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f9bbb68233
Orangefs has no open, and orangefs checks file permissions on each file access. Posix requires that file permissions be checked on open and nowhere else. Orangefs-through-the-kernel needs to seem posix compliant. The VFS opens files, even if the filesystem provides no method. We can see if a file was successfully opened for read and or for write by looking at file->f_mode. When writes are flowing from the page cache, file is no longer available. We can trust the VFS to have checked file->f_mode before writing to the page cache. The mode of a file might change between when it is opened and IO commences, or it might be created with an arbitrary mode. We'll make sure we don't hit EACCES during the IO stage by using UID 0. Some of the time we have access without changing to UID 0 - how to check? Signed-off-by: Mike Marshall <hubcap@omnibond.com>
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.