fs/ntfs3: Changing locking in ntfs_rename

In some cases we can be in deadlock
because we tried to lock the same dir.

Signed-off-by: Konstantin Komarov <almaz.alexandrovich@paragon-software.com>

Author: aalexandrovich

fs/ntfs3/namei.c

@@ -305,6 +305,8 @@ static int ntfs_rename(struct user_namespace *mnt_userns, struct inode *dir,
 
 	ni_lock_dir(dir_ni);
 	ni_lock(ni);
+	if (dir_ni != new_dir_ni)
+		ni_lock_dir2(new_dir_ni);
 
 	is_bad = false;
 	err = ni_rename(dir_ni, new_dir_ni, ni, de, new_de, &is_bad);
@@ -328,6 +330,8 @@ static int ntfs_rename(struct user_namespace *mnt_userns, struct inode *dir,
 			ntfs_sync_inode(inode);
 	}
 
+	if (dir_ni != new_dir_ni)
+		ni_unlock(new_dir_ni);
 	ni_unlock(ni);
 	ni_unlock(dir_ni);
 out:

fs/ntfs3/ntfs_fs.h

@@ -334,6 +334,7 @@ enum ntfs_inode_mutex_lock_class {
 	NTFS_INODE_MUTEX_REPARSE,
 	NTFS_INODE_MUTEX_NORMAL,
 	NTFS_INODE_MUTEX_PARENT,
+	NTFS_INODE_MUTEX_PARENT2,
 };
 
 /*
@@ -1121,6 +1122,11 @@ static inline void ni_lock_dir(struct ntfs_inode *ni)
 	mutex_lock_nested(&ni->ni_lock, NTFS_INODE_MUTEX_PARENT);
 }
 
+static inline void ni_lock_dir2(struct ntfs_inode *ni)
+{
+	mutex_lock_nested(&ni->ni_lock, NTFS_INODE_MUTEX_PARENT2);
+}
+
 static inline void ni_unlock(struct ntfs_inode *ni)
 {
 	mutex_unlock(&ni->ni_lock);