[ Upstream commit b10b85fe5149ee8b39fbbf86095b303632dde2cd ] When mounting overlayfs in an unprivileged user namespace, trusted xattr creation will fail. This will lead to failures in some file operations, e.g. in the following situation: mkdir lower upper work merged mkdir lower/directory mount -toverlay -olowerdir=lower,upperdir=upper,workdir=work none merged rmdir merged/directory mkdir merged/directory The last mkdir will fail: mkdir: cannot create directory 'merged/directory': Input/output error The cause for these failures is currently extremely non-obvious and hard to debug. Hence, warn the user and suggest using the userxattr mount option, if it is not already supplied and xattr creation fails during the self-check. Reported-by: Alois Wohlschlager <alois1@gmx-topmail.de> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com> Signed-off-by: Sasha Levin <sashal@kernel.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.
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