linux-kernel - [PATCH 06/14] fs/ntfs3: Changing locking in ntfs

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Date:   Fri, 28 Oct 2022 20:04:26 +0300
From:   Konstantin Komarov <almaz.alexandrovich@...agon-software.com>
To:     <ntfs3@...ts.linux.dev>
CC:     <linux-kernel@...r.kernel.org>, <linux-fsdevel@...r.kernel.org>
Subject: [PATCH 06/14] 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@...agon-software.com>
---
  fs/ntfs3/namei.c   | 4 ++++
  fs/ntfs3/ntfs_fs.h | 6 ++++++
  2 files changed, 10 insertions(+)

diff --git a/fs/ntfs3/namei.c b/fs/ntfs3/namei.c
index 1af02d4f6b4d..13d6acc0747f 100644
--- a/fs/ntfs3/namei.c
+++ b/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:
diff --git a/fs/ntfs3/ntfs_fs.h b/fs/ntfs3/ntfs_fs.h
index c45a411f82f6..5fad93a2c3fd 100644
--- a/fs/ntfs3/ntfs_fs.h
+++ b/fs/ntfs3/ntfs_fs.h
@@ -333,6 +333,7 @@ enum ntfs_inode_mutex_lock_class {
  	NTFS_INODE_MUTEX_REPARSE,
  	NTFS_INODE_MUTEX_NORMAL,
  	NTFS_INODE_MUTEX_PARENT,
+	NTFS_INODE_MUTEX_PARENT2,
  };
  
  /*
@@ -1119,6 +1120,11 @@ 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);
-- 
2.37.0