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Relocation COWs metadata blocks in two cases for the reloc root: - copying the subvolume root item when creating the reloc root - copying a btree node when there is a COW during relocation In both cases, the resulting btree node hits an abnormal code path with respect to the owner field in its btrfs_header. It first creates the root item for the new objectid, which populates the reloc root id, and it at this point that delayed refs are created. Later, it fully copies the old node into the new node (including the original owner field) which overwrites it. This results in a simple quotas mismatch where we run the delayed ref for the reloc root which has no simple quota effect (reloc root is not an fstree) but when we ultimately delete the node, the owner is the real original fstree and we do free the space. To work around this without tampering with the behavior of relocation, add a parameter to btrfs_add_tree_block that lets the relocation code path specify a different owning root than the "operating" root (in this case, owning root is the real root and the operating root is the reloc root). These can naturally be plumbed into delayed refs that have the same concept. Note that this is a double count in some sense, but a relatively natural one, as there are really two extents, and the old one will be deleted soon. This is consistent with how data relocation extents are accounted by simple quotas. Reviewed-by: Josef Bacik <josef@toxicpanda.com> 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.