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7b63259618
__qgroup_excl_accounting() uses the qgroup iterator machinery to
update the account of one qgroups usage for all its parent hierarchy,
when we either add or remove a relation and have only exclusive usage.
However, there is a small bug there: we loop with an extra iteration
temporary qgroup called `cur` but never actually refer to that in the
body of the loop. As a result, we redundantly account the same usage to
the first qgroup in the list.
This can be reproduced in the following way:
mkfs.btrfs -f -O squota <dev>
mount <dev> <mnt>
btrfs subvol create <mnt>/sv
dd if=/dev/zero of=<mnt>/sv/f bs=1M count=1
sync
btrfs qgroup create 1/100 <mnt>
btrfs qgroup create 2/200 <mnt>
btrfs qgroup assign 1/100 2/200 <mnt>
btrfs qgroup assign 0/256 1/100 <mnt>
btrfs qgroup show <mnt>
and the broken result is (note the 2MiB on 1/100 and 0Mib on 2/100):
Qgroupid Referenced Exclusive Path
-------- ---------- --------- ----
0/5 16.00KiB 16.00KiB <toplevel>
0/256 1.02MiB 1.02MiB sv
Qgroupid Referenced Exclusive Path
-------- ---------- --------- ----
0/5 16.00KiB 16.00KiB <toplevel>
0/256 1.02MiB 1.02MiB sv
1/100 2.03MiB 2.03MiB 2/100<1 member qgroup>
2/100 0.00B 0.00B <0 member qgroups>
With this fix, which simply re-uses `qgroup` as the iteration variable,
we see the expected result:
Qgroupid Referenced Exclusive Path
-------- ---------- --------- ----
0/5 16.00KiB 16.00KiB <toplevel>
0/256 1.02MiB 1.02MiB sv
Qgroupid Referenced Exclusive Path
-------- ---------- --------- ----
0/5 16.00KiB 16.00KiB <toplevel>
0/256 1.02MiB 1.02MiB sv
1/100 1.02MiB 1.02MiB 2/100<1 member qgroup>
2/100 1.02MiB 1.02MiB <0 member qgroups>
The existing fstests did not exercise two layer inheritance so this bug
was missed. I intend to add that testing there, as well.
Fixes:
|
||
|---|---|---|
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| io_uring | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| rust | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .clippy.toml | ||
| .cocciconfig | ||
| .editorconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| .pylintrc | ||
| .rustfmt.toml | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
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 reStructuredText 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.