[PATCH v2 2/2] md: enable io polling

Andrzej Jakowski
2020-02-11T19:18:13Z

From: Artur Paszkiewicz <artur.paszkiewicz@intel.com>

Provide a callback for polling the mddev which in turn polls the active
member devices in non-spinning manner. Enable it only if all members
support polling.

Signed-off-by: Artur Paszkiewicz <artur.paszkiewicz@intel.com>
Signed-off-by: Andrzej Jakowski <andrzej.jakowski@linux.intel.com>
---
drivers/md/md.c | 40 ++++++++++++++++++++++++++++++++++++----
1 file changed, 36 insertions(+), 4 deletions(-)

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 469f551863be..849d22a2108f 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -5564,6 +5564,28 @@ int mddev_init_writes_pending(struct mddev *mddev)
}
EXPORT_SYMBOL_GPL(mddev_init_writes_pending);

+static int md_poll(struct request_queue *q, blk_qc_t cookie, bool spin)
+{
+ struct mddev *mddev = q->queuedata;
+ struct md_rdev *rdev;
+ int ret = 0;
+ int rv;
+
+ rdev_for_each(rdev, mddev) {
+ if (rdev->raid_disk < 0 || test_bit(Faulty, &rdev->flags))
+ continue;
+
+ rv = blk_poll(bdev_get_queue(rdev->bdev), cookie, false);
+ if (rv < 0) {
+ ret = rv;
+ break;
+ }
+ ret += rv;
+ }
+
+ return ret;
+}
+
static int md_alloc(dev_t dev, char *name)
{
/*
@@ -5628,6 +5650,7 @@ static int md_alloc(dev_t dev, char *name)

blk_queue_make_request(mddev->queue, md_make_request);
blk_set_stacking_limits(&mddev->queue->limits);
+ mddev->queue->poll_fn = md_poll;

disk = alloc_disk(1 << shift);
if (!disk) {
@@ -5932,12 +5955,17 @@ int md_run(struct mddev *mddev)

if (mddev->queue) {
bool nonrot = true;
+ bool poll = true;

rdev_for_each(rdev, mddev) {
- if (rdev->raid_disk >= 0 &&
- !blk_queue_nonrot(bdev_get_queue(rdev->bdev))) {
- nonrot = false;
- break;
+ if (rdev->raid_disk >= 0) {
+ struct request_queue *q;
+
+ q = bdev_get_queue(rdev->bdev);
+ if (!blk_queue_nonrot(q))
+ nonrot = false;
+ if (!test_bit(QUEUE_FLAG_POLL, &q->queue_flags))
+ poll = false;
}
}
if (mddev->degraded)
@@ -5946,6 +5974,10 @@ int md_run(struct mddev *mddev)
blk_queue_flag_set(QUEUE_FLAG_NONROT, mddev->queue);
else
blk_queue_flag_clear(QUEUE_FLAG_NONROT, mddev->queue);
+ if (poll)
+ blk_queue_flag_set(QUEUE_FLAG_POLL, mddev->queue);
+ else
+ blk_queue_flag_clear(QUEUE_FLAG_POLL, mddev->queue);
mddev->queue->backing_dev_info->congested_data = mddev;
mddev->queue->backing_dev_info->congested_fn = md_congested;
}
--
2.20.1