]) # LIBCFS_CLEAR_AND_WAKE_UP_BIT
#
+# LIBCFS_XARRAY_SUPPORT
+#
+# 4.19-rc5 kernel commit 3159f943aafdbacb2f94c38fdaadabf2bbde2a14
+# replaced the radix tree implementation with Xarrays. This change
+# introduced functionaly needed for general Xarray support
+#
+AC_DEFUN([LIBCFS_XARRAY_SUPPORT], [
+tmp_flags="$EXTRA_KCFLAGS"
+EXTRA_KCFLAGS="-Werror"
+LB_CHECK_COMPILE([if page cache uses Xarray],
+xarray_support, [
+ #include <linux/radix-tree.h>
+],[
+ radix_tree_exceptional_entry(NULL);
+],[
+ AC_DEFINE(HAVE_RADIX_TREE_EXCEPTIONAL_ENTRY, 1,
+ [kernel lacks 'xa_is_value'])
+])
+EXTRA_KCFLAGS="$tmp_flags"
+]) # LIBCFS_XARRAY_SUPPORT
+
+#
# LIBCFS_HAVE_IOV_ITER_TYPE
#
# kernel 4.20 commit 00e23707442a75b404392cef1405ab4fd498de6b
LIBCFS_WAIT_VAR_EVENT
# 4.17
LIBCFS_CLEAR_AND_WAKE_UP_BIT
+# 4.19
+LIBCFS_XARRAY_SUPPORT
# 4.20
LIBCFS_HAVE_IOV_ITER_TYPE
# 5.0
EXTRA_DIST = linux-misc.h linux-fs.h linux-mem.h linux-time.h linux-cpu.h \
linux-list.h linux-hash.h linux-uuid.h linux-wait.h \
- refcount.h processor.h
+ refcount.h processor.h xarray.h
--- /dev/null
+/* SPDX-License-Identifier: GPL-2.0+ */
+#ifndef _LINUX_XARRAY_H
+#define _LINUX_XARRAY_H
+/*
+ * eXtensible Arrays
+ * Copyright (c) 2017 Microsoft Corporation
+ * Author: Matthew Wilcox <willy@infradead.org>
+ *
+ * This is taken from kernel commit:
+ *
+ * 7b785645e ("mm: fix page cache convergence regression")
+ *
+ * at kernel verison 5.2-rc2
+ *
+ * See Documentation/core-api/xarray.rst for how to use the XArray.
+ */
+#ifdef HAVE_RADIX_TREE_EXCEPTIONAL_ENTRY
+#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)
+#define xa_unlock(xa) spin_unlock(&(xa)->xa_lock)
+#define xa_lock_bh(xa) spin_lock_bh(&(xa)->xa_lock)
+#define xa_unlock_bh(xa) spin_unlock_bh(&(xa)->xa_lock)
+#define xa_lock_irq(xa) spin_lock_irq(&(xa)->xa_lock)
+#define xa_unlock_irq(xa) spin_unlock_irq(&(xa)->xa_lock)
+#define xa_lock_irqsave(xa, flags) \
+ spin_lock_irqsave(&(xa)->xa_lock, flags)
+#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 /* HAVE_RADIX_TREE_EXCEPTIONAL_ENTRY */
+
+#endif /* _LINUX_XARRAY_H */
libcfs-linux-objs += linux-curproc.o
libcfs-linux-objs += linux-hash.o
libcfs-linux-objs += linux-wait.o
+libcfs-linux-objs += xarray.o
libcfs-crypto-objs := crypto.o fname.o hkdf.o hooks.o keyring.o
libcfs-crypto-objs += keysetup.o keysetup_v1.o policy.o bio.o
EXTRA_DIST = linux-prim.c \
linux-curproc.c \
linux-hash.c \
- linux-wait.c
+ linux-wait.c \
+ xarray.c
}
EXPORT_SYMBOL_GPL(cfs_apply_workqueue_attrs);
-struct kmem_cache (*cfs_radix_tree_node_cachep);
+struct kmem_cache (*radix_tree_node_cachep);
void __init cfs_arch_init(void)
{
#endif
cfs_apply_workqueue_attrs_t =
(void *)kallsyms_lookup_name("apply_workqueue_attrs");
+ radix_tree_node_cachep =
+ (void *)kallsyms_lookup_name("radix_tree_node_cachep");
}
int cfs_kernel_write(struct file *filp, const void *buf, size_t count,
--- /dev/null
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * XArray implementation
+ * Copyright (c) 2017 Microsoft Corporation
+ * Author: Matthew Wilcox <willy@infradead.org>
+ *
+ * This is taken from kernel commit:
+ *
+ * 7b785645e ("mm: fix page cache convergence regression")
+ *
+ * at kernel verison 5.2-rc2
+ */
+#ifdef HAVE_RADIX_TREE_EXCEPTIONAL_ENTRY
+#include <linux/bitmap.h>
+#include <linux/export.h>
+#include <linux/list.h>
+#include <linux/slab.h>
+#include <linux/radix-tree.h>
+#include <libcfs/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
+ */
+
+static inline unsigned int xa_lock_type(const struct xarray *xa)
+{
+ return (__force unsigned int)xa->xa_flags & 3;
+}
+
+static inline void xas_lock_type(struct xa_state *xas, unsigned int lock_type)
+{
+ if (lock_type == XA_LOCK_IRQ)
+ xas_lock_irq(xas);
+ else if (lock_type == XA_LOCK_BH)
