Commit 4f4374a9 authored Jul 18, 2018 by Miklos Szeredi Committed by Greg Kroah-Hartman Sep 26, 2018

vfs: fix freeze protection in mnt_want_write_file() for overlayfs



[ Upstream commit a6795a585929d94ca3e931bc8518f8deb8bbe627 ]

The underlying real file used by overlayfs still contains the overlay path.
This results in mnt_want_write_file() calls by the filesystem getting
freeze protection on the wrong inode (the overlayfs one instead of the real
one).

Fix by using file_inode(file)->i_sb instead of file->f_path.mnt->mnt_sb.

Reported-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent b888dba2

fs/namespace.c

+4 −3

Original line number	Diff line number	Diff line
		@@ -446,10 +446,10 @@ int mnt_want_write_file_path(struct file *file)
		{
		int ret;

		sb_start_write(file->f_path.mnt->mnt_sb);
		sb_start_write(file_inode(file)->i_sb);
		ret = __mnt_want_write_file(file);
		if (ret)
		sb_end_write(file->f_path.mnt->mnt_sb);
		sb_end_write(file_inode(file)->i_sb);
		return ret;
		}

		@@ -540,7 +540,8 @@ void __mnt_drop_write_file(struct file *file)

		void mnt_drop_write_file_path(struct file *file)
		{
		mnt_drop_write(file->f_path.mnt);
		__mnt_drop_write_file(file);
		sb_end_write(file_inode(file)->i_sb);
		}

		void mnt_drop_write_file(struct file *file)