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[ Upstream commitfa2068d7e9] The naming of space_info->active_total_bytes is misleading. It counts not only active block groups but also full ones which are previously active but now inactive. That confusion results in a bug not counting the full BGs into active_total_bytes on mount time. For a background, there are three kinds of block groups in terms of activation. 1. Block groups never activated 2. Block groups currently active 3. Block groups previously active and currently inactive (due to fully written or zone finish) What we really wanted to exclude from "total_bytes" is the total size of BGs #1. They seem empty and allocatable but since they are not activated, we cannot rely on them to do the space reservation. And, since BGs #1 never get activated, they should have no "used", "reserved" and "pinned" bytes. OTOH, BGs #3 can be counted in the "total", since they are already full we cannot allocate from them anyway. For them, "total_bytes == used + reserved + pinned + zone_unusable" should hold. Tracking #2 and #3 as "active_total_bytes" (current implementation) is confusing. And, tracking #1 and subtract that properly from "total_bytes" every time you need space reservation is cumbersome. Instead, we can count the whole region of a newly allocated block group as zone_unusable. Then, once that block group is activated, release [0 .. zone_capacity] from the zone_unusable counters. With this, we can eliminate the confusing ->active_total_bytes and the code will be common among regular and the zoned mode. Also, no additional counter is needed with this approach. Fixes:6a921de589("btrfs: zoned: introduce space_info->active_total_bytes") CC: stable@vger.kernel.org # 6.1+ Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com> Signed-off-by: David Sterba <dsterba@suse.com> Signed-off-by: Sasha Levin <sashal@kernel.org>
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.