diff --git a/include/linux/xarray.h b/include/linux/xarray.h
index 2dfc800..86eecbd 100644
--- a/include/linux/xarray.h
+++ b/include/linux/xarray.h
@@ -4,10 +4,498 @@
 /*
  * eXtensible Arrays
  * Copyright (c) 2017 Microsoft Corporation
- * Author: Matthew Wilcox <mawilcox@microsoft.com>
+ * Author: Matthew Wilcox <willy@infradead.org>
+ *
+ * See Documentation/core-api/xarray.rst for how to use the XArray.
  */
 
+#include <linux/bug.h>
+#include <linux/compiler.h>
+#include <linux/gfp.h>
+#include <linux/kconfig.h>
+#include <linux/kernel.h>
+#include <linux/rcupdate.h>
 #include <linux/spinlock.h>
+#include <linux/types.h>
+
+/*
+ * The bottom two bits of the entry determine how the XArray interprets
+ * the contents:
+ *
+ * 00: Pointer entry
+ * 10: Internal entry
+ * x1: Value entry or tagged pointer
+ *
+ * Attempting to store internal entries in the XArray is a bug.
+ *
+ * Most internal entries are pointers to the next node in the tree.
+ * The following internal entries have a special meaning:
+ *
+ * 0-62: Sibling entries
+ * 256: Zero entry
+ * 257: Retry entry
+ *
+ * Errors are also represented as internal entries, but use the negative
+ * space (-4094 to -2).  They're never stored in the slots array; only
+ * returned by the normal API.
+ */
+
+#define BITS_PER_XA_VALUE	(BITS_PER_LONG - 1)
+
+/**
+ * xa_mk_value() - Create an XArray entry from an integer.
+ * @v: Value to store in XArray.
+ *
+ * Context: Any context.
+ * Return: An entry suitable for storing in the XArray.
+ */
+static inline void *xa_mk_value(unsigned long v)
+{
+	WARN_ON((long)v < 0);
+	return (void *)((v << 1) | 1);
+}
+
+/**
+ * xa_to_value() - Get value stored in an XArray entry.
+ * @entry: XArray entry.
+ *
+ * Context: Any context.
+ * Return: The value stored in the XArray entry.
+ */
+static inline unsigned long xa_to_value(const void *entry)
+{
+	return (unsigned long)entry >> 1;
+}
+
+/**
+ * xa_is_value() - Determine if an entry is a value.
+ * @entry: XArray entry.
+ *
+ * Context: Any context.
+ * Return: True if the entry is a value, false if it is a pointer.
+ */
+static inline bool xa_is_value(const void *entry)
+{
+	return (unsigned long)entry & 1;
+}
+
+/**
+ * xa_tag_pointer() - Create an XArray entry for a tagged pointer.
+ * @p: Plain pointer.
+ * @tag: Tag value (0, 1 or 3).
+ *
+ * If the user of the XArray prefers, they can tag their pointers instead
+ * of storing value entries.  Three tags are available (0, 1 and 3).
+ * These are distinct from the xa_mark_t as they are not replicated up
+ * through the array and cannot be searched for.
+ *
+ * Context: Any context.
+ * Return: An XArray entry.
+ */
+static inline void *xa_tag_pointer(void *p, unsigned long tag)
+{
+	return (void *)((unsigned long)p | tag);
+}
+
+/**
+ * xa_untag_pointer() - Turn an XArray entry into a plain pointer.
+ * @entry: XArray entry.
+ *
+ * If you have stored a tagged pointer in the XArray, call this function
+ * to get the untagged version of the pointer.
+ *
+ * Context: Any context.
+ * Return: A pointer.
+ */
+static inline void *xa_untag_pointer(void *entry)
+{
+	return (void *)((unsigned long)entry & ~3UL);
+}
+
+/**
+ * xa_pointer_tag() - Get the tag stored in an XArray entry.
+ * @entry: XArray entry.
+ *
+ * If you have stored a tagged pointer in the XArray, call this function
+ * to get the tag of that pointer.
+ *
+ * Context: Any context.
+ * Return: A tag.
+ */
+static inline unsigned int xa_pointer_tag(void *entry)
+{
+	return (unsigned long)entry & 3UL;
+}
+
+/*
+ * xa_mk_internal() - Create an internal entry.
+ * @v: Value to turn into an internal entry.
+ *
+ * Internal entries are used for a number of purposes.  Entries 0-255 are
+ * used for sibling entries (only 0-62 are used by the current code).  256
+ * is used for the retry entry.  257 is used for the reserved / zero entry.
+ * Negative internal entries are used to represent errnos.  Node pointers
+ * are also tagged as internal entries in some situations.
+ *
+ * Context: Any context.
+ * Return: An XArray internal entry corresponding to this value.
+ */
+static inline void *xa_mk_internal(unsigned long v)
+{
+	return (void *)((v << 2) | 2);
+}
+
+/*
+ * xa_to_internal() - Extract the value from an internal entry.
+ * @entry: XArray entry.
+ *
+ * Context: Any context.
+ * Return: The value which was stored in the internal entry.
+ */
+static inline unsigned long xa_to_internal(const void *entry)
+{
+	return (unsigned long)entry >> 2;
+}
+
+/*
+ * xa_is_internal() - Is the entry an internal entry?
+ * @entry: XArray entry.
+ *
+ * Context: Any context.
+ * Return: %true if the entry is an internal entry.
+ */
+static inline bool xa_is_internal(const void *entry)
+{
+	return ((unsigned long)entry & 3) == 2;
+}
+
+#define XA_ZERO_ENTRY		xa_mk_internal(257)
+
+/**
+ * xa_is_zero() - Is the entry a zero entry?
+ * @entry: Entry retrieved from the XArray
+ *
+ * The normal API will return NULL as the contents of a slot containing
+ * a zero entry.  You can only see zero entries by using the advanced API.
+ *
+ * Return: %true if the entry is a zero entry.
+ */
+static inline bool xa_is_zero(const void *entry)
+{
+	return unlikely(entry == XA_ZERO_ENTRY);
+}
+
+/**
+ * xa_is_err() - Report whether an XArray operation returned an error
+ * @entry: Result from calling an XArray function
+ *
+ * If an XArray operation cannot complete an operation, it will return
+ * a special value indicating an error.  This function tells you
+ * whether an error occurred; xa_err() tells you which error occurred.
+ *
+ * Context: Any context.
+ * Return: %true if the entry indicates an error.
+ */
+static inline bool xa_is_err(const void *entry)
+{
+	return unlikely(xa_is_internal(entry) &&
+			entry >= xa_mk_internal(-MAX_ERRNO));
+}
+
+/**
+ * xa_err() - Turn an XArray result into an errno.
+ * @entry: Result from calling an XArray function.
+ *
+ * If an XArray operation cannot complete an operation, it will return
+ * a special pointer value which encodes an errno.  This function extracts
+ * the errno from the pointer value, or returns 0 if the pointer does not
+ * represent an errno.
+ *
+ * Context: Any context.
+ * Return: A negative errno or 0.
+ */
+static inline int xa_err(void *entry)
+{
+	/* xa_to_internal() would not do sign extension. */
+	if (xa_is_err(entry))
+		return (long)entry >> 2;
+	return 0;
+}
+
+/**
+ * struct xa_limit - Represents a range of IDs.
+ * @min: The lowest ID to allocate (inclusive).
+ * @max: The maximum ID to allocate (inclusive).
+ *
+ * This structure is used either directly or via the XA_LIMIT() macro
+ * to communicate the range of IDs that are valid for allocation.
+ * Two common ranges are predefined for you:
+ * * xa_limit_32b	- [0 - UINT_MAX]
+ * * xa_limit_31b	- [0 - INT_MAX]
+ */
+struct xa_limit {
+	u32 max;
+	u32 min;
+};
+
+#define XA_LIMIT(_min, _max) (struct xa_limit) { .min = _min, .max = _max }
+
+#define xa_limit_32b	XA_LIMIT(0, UINT_MAX)
+#define xa_limit_31b	XA_LIMIT(0, INT_MAX)
+
+typedef unsigned __bitwise xa_mark_t;
+#define XA_MARK_0		((__force xa_mark_t)0U)
+#define XA_MARK_1		((__force xa_mark_t)1U)
+#define XA_MARK_2		((__force xa_mark_t)2U)
+#define XA_PRESENT		((__force xa_mark_t)8U)
+#define XA_MARK_MAX		XA_MARK_2
+#define XA_FREE_MARK		XA_MARK_0
+
+enum xa_lock_type {
+	XA_LOCK_IRQ = 1,
+	XA_LOCK_BH = 2,
+};
+
+/*
+ * Values for xa_flags.  The radix tree stores its GFP flags in the xa_flags,
+ * and we remain compatible with that.
