[PATCH 4.9 42/43] fs: warn about impending deprecation of mandatory locks

[Sasha Levin]

From: Jeff Layton <jlayton@xxxxxxxxxx>

[ Upstream commit fdd92b64d15bc4aec973caa25899afd782402e68 ]

We've had CONFIG_MANDATORY_FILE_LOCKING since 2015 and a lot of distros
have disabled it. Warn the stragglers that still use "-o mand" that
we'll be dropping support for that mount option.

Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 fs/namespace.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/fs/namespace.c b/fs/namespace.c
index 68457fa2f981..b9e30a385c01 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -1670,8 +1670,12 @@ static inline bool may_mount(void)
 }
 
 #ifdef	CONFIG_MANDATORY_FILE_LOCKING
-static inline bool may_mandlock(void)
+static bool may_mandlock(void)
 {
+	pr_warn_once("======================================================\n"
+		     "WARNING: the mand mount option is being deprecated and\n"
+		     "         will be removed in v5.15!\n"
+		     "======================================================\n");
 	return capable(CAP_SYS_ADMIN);
 }
 #else
-- 
2.30.2