fa58cc888d
When a direct I/O write is performed, iomap_dio_rw() invalidates the part of the page cache which the write is going to before carrying out the write. In the odd case, the direct I/O write will be reading from the same page it is writing to. gfs2 carries out writes with page faults disabled, so it should have been obvious that this page invalidation can cause iomap_dio_rw() to never make any progress. Currently, gfs2 will end up in an endless retry loop in gfs2_file_direct_write() instead, though. Break this endless loop by limiting the number of retries and falling back to buffered I/O after that. Also simplify should_fault_in_pages() sightly and add a comment to make the above case easier to understand. Reported-by: Jan Kara <jack@suse.cz> Signed-off-by: Andreas Gruenbacher <agruenba@redhat.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.