+ */
+#define XA_FLAGS_LOCK_IRQ	((__force gfp_t)XA_LOCK_IRQ)
+#define XA_FLAGS_LOCK_BH	((__force gfp_t)XA_LOCK_BH)
+#define XA_FLAGS_TRACK_FREE	((__force gfp_t)4U)
+#define XA_FLAGS_ZERO_BUSY	((__force gfp_t)8U)
+#define XA_FLAGS_ALLOC_WRAPPED	((__force gfp_t)16U)
+#define XA_FLAGS_ACCOUNT	((__force gfp_t)32U)
+#define XA_FLAGS_MARK(mark)	((__force gfp_t)((1U << __GFP_BITS_SHIFT) << \
+						(__force unsigned)(mark)))
+
+/* ALLOC is for a normal 0-based alloc.  ALLOC1 is for an 1-based alloc */
+#define XA_FLAGS_ALLOC	(XA_FLAGS_TRACK_FREE | XA_FLAGS_MARK(XA_FREE_MARK))
+#define XA_FLAGS_ALLOC1	(XA_FLAGS_TRACK_FREE | XA_FLAGS_ZERO_BUSY)
+
+/**
+ * struct xarray - The anchor of the XArray.
+ * @xa_lock: Lock that protects the contents of the XArray.
+ *
+ * To use the xarray, define it statically or embed it in your data structure.
+ * It is a very small data structure, so it does not usually make sense to
+ * allocate it separately and keep a pointer to it in your data structure.
+ *
+ * You may use the xa_lock to protect your own data structures as well.
+ */
+/*
+ * If all of the entries in the array are NULL, @xa_head is a NULL pointer.
+ * If the only non-NULL entry in the array is at index 0, @xa_head is that
+ * entry.  If any other entry in the array is non-NULL, @xa_head points
+ * to an @xa_node.
+ */
+struct xarray {
+	spinlock_t	xa_lock;
+/* private: The rest of the data structure is not to be used directly. */
+	gfp_t		xa_flags;
+	void __rcu *	xa_head;
+};
+
+#define XARRAY_INIT(name, flags) {				\
+	.xa_lock = __SPIN_LOCK_UNLOCKED(name.xa_lock),		\
+	.xa_flags = flags,					\
+	.xa_head = NULL,					\
+}
+
+/**
+ * DEFINE_XARRAY_FLAGS() - Define an XArray with custom flags.
+ * @name: A string that names your XArray.
+ * @flags: XA_FLAG values.
+ *
+ * This is intended for file scope definitions of XArrays.  It declares
+ * and initialises an empty XArray with the chosen name and flags.  It is
+ * equivalent to calling xa_init_flags() on the array, but it does the
+ * initialisation at compiletime instead of runtime.
+ */
+#define DEFINE_XARRAY_FLAGS(name, flags)				\
+	struct xarray name = XARRAY_INIT(name, flags)
+
+/**
+ * DEFINE_XARRAY() - Define an XArray.
+ * @name: A string that names your XArray.
+ *
+ * This is intended for file scope definitions of XArrays.  It declares
+ * and initialises an empty XArray with the chosen name.  It is equivalent
+ * to calling xa_init() on the array, but it does the initialisation at
+ * compiletime instead of runtime.
+ */
+#define DEFINE_XARRAY(name) DEFINE_XARRAY_FLAGS(name, 0)
+
+/**
+ * DEFINE_XARRAY_ALLOC() - Define an XArray which allocates IDs starting at 0.
+ * @name: A string that names your XArray.
+ *
+ * This is intended for file scope definitions of allocating XArrays.
+ * See also DEFINE_XARRAY().
+ */
+#define DEFINE_XARRAY_ALLOC(name) DEFINE_XARRAY_FLAGS(name, XA_FLAGS_ALLOC)
+
+/**
+ * DEFINE_XARRAY_ALLOC1() - Define an XArray which allocates IDs starting at 1.
+ * @name: A string that names your XArray.
+ *
+ * This is intended for file scope definitions of allocating XArrays.
+ * See also DEFINE_XARRAY().
+ */
+#define DEFINE_XARRAY_ALLOC1(name) DEFINE_XARRAY_FLAGS(name, XA_FLAGS_ALLOC1)
+
+void *xa_load(struct xarray *, unsigned long index);
+void *xa_store(struct xarray *, unsigned long index, void *entry, gfp_t);
+void *xa_erase(struct xarray *, unsigned long index);
+void *xa_store_range(struct xarray *, unsigned long first, unsigned long last,
+			void *entry, gfp_t);
+bool xa_get_mark(struct xarray *, unsigned long index, xa_mark_t);
+void xa_set_mark(struct xarray *, unsigned long index, xa_mark_t);
+void xa_clear_mark(struct xarray *, unsigned long index, xa_mark_t);
+void *xa_find(struct xarray *xa, unsigned long *index,
+		unsigned long max, xa_mark_t) __attribute__((nonnull(2)));
+void *xa_find_after(struct xarray *xa, unsigned long *index,
+		unsigned long max, xa_mark_t) __attribute__((nonnull(2)));
+unsigned int xa_extract(struct xarray *, void **dst, unsigned long start,
+		unsigned long max, unsigned int n, xa_mark_t);
+void xa_destroy(struct 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.
+ */
+static inline void xa_init_flags(struct xarray *xa, gfp_t flags)
+{
+	spin_lock_init(&xa->xa_lock);
+	xa->xa_flags = flags;
+	xa->xa_head = NULL;
+}
+
+/**
+ * xa_init() - Initialise an empty XArray.
+ * @xa: XArray.
+ *
+ * An empty XArray is full of NULL entries.
+ *
+ * Context: Any context.
+ */
+static inline void xa_init(struct xarray *xa)
+{
+	xa_init_flags(xa, 0);
+}
+
+/**
+ * xa_empty() - Determine if an array has any present entries.
+ * @xa: XArray.
+ *
+ * Context: Any context.
+ * Return: %true if the array contains only NULL pointers.
+ */
+static inline bool xa_empty(const struct xarray *xa)
+{
+	return xa->xa_head == NULL;
+}
+
+/**
+ * xa_marked() - Inquire whether any entry in this array has a mark set
+ * @xa: Array
+ * @mark: Mark value
+ *
+ * Context: Any context.
+ * Return: %true if any entry has this mark set.
+ */
+static inline bool xa_marked(const struct xarray *xa, xa_mark_t mark)
+{
+	return xa->xa_flags & XA_FLAGS_MARK(mark);
+}
+
+/**
+ * xa_for_each_start() - Iterate over a portion of an XArray.
+ * @xa: XArray.
+ * @index: Index of @entry.
+ * @entry: Entry retrieved from array.
+ * @start: First index to retrieve from array.
+ *
+ * During the iteration, @entry will have the value of the entry stored
+ * in @xa at @index.  You may modify @index during the iteration if you
+ * want to skip or reprocess indices.  It is safe to modify the array
+ * during the iteration.  At the end of the iteration, @entry will be set
+ * to NULL and @index will have a value less than or equal to max.
+ *
+ * xa_for_each_start() is O(n.log(n)) while xas_for_each() is O(n).  You have
+ * to handle your own locking with xas_for_each(), and if you have to unlock
+ * after each iteration, it will also end up being O(n.log(n)).
+ * xa_for_each_start() will spin if it hits a retry entry; if you intend to
+ * see retry entries, you should use the xas_for_each() iterator instead.
+ * The xas_for_each() iterator will expand into more inline code than
+ * xa_for_each_start().
+ *
+ * Context: Any context.  Takes and releases the RCU lock.
