cf79ac4793
Simple quotas requires tracking the original creating root of any given extent. This gets complicated when multiple subvolumes create overlapping/contradictory refs in the same transaction. For example, due to modifying or deleting an extent while also snapshotting it. To resolve this in a general way, take advantage of the fact that we are essentially already tracking this for handling releasing reservations. The head ref coalesces the various refs and uses must_insert_reserved to check if it needs to create an extent/free reservation. Store the ref that set must_insert_reserved as the owning ref on the head ref. Note that this can result in writing an extent for the very first time with an owner different from its only ref, but it will look the same as if you first created it with the original owning ref, then added the other ref, then removed the owning ref. Signed-off-by: Boris Burkov <boris@bur.io> Signed-off-by: David Sterba <dsterba@suse.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.