drbd: Do not send two barriers without any writes between 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_main.c b/drivers/block/drbd/drbd_main.c
index a8a0341..7d35986 100644
--- a/drivers/block/drbd/drbd_main.c
+++ b/drivers/block/drbd/drbd_main.c
@@ -344,7 +344,7 @@
static void _tl_restart(struct drbd_conf *mdev, enum drbd_req_event what)
{
struct drbd_tl_epoch *b, *tmp, **pn;
- struct list_head *le, *tle;
+ struct list_head *le, *tle, carry_reads;
struct drbd_request *req;
int rv, n_writes, n_reads;
@@ -353,6 +353,7 @@
while (b) {
n_writes = 0;
n_reads = 0;
+ INIT_LIST_HEAD(&carry_reads);
list_for_each_safe(le, tle, &b->requests) {
req = list_entry(le, struct drbd_request, tl_requests);
rv = _req_mod(req, what);
@@ -362,7 +363,7 @@
}
tmp = b->next;
- if (n_writes + n_reads) {
+ if (n_writes) {
if (what == resend) {
b->n_writes = n_writes;
if (b->w.cb == NULL) {
@@ -375,6 +376,8 @@
}
pn = &b->next;
} else {
+ if (n_reads)
+ list_add(&carry_reads, &b->requests);
/* there could still be requests on that ring list,
* in case local io is still pending */
list_del(&b->requests);
@@ -389,6 +392,7 @@
/* recycle, but reinit! */
D_ASSERT(tmp == NULL);
INIT_LIST_HEAD(&b->requests);
+ list_splice(&carry_reads, &b->requests);
INIT_LIST_HEAD(&b->w.list);
b->w.cb = NULL;
b->br_number = net_random();
@@ -401,6 +405,7 @@
kfree(b);
}
b = tmp;
+ list_splice(&carry_reads, &b->requests);
}
}