freezer: Add unsafe version of freezable_schedule_timeout_interruptible() for NFS

mainline inclusion
from mainline-v5.9-rc1
commit 59679d99
category: bugfix
bugzilla: NA
CVE: NA

--------------------------------

commit 0688e64b ("NFS: Allow signal interruption of
NFS4ERR_DELAYed operations") introduces nfs4_delay_interruptible
which also needs an _unsafe version to avoid the following call
trace for the same reason explained in commit 416ad3c9 ("freezer:
add unsafe versions of freezable helpers for NFS")

CPU: 4 PID: 3968 Comm: rm Tainted: G W 5.8.0-rc4 #1
Hardware name: Marvell OcteonTX CN96XX board (DT)
Call trace:
dump_backtrace+0x0/0x1dc
show_stack+0x20/0x30
dump_stack+0xdc/0x150
debug_check_no_locks_held+0x98/0xa0
nfs4_delay_interruptible+0xd8/0x120
nfs4_handle_exception+0x130/0x170
nfs4_proc_rmdir+0x8c/0x220
nfs_rmdir+0xa4/0x360
vfs_rmdir.part.0+0x6c/0x1b0
do_rmdir+0x18c/0x210
__arm64_sys_unlinkat+0x64/0x7c
el0_svc_common.constprop.0+0x7c/0x110
do_el0_svc+0x24/0xa0
el0_sync_handler+0x13c/0x1b8
el0_sync+0x158/0x180
Signed-off-by: NHe Zhe <zhe.he@windriver.com>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: NZhang Xiaoxu <zhangxiaoxu5@huawei.com>
Reviewed-by: NHou Tao <houtao1@huawei.com>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>

fs/nfs/nfs4proc.c

@@ -415,7 +415,7 @@ static int nfs4_delay_interruptible(long *timeout)
 {
 	might_sleep();
 
-	freezable_schedule_timeout_interruptible(nfs4_update_delay(timeout));
+	freezable_schedule_timeout_interruptible_unsafe(nfs4_update_delay(timeout));
 	if (!signal_pending(current))
 		return 0;
 	return __fatal_signal_pending(current) ? -EINTR :-ERESTARTSYS;

include/linux/freezer.h

@@ -207,6 +207,17 @@ static inline long freezable_schedule_timeout_interruptible(long timeout)
 	return __retval;
 }
 
+/* DO NOT ADD ANY NEW CALLERS OF THIS FUNCTION */
+static inline long freezable_schedule_timeout_interruptible_unsafe(long timeout)
+{
+	long __retval;
+
+	freezer_do_not_count();
+	__retval = schedule_timeout_interruptible(timeout);
+	freezer_count_unsafe();
+	return __retval;
+}
+
 /* Like schedule_timeout_killable(), but should not block the freezer. */
 static inline long freezable_schedule_timeout_killable(long timeout)
 {
@@ -285,6 +296,9 @@ static inline void set_freezable(void) {}
 #define freezable_schedule_timeout_interruptible(timeout)		\
 	schedule_timeout_interruptible(timeout)
 
+#define freezable_schedule_timeout_interruptible_unsafe(timeout)	\
+	schedule_timeout_interruptible(timeout)
+
 #define freezable_schedule_timeout_killable(timeout)			\
 	schedule_timeout_killable(timeout)