+ xas_lock_bh(xas);
+ else
+ xas_lock(xas);
+}
+
+static inline void xas_unlock_type(struct xa_state *xas, unsigned int lock_type)
+{
+ if (lock_type == XA_LOCK_IRQ)
+ xas_unlock_irq(xas);
+ else if (lock_type == XA_LOCK_BH)
+ xas_unlock_bh(xas);
+ else
+ xas_unlock(xas);
+}
+
+static inline bool xa_track_free(const struct xarray *xa)
+{
+ return xa->xa_flags & XA_FLAGS_TRACK_FREE;
+}
+
+static inline bool xa_zero_busy(const struct xarray *xa)
+{
+ return xa->xa_flags & XA_FLAGS_ZERO_BUSY;
+}
+
+static inline void xa_mark_set(struct xarray *xa, xa_mark_t mark)
+{
+ if (!(xa->xa_flags & XA_FLAGS_MARK(mark)))
+ xa->xa_flags |= XA_FLAGS_MARK(mark);
+}
+
+static inline void xa_mark_clear(struct xarray *xa, xa_mark_t mark)
+{
+ if (xa->xa_flags & XA_FLAGS_MARK(mark))
+ xa->xa_flags &= ~(XA_FLAGS_MARK(mark));
+}
+
+static inline unsigned long *node_marks(struct xa_node *node, xa_mark_t mark)
+{
+ return node->marks[(__force unsigned)mark];
+}
+
+static inline bool node_get_mark(struct xa_node *node,
+ unsigned int offset, xa_mark_t mark)
+{
+ return test_bit(offset, node_marks(node, mark));
+}
+
+/* returns true if the bit was set */
+static inline bool node_set_mark(struct xa_node *node, unsigned int offset,
+ xa_mark_t mark)
+{
+ return __test_and_set_bit(offset, node_marks(node, mark));
+}
+
+/* returns true if the bit was set */
+static inline bool node_clear_mark(struct xa_node *node, unsigned int offset,
+ xa_mark_t mark)
+{
+ return __test_and_clear_bit(offset, node_marks(node, mark));
+}
+
+static inline bool node_any_mark(struct xa_node *node, xa_mark_t mark)
+{
+ return !bitmap_empty(node_marks(node, mark), XA_CHUNK_SIZE);
+}
+
+static inline void node_mark_all(struct xa_node *node, xa_mark_t mark)
+{
+ bitmap_fill(node_marks(node, mark), XA_CHUNK_SIZE);
+}
+
+#define mark_inc(mark) do { \
+ mark = (__force xa_mark_t)((__force unsigned)(mark) + 1); \
+} while (0)
+
+/*
+ * xas_squash_marks() - Merge all marks to the first entry
+ * @xas: Array operation state.
+ *
+ * Set a mark on the first entry if any entry has it set. Clear marks on
+ * all sibling entries.
+ */
+static void xas_squash_marks(const struct xa_state *xas)
+{
+ unsigned int mark = 0;
+ unsigned int limit = xas->xa_offset + xas->xa_sibs + 1;
+
+ if (!xas->xa_sibs)
+ return;
+
+ do {
+ unsigned long *marks = xas->xa_node->marks[mark];
+ if (find_next_bit(marks, limit, xas->xa_offset + 1) == limit)
+ continue;
+ __set_bit(xas->xa_offset, marks);
+ bitmap_clear(marks, xas->xa_offset + 1, xas->xa_sibs);
+ } while (mark++ != (__force unsigned)XA_MARK_MAX);
+}
+
+/* extracts the offset within this node from the index */
+static unsigned int get_offset(unsigned long index, struct xa_node *node)
+{
+ return (index >> node->shift) & XA_CHUNK_MASK;
+}
+
+static void xas_set_offset(struct xa_state *xas)
+{
+ xas->xa_offset = get_offset(xas->xa_index, xas->xa_node);
+}
+
+/* move the index either forwards (find) or backwards (sibling slot) */
+static void xas_move_index(struct xa_state *xas, unsigned long offset)
+{
+ unsigned int shift = xas->xa_node->shift;
+ xas->xa_index &= ~XA_CHUNK_MASK << shift;
+ xas->xa_index += offset << shift;
+}
+
+static void xas_advance(struct xa_state *xas)
+{
+ xas->xa_offset++;
+ xas_move_index(xas, xas->xa_offset);
+}
+
+static void *set_bounds(struct xa_state *xas)
+{
+ xas->xa_node = XAS_BOUNDS;
+ return NULL;
+}
+
+/*
+ * Starts a walk. If the @xas is already valid, we assume that it's on
+ * the right path and just return where we've got to. If we're in an
+ * error state, return NULL. If the index is outside the current scope
+ * of the xarray, return NULL without changing @xas->xa_node. Otherwise
+ * set @xas->xa_node to NULL and return the current head of the array.
