raid_partial_stripes_expensive;
};
struct request_queue {
--
1.8.5.1
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