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6140ba8a0a
The radix-tree has been superseded by the xarray (https://lwn.net/Articles/745073), this patch converts the btrfs_root::delayed_nodes, the APIs are used in a simple way. First idea is to do xa_insert() but this would require GFP_ATOMIC allocation which we want to avoid if possible. The preload mechanism of radix-tree can be emulated within the xarray API. - xa_reserve() with GFP_NOFS outside of the lock, the reserved entry is inserted atomically at most once - xa_store() under a lock, in case something races in we can detect that and xa_load() returns a valid pointer All uses of xa_load() must check for a valid pointer in case they manage to get between the xa_reserve() and xa_store(), this is handled in btrfs_get_delayed_node(). Otherwise the functionality is equivalent, xarray implements the radix-tree and there should be no performance difference. The patch continues the efforts started in253bf57555("btrfs: turn delayed_nodes_tree into an XArray") and fixes the problems with locking and GFP flags088aea3b97("Revert "btrfs: turn delayed_nodes_tree into an XArray""). Reviewed-by: Filipe Manana <fdmanana@suse.com> 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.