+ */
+static void *xas_start(struct xa_state *xas)
+{
+ void *entry;
+
+ if (xas_valid(xas))
+ return xas_reload(xas);
+ if (xas_error(xas))
+ return NULL;
+
+ entry = xa_head(xas->xa);
+ if (!xa_is_node(entry)) {
+ if (xas->xa_index)
+ return set_bounds(xas);
+ } else {
+ if ((xas->xa_index >> xa_to_node(entry)->shift) > XA_CHUNK_MASK)
+ return set_bounds(xas);
+ }
+
+ xas->xa_node = NULL;
+ return entry;
+}
+
+static void *xas_descend(struct xa_state *xas, struct xa_node *node)
+{
+ unsigned int offset = get_offset(xas->xa_index, node);
+ void *entry = xa_entry(xas->xa, node, offset);
+
+ xas->xa_node = node;
+ if (xa_is_sibling(entry)) {
+ offset = xa_to_sibling(entry);
+ entry = xa_entry(xas->xa, node, offset);
+ }
+
+ xas->xa_offset = offset;
+ return entry;
+}
+
+/**
+ * xas_load() - Load an entry from the XArray (advanced).
+ * @xas: XArray operation state.
+ *
+ * Usually walks the @xas to the appropriate state to load the entry
+ * stored at xa_index. However, it will do nothing and return %NULL if
+ * @xas is in an error state. xas_load() will never expand the tree.
+ *
+ * If the xa_state is set up to operate on a multi-index entry, xas_load()
+ * may return %NULL or an internal entry, even if there are entries
+ * present within the range specified by @xas.
+ *
+ * Context: Any context. The caller should hold the xa_lock or the RCU lock.
+ * Return: Usually an entry in the XArray, but see description for exceptions.
+ */
+void *xas_load(struct xa_state *xas)
+{
+ void *entry = xas_start(xas);
+
+ while (xa_is_node(entry)) {
+ struct xa_node *node = xa_to_node(entry);
+
+ if (xas->xa_shift > node->shift)
+ break;
+ entry = xas_descend(xas, node);
+ if (node->shift == 0)
+ break;
+ }
+ return entry;
+}
+EXPORT_SYMBOL_GPL(xas_load);
+
+/* Move the radix tree node cache here */
+extern struct kmem_cache *radix_tree_node_cachep;
+
+static inline void tag_clear(struct radix_tree_node *node, unsigned int tag,
+ int offset)
+{
+ __clear_bit(offset, node->tags[tag]);
+}
+
+static void radix_tree_node_rcu_free(struct rcu_head *head)
+{
+ struct radix_tree_node *node =
+ container_of(head, struct radix_tree_node, rcu_head);
+ int i;
+
+ /*
+ * must only free zeroed nodes into the slab. radix_tree_shrink
+ * can leave us with a non-NULL entry in the first slot, so clear
+ * that here to make sure.
+ */
+ for (i = 0; i < RADIX_TREE_MAX_TAGS; i++)
+ tag_clear(node, i, 0);
+
+ node->slots[0] = NULL;
+ node->count = 0;
+
+ kmem_cache_free(radix_tree_node_cachep, node);
+}
+
+#define XA_RCU_FREE ((struct xarray *)1)
+
+static void xa_node_free(struct xa_node *node)
+{
+ XA_NODE_BUG_ON(node, !list_empty(&node->private_list));
+ node->array = XA_RCU_FREE;
+ call_rcu(&node->rcu_head, radix_tree_node_rcu_free);
+}
+
+/*
+ * xas_destroy() - Free any resources allocated during the XArray operation.
+ * @xas: XArray operation state.
+ *
+ * This function is now internal-only.
+ */
+static void xas_destroy(struct xa_state *xas)
+{
+ struct xa_node *node = xas->xa_alloc;
+
+ if (!node)
+ return;
+ XA_NODE_BUG_ON(node, !list_empty(&node->private_list));
+ kmem_cache_free(radix_tree_node_cachep, node);
+ xas->xa_alloc = NULL;
+}
+
+/**
+ * xas_nomem() - Allocate memory if needed.
+ * @xas: XArray operation state.
+ * @gfp: Memory allocation flags.
+ *
+ * If we need to add new nodes to the XArray, we try to allocate memory
+ * with GFP_NOWAIT while holding the lock, which will usually succeed.
+ * If it fails, @xas is flagged as needing memory to continue. The caller
+ * should drop the lock and call xas_nomem(). If xas_nomem() succeeds,
+ * the caller should retry the operation.
+ *
+ * Forward progress is guaranteed as one node is allocated here and
+ * stored in the xa_state where it will be found by xas_alloc(). More
+ * nodes will likely be found in the slab allocator, but we do not tie
+ * them up here.
