From dbd4540df2b2857a91593754275c02f3e415fc30 Mon Sep 17 00:00:00 2001
From: Al Viro <viro@zeniv.linux.org.uk>
Date: Sun, 19 Nov 2023 22:21:00 -0500
Subject: [PATCH] kill lock_two_inodes()
Git-commit: dbd4540df2b2857a91593754275c02f3e415fc30
Patch-mainline: v6.8-rc1
References: bsc#1221044 CVE-2023-52591

There's only one caller left (lock_two_nondirectories()), and it
needs less complexity.  Fold lock_two_inodes() in there and
simplify.

Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Acked-by: Jan Kara <jack@suse.cz>

---
 fs/inode.c    |   49 ++++++-------------------------------------------
 fs/internal.h |    2 --
 2 files changed, 6 insertions(+), 45 deletions(-)

--- a/fs/inode.c
+++ b/fs/inode.c
@@ -973,48 +973,6 @@ void unlock_new_inode(struct inode *inod
 EXPORT_SYMBOL(unlock_new_inode);
 
 /**
- * lock_two_inodes - lock two inodes (may be regular files but also dirs)
- *
- * Lock any non-NULL argument. The caller must make sure that if he is passing
- * in two directories, one is not ancestor of the other.  Zero, one or two
- * objects may be locked by this function.
- *
- * @inode1: first inode to lock
- * @inode2: second inode to lock
- * @subclass1: inode lock subclass for the first lock obtained
- * @subclass2: inode lock subclass for the second lock obtained
- */
-void lock_two_inodes(struct inode *inode1, struct inode *inode2,
-		     unsigned subclass1, unsigned subclass2)
-{
-	if (!inode1 || !inode2) {
-		/*
-		 * Make sure @subclass1 will be used for the acquired lock.
-		 * This is not strictly necessary (no current caller cares) but
-		 * let's keep things consistent.
-		 */
-		if (!inode1)
-			swap(inode1, inode2);
-		goto lock;
-	}
-
-	/*
-	 * If one object is directory and the other is not, we must make sure
-	 * to lock directory first as the other object may be its child.
-	 */
-	if (S_ISDIR(inode2->i_mode) == S_ISDIR(inode1->i_mode)) {
-		if (inode1 > inode2)
-			swap(inode1, inode2);
-	} else if (!S_ISDIR(inode1->i_mode))
-		swap(inode1, inode2);
-lock:
-	if (inode1)
-		inode_lock_nested(inode1, subclass1);
-	if (inode2 && inode2 != inode1)
-		inode_lock_nested(inode2, subclass2);
-}
-
-/**
  * lock_two_nondirectories - take two i_mutexes on non-directory objects
  *
  * Lock any non-NULL argument. Passed objects must not be directories.
@@ -1029,7 +987,12 @@ void lock_two_nondirectories(struct inod
 		WARN_ON_ONCE(S_ISDIR(inode1->i_mode));
 	if (inode2)
 		WARN_ON_ONCE(S_ISDIR(inode2->i_mode));
-	lock_two_inodes(inode1, inode2, I_MUTEX_NORMAL, I_MUTEX_NONDIR2);
+	if (inode1 > inode2)
+		swap(inode1, inode2);
+	if (inode1)
+		inode_lock(inode1);
+	if (inode2 && inode2 != inode1)
+		inode_lock_nested(inode2, I_MUTEX_NONDIR2);
 }
 EXPORT_SYMBOL(lock_two_nondirectories);
 
--- a/fs/internal.h
+++ b/fs/internal.h
@@ -117,8 +117,6 @@ extern int vfs_open(const struct path *,
 extern long prune_icache_sb(struct super_block *sb, struct shrink_control *sc);
 extern void inode_add_lru(struct inode *inode);
 extern int dentry_needs_remove_privs(struct dentry *dentry);
-void lock_two_inodes(struct inode *inode1, struct inode *inode2,
-		     unsigned subclass1, unsigned subclass2);
 
 extern bool __atime_needs_update(const struct path *, struct inode *, bool);
 static inline bool atime_needs_update_rcu(const struct path *path,