b6bf9171ef
Ext4 does not always reduce the reserved cluster count by the number of clusters allocated when mapping a delayed extent. It sometimes adds back one or more clusters after allocation if delalloc blocks adjacent to the range allocated by ext4_ext_map_blocks() share the clusters newly allocated for that range. However, this overcounts the number of clusters needed to satisfy future mapping requests (holding one or more reservations for clusters that have already been allocated) and premature ENOSPC and quota failures, etc., result. Ext4 also does not reduce the reserved cluster count when allocating clusters for non-delayed allocated writes that have previously been reserved for delayed writes. This also results in overcounts. To make it possible to handle reserved cluster accounting for fallocated regions in the same manner as used for other non-delayed writes, do the reserved cluster accounting for them at the time of allocation. In the current code, this is only done later when a delayed extent sharing the fallocated region is finally mapped. Address comment correcting handling of unsigned long long constant from Jan Kara's review of RFC version of this patch. Signed-off-by: Eric Whitney <enwlinux@gmail.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
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.
See Documentation/00-INDEX for a list of what is contained in each file.
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.