+ */
+#define xa_for_each_start(xa, index, entry, start)			\
+	for (index = start,						\
+	     entry = xa_find(xa, &index, ULONG_MAX, XA_PRESENT);	\
+	     entry;							\
+	     entry = xa_find_after(xa, &index, ULONG_MAX, XA_PRESENT))
+
+/**
+ * xa_for_each() - Iterate over present entries in an XArray.
+ * @xa: XArray.
+ * @index: Index of @entry.
+ * @entry: Entry retrieved from array.
+ *
+ * During the iteration, @entry will have the value of the entry stored
+ * in @xa at @index.  You may modify @index during the iteration if you want
+ * to skip or reprocess indices.  It is safe to modify the array during the
+ * iteration.  At the end of the iteration, @entry will be set to NULL and
+ * @index will have a value less than or equal to max.
+ *
+ * xa_for_each() is O(n.log(n)) while xas_for_each() is O(n).  You have
+ * to handle your own locking with xas_for_each(), and if you have to unlock
+ * after each iteration, it will also end up being O(n.log(n)).  xa_for_each()
+ * will spin if it hits a retry entry; if you intend to see retry entries,
+ * you should use the xas_for_each() iterator instead.  The xas_for_each()
+ * iterator will expand into more inline code than xa_for_each().
+ *
+ * Context: Any context.  Takes and releases the RCU lock.
+ */
+#define xa_for_each(xa, index, entry) \
+	xa_for_each_start(xa, index, entry, 0)
+
+/**
+ * xa_for_each_marked() - Iterate over marked entries in an XArray.
+ * @xa: XArray.
+ * @index: Index of @entry.
+ * @entry: Entry retrieved from array.
+ * @filter: Selection criterion.
+ *
+ * During the iteration, @entry will have the value of the entry stored
+ * in @xa at @index.  The iteration will skip all entries in the array
+ * which do not match @filter.  You may modify @index during the iteration
+ * if you want to skip or reprocess indices.  It is safe to modify the array
+ * during the iteration.  At the end of the iteration, @entry will be set to
+ * NULL and @index will have a value less than or equal to max.
+ *
+ * xa_for_each_marked() is O(n.log(n)) while xas_for_each_marked() is O(n).
+ * You have to handle your own locking with xas_for_each(), and if you have
+ * to unlock after each iteration, it will also end up being O(n.log(n)).
+ * xa_for_each_marked() will spin if it hits a retry entry; if you intend to
+ * see retry entries, you should use the xas_for_each_marked() iterator
+ * instead.  The xas_for_each_marked() iterator will expand into more inline
+ * code than xa_for_each_marked().
+ *
+ * Context: Any context.  Takes and releases the RCU lock.
+ */
+#define xa_for_each_marked(xa, index, entry, filter) \
+	for (index = 0, entry = xa_find(xa, &index, ULONG_MAX, filter); \
+	     entry; entry = xa_find_after(xa, &index, ULONG_MAX, filter))
 
 #define xa_trylock(xa)		spin_trylock(&(xa)->xa_lock)
 #define xa_lock(xa)		spin_lock(&(xa)->xa_lock)
@@ -21,4 +509,1242 @@
 #define xa_unlock_irqrestore(xa, flags) \
 				spin_unlock_irqrestore(&(xa)->xa_lock, flags)
 
+/*
+ * Versions of the normal API which require the caller to hold the
+ * xa_lock.  If the GFP flags allow it, they will drop the lock to
+ * allocate memory, then reacquire it afterwards.  These functions
+ * may also re-enable interrupts if the XArray flags indicate the
+ * locking should be interrupt safe.
+ */
+void *__xa_erase(struct xarray *, unsigned long index);
+void *__xa_store(struct xarray *, unsigned long index, void *entry, gfp_t);
+void *__xa_cmpxchg(struct xarray *, unsigned long index, void *old,
+		void *entry, gfp_t);
+int __must_check __xa_insert(struct xarray *, unsigned long index,
+		void *entry, gfp_t);
+int __must_check __xa_alloc(struct xarray *, u32 *id, void *entry,
+		struct xa_limit, gfp_t);
+int __must_check __xa_alloc_cyclic(struct xarray *, u32 *id, void *entry,
+		struct xa_limit, u32 *next, gfp_t);
+void __xa_set_mark(struct xarray *, unsigned long index, xa_mark_t);
+void __xa_clear_mark(struct xarray *, unsigned long index, xa_mark_t);
+
+/**
+ * xa_store_bh() - Store this entry in the XArray.
+ * @xa: XArray.
+ * @index: Index into array.
+ * @entry: New entry.
+ * @gfp: Memory allocation flags.
+ *
+ * This function is like calling xa_store() except it disables softirqs
+ * while holding the array lock.
+ *
+ * Context: Any context.  Takes and releases the xa_lock while
+ * disabling softirqs.
+ * Return: The entry which used to be at this index.
+ */
+static inline void *xa_store_bh(struct xarray *xa, unsigned long index,
+		void *entry, gfp_t gfp)
+{
+	void *curr;
+
+	xa_lock_bh(xa);
+	curr = __xa_store(xa, index, entry, gfp);
+	xa_unlock_bh(xa);
+
+	return curr;
+}
+
+/**
+ * xa_store_irq() - Store this entry in the XArray.
+ * @xa: XArray.
+ * @index: Index into array.
+ * @entry: New entry.
+ * @gfp: Memory allocation flags.
+ *
+ * This function is like calling xa_store() except it disables interrupts
+ * while holding the array lock.
+ *
+ * Context: Process context.  Takes and releases the xa_lock while
+ * disabling interrupts.
+ * Return: The entry which used to be at this index.
+ */
+static inline void *xa_store_irq(struct xarray *xa, unsigned long index,
+		void *entry, gfp_t gfp)
+{
+	void *curr;
+
+	xa_lock_irq(xa);
+	curr = __xa_store(xa, index, entry, gfp);
+	xa_unlock_irq(xa);
+
+	return curr;
+}
+
+/**
+ * xa_erase_bh() - Erase this entry from the XArray.
+ * @xa: XArray.
+ * @index: Index of entry.
+ *
+ * After this function returns, loading from @index will return %NULL.
+ * If the index is part of a multi-index entry, all indices will be erased
+ * and none of the entries will be part of a multi-index entry.
+ *
+ * Context: Any context.  Takes and releases the xa_lock while
+ * disabling softirqs.
+ * Return: The entry which used to be at this index.
+ */
+static inline void *xa_erase_bh(struct xarray *xa, unsigned long index)
+{
+	void *entry;
+
+	xa_lock_bh(xa);
+	entry = __xa_erase(xa, index);
+	xa_unlock_bh(xa);
+
+	return entry;
+}
+
+/**
+ * xa_erase_irq() - Erase this entry from the XArray.
+ * @xa: XArray.
+ * @index: Index of entry.
+ *
+ * After this function returns, loading from @index will return %NULL.
+ * If the index is part of a multi-index entry, all indices will be erased
+ * and none of the entries will be part of a multi-index entry.
+ *
+ * Context: Process context.  Takes and releases the xa_lock while
+ * disabling interrupts.
+ * Return: The entry which used to be at this index.
+ */
+static inline void *xa_erase_irq(struct xarray *xa, unsigned long index)
+{
+	void *entry;
+
+	xa_lock_irq(xa);
+	entry = __xa_erase(xa, index);
+	xa_unlock_irq(xa);
+
+	return entry;
+}
+
+/**
+ * xa_cmpxchg() - Conditionally replace an entry in the XArray.
+ * @xa: XArray.
+ * @index: Index into array.
+ * @old: Old value to test against.
+ * @entry: New value to place in array.
+ * @gfp: Memory allocation flags.
+ *
+ * If the entry at @index is the same as @old, replace it with @entry.
+ * If the return value is equal to @old, then the exchange was successful.
+ *
+ * Context: Any context.  Takes and releases the xa_lock.  May sleep
+ * if the @gfp flags permit.
+ * Return: The old value at this index or xa_err() if an error happened.
+ */
+static inline void *xa_cmpxchg(struct xarray *xa, unsigned long index,
+			void *old, void *entry, gfp_t gfp)
+{
+	void *curr;
+
+	xa_lock(xa);
+	curr = __xa_cmpxchg(xa, index, old, entry, gfp);
+	xa_unlock(xa);
+
+	return curr;
+}
+
+/**
+ * xa_cmpxchg_bh() - Conditionally replace an entry in the XArray.