+ *
+ * Return: true if memory was needed, and was successfully allocated.
+ */
+bool xas_nomem(struct xa_state *xas, gfp_t gfp)
+{
+ if (xas->xa_node != XA_ERROR(-ENOMEM)) {
+ xas_destroy(xas);
+ return false;
+ }
+#ifdef __GFP_ACCOUNT
+ if (xas->xa->xa_flags & XA_FLAGS_ACCOUNT)
+ gfp |= __GFP_ACCOUNT;
+#endif
+ xas->xa_alloc = kmem_cache_alloc(radix_tree_node_cachep, gfp);
+ if (!xas->xa_alloc)
+ return false;
+ XA_NODE_BUG_ON(xas->xa_alloc, !list_empty(&xas->xa_alloc->private_list));
+ xas->xa_node = XAS_RESTART;
+ return true;
+}
+EXPORT_SYMBOL_GPL(xas_nomem);
+
+/*
+ * __xas_nomem() - Drop locks and allocate memory if needed.
+ * @xas: XArray operation state.
+ * @gfp: Memory allocation flags.
+ *
+ * Internal variant of xas_nomem().
+ *
+ * Return: true if memory was needed, and was successfully allocated.
+ */
+static bool __xas_nomem(struct xa_state *xas, gfp_t gfp)
+ __must_hold(xas->xa->xa_lock)
+{
+ unsigned int lock_type = xa_lock_type(xas->xa);
+
+ if (xas->xa_node != XA_ERROR(-ENOMEM)) {
+ xas_destroy(xas);
+ return false;
+ }
+#ifdef __GFP_ACCOUNT
+ if (xas->xa->xa_flags & XA_FLAGS_ACCOUNT)
+ gfp |= __GFP_ACCOUNT;
+#endif
+ if (gfpflags_allow_blocking(gfp)) {
+ xas_unlock_type(xas, lock_type);
+ xas->xa_alloc = kmem_cache_alloc(radix_tree_node_cachep, gfp);
+ xas_lock_type(xas, lock_type);
+ } else {
+ xas->xa_alloc = kmem_cache_alloc(radix_tree_node_cachep, gfp);
+ }
+ if (!xas->xa_alloc)
+ return false;
+ XA_NODE_BUG_ON(xas->xa_alloc, !list_empty(&xas->xa_alloc->private_list));
+ xas->xa_node = XAS_RESTART;
+ return true;
+}
+
+static void xas_update(struct xa_state *xas, struct xa_node *node)
+{
+ if (xas->xa_update)
+ xas->xa_update(node);
+ else
+ XA_NODE_BUG_ON(node, !list_empty(&node->private_list));
+}
+
+static void *xas_alloc(struct xa_state *xas, unsigned int shift)
+{
+ struct xa_node *parent = xas->xa_node;
+ struct xa_node *node = xas->xa_alloc;
+
+ if (xas_invalid(xas))
+ return NULL;
+
+ if (node) {
+ xas->xa_alloc = NULL;
+ } else {
+ gfp_t gfp = GFP_NOWAIT | __GFP_NOWARN;
+#ifdef __GFP_ACCOUNT
+ if (xas->xa->xa_flags & XA_FLAGS_ACCOUNT)
+ gfp |= __GFP_ACCOUNT;
+#endif
+ node = kmem_cache_alloc(radix_tree_node_cachep, gfp);
+ if (!node) {
+ xas_set_err(xas, -ENOMEM);
+ return NULL;
+ }
+ }
+
+ if (parent) {
+ node->offset = xas->xa_offset;
+ parent->count++;
+ XA_NODE_BUG_ON(node, parent->count > XA_CHUNK_SIZE);
+ xas_update(xas, parent);
+ }
+ XA_NODE_BUG_ON(node, shift > BITS_PER_LONG);
+ XA_NODE_BUG_ON(node, !list_empty(&node->private_list));
+ node->shift = shift;
+ node->count = 0;
+ node->nr_values = 0;
+ RCU_INIT_POINTER(node->parent, xas->xa_node);
+ node->array = xas->xa;
+
+ return node;
+}
+
+#ifdef CONFIG_XARRAY_MULTI
+/* Returns the number of indices covered by a given xa_state */
+static unsigned long xas_size(const struct xa_state *xas)
+{
+ return (xas->xa_sibs + 1UL) << xas->xa_shift;
+}
+#endif
+
+/*
+ * Use this to calculate the maximum index that will need to be created
+ * in order to add the entry described by @xas. Because we cannot store a
+ * multiple-index entry at index 0, the calculation is a little more complex
+ * than you might expect.
