ec8e701f9e
commit 02c0cab8e7345b06f1c0838df444e2902e4138d3 upstream. Overlayfs may fail to complete updates when a filesystem lacks fileattr/xattr syscall support and responds with an ENOSYS error code, resulting in an unexpected "Function not implemented" error. This bug may occur with FUSE filesystems, such as davfs2. Steps to reproduce: # install davfs2, e.g., apk add davfs2 mkdir /test mkdir /test/lower /test/upper /test/work /test/mnt yes '' | mount -t davfs -o ro http://some-web-dav-server/path \ /test/lower mount -t overlay -o upperdir=/test/upper,lowerdir=/test/lower \ -o workdir=/test/work overlay /test/mnt # when "some-file" exists in the lowerdir, this fails with "Function # not implemented", with dmesg showing "overlayfs: failed to retrieve # lower fileattr (/some-file, err=-38)" touch /test/mnt/some-file The underlying cause of this regresion is actually in FUSE, which fails to translate the ENOSYS error code returned by userspace filesystem (which means that the ioctl operation is not supported) to ENOTTY. Reported-by: Christian Kohlschütter <christian@kohlschutter.com> Fixes: 72db82115d2b ("ovl: copy up sync/noatime fileattr flags") Fixes: 59efec7b9039 ("fuse: implement ioctl support") Cc: <stable@vger.kernel.org> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.