+ * @xa: XArray.
+ * @index: Index into array.
+ * @old: Old value to test against.
+ * @entry: New value to place in array.
+ * @gfp: Memory allocation flags.
+ *
+ * This function is like calling xa_cmpxchg() except it disables softirqs
+ * while holding the array lock.
+ *
+ * Context: Any context.  Takes and releases the xa_lock while
+ * disabling softirqs.  May sleep if the @gfp flags permit.
+ * Return: The old value at this index or xa_err() if an error happened.
+ */
+static inline void *xa_cmpxchg_bh(struct xarray *xa, unsigned long index,
+			void *old, void *entry, gfp_t gfp)
+{
+	void *curr;
+
+	xa_lock_bh(xa);
+	curr = __xa_cmpxchg(xa, index, old, entry, gfp);
+	xa_unlock_bh(xa);
+
+	return curr;
+}
+
+/**
+ * xa_cmpxchg_irq() - Conditionally replace an entry in the XArray.
+ * @xa: XArray.
+ * @index: Index into array.
+ * @old: Old value to test against.
+ * @entry: New value to place in array.
+ * @gfp: Memory allocation flags.
+ *
+ * This function is like calling xa_cmpxchg() except it disables interrupts
+ * while holding the array lock.
+ *
+ * Context: Process context.  Takes and releases the xa_lock while
+ * disabling interrupts.  May sleep if the @gfp flags permit.
+ * Return: The old value at this index or xa_err() if an error happened.
+ */
+static inline void *xa_cmpxchg_irq(struct xarray *xa, unsigned long index,
+			void *old, void *entry, gfp_t gfp)
+{
+	void *curr;
+
+	xa_lock_irq(xa);
+	curr = __xa_cmpxchg(xa, index, old, entry, gfp);
+	xa_unlock_irq(xa);
+
+	return curr;
+}
+
+/**
+ * xa_insert() - Store this entry in the XArray unless another entry is
+ *			already present.
+ * @xa: XArray.
+ * @index: Index into array.
+ * @entry: New entry.
+ * @gfp: Memory allocation flags.
+ *
+ * Inserting a NULL entry will store a reserved entry (like xa_reserve())
+ * if no entry is present.  Inserting will fail if a reserved entry is
+ * present, even though loading from this index will return NULL.
+ *
+ * Context: Any context.  Takes and releases the xa_lock.  May sleep if
+ * the @gfp flags permit.
+ * Return: 0 if the store succeeded.  -EBUSY if another entry was present.
+ * -ENOMEM if memory could not be allocated.
+ */
+static inline int __must_check xa_insert(struct xarray *xa,
+		unsigned long index, void *entry, gfp_t gfp)
+{
+	int err;
+
+	xa_lock(xa);
+	err = __xa_insert(xa, index, entry, gfp);
+	xa_unlock(xa);
+
+	return err;
+}
+
+/**
+ * xa_insert_bh() - Store this entry in the XArray unless another entry is
+ *			already present.
+ * @xa: XArray.
+ * @index: Index into array.
+ * @entry: New entry.
+ * @gfp: Memory allocation flags.
+ *
+ * Inserting a NULL entry will store a reserved entry (like xa_reserve())
+ * if no entry is present.  Inserting will fail if a reserved entry is
+ * present, even though loading from this index will return NULL.
+ *
+ * Context: Any context.  Takes and releases the xa_lock while
+ * disabling softirqs.  May sleep if the @gfp flags permit.
+ * Return: 0 if the store succeeded.  -EBUSY if another entry was present.
+ * -ENOMEM if memory could not be allocated.
+ */
+static inline int __must_check xa_insert_bh(struct xarray *xa,
+		unsigned long index, void *entry, gfp_t gfp)
+{
+	int err;
+
+	xa_lock_bh(xa);
+	err = __xa_insert(xa, index, entry, gfp);
+	xa_unlock_bh(xa);
+
+	return err;
+}
+
+/**
+ * xa_insert_irq() - Store this entry in the XArray unless another entry is
+ *			already present.
+ * @xa: XArray.
+ * @index: Index into array.
+ * @entry: New entry.
+ * @gfp: Memory allocation flags.
+ *
+ * Inserting a NULL entry will store a reserved entry (like xa_reserve())
+ * if no entry is present.  Inserting will fail if a reserved entry is
+ * present, even though loading from this index will return NULL.
+ *
+ * Context: Process context.  Takes and releases the xa_lock while
+ * disabling interrupts.  May sleep if the @gfp flags permit.
+ * Return: 0 if the store succeeded.  -EBUSY if another entry was present.
+ * -ENOMEM if memory could not be allocated.
+ */
+static inline int __must_check xa_insert_irq(struct xarray *xa,
+		unsigned long index, void *entry, gfp_t gfp)
+{
+	int err;
+
+	xa_lock_irq(xa);
+	err = __xa_insert(xa, index, entry, gfp);
+	xa_unlock_irq(xa);
+
+	return err;
+}
+
+/**
+ * xa_alloc() - Find somewhere to store this entry in the XArray.
+ * @xa: XArray.
+ * @id: Pointer to ID.
+ * @entry: New entry.
+ * @limit: Range of ID to allocate.
+ * @gfp: Memory allocation flags.
+ *
+ * Finds an empty entry in @xa between @limit.min and @limit.max,
+ * stores the index into the @id pointer, then stores the entry at
+ * that index.  A concurrent lookup will not see an uninitialised @id.
+ *
+ * Context: Any context.  Takes and releases the xa_lock.  May sleep if
+ * the @gfp flags permit.
+ * Return: 0 on success, -ENOMEM if memory could not be allocated or
+ * -EBUSY if there are no free entries in @limit.
+ */
+static inline __must_check int xa_alloc(struct xarray *xa, u32 *id,
+		void *entry, struct xa_limit limit, gfp_t gfp)
+{
+	int err;
+
+	xa_lock(xa);
+	err = __xa_alloc(xa, id, entry, limit, gfp);
+	xa_unlock(xa);
+
+	return err;
+}
+
+/**
+ * xa_alloc_bh() - Find somewhere to store this entry in the XArray.
+ * @xa: XArray.
+ * @id: Pointer to ID.
+ * @entry: New entry.
+ * @limit: Range of ID to allocate.
+ * @gfp: Memory allocation flags.
+ *
+ * Finds an empty entry in @xa between @limit.min and @limit.max,
+ * stores the index into the @id pointer, then stores the entry at
+ * that index.  A concurrent lookup will not see an uninitialised @id.
+ *
+ * Context: Any context.  Takes and releases the xa_lock while
+ * disabling softirqs.  May sleep if the @gfp flags permit.
+ * Return: 0 on success, -ENOMEM if memory could not be allocated or
+ * -EBUSY if there are no free entries in @limit.
+ */
+static inline int __must_check xa_alloc_bh(struct xarray *xa, u32 *id,
+		void *entry, struct xa_limit limit, gfp_t gfp)
+{
+	int err;
+
+	xa_lock_bh(xa);
+	err = __xa_alloc(xa, id, entry, limit, gfp);
+	xa_unlock_bh(xa);
+
+	return err;
+}
+
+/**
+ * xa_alloc_irq() - Find somewhere to store this entry in the XArray.
+ * @xa: XArray.
+ * @id: Pointer to ID.
+ * @entry: New entry.
+ * @limit: Range of ID to allocate.
+ * @gfp: Memory allocation flags.
+ *
+ * Finds an empty entry in @xa between @limit.min and @limit.max,
+ * stores the index into the @id pointer, then stores the entry at
+ * that index.  A concurrent lookup will not see an uninitialised @id.
+ *
+ * Context: Process context.  Takes and releases the xa_lock while
+ * disabling interrupts.  May sleep if the @gfp flags permit.
+ * Return: 0 on success, -ENOMEM if memory could not be allocated or
+ * -EBUSY if there are no free entries in @limit.