+ */
+static unsigned long xas_max(struct xa_state *xas)
+{
+ unsigned long max = xas->xa_index;
+
+#ifdef CONFIG_XARRAY_MULTI
+ if (xas->xa_shift || xas->xa_sibs) {
+ unsigned long mask = xas_size(xas) - 1;
+ max |= mask;
+ if (mask == max)
+ max++;
+ }
+#endif
+
+ return max;
+}
+
+/* The maximum index that can be contained in the array without expanding it */
+static unsigned long max_index(void *entry)
+{
+ if (!xa_is_node(entry))
+ return 0;
+ return (XA_CHUNK_SIZE << xa_to_node(entry)->shift) - 1;
+}
+
+static void xas_shrink(struct xa_state *xas)
+{
+ struct xarray *xa = xas->xa;
+ struct xa_node *node = xas->xa_node;
+
+ for (;;) {
+ void *entry;
+
+ XA_NODE_BUG_ON(node, node->count > XA_CHUNK_SIZE);
+ if (node->count != 1)
+ break;
+ entry = xa_entry_locked(xa, node, 0);
+ if (!entry)
+ break;
+ if (!xa_is_node(entry) && node->shift)
+ break;
+ if (xa_is_zero(entry) && xa_zero_busy(xa))
+ entry = NULL;
+ xas->xa_node = XAS_BOUNDS;
+
+ RCU_INIT_POINTER(xa->xa_head, entry);
+ if (xa_track_free(xa) && !node_get_mark(node, 0, XA_FREE_MARK))
+ xa_mark_clear(xa, XA_FREE_MARK);
+
+ node->count = 0;
+ node->nr_values = 0;
+ if (!xa_is_node(entry))
+ RCU_INIT_POINTER(node->slots[0], XA_RETRY_ENTRY);
+ xas_update(xas, node);
+ xa_node_free(node);
+ if (!xa_is_node(entry))
+ break;
+ node = xa_to_node(entry);
+ node->parent = NULL;
+ }
+}
+
+/*
+ * xas_delete_node() - Attempt to delete an xa_node
+ * @xas: Array operation state.
+ *
+ * Attempts to delete the @xas->xa_node. This will fail if xa->node has
+ * a non-zero reference count.
+ */
+static void xas_delete_node(struct xa_state *xas)
+{
+ struct xa_node *node = xas->xa_node;
+
+ for (;;) {
+ struct xa_node *parent;
+
+ XA_NODE_BUG_ON(node, node->count > XA_CHUNK_SIZE);
+ if (node->count)
+ break;
+
+ parent = xa_parent_locked(xas->xa, node);
+ xas->xa_node = parent;
+ xas->xa_offset = node->offset;
+ xa_node_free(node);
+
+ if (!parent) {
+ xas->xa->xa_head = NULL;
+ xas->xa_node = XAS_BOUNDS;
+ return;
+ }
+
+ parent->slots[xas->xa_offset] = NULL;
+ parent->count--;
+ XA_NODE_BUG_ON(parent, parent->count > XA_CHUNK_SIZE);
+ node = parent;
+ xas_update(xas, node);
+ }
+
+ if (!node->parent)
+ xas_shrink(xas);
+}
+
+/**
+ * xas_free_nodes() - Free this node and all nodes that it references
+ * @xas: Array operation state.
+ * @top: Node to free
+ *
+ * This node has been removed from the tree. We must now free it and all
+ * of its subnodes. There may be RCU walkers with references into the tree,
+ * so we must replace all entries with retry markers.
+ */
+static void xas_free_nodes(struct xa_state *xas, struct xa_node *top)
+{
+ unsigned int offset = 0;
+ struct xa_node *node = top;
+
+ for (;;) {
+ void *entry = xa_entry_locked(xas->xa, node, offset);
+
+ if (node->shift && xa_is_node(entry)) {
+ node = xa_to_node(entry);
+ offset = 0;
+ continue;
+ }
+ if (entry)
+ RCU_INIT_POINTER(node->slots[offset], XA_RETRY_ENTRY);
+ offset++;
+ while (offset == XA_CHUNK_SIZE) {
+ struct xa_node *parent;
+
+ parent = xa_parent_locked(xas->xa, node);
+ offset = node->offset + 1;
+ node->count = 0;
+ node->nr_values = 0;
+ xas_update(xas, node);
+ xa_node_free(node);
+ if (node == top)
+ return;
+ node = parent;
+ }
+ }
+}
+
+/*
+ * xas_expand adds nodes to the head of the tree until it has reached
+ * sufficient height to be able to contain @xas->xa_index
+ */
+static int xas_expand(struct xa_state *xas, void *head)
+{
+ struct xarray *xa = xas->xa;
+ struct xa_node *node = NULL;
+ unsigned int shift = 0;
+ unsigned long max = xas_max(xas);
