drbd: introduce completion_ref and kref to struct drbd_request
cherry-picked and adapted from drbd 9 devel branch
completion_ref will count pending events necessary for completion.
kref is for destruction.
This only introduces these new members of struct drbd_request,
a followup patch will make actual use of them.
Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
diff --git a/drivers/block/drbd/drbd_int.h b/drivers/block/drbd/drbd_int.h
index 8536fab..52ad1bf 100644
--- a/drivers/block/drbd/drbd_int.h
+++ b/drivers/block/drbd/drbd_int.h
@@ -577,6 +577,11 @@
struct bio *master_bio; /* master bio pointer */
unsigned long rq_state; /* see comments above _req_mod() */
unsigned long start_time;
+
+ /* once it hits 0, we may complete the master_bio */
+ atomic_t completion_ref;
+ /* once it hits 0, we may destroy this drbd_request object */
+ struct kref kref;
};
struct drbd_epoch {
diff --git a/drivers/block/drbd/drbd_req.c b/drivers/block/drbd/drbd_req.c
index 6bac415..ae894af 100644
--- a/drivers/block/drbd/drbd_req.c
+++ b/drivers/block/drbd/drbd_req.c
@@ -85,17 +85,15 @@
INIT_LIST_HEAD(&req->tl_requests);
INIT_LIST_HEAD(&req->w.list);
+ atomic_set(&req->completion_ref, 1);
+ kref_init(&req->kref);
return req;
}
-static void drbd_req_free(struct drbd_request *req)
+static void drbd_req_destroy(struct kref *kref)
{
- mempool_free(req, drbd_request_mempool);
-}
-
-/* rw is bio_data_dir(), only READ or WRITE */
-static void _req_is_done(struct drbd_conf *mdev, struct drbd_request *req, const int rw)
-{
+ struct drbd_request *req = container_of(kref, struct drbd_request, kref);
+ struct drbd_conf *mdev = req->w.mdev;
const unsigned long s = req->rq_state;
/* remove it from the transfer log.
@@ -109,7 +107,7 @@
/* if it was a write, we may have to set the corresponding
* bit(s) out-of-sync first. If it had a local part, we need to
* release the reference to the activity log. */
- if (rw == WRITE) {
+ if (s & RQ_WRITE) {
/* Set out-of-sync unless both OK flags are set
* (local only or remote failed).
* Other places where we set out-of-sync:
@@ -146,7 +144,7 @@
if (s & RQ_POSTPONED)
drbd_restart_request(req);
else
- drbd_req_free(req);
+ mempool_free(req, drbd_request_mempool);
}
static void wake_all_senders(struct drbd_tconn *tconn) {
@@ -196,12 +194,10 @@
void req_may_be_done(struct drbd_request *req)
{
const unsigned long s = req->rq_state;
- struct drbd_conf *mdev = req->w.mdev;
- int rw = req->rq_state & RQ_WRITE ? WRITE : READ;
/* req->master_bio still present means: Not yet completed.
*
- * Unless this is RQ_POSTPONED, which will cause _req_is_done() to
+ * Unless this is RQ_POSTPONED, which will cause drbd_req_destroy() to
* queue it on the retry workqueue instead of destroying it.
*/
if (req->master_bio && !(s & RQ_POSTPONED))
@@ -216,7 +212,7 @@
/* this is disconnected (local only) operation,
* or protocol A, B, or C P_BARRIER_ACK,
* or killed from the transfer log due to connection loss. */
- _req_is_done(mdev, req, rw);
+ kref_put(&req->kref, drbd_req_destroy);
}
/* else: network part and not DONE yet. that is
* protocol A, B, or C, barrier ack still pending... */
@@ -250,6 +246,15 @@
if (s & RQ_NET_PENDING)
return;
+ /* FIXME
+ * instead of all the RQ_FLAGS, actually use the completion_ref
+ * to decide if this is ready to be completed. */
+ if (req->master_bio) {
+ int complete = atomic_dec_and_test(&req->completion_ref);
+ D_ASSERT(complete != 0);
+ } else
+ D_ASSERT(atomic_read(&req->completion_ref) == 0);
+
if (req->master_bio) {
int rw = bio_rw(req->master_bio);
@@ -1113,7 +1118,7 @@
* and find the oldest not yet completed request */
struct drbd_request *r;
list_for_each_entry(r, &tconn->transfer_log, tl_requests) {
- if (r->rq_state & (RQ_NET_PENDING|RQ_LOCAL_PENDING))
+ if (atomic_read(&r->completion_ref))
return r;
}
return NULL;