+ */
+static inline int __must_check xa_alloc_irq(struct xarray *xa, u32 *id,
+		void *entry, struct xa_limit limit, gfp_t gfp)
+{
+	int err;
+
+	xa_lock_irq(xa);
+	err = __xa_alloc(xa, id, entry, limit, gfp);
+	xa_unlock_irq(xa);
+
+	return err;
+}
+
+/**
+ * xa_alloc_cyclic() - Find somewhere to store this entry in the XArray.
+ * @xa: XArray.
+ * @id: Pointer to ID.
+ * @entry: New entry.
+ * @limit: Range of allocated ID.
+ * @next: Pointer to next ID to allocate.
+ * @gfp: Memory allocation flags.
+ *
+ * Finds an empty entry in @xa between @limit.min and @limit.max,
+ * stores the index into the @id pointer, then stores the entry at
+ * that index.  A concurrent lookup will not see an uninitialised @id.
+ * The search for an empty entry will start at @next and will wrap
+ * around if necessary.
+ *
+ * Context: Any context.  Takes and releases the xa_lock.  May sleep if
+ * the @gfp flags permit.
+ * Return: 0 if the allocation succeeded without wrapping.  1 if the
+ * allocation succeeded after wrapping, -ENOMEM if memory could not be
+ * allocated or -EBUSY if there are no free entries in @limit.
+ */
+static inline int xa_alloc_cyclic(struct xarray *xa, u32 *id, void *entry,
+		struct xa_limit limit, u32 *next, gfp_t gfp)
+{
+	int err;
+
+	xa_lock(xa);
+	err = __xa_alloc_cyclic(xa, id, entry, limit, next, gfp);
+	xa_unlock(xa);
+
+	return err;
+}
+
+/**
+ * xa_alloc_cyclic_bh() - Find somewhere to store this entry in the XArray.
+ * @xa: XArray.
+ * @id: Pointer to ID.
+ * @entry: New entry.
+ * @limit: Range of allocated ID.
+ * @next: Pointer to next ID to allocate.
+ * @gfp: Memory allocation flags.
+ *
+ * Finds an empty entry in @xa between @limit.min and @limit.max,
+ * stores the index into the @id pointer, then stores the entry at
+ * that index.  A concurrent lookup will not see an uninitialised @id.
+ * The search for an empty entry will start at @next and will wrap
+ * around if necessary.
+ *
+ * Context: Any context.  Takes and releases the xa_lock while
+ * disabling softirqs.  May sleep if the @gfp flags permit.
+ * Return: 0 if the allocation succeeded without wrapping.  1 if the
+ * allocation succeeded after wrapping, -ENOMEM if memory could not be
+ * allocated or -EBUSY if there are no free entries in @limit.
+ */
+static inline int xa_alloc_cyclic_bh(struct xarray *xa, u32 *id, void *entry,
+		struct xa_limit limit, u32 *next, gfp_t gfp)
+{
+	int err;
+
+	xa_lock_bh(xa);
+	err = __xa_alloc_cyclic(xa, id, entry, limit, next, gfp);
+	xa_unlock_bh(xa);
+
+	return err;
+}
+
+/**
+ * xa_alloc_cyclic_irq() - Find somewhere to store this entry in the XArray.
+ * @xa: XArray.
+ * @id: Pointer to ID.
+ * @entry: New entry.
+ * @limit: Range of allocated ID.
+ * @next: Pointer to next ID to allocate.
+ * @gfp: Memory allocation flags.
+ *
+ * Finds an empty entry in @xa between @limit.min and @limit.max,
+ * stores the index into the @id pointer, then stores the entry at
+ * that index.  A concurrent lookup will not see an uninitialised @id.
+ * The search for an empty entry will start at @next and will wrap
+ * around if necessary.
+ *
+ * Context: Process context.  Takes and releases the xa_lock while
+ * disabling interrupts.  May sleep if the @gfp flags permit.
+ * Return: 0 if the allocation succeeded without wrapping.  1 if the
+ * allocation succeeded after wrapping, -ENOMEM if memory could not be
+ * allocated or -EBUSY if there are no free entries in @limit.
+ */
+static inline int xa_alloc_cyclic_irq(struct xarray *xa, u32 *id, void *entry,
+		struct xa_limit limit, u32 *next, gfp_t gfp)
+{
+	int err;
+
+	xa_lock_irq(xa);
+	err = __xa_alloc_cyclic(xa, id, entry, limit, next, gfp);
+	xa_unlock_irq(xa);
+
+	return err;
+}
+
+/**
+ * xa_reserve() - Reserve this index in the XArray.
+ * @xa: XArray.
+ * @index: Index into array.
+ * @gfp: Memory allocation flags.
+ *
+ * Ensures there is somewhere to store an entry at @index in the array.
+ * If there is already something stored at @index, this function does
+ * nothing.  If there was nothing there, the entry is marked as reserved.
+ * Loading from a reserved entry returns a %NULL pointer.
+ *
+ * If you do not use the entry that you have reserved, call xa_release()
+ * or xa_erase() to free any unnecessary memory.
+ *
+ * Context: Any context.  Takes and releases the xa_lock.
+ * May sleep if the @gfp flags permit.
+ * Return: 0 if the reservation succeeded or -ENOMEM if it failed.
+ */
+static inline __must_check
+int xa_reserve(struct xarray *xa, unsigned long index, gfp_t gfp)
+{
+	return xa_err(xa_cmpxchg(xa, index, NULL, XA_ZERO_ENTRY, gfp));
+}
+
+/**
+ * xa_reserve_bh() - Reserve this index in the XArray.
+ * @xa: XArray.
+ * @index: Index into array.
+ * @gfp: Memory allocation flags.
+ *
+ * A softirq-disabling version of xa_reserve().
+ *
+ * Context: Any context.  Takes and releases the xa_lock while
+ * disabling softirqs.
+ * Return: 0 if the reservation succeeded or -ENOMEM if it failed.
+ */
+static inline __must_check
+int xa_reserve_bh(struct xarray *xa, unsigned long index, gfp_t gfp)
+{
+	return xa_err(xa_cmpxchg_bh(xa, index, NULL, XA_ZERO_ENTRY, gfp));
+}
+
+/**
+ * xa_reserve_irq() - Reserve this index in the XArray.
+ * @xa: XArray.
+ * @index: Index into array.
+ * @gfp: Memory allocation flags.
+ *
+ * An interrupt-disabling version of xa_reserve().
+ *
+ * Context: Process context.  Takes and releases the xa_lock while
+ * disabling interrupts.
+ * Return: 0 if the reservation succeeded or -ENOMEM if it failed.
+ */
+static inline __must_check
+int xa_reserve_irq(struct xarray *xa, unsigned long index, gfp_t gfp)
+{
+	return xa_err(xa_cmpxchg_irq(xa, index, NULL, XA_ZERO_ENTRY, gfp));
+}
+
+/**
+ * xa_release() - Release a reserved entry.
+ * @xa: XArray.
+ * @index: Index of entry.
+ *
+ * After calling xa_reserve(), you can call this function to release the
+ * reservation.  If the entry at @index has been stored to, this function
+ * will do nothing.
+ */
+static inline void xa_release(struct xarray *xa, unsigned long index)
+{
+	xa_cmpxchg(xa, index, XA_ZERO_ENTRY, NULL, 0);
+}
+
+/* Everything below here is the Advanced API.  Proceed with caution. */
+
+/*
+ * The xarray is constructed out of a set of 'chunks' of pointers.  Choosing
+ * the best chunk size requires some tradeoffs.  A power of two recommends
+ * itself so that we can walk the tree based purely on shifts and masks.
+ * Generally, the larger the better; as the number of slots per level of the
+ * tree increases, the less tall the tree needs to be.  But that needs to be
+ * balanced against the memory consumption of each node.  On a 64-bit system,
+ * xa_node is currently 576 bytes, and we get 7 of them per 4kB page.  If we
+ * doubled the number of slots per node, we'd get only 3 nodes per 4kB page.
