[PATCH 13/30] drbd: zero-out partial unaligned discards on local backend

From: Philipp Reisner
Date: Mon Apr 25 2016 - 08:19:48 EST


From: Lars Ellenberg <lars.ellenberg@xxxxxxxxxx>

For consistency, also zero-out partial unaligned chunks of discard
requests on the local backend.

Signed-off-by: Philipp Reisner <philipp.reisner@xxxxxxxxxx>
Signed-off-by: Lars Ellenberg <lars.ellenberg@xxxxxxxxxx>
---
drivers/block/drbd/drbd_int.h | 2 ++
drivers/block/drbd/drbd_req.c | 29 +++++++++++++++++++++++------
2 files changed, 25 insertions(+), 6 deletions(-)

diff --git a/drivers/block/drbd/drbd_int.h b/drivers/block/drbd/drbd_int.h
index 8cc2955..d818e7d 100644
--- a/drivers/block/drbd/drbd_int.h
+++ b/drivers/block/drbd/drbd_int.h
@@ -1553,6 +1553,8 @@ extern void start_resync_timer_fn(unsigned long data);
extern void drbd_endio_write_sec_final(struct drbd_peer_request *peer_req);

/* drbd_receiver.c */
+extern int drbd_issue_discard_or_zero_out(struct drbd_device *device,
+ sector_t start, unsigned int nr_sectors, bool discard);
extern int drbd_receiver(struct drbd_thread *thi);
extern int drbd_ack_receiver(struct drbd_thread *thi);
extern void drbd_send_ping_wf(struct work_struct *ws);
diff --git a/drivers/block/drbd/drbd_req.c b/drivers/block/drbd/drbd_req.c
index 6dbf1f1..7e441ff 100644
--- a/drivers/block/drbd/drbd_req.c
+++ b/drivers/block/drbd/drbd_req.c
@@ -1156,6 +1156,16 @@ static int drbd_process_write_request(struct drbd_request *req)
return remote;
}

+static void drbd_process_discard_req(struct drbd_request *req)
+{
+ int err = drbd_issue_discard_or_zero_out(req->device,
+ req->i.sector, req->i.size >> 9, true);
+
+ if (err)
+ req->private_bio->bi_error = -EIO;
+ bio_endio(req->private_bio);
+}
+
static void
drbd_submit_req_private_bio(struct drbd_request *req)
{
@@ -1176,6 +1186,8 @@ drbd_submit_req_private_bio(struct drbd_request *req)
: rw == READ ? DRBD_FAULT_DT_RD
: DRBD_FAULT_DT_RA))
bio_io_error(bio);
+ else if (bio->bi_rw & REQ_DISCARD)
+ drbd_process_discard_req(req);
else
generic_make_request(bio);
put_ldev(device);
@@ -1227,18 +1239,23 @@ drbd_request_prepare(struct drbd_device *device, struct bio *bio, unsigned long
/* Update disk stats */
_drbd_start_io_acct(device, req);

+ /* process discards always from our submitter thread */
+ if (bio->bi_rw & REQ_DISCARD)
+ goto queue_for_submitter_thread;
+
if (rw == WRITE && req->private_bio && req->i.size
&& !test_bit(AL_SUSPENDED, &device->flags)) {
- if (!drbd_al_begin_io_fastpath(device, &req->i)) {
- atomic_inc(&device->ap_actlog_cnt);
- drbd_queue_write(device, req);
- return NULL;
- }
+ if (!drbd_al_begin_io_fastpath(device, &req->i))
+ goto queue_for_submitter_thread;
req->rq_state |= RQ_IN_ACT_LOG;
req->in_actlog_jif = jiffies;
}
-
return req;
+
+ queue_for_submitter_thread:
+ atomic_inc(&device->ap_actlog_cnt);
+ drbd_queue_write(device, req);
+ return NULL;
}

static void drbd_send_and_submit(struct drbd_device *device, struct drbd_request *req)
--
1.9.1