aboutsummaryrefslogtreecommitdiff
path: root/drivers
diff options
context:
space:
mode:
authorLars Ellenberg <lars.ellenberg@linbit.com>2012-07-30 09:08:25 +0200
committerPhilipp Reisner <philipp.reisner@linbit.com>2012-11-08 16:58:39 +0100
commit6f3465ed82b10922effe364676103cbd4f2bcd81 (patch)
tree9dc3f63d3faffecd49cac56a3affc55b1df08ae8 /drivers
parent0c849666016cbf541c1030eec55f5f8dd1fba513 (diff)
downloadvexpress-lsk-6f3465ed82b10922effe364676103cbd4f2bcd81.tar.gz
drbd: report congestion if we are waiting for some userland callback
If the drbd worker thread is synchronously waiting for some userland callback, we don't want some casual pageout to block on us. Have drbd_congested() report congestion in that case. Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com> Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/block/drbd/drbd_int.h6
-rw-r--r--drivers/block/drbd/drbd_main.c16
-rw-r--r--drivers/block/drbd/drbd_nl.c9
3 files changed, 30 insertions, 1 deletions
diff --git a/drivers/block/drbd/drbd_int.h b/drivers/block/drbd/drbd_int.h
index 963766bafab..e010afff336 100644
--- a/drivers/block/drbd/drbd_int.h
+++ b/drivers/block/drbd/drbd_int.h
@@ -815,6 +815,12 @@ enum {
CONN_DRY_RUN, /* Expect disconnect after resync handshake. */
CREATE_BARRIER, /* next P_DATA is preceded by a P_BARRIER */
STATE_SENT, /* Do not change state/UUIDs while this is set */
+ CALLBACK_PENDING, /* Whether we have a call_usermodehelper(, UMH_WAIT_PROC)
+ * pending, from drbd worker context.
+ * If set, bdi_write_congested() returns true,
+ * so shrink_page_list() would not recurse into,
+ * and potentially deadlock on, this drbd worker.
+ */
};
struct drbd_tconn { /* is a resource from the config file */
diff --git a/drivers/block/drbd/drbd_main.c b/drivers/block/drbd/drbd_main.c
index 849e5de9ea8..f2af74d0686 100644
--- a/drivers/block/drbd/drbd_main.c
+++ b/drivers/block/drbd/drbd_main.c
@@ -2338,6 +2338,22 @@ static int drbd_congested(void *congested_data, int bdi_bits)
goto out;
}
+ if (test_bit(CALLBACK_PENDING, &mdev->tconn->flags)) {
+ r |= (1 << BDI_async_congested);
+ /* Without good local data, we would need to read from remote,
+ * and that would need the worker thread as well, which is
+ * currently blocked waiting for that usermode helper to
+ * finish.
+ */
+ if (!get_ldev_if_state(mdev, D_UP_TO_DATE))
+ r |= (1 << BDI_sync_congested);
+ else
+ put_ldev(mdev);
+ r &= bdi_bits;
+ reason = 'c';
+ goto out;
+ }
+
if (get_ldev(mdev)) {
q = bdev_get_queue(mdev->ldev->backing_bdev);
r = bdi_congested(&q->backing_dev_info, bdi_bits);
diff --git a/drivers/block/drbd/drbd_nl.c b/drivers/block/drbd/drbd_nl.c
index d4c05e26a13..05ed4804c72 100644
--- a/drivers/block/drbd/drbd_nl.c
+++ b/drivers/block/drbd/drbd_nl.c
@@ -323,11 +323,15 @@ int drbd_khelper(struct drbd_conf *mdev, char *cmd)
NULL };
char mb[12];
char *argv[] = {usermode_helper, cmd, mb, NULL };
+ struct drbd_tconn *tconn = mdev->tconn;
struct sib_info sib;
int ret;
+ if (current == tconn->worker.task)
+ set_bit(CALLBACK_PENDING, &tconn->flags);
+
snprintf(mb, 12, "minor-%d", mdev_to_minor(mdev));
- setup_khelper_env(mdev->tconn, envp);
+ setup_khelper_env(tconn, envp);
/* The helper may take some time.
* write out any unsynced meta data changes now */
@@ -350,6 +354,9 @@ int drbd_khelper(struct drbd_conf *mdev, char *cmd)
sib.helper_exit_code = ret;
drbd_bcast_event(mdev, &sib);
+ if (current == tconn->worker.task)
+ clear_bit(CALLBACK_PENDING, &tconn->flags);
+
if (ret < 0) /* Ignore any ERRNOs we got. */
ret = 0;