+
+ if (!head) {
+ if (max == 0)
+ return 0;
+ while ((max >> shift) >= XA_CHUNK_SIZE)
+ shift += XA_CHUNK_SHIFT;
+ return shift + XA_CHUNK_SHIFT;
+ } else if (xa_is_node(head)) {
+ node = xa_to_node(head);
+ shift = node->shift + XA_CHUNK_SHIFT;
+ }
+ xas->xa_node = NULL;
+
+ while (max > max_index(head)) {
+ xa_mark_t mark = 0;
+
+ XA_NODE_BUG_ON(node, shift > BITS_PER_LONG);
+ node = xas_alloc(xas, shift);
+ if (!node)
+ return -ENOMEM;
+
+ node->count = 1;
+ if (xa_is_value(head))
+ node->nr_values = 1;
+ RCU_INIT_POINTER(node->slots[0], head);
+
+ /* Propagate the aggregated mark info to the new child */
+ for (;;) {
+ if (xa_track_free(xa) && mark == XA_FREE_MARK) {
+ node_mark_all(node, XA_FREE_MARK);
+ if (!xa_marked(xa, XA_FREE_MARK)) {
+ node_clear_mark(node, 0, XA_FREE_MARK);
+ xa_mark_set(xa, XA_FREE_MARK);
+ }
+ } else if (xa_marked(xa, mark)) {
+ node_set_mark(node, 0, mark);
+ }
+ if (mark == XA_MARK_MAX)
+ break;
+ mark_inc(mark);
+ }
+
+ /*
+ * Now that the new node is fully initialised, we can add
+ * it to the tree
+ */
+ if (xa_is_node(head)) {
+ xa_to_node(head)->offset = 0;
+ rcu_assign_pointer(xa_to_node(head)->parent, node);
+ }
+ head = xa_mk_node(node);
+ rcu_assign_pointer(xa->xa_head, head);
+ xas_update(xas, node);
+
+ shift += XA_CHUNK_SHIFT;
+ }
+
+ xas->xa_node = node;
+ return shift;
+}
+
+/*
+ * xas_create() - Create a slot to store an entry in.
+ * @xas: XArray operation state.
+ * @allow_root: %true if we can store the entry in the root directly
+ *
+ * Most users will not need to call this function directly, as it is called
+ * by xas_store(). It is useful for doing conditional store operations
+ * (see the xa_cmpxchg() implementation for an example).
+ *
+ * Return: If the slot already existed, returns the contents of this slot.
+ * If the slot was newly created, returns %NULL. If it failed to create the
+ * slot, returns %NULL and indicates the error in @xas.
+ */
+static void *xas_create(struct xa_state *xas, bool allow_root)
+{
+ struct xarray *xa = xas->xa;
+ void *entry;
+ void __rcu **slot;
+ struct xa_node *node = xas->xa_node;
+ int shift;
+ unsigned int order = xas->xa_shift;
+
+ if (xas_top(node)) {
+ entry = xa_head_locked(xa);
+ xas->xa_node = NULL;
+ if (!entry && xa_zero_busy(xa))
+ entry = XA_ZERO_ENTRY;
+ shift = xas_expand(xas, entry);
+ if (shift < 0)
+ return NULL;
+ if (!shift && !allow_root)
+ shift = XA_CHUNK_SHIFT;
+ entry = xa_head_locked(xa);
+ slot = &xa->xa_head;
+ } else if (xas_error(xas)) {
+ return NULL;
+ } else if (node) {
+ unsigned int offset = xas->xa_offset;
+
+ shift = node->shift;
+ entry = xa_entry_locked(xa, node, offset);
+ slot = &node->slots[offset];
+ } else {
+ shift = 0;
+ entry = xa_head_locked(xa);
+ slot = &xa->xa_head;
+ }
+
+ while (shift > order) {
+ shift -= XA_CHUNK_SHIFT;
+ if (!entry) {
+ node = xas_alloc(xas, shift);
+ if (!node)
+ break;
+ if (xa_track_free(xa))
+ node_mark_all(node, XA_FREE_MARK);
+ rcu_assign_pointer(*slot, xa_mk_node(node));
+ } else if (xa_is_node(entry)) {
+ node = xa_to_node(entry);
+ } else {
+ break;
+ }
+ entry = xas_descend(xas, node);
+ slot = &node->slots[xas->xa_offset];
+ }
+
+ return entry;
+}
+
+/**
+ * xas_create_range() - Ensure that stores to this range will succeed
+ * @xas: XArray operation state.
+ *
+ * Creates all of the slots in the range covered by @xas. Sets @xas to
+ * create single-index entries and positions it at the beginning of the
+ * range. This is for the benefit of users which have not yet been
+ * converted to use multi-index entries.
