fs: remove mandatory file locking support

We added CONFIG_MANDATORY_FILE_LOCKING in 2015, and soon after turned it
off in Fedora and RHEL8. Several other distros have followed suit.

I've heard of one problem in all that time: Someone migrated from an
older distro that supported "-o mand" to one that didn't, and the host
had a fstab entry with "mand" in it which broke on reboot. They didn't
actually _use_ mandatory locking so they just removed the mount option
and moved on.

This patch rips out mandatory locking support wholesale from the kernel,
along with the Kconfig option and the Documentation file. It also
changes the mount code to ignore the "mand" mount option instead of
erroring out, and to throw a big, ugly warning.

Signed-off-by: Jeff Layton <jlayton@kernel.org>

1 files changed, 0 insertions, 12 deletions

diff --git a/fs/remap_range.c b/fs/remap_range.c
index e4a5fdd7ad7b..6d4a9beaa097 100644
--- a/fs/remap_range.c
+++ b/fs/remap_range.c
@@ -99,24 +99,12 @@ static int generic_remap_checks(struct file *file_in, loff_t pos_in,
 static int remap_verify_area(struct file *file, loff_t pos, loff_t len,
 			     bool write)
 {
-	struct inode *inode = file_inode(file);
-
 	if (unlikely(pos < 0 || len < 0))
 		return -EINVAL;
 
 	if (unlikely((loff_t) (pos + len) < 0))
 		return -EINVAL;
 
-	if (unlikely(inode->i_flctx && mandatory_lock(inode))) {
-		loff_t end = len ? pos + len - 1 : OFFSET_MAX;
-		int retval;
-
-		retval = locks_mandatory_area(inode, file, pos, end,
-				write ? F_WRLCK : F_RDLCK);
-		if (retval < 0)
-			return retval;
-	}
-
 	return security_file_permission(file, write ? MAY_WRITE : MAY_READ);
 }