+ */
+#ifndef XA_CHUNK_SHIFT
+#define XA_CHUNK_SHIFT		(CONFIG_BASE_SMALL ? 4 : 6)
+#endif
+#define XA_CHUNK_SIZE		(1UL << XA_CHUNK_SHIFT)
+#define XA_CHUNK_MASK		(XA_CHUNK_SIZE - 1)
+#define XA_MAX_MARKS		3
+#define XA_MARK_LONGS		DIV_ROUND_UP(XA_CHUNK_SIZE, BITS_PER_LONG)
+
+/*
+ * @count is the count of every non-NULL element in the ->slots array
+ * whether that is a value entry, a retry entry, a user pointer,
+ * a sibling entry or a pointer to the next level of the tree.
+ * @nr_values is the count of every element in ->slots which is
+ * either a value entry or a sibling of a value entry.
+ */
+struct xa_node {
+	unsigned char	shift;		/* Bits remaining in each slot */
+	unsigned char	offset;		/* Slot offset in parent */
+	unsigned char	count;		/* Total entry count */
+	unsigned char	nr_values;	/* Value entry count */
+	struct xa_node __rcu *parent;	/* NULL at top of tree */
+	struct xarray	*array;		/* The array we belong to */
+	union {
+		struct list_head private_list;	/* For tree user */
+		struct rcu_head	rcu_head;	/* Used when freeing node */
+	};
+	void __rcu	*slots[XA_CHUNK_SIZE];
+	union {
+		unsigned long	tags[XA_MAX_MARKS][XA_MARK_LONGS];
+		unsigned long	marks[XA_MAX_MARKS][XA_MARK_LONGS];
+	};
+};
+
+void xa_dump(const struct xarray *);
+void xa_dump_node(const struct xa_node *);
+
+#ifdef XA_DEBUG
+#define XA_BUG_ON(xa, x) do {					\
+		if (x) {					\
+			xa_dump(xa);				\
+			BUG();					\
+		}						\
+	} while (0)
+#define XA_NODE_BUG_ON(node, x) do {				\
+		if (x) {					\
+			if (node) xa_dump_node(node);		\
+			BUG();					\
+		}						\
+	} while (0)
+#else
+#define XA_BUG_ON(xa, x)	do { } while (0)
+#define XA_NODE_BUG_ON(node, x)	do { } while (0)
+#endif
+
+/* Private */
+static inline void *xa_head(const struct xarray *xa)
+{
+	return rcu_dereference_check(xa->xa_head,
+						lockdep_is_held(&xa->xa_lock));
+}
+
+/* Private */
+static inline void *xa_head_locked(const struct xarray *xa)
+{
+	return rcu_dereference_protected(xa->xa_head,
+						lockdep_is_held(&xa->xa_lock));
+}
+
+/* Private */
+static inline void *xa_entry(const struct xarray *xa,
+				const struct xa_node *node, unsigned int offset)
+{
+	XA_NODE_BUG_ON(node, offset >= XA_CHUNK_SIZE);
+	return rcu_dereference_check(node->slots[offset],
+						lockdep_is_held(&xa->xa_lock));
+}
+
+/* Private */
+static inline void *xa_entry_locked(const struct xarray *xa,
+				const struct xa_node *node, unsigned int offset)
+{
+	XA_NODE_BUG_ON(node, offset >= XA_CHUNK_SIZE);
+	return rcu_dereference_protected(node->slots[offset],
+						lockdep_is_held(&xa->xa_lock));
+}
+
+/* Private */
+static inline struct xa_node *xa_parent(const struct xarray *xa,
+					const struct xa_node *node)
+{
+	return rcu_dereference_check(node->parent,
+						lockdep_is_held(&xa->xa_lock));
+}
+
+/* Private */
+static inline struct xa_node *xa_parent_locked(const struct xarray *xa,
+					const struct xa_node *node)
+{
+	return rcu_dereference_protected(node->parent,
+						lockdep_is_held(&xa->xa_lock));
+}
+
+/* Private */
+static inline void *xa_mk_node(const struct xa_node *node)
+{
+	return (void *)((unsigned long)node | 2);
+}
+
+/* Private */
+static inline struct xa_node *xa_to_node(const void *entry)
+{
+	return (struct xa_node *)((unsigned long)entry - 2);
+}
+
+/* Private */
+static inline bool xa_is_node(const void *entry)
+{
+	return xa_is_internal(entry) && (unsigned long)entry > 4096;
+}
+
+/* Private */
+static inline void *xa_mk_sibling(unsigned int offset)
+{
+	return xa_mk_internal(offset);
+}
+
+/* Private */
+static inline unsigned long xa_to_sibling(const void *entry)
+{
+	return xa_to_internal(entry);
+}
+
+/**
+ * xa_is_sibling() - Is the entry a sibling entry?
+ * @entry: Entry retrieved from the XArray
+ *
+ * Return: %true if the entry is a sibling entry.
+ */
+static inline bool xa_is_sibling(const void *entry)
+{
+	return IS_ENABLED(CONFIG_XARRAY_MULTI) && xa_is_internal(entry) &&
+		(entry < xa_mk_sibling(XA_CHUNK_SIZE - 1));
+}
+
+#define XA_RETRY_ENTRY		xa_mk_internal(256)
+
+/**
+ * xa_is_retry() - Is the entry a retry entry?
+ * @entry: Entry retrieved from the XArray
+ *
+ * Return: %true if the entry is a retry entry.
+ */
+static inline bool xa_is_retry(const void *entry)
+{
+	return unlikely(entry == XA_RETRY_ENTRY);
+}
+
+/**
+ * xa_is_advanced() - Is the entry only permitted for the advanced API?
+ * @entry: Entry to be stored in the XArray.
+ *
+ * Return: %true if the entry cannot be stored by the normal API.
+ */
+static inline bool xa_is_advanced(const void *entry)
+{
+	return xa_is_internal(entry) && (entry <= XA_RETRY_ENTRY);
+}
+
+/**
+ * typedef xa_update_node_t - A callback function from the XArray.
+ * @node: The node which is being processed
+ *
+ * This function is called every time the XArray updates the count of
+ * present and value entries in a node.  It allows advanced users to
+ * maintain the private_list in the node.
+ *
+ * Context: The xa_lock is held and interrupts may be disabled.
+ *	    Implementations should not drop the xa_lock, nor re-enable
+ *	    interrupts.
+ */
+typedef void (*xa_update_node_t)(struct xa_node *node);
+
+/*
+ * The xa_state is opaque to its users.  It contains various different pieces
+ * of state involved in the current operation on the XArray.  It should be
+ * declared on the stack and passed between the various internal routines.
+ * The various elements in it should not be accessed directly, but only
+ * through the provided accessor functions.  The below documentation is for
+ * the benefit of those working on the code, not for users of the XArray.
+ *
+ * @xa_node usually points to the xa_node containing the slot we're operating
+ * on (and @xa_offset is the offset in the slots array).  If there is a
+ * single entry in the array at index 0, there are no allocated xa_nodes to
+ * point to, and so we store %NULL in @xa_node.  @xa_node is set to
+ * the value %XAS_RESTART if the xa_state is not walked to the correct
+ * position in the tree of nodes for this operation.  If an error occurs
+ * during an operation, it is set to an %XAS_ERROR value.  If we run off the
+ * end of the allocated nodes, it is set to %XAS_BOUNDS.
+ */
+struct xa_state {
+	struct xarray *xa;
+	unsigned long xa_index;
+	unsigned char xa_shift;
+	unsigned char xa_sibs;
+	unsigned char xa_offset;
+	unsigned char xa_pad;		/* Helps gcc generate better code */
+	struct xa_node *xa_node;
+	struct xa_node *xa_alloc;
+	xa_update_node_t xa_update;
+};
+
+/*
+ * We encode errnos in the xas->xa_node.  If an error has happened, we need to
+ * drop the lock to fix it, and once we've done so the xa_state is invalid.
+ */
+#define XA_ERROR(errno) ((struct xa_node *)(((unsigned long)errno << 2) | 2UL))
+#define XAS_BOUNDS	((struct xa_node *)1UL)
+#define XAS_RESTART	((struct xa_node *)3UL)
+
+#define __XA_STATE(array, index, shift, sibs)  {	\
+	.xa = array,					\
+	.xa_index = index,				\
+	.xa_shift = shift,				\
+	.xa_sibs = sibs,				\
+	.xa_offset = 0,					\
+	.xa_pad = 0,					\
+	.xa_node = XAS_RESTART,				\
+	.xa_alloc = NULL,				\
+	.xa_update = NULL				\
+}
+
+/**
+ * XA_STATE() - Declare an XArray operation state.
