From 94b25662c51696ec081494e69efb5896566dede2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Arkadiusz=20Buba=C5=82a?= <arkadiusz.bubala@open-e.com>
Date: Thu, 6 Jul 2017 17:38:24 +0200
Subject: [PATCH] Reschedule processes on -ERESTARTSYS
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On the single core machine the system may hang when the
spa_namespare_lock acquisition fails in the zvol_first_open
function. It returns -ERESTARTSYS error what causes the
endless loop in __blkdev_get function.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: George Melikov <mail@gmelikov.ru>
Signed-off-by: Arkadiusz Bubała <arkadiusz.bubala@open-e.com>
Closes #6283
Closes #6312
---
 module/zfs/zvol.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/module/zfs/zvol.c b/module/zfs/zvol.c
index 3e9f004ef3..4f1601ec63 100644
--- a/module/zfs/zvol.c
+++ b/module/zfs/zvol.c
@@ -1358,6 +1358,8 @@ out_mutex:
 	mutex_exit(&zv->zv_state_lock);
 	if (drop_suspend)
 		rw_exit(&zv->zv_suspend_lock);
+	if (error == -ERESTARTSYS)
+		schedule();
 
 	return (SET_ERROR(error));
 }