Patch "fscrypto: lock inode while setting encryption policy" has been added to the 4.4-stable tree

This is a note to let you know that I've just added the patch titled

fscrypto: lock inode while setting encryption policy

to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
fscrypto-lock-inode-while-setting-encryption-policy.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Eric Biggers <[email protected]>
Date: Sat, 15 Oct 2016 09:48:50 -0400
Subject: fscrypto: lock inode while setting encryption policy

From: Eric Biggers <[email protected]>

commit 8906a8223ad4909b391c5628f7991ebceda30e52 upstream.

i_rwsem needs to be acquired while setting an encryption policy so that concurrent calls to FS_IOC_SET_ENCRYPTION_POLICY are correctly serialized (especially the ->get_context() + ->set_context() pair), and so that new files cannot be created in the directory during or after the ->empty_dir() check.

---
 fs/ext4/ioctl.c |    4 ++++
 fs/f2fs/file.c  |    9 ++++++++-
 2 files changed, 12 insertions(+), 1 deletion(-)

@@ -633,8 +633,12 @@ resizefs_out:
 		if (err)
 			goto encryption_policy_out;
 
+		mutex_lock(&inode->i_mutex);
+
 		err = ext4_process_policy(&policy, inode);
 
+		mutex_unlock(&inode->i_mutex);
+
 		mnt_drop_write_file(filp);
 encryption_policy_out:
 		return err;

@@ -1535,12 +1535,19 @@ static int f2fs_ioc_set_encryption_polic
 #ifdef CONFIG_F2FS_FS_ENCRYPTION
 	struct f2fs_encryption_policy policy;
 	struct inode *inode = file_inode(filp);
+	int err;
 
 	if (copy_from_user(&policy, (struct f2fs_encryption_policy __user *)arg,
 				sizeof(policy)))
 		return -EFAULT;
 
-	return f2fs_process_policy(&policy, inode);
+	mutex_lock(&inode->i_mutex);
+
+	err = f2fs_process_policy(&policy, inode);
+
+	mutex_unlock(&inode->i_mutex);
+
+	return err;
 #else
 	return -EOPNOTSUPP;
 #endif

Patches currently in stable-queue which might be from [email protected] are

queue-4.4/fscrypto-lock-inode-while-setting-encryption-policy.patch queue-4.4/fscrypt-fix-renaming-and-linking-special-files.patch