xarray: Add definition of struct xarray

[mirror_ubuntu-kernels.git] / lib / xarray.c

// SPDX-License-Identifier: GPL-2.0+
/*
 * XArray implementation
 * Copyright (c) 2017 Microsoft Corporation
 * Author: Matthew Wilcox <willy@infradead.org>
 */

#include <linux/export.h>
#include <linux/xarray.h>

/*
 * Coding conventions in this file:
 *
 * @xa is used to refer to the entire xarray.
 * @xas is the 'xarray operation state'.  It may be either a pointer to
 * an xa_state, or an xa_state stored on the stack.  This is an unfortunate
 * ambiguity.
 * @index is the index of the entry being operated on
 * @mark is an xa_mark_t; a small number indicating one of the mark bits.
 * @node refers to an xa_node; usually the primary one being operated on by
 * this function.
 * @offset is the index into the slots array inside an xa_node.
 * @parent refers to the @xa_node closer to the head than @node.
 * @entry refers to something stored in a slot in the xarray
 */

/**
 * xa_init_flags() - Initialise an empty XArray with flags.
 * @xa: XArray.
 * @flags: XA_FLAG values.
 *
 * If you need to initialise an XArray with special flags (eg you need
 * to take the lock from interrupt context), use this function instead
 * of xa_init().
 *
 * Context: Any context.
 */
void xa_init_flags(struct xarray *xa, gfp_t flags)
{
	spin_lock_init(&xa->xa_lock);
	xa->xa_flags = flags;
	xa->xa_head = NULL;
}
EXPORT_SYMBOL(xa_init_flags);