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f658adeea4
fuse_direct_io() can end up advancing the iterator by more than the amount
of data read or written. This case is handled by the generic code if going
through ->direct_IO(), but not in the FOPEN_DIRECT_IO case.
Fix by reverting the extra bytes from the iterator in case of error or a
short count.
To test: install lxcfs, then the following testcase
int fd = open("/var/lib/lxcfs/proc/uptime", O_RDONLY);
sendfile(1, fd, NULL, 16777216);
sendfile(1, fd, NULL, 16777216);
will spew WARN_ON() in iov_iter_pipe().
Reported-by: Peter Geis <pgwipeout@gmail.com>
Reported-by: Al Viro <viro@zeniv.linux.org.uk>
Fixes: 3c3db095b6 ("fuse: use iov_iter based generic splice helpers")
Cc: <stable@vger.kernel.org> # v5.1
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
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Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
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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.