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-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;