fs: warn about impending deprecation of mandatory locks

[ 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@vger.kernel.org
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/fs/namespace.c b/fs/namespace.c
index 8d2bf350e7c6a2a37fa57aec741eba914ca7c2a0..2f3c6a0350a8ddb2bbae2af0de6263f3b975e0c7 100644 (file)
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -1611,8 +1611,12 @@ 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