+ * @name: Name of this operation state (usually xas).
+ * @array: Array to operate on.
+ * @index: Initial index of interest.
+ *
+ * Declare and initialise an xa_state on the stack.
+ */
+#define XA_STATE(name, array, index)				\
+	struct xa_state name = __XA_STATE(array, index, 0, 0)
+
+/**
+ * XA_STATE_ORDER() - Declare an XArray operation state.
+ * @name: Name of this operation state (usually xas).
+ * @array: Array to operate on.
+ * @index: Initial index of interest.
+ * @order: Order of entry.
+ *
+ * Declare and initialise an xa_state on the stack.  This variant of
+ * XA_STATE() allows you to specify the 'order' of the element you
+ * want to operate on.`
+ */
+#define XA_STATE_ORDER(name, array, index, order)		\
+	struct xa_state name = __XA_STATE(array,		\
+			(index >> order) << order,		\
+			order - (order % XA_CHUNK_SHIFT),	\
+			(1U << (order % XA_CHUNK_SHIFT)) - 1)
+
+#define xas_marked(xas, mark)	xa_marked((xas)->xa, (mark))
+#define xas_trylock(xas)	xa_trylock((xas)->xa)
+#define xas_lock(xas)		xa_lock((xas)->xa)
+#define xas_unlock(xas)		xa_unlock((xas)->xa)
+#define xas_lock_bh(xas)	xa_lock_bh((xas)->xa)
+#define xas_unlock_bh(xas)	xa_unlock_bh((xas)->xa)
+#define xas_lock_irq(xas)	xa_lock_irq((xas)->xa)
+#define xas_unlock_irq(xas)	xa_unlock_irq((xas)->xa)
+#define xas_lock_irqsave(xas, flags) \
+				xa_lock_irqsave((xas)->xa, flags)
+#define xas_unlock_irqrestore(xas, flags) \
+				xa_unlock_irqrestore((xas)->xa, flags)
+
+/**
+ * xas_error() - Return an errno stored in the xa_state.
+ * @xas: XArray operation state.
+ *
+ * Return: 0 if no error has been noted.  A negative errno if one has.
+ */
+static inline int xas_error(const struct xa_state *xas)
+{
+	return xa_err(xas->xa_node);
+}
+
+/**
+ * xas_set_err() - Note an error in the xa_state.
+ * @xas: XArray operation state.
+ * @err: Negative error number.
+ *
+ * Only call this function with a negative @err; zero or positive errors
+ * will probably not behave the way you think they should.  If you want
+ * to clear the error from an xa_state, use xas_reset().
+ */
+static inline void xas_set_err(struct xa_state *xas, long err)
+{
+	xas->xa_node = XA_ERROR(err);
+}
+
+/**
+ * xas_invalid() - Is the xas in a retry or error state?
+ * @xas: XArray operation state.
+ *
+ * Return: %true if the xas cannot be used for operations.
+ */
+static inline bool xas_invalid(const struct xa_state *xas)
+{
+	return (unsigned long)xas->xa_node & 3;
+}
+
+/**
+ * xas_valid() - Is the xas a valid cursor into the array?
+ * @xas: XArray operation state.
+ *
+ * Return: %true if the xas can be used for operations.
+ */
+static inline bool xas_valid(const struct xa_state *xas)
+{
+	return !xas_invalid(xas);
+}
+
+/**
+ * xas_is_node() - Does the xas point to a node?
+ * @xas: XArray operation state.
+ *
+ * Return: %true if the xas currently references a node.
+ */
+static inline bool xas_is_node(const struct xa_state *xas)
+{
+	return xas_valid(xas) && xas->xa_node;
+}
+
+/* True if the pointer is something other than a node */
+static inline bool xas_not_node(struct xa_node *node)
+{
+	return ((unsigned long)node & 3) || !node;
+}
+
+/* True if the node represents RESTART or an error */
+static inline bool xas_frozen(struct xa_node *node)
+{
+	return (unsigned long)node & 2;
+}
+
+/* True if the node represents head-of-tree, RESTART or BOUNDS */
+static inline bool xas_top(struct xa_node *node)
+{
+	return node <= XAS_RESTART;
+}
+
+/**
+ * xas_reset() - Reset an XArray operation state.
+ * @xas: XArray operation state.
+ *
+ * Resets the error or walk state of the @xas so future walks of the
+ * array will start from the root.  Use this if you have dropped the
+ * xarray lock and want to reuse the xa_state.
+ *
+ * Context: Any context.
+ */
+static inline void xas_reset(struct xa_state *xas)
+{
+	xas->xa_node = XAS_RESTART;
+}
+
+/**
+ * xas_retry() - Retry the operation if appropriate.
+ * @xas: XArray operation state.
+ * @entry: Entry from xarray.
+ *
+ * The advanced functions may sometimes return an internal entry, such as
+ * a retry entry or a zero entry.  This function sets up the @xas to restart
+ * the walk from the head of the array if needed.
+ *
+ * Context: Any context.
+ * Return: true if the operation needs to be retried.
+ */
+static inline bool xas_retry(struct xa_state *xas, const void *entry)
+{
+	if (xa_is_zero(entry))
+		return true;
+	if (!xa_is_retry(entry))
+		return false;
+	xas_reset(xas);
+	return true;
+}
+
+void *xas_load(struct xa_state *);
+void *xas_store(struct xa_state *, void *entry);
+void *xas_find(struct xa_state *, unsigned long max);
+void *xas_find_conflict(struct xa_state *);
+
+bool xas_get_mark(const struct xa_state *, xa_mark_t);
+void xas_set_mark(const struct xa_state *, xa_mark_t);
+void xas_clear_mark(const struct xa_state *, xa_mark_t);
+void *xas_find_marked(struct xa_state *, unsigned long max, xa_mark_t);
+void xas_init_marks(const struct xa_state *);
+
+bool xas_nomem(struct xa_state *, gfp_t);
+void xas_pause(struct xa_state *);
+
+void xas_create_range(struct xa_state *);
+
+/**
+ * xas_reload() - Refetch an entry from the xarray.
+ * @xas: XArray operation state.
+ *
+ * Use this function to check that a previously loaded entry still has
+ * the same value.  This is useful for the lockless pagecache lookup where
+ * we walk the array with only the RCU lock to protect us, lock the page,
+ * then check that the page hasn't moved since we looked it up.
+ *
+ * The caller guarantees that @xas is still valid.  If it may be in an
+ * error or restart state, call xas_load() instead.
+ *
+ * Return: The entry at this location in the xarray.
+ */
+static inline void *xas_reload(struct xa_state *xas)
+{
+	struct xa_node *node = xas->xa_node;
+
+	if (node)
+		return xa_entry(xas->xa, node, xas->xa_offset);
+	return xa_head(xas->xa);
+}
+
+/**
+ * xas_set() - Set up XArray operation state for a different index.
+ * @xas: XArray operation state.
+ * @index: New index into the XArray.
+ *
+ * Move the operation state to refer to a different index.  This will
+ * have the effect of starting a walk from the top; see xas_next()
+ * to move to an adjacent index.
+ */
+static inline void xas_set(struct xa_state *xas, unsigned long index)
+{
+	xas->xa_index = index;
+	xas->xa_node = XAS_RESTART;
+}
+
+/**
+ * xas_set_order() - Set up XArray operation state for a multislot entry.
+ * @xas: XArray operation state.
+ * @index: Target of the operation.
+ * @order: Entry occupies 2^@order indices.
+ */
+static inline void xas_set_order(struct xa_state *xas, unsigned long index,
+					unsigned int order)
+{
+#ifdef CONFIG_XARRAY_MULTI
+	xas->xa_index = order < BITS_PER_LONG ? (index >> order) << order : 0;
+	xas->xa_shift = order - (order % XA_CHUNK_SHIFT);
+	xas->xa_sibs = (1 << (order % XA_CHUNK_SHIFT)) - 1;
+	xas->xa_node = XAS_RESTART;
+#else
+	BUG_ON(order > 0);
+	xas_set(xas, index);
+#endif
+}
+
+/**
+ * xas_set_update() - Set up XArray operation state for a callback.
