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, 84 deletions

diff --git a/include/linux/fs.h b/include/linux/fs.h
index 640574294216..f51c63b37636 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2570,90 +2570,6 @@ extern struct kobject *fs_kobj;
 
 #define MAX_RW_COUNT (INT_MAX & PAGE_MASK)
 
-#ifdef CONFIG_MANDATORY_FILE_LOCKING
-extern int locks_mandatory_locked(struct file *);
-extern int locks_mandatory_area(struct inode *, struct file *, loff_t, loff_t, unsigned char);
-
-/*
- * Candidates for mandatory locking have the setgid bit set
- * but no group execute bit -  an otherwise meaningless combination.
- */
-
-static inline int __mandatory_lock(struct inode *ino)
-{
-	return (ino->i_mode & (S_ISGID | S_IXGRP)) == S_ISGID;
-}
-
-/*
- * ... and these candidates should be on SB_MANDLOCK mounted fs,
- * otherwise these will be advisory locks
- */
-
-static inline int mandatory_lock(struct inode *ino)
-{
-	return IS_MANDLOCK(ino) && __mandatory_lock(ino);
-}
-
-static inline int locks_verify_locked(struct file *file)
-{
-	if (mandatory_lock(locks_inode(file)))
-		return locks_mandatory_locked(file);
-	return 0;
-}
-
-static inline int locks_verify_truncate(struct inode *inode,
-				    struct file *f,
-				    loff_t size)
-{
-	if (!inode->i_flctx || !mandatory_lock(inode))
-		return 0;
-
-	if (size < inode->i_size) {
-		return locks_mandatory_area(inode, f, size, inode->i_size - 1,
-				F_WRLCK);
-	} else {
-		return locks_mandatory_area(inode, f, inode->i_size, size - 1,
-				F_WRLCK);
-	}
-}
-
-#else /* !CONFIG_MANDATORY_FILE_LOCKING */
-
-static inline int locks_mandatory_locked(struct file *file)
-{
-	return 0;
-}
-
-static inline int locks_mandatory_area(struct inode *inode, struct file *filp,
-                                       loff_t start, loff_t end, unsigned char type)
-{
-	return 0;
-}
-
-static inline int __mandatory_lock(struct inode *inode)
-{
-	return 0;
-}
-
-static inline int mandatory_lock(struct inode *inode)
-{
-	return 0;
-}
-
-static inline int locks_verify_locked(struct file *file)
-{
-	return 0;
-}
-
-static inline int locks_verify_truncate(struct inode *inode, struct file *filp,
-					size_t size)
-{
-	return 0;
-}
-
-#endif /* CONFIG_MANDATORY_FILE_LOCKING */
-
-
 #ifdef CONFIG_FILE_LOCKING
 static inline int break_lease(struct inode *inode, unsigned int mode)
 {