9fe671496b
Modify ext4_ext_remove_space() and the code it calls to correct the reserved cluster count for pending reservations (delayed allocated clusters shared with allocated blocks) when a block range is removed from the extent tree. Pending reservations may be found for the clusters at the ends of written or unwritten extents when a block range is removed. If a physical cluster at the end of an extent is freed, it's necessary to increment the reserved cluster count to maintain correct accounting if the corresponding logical cluster is shared with at least one delayed and unwritten extent as found in the extents status tree. Add a new function, ext4_rereserve_cluster(), to reapply a reservation on a delayed allocated cluster sharing blocks with a freed allocated cluster. To avoid ENOSPC on reservation, a flag is applied to ext4_free_blocks() to briefly defer updating the freeclusters counter when an allocated cluster is freed. This prevents another thread from allocating the freed block before the reservation can be reapplied. Redefine the partial cluster object as a struct to carry more state information and to clarify the code using it. Adjust the conditional code structure in ext4_ext_remove_space to reduce the indentation level in the main body of the code to improve readability. 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.