+ * @xas: XArray operation state.
+ * @update: Function to call when updating a node.
+ *
+ * The XArray can notify a caller after it has updated an xa_node.
+ * This is advanced functionality and is only needed by the page cache.
+ */
+static inline void xas_set_update(struct xa_state *xas, xa_update_node_t update)
+{
+	xas->xa_update = update;
+}
+
+/**
+ * xas_next_entry() - Advance iterator to next present entry.
+ * @xas: XArray operation state.
+ * @max: Highest index to return.
+ *
+ * xas_next_entry() is an inline function to optimise xarray traversal for
+ * speed.  It is equivalent to calling xas_find(), and will call xas_find()
+ * for all the hard cases.
+ *
+ * Return: The next present entry after the one currently referred to by @xas.
+ */
+static inline void *xas_next_entry(struct xa_state *xas, unsigned long max)
+{
+	struct xa_node *node = xas->xa_node;
+	void *entry;
+
+	if (unlikely(xas_not_node(node) || node->shift ||
+			xas->xa_offset != (xas->xa_index & XA_CHUNK_MASK)))
+		return xas_find(xas, max);
+
+	do {
+		if (unlikely(xas->xa_index >= max))
+			return xas_find(xas, max);
+		if (unlikely(xas->xa_offset == XA_CHUNK_MASK))
+			return xas_find(xas, max);
+		entry = xa_entry(xas->xa, node, xas->xa_offset + 1);
+		if (unlikely(xa_is_internal(entry)))
+			return xas_find(xas, max);
+		xas->xa_offset++;
+		xas->xa_index++;
+	} while (!entry);
+
+	return entry;
+}
+
+/* Private */
+static inline unsigned int xas_find_chunk(struct xa_state *xas, bool advance,
+		xa_mark_t mark)
+{
+	unsigned long *addr = xas->xa_node->marks[(__force unsigned)mark];
+	unsigned int offset = xas->xa_offset;
+
+	if (advance)
+		offset++;
+	if (XA_CHUNK_SIZE == BITS_PER_LONG) {
+		if (offset < XA_CHUNK_SIZE) {
+			unsigned long data = *addr & (~0UL << offset);
+			if (data)
+				return __ffs(data);
+		}
+		return XA_CHUNK_SIZE;
+	}
+
+	return find_next_bit(addr, XA_CHUNK_SIZE, offset);
+}
+
+/**
+ * xas_next_marked() - Advance iterator to next marked entry.
+ * @xas: XArray operation state.
+ * @max: Highest index to return.
+ * @mark: Mark to search for.
+ *
+ * xas_next_marked() is an inline function to optimise xarray traversal for
+ * speed.  It is equivalent to calling xas_find_marked(), and will call
+ * xas_find_marked() for all the hard cases.
+ *
+ * Return: The next marked entry after the one currently referred to by @xas.
+ */
+static inline void *xas_next_marked(struct xa_state *xas, unsigned long max,
+								xa_mark_t mark)
+{
+	struct xa_node *node = xas->xa_node;
+	unsigned int offset;
+
+	if (unlikely(xas_not_node(node) || node->shift))
+		return xas_find_marked(xas, max, mark);
+	offset = xas_find_chunk(xas, true, mark);
+	xas->xa_offset = offset;
+	xas->xa_index = (xas->xa_index & ~XA_CHUNK_MASK) + offset;
+	if (xas->xa_index > max)
+		return NULL;
+	if (offset == XA_CHUNK_SIZE)
+		return xas_find_marked(xas, max, mark);
+	return xa_entry(xas->xa, node, offset);
+}
+
+/*
+ * If iterating while holding a lock, drop the lock and reschedule
+ * every %XA_CHECK_SCHED loops.
+ */
+enum {
+	XA_CHECK_SCHED = 4096,
+};
+
+/**
+ * xas_for_each() - Iterate over a range of an XArray.
+ * @xas: XArray operation state.
+ * @entry: Entry retrieved from the array.
+ * @max: Maximum index to retrieve from array.
+ *
+ * The loop body will be executed for each entry present in the xarray
+ * between the current xas position and @max.  @entry will be set to
+ * the entry retrieved from the xarray.  It is safe to delete entries
+ * from the array in the loop body.  You should hold either the RCU lock
+ * or the xa_lock while iterating.  If you need to drop the lock, call
+ * xas_pause() first.
+ */
+#define xas_for_each(xas, entry, max) \
+	for (entry = xas_find(xas, max); entry; \
+	     entry = xas_next_entry(xas, max))
+
+/**
+ * xas_for_each_marked() - Iterate over a range of an XArray.
+ * @xas: XArray operation state.
+ * @entry: Entry retrieved from the array.
+ * @max: Maximum index to retrieve from array.
+ * @mark: Mark to search for.
+ *
+ * The loop body will be executed for each marked entry in the xarray
+ * between the current xas position and @max.  @entry will be set to
+ * the entry retrieved from the xarray.  It is safe to delete entries
+ * from the array in the loop body.  You should hold either the RCU lock
+ * or the xa_lock while iterating.  If you need to drop the lock, call
+ * xas_pause() first.
+ */
+#define xas_for_each_marked(xas, entry, max, mark) \
+	for (entry = xas_find_marked(xas, max, mark); entry; \
+	     entry = xas_next_marked(xas, max, mark))
+
+/**
+ * xas_for_each_conflict() - Iterate over a range of an XArray.
+ * @xas: XArray operation state.
+ * @entry: Entry retrieved from the array.
+ *
+ * The loop body will be executed for each entry in the XArray that lies
+ * within the range specified by @xas.  If the loop completes successfully,
+ * any entries that lie in this range will be replaced by @entry.  The caller
+ * may break out of the loop; if they do so, the contents of the XArray will
+ * be unchanged.  The operation may fail due to an out of memory condition.
+ * The caller may also call xa_set_err() to exit the loop while setting an
+ * error to record the reason.
+ */
+#define xas_for_each_conflict(xas, entry) \
+	while ((entry = xas_find_conflict(xas)))
+
+void *__xas_next(struct xa_state *);
+void *__xas_prev(struct xa_state *);
+
+/**
+ * xas_prev() - Move iterator to previous index.
+ * @xas: XArray operation state.
+ *
+ * If the @xas was in an error state, it will remain in an error state
+ * and this function will return %NULL.  If the @xas has never been walked,
+ * it will have the effect of calling xas_load().  Otherwise one will be
+ * subtracted from the index and the state will be walked to the correct
+ * location in the array for the next operation.
+ *
+ * If the iterator was referencing index 0, this function wraps
+ * around to %ULONG_MAX.
+ *
+ * Return: The entry at the new index.  This may be %NULL or an internal
+ * entry.
+ */
+static inline void *xas_prev(struct xa_state *xas)
+{
+	struct xa_node *node = xas->xa_node;
+
+	if (unlikely(xas_not_node(node) || node->shift ||
+				xas->xa_offset == 0))
+		return __xas_prev(xas);
+
+	xas->xa_index--;
+	xas->xa_offset--;
+	return xa_entry(xas->xa, node, xas->xa_offset);
+}
+
+/**
+ * xas_next() - Move state to next index.
+ * @xas: XArray operation state.
+ *
+ * If the @xas was in an error state, it will remain in an error state
+ * and this function will return %NULL.  If the @xas has never been walked,
+ * it will have the effect of calling xas_load().  Otherwise one will be
+ * added to the index and the state will be walked to the correct
+ * location in the array for the next operation.
+ *
+ * If the iterator was referencing index %ULONG_MAX, this function wraps
+ * around to 0.
+ *
+ * Return: The entry at the new index.  This may be %NULL or an internal
+ * entry.
+ */
+static inline void *xas_next(struct xa_state *xas)
+{
+	struct xa_node *node = xas->xa_node;
+
+	if (unlikely(xas_not_node(node) || node->shift ||
+				xas->xa_offset == XA_CHUNK_MASK))
+		return __xas_next(xas);
+
+	xas->xa_index++;
+	xas->xa_offset++;
+	return xa_entry(xas->xa, node, xas->xa_offset);
+}
+
 #endif /* _LINUX_XARRAY_H */