+ */
+void xas_create_range(struct xa_state *xas)
+{
+ unsigned long index = xas->xa_index;
+ unsigned char shift = xas->xa_shift;
+ unsigned char sibs = xas->xa_sibs;
+
+ xas->xa_index |= ((sibs + 1) << shift) - 1;
+ if (xas_is_node(xas) && xas->xa_node->shift == xas->xa_shift)
+ xas->xa_offset |= sibs;
+ xas->xa_shift = 0;
+ xas->xa_sibs = 0;
+
+ for (;;) {
+ xas_create(xas, true);
+ if (xas_error(xas))
+ goto restore;
+ if (xas->xa_index <= (index | XA_CHUNK_MASK))
+ goto success;
+ xas->xa_index -= XA_CHUNK_SIZE;
+
+ for (;;) {
+ struct xa_node *node = xas->xa_node;
+ xas->xa_node = xa_parent_locked(xas->xa, node);
+ xas->xa_offset = node->offset - 1;
+ if (node->offset != 0)
+ break;
+ }
+ }
+
+restore:
+ xas->xa_shift = shift;
+ xas->xa_sibs = sibs;
+ xas->xa_index = index;
+ return;
+success:
+ xas->xa_index = index;
+ if (xas->xa_node)
+ xas_set_offset(xas);
+}
+EXPORT_SYMBOL_GPL(xas_create_range);
+
+static void update_node(struct xa_state *xas, struct xa_node *node,
+ int count, int values)
+{
+ if (!node || (!count && !values))
+ return;
+
+ node->count += count;
+ node->nr_values += values;
+ XA_NODE_BUG_ON(node, node->count > XA_CHUNK_SIZE);
+ XA_NODE_BUG_ON(node, node->nr_values > XA_CHUNK_SIZE);
+ xas_update(xas, node);
+ if (count < 0)
+ xas_delete_node(xas);
+}
+
+/**
+ * xas_store() - Store this entry in the XArray.
+ * @xas: XArray operation state.
+ * @entry: New entry.
+ *
+ * If @xas is operating on a multi-index entry, the entry returned by this
+ * function is essentially meaningless (it may be an internal entry or it
+ * may be %NULL, even if there are non-NULL entries at some of the indices
+ * covered by the range). This is not a problem for any current users,
+ * and can be changed if needed.
+ *
+ * Return: The old entry at this index.
+ */
+void *xas_store(struct xa_state *xas, void *entry)
+{
+ struct xa_node *node;
+ void __rcu **slot = &xas->xa->xa_head;
+ unsigned int offset, max;
+ int count = 0;
+ int values = 0;
+ void *first, *next;
+ bool value = xa_is_value(entry);
+
+ if (entry) {
+ bool allow_root = !xa_is_node(entry) && !xa_is_zero(entry);
+ first = xas_create(xas, allow_root);
+ } else {
+ first = xas_load(xas);
+ }
+
+ if (xas_invalid(xas))
+ return first;
+ node = xas->xa_node;
+ if (node && (xas->xa_shift < node->shift))
+ xas->xa_sibs = 0;
+ if ((first == entry) && !xas->xa_sibs)
+ return first;
+
+ next = first;
+ offset = xas->xa_offset;
+ max = xas->xa_offset + xas->xa_sibs;
+ if (node) {
+ slot = &node->slots[offset];
+ if (xas->xa_sibs)
+ xas_squash_marks(xas);
+ }
+ if (!entry)
+ xas_init_marks(xas);
+
+ for (;;) {
+ /*
+ * Must clear the marks before setting the entry to NULL,
+ * otherwise xas_for_each_marked may find a NULL entry and
+ * stop early. rcu_assign_pointer contains a release barrier
+ * so the mark clearing will appear to happen before the
+ * entry is set to NULL.
+ */
+ rcu_assign_pointer(*slot, entry);
+ if (xa_is_node(next) && (!node || node->shift))
+ xas_free_nodes(xas, xa_to_node(next));
+ if (!node)
+ break;
+ count += !next - !entry;
+ values += !xa_is_value(first) - !value;
+ if (entry) {
+ if (offset == max)
+ break;
+ if (!xa_is_sibling(entry))
+ entry = xa_mk_sibling(xas->xa_offset);
+ } else {
+ if (offset == XA_CHUNK_MASK)
+ break;
+ }
+ next = xa_entry_locked(xas->xa, node, ++offset);
+ if (!xa_is_sibling(next)) {
+ if (!entry && (offset > max))
+ break;
+ first = next;
+ }
+ slot++;
+ }
+
+ update_node(xas, node, count, values);
+ return first;
+}
+EXPORT_SYMBOL_GPL(xas_store);
+
+/**
+ * xas_get_mark() - Returns the state of this mark.
+ * @xas: XArray operation state.
+ * @mark: Mark number.
+ *
+ * Return: true if the mark is set, false if the mark is clear or @xas
+ * is in an error state.
+ */
+bool xas_get_mark(const struct xa_state *xas, xa_mark_t mark)
+{
+ if (xas_invalid(xas))
+ return false;
+ if (!xas->xa_node)
+ return xa_marked(xas->xa, mark);
+ return node_get_mark(xas->xa_node, xas->xa_offset, mark);
+}
+EXPORT_SYMBOL_GPL(xas_get_mark);
+
+/**
+ * xas_set_mark() - Sets the mark on this entry and its parents.
+ * @xas: XArray operation state.
+ * @mark: Mark number.
+ *
+ * Sets the specified mark on this entry, and walks up the tree setting it
+ * on all the ancestor entries. Does nothing if @xas has not been walked to
+ * an entry, or is in an error state.
