1 files changed, 54 insertions, 11 deletions

diff --git a/fs/inode.c b/fs/inode.c
index 577799b7855f..d37fad91c8da 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -1104,9 +1104,51 @@ void discard_new_inode(struct inode *inode)
 EXPORT_SYMBOL(discard_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 that is not a directory.
+ * Lock any non-NULL argument. Passed objects must not be directories.
  * Zero, one or two objects may be locked by this function.
  *
  * @inode1: first inode to lock
@@ -1114,13 +1156,9 @@ EXPORT_SYMBOL(discard_new_inode);
  */
 void lock_two_nondirectories(struct inode *inode1, struct inode *inode2)
 {
-	if (inode1 > inode2)
-		swap(inode1, inode2);
-
-	if (inode1 && !S_ISDIR(inode1->i_mode))
-		inode_lock(inode1);
-	if (inode2 && !S_ISDIR(inode2->i_mode) && inode2 != inode1)
-		inode_lock_nested(inode2, I_MUTEX_NONDIR2);
+	WARN_ON_ONCE(S_ISDIR(inode1->i_mode));
+	WARN_ON_ONCE(S_ISDIR(inode2->i_mode));
+	lock_two_inodes(inode1, inode2, I_MUTEX_NORMAL, I_MUTEX_NONDIR2);
 }
 EXPORT_SYMBOL(lock_two_nondirectories);
 
@@ -1131,10 +1169,14 @@ EXPORT_SYMBOL(lock_two_nondirectories);
  */
 void unlock_two_nondirectories(struct inode *inode1, struct inode *inode2)
 {
-	if (inode1 && !S_ISDIR(inode1->i_mode))
+	if (inode1) {
+		WARN_ON_ONCE(S_ISDIR(inode1->i_mode));
 		inode_unlock(inode1);
-	if (inode2 && !S_ISDIR(inode2->i_mode) && inode2 != inode1)
+	}
+	if (inode2 && inode2 != inode1) {
+		WARN_ON_ONCE(S_ISDIR(inode2->i_mode));
 		inode_unlock(inode2);
+	}
 }
 EXPORT_SYMBOL(unlock_two_nondirectories);
 
@@ -2264,7 +2306,8 @@ void init_special_inode(struct inode *inode, umode_t mode, dev_t rdev)
 		inode->i_fop = &def_chr_fops;
 		inode->i_rdev = rdev;
 	} else if (S_ISBLK(mode)) {
-		inode->i_fop = &def_blk_fops;
+		if (IS_ENABLED(CONFIG_BLOCK))
+			inode->i_fop = &def_blk_fops;
 		inode->i_rdev = rdev;
 	} else if (S_ISFIFO(mode))
 		inode->i_fop = &pipefifo_fops;