+ */
+void xas_set_mark(const struct xa_state *xas, xa_mark_t mark)
+{
+ struct xa_node *node = xas->xa_node;
+ unsigned int offset = xas->xa_offset;
+
+ if (xas_invalid(xas))
+ return;
+
+ while (node) {
+ if (node_set_mark(node, offset, mark))
+ return;
+ offset = node->offset;
+ node = xa_parent_locked(xas->xa, node);
+ }
+
+ if (!xa_marked(xas->xa, mark))
+ xa_mark_set(xas->xa, mark);
+}
+EXPORT_SYMBOL_GPL(xas_set_mark);
+
+/**
+ * xas_clear_mark() - Clears the mark on this entry and its parents.
+ * @xas: XArray operation state.
+ * @mark: Mark number.
+ *
+ * Clears the specified mark on this entry, and walks back to the head
+ * attempting to clear it on all the ancestor entries. Does nothing if
+ * @xas has not been walked to an entry, or is in an error state.
+ */
+void xas_clear_mark(const struct xa_state *xas, xa_mark_t mark)
+{
+ struct xa_node *node = xas->xa_node;
+ unsigned int offset = xas->xa_offset;
+
+ if (xas_invalid(xas))
+ return;
+
+ while (node) {
+ if (!node_clear_mark(node, offset, mark))
+ return;
+ if (node_any_mark(node, mark))
+ return;
+
+ offset = node->offset;
+ node = xa_parent_locked(xas->xa, node);
+ }
+
+ if (xa_marked(xas->xa, mark))
+ xa_mark_clear(xas->xa, mark);
+}
+EXPORT_SYMBOL_GPL(xas_clear_mark);
+
+/**
+ * xas_init_marks() - Initialise all marks for the entry
+ * @xas: Array operations state.
+ *
+ * Initialise all marks for the entry specified by @xas. If we're tracking
+ * free entries with a mark, we need to set it on all entries. All other
+ * marks are cleared.
+ *
+ * This implementation is not as efficient as it could be; we may walk
+ * up the tree multiple times.
+ */
+void xas_init_marks(const struct xa_state *xas)
+{
+ xa_mark_t mark = 0;
+
+ for (;;) {
+ if (xa_track_free(xas->xa) && mark == XA_FREE_MARK)
+ xas_set_mark(xas, mark);
+ else
+ xas_clear_mark(xas, mark);
+ if (mark == XA_MARK_MAX)
+ break;
+ mark_inc(mark);
+ }
+}
+EXPORT_SYMBOL_GPL(xas_init_marks);
+
+/**
+ * xas_pause() - Pause a walk to drop a lock.
+ * @xas: XArray operation state.
+ *
+ * Some users need to pause a walk and drop the lock they're holding in
+ * order to yield to a higher priority thread or carry out an operation
+ * on an entry. Those users should call this function before they drop
+ * the lock. It resets the @xas to be suitable for the next iteration
+ * of the loop after the user has reacquired the lock. If most entries
+ * found during a walk require you to call xas_pause(), the xa_for_each()
+ * iterator may be more appropriate.
+ *
+ * Note that xas_pause() only works for forward iteration. If a user needs
+ * to pause a reverse iteration, we will need a xas_pause_rev().
+ */
+void xas_pause(struct xa_state *xas)
+{
+ struct xa_node *node = xas->xa_node;
+
+ if (xas_invalid(xas))
+ return;
+
+ if (node) {
+ unsigned int offset = xas->xa_offset;
+ while (++offset < XA_CHUNK_SIZE) {
+ if (!xa_is_sibling(xa_entry(xas->xa, node, offset)))
+ break;
+ }
+ xas->xa_index += (offset - xas->xa_offset) << node->shift;
+ } else {
+ xas->xa_index++;
+ }
+ xas->xa_node = XAS_RESTART;
+}
+EXPORT_SYMBOL_GPL(xas_pause);
+
+/*
+ * __xas_prev() - Find the previous entry in the XArray.
+ * @xas: XArray operation state.
+ *
+ * Helper function for xas_prev() which handles all the complex cases
+ * out of line.
+ */
+void *__xas_prev(struct xa_state *xas)
+{
+ void *entry;
+
+ if (!xas_frozen(xas->xa_node))
+ xas->xa_index--;
+ if (!xas->xa_node)
+ return set_bounds(xas);
+ if (xas_not_node(xas->xa_node))
+ return xas_load(xas);
+
+ if (xas->xa_offset != get_offset(xas->xa_index, xas->xa_node))
+ xas->xa_offset--;
+
+ while (xas->xa_offset == 255) {
+ xas->xa_offset = xas->xa_node->offset - 1;
+ xas->xa_node = xa_parent(xas->xa, xas->xa_node);
+ if (!xas->xa_node)
+ return set_bounds(xas);
+ }
+
+ for (;;) {
+ entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset);
+ if (!xa_is_node(entry))
+ return entry;
+
+ xas->xa_node = xa_to_node(entry);
+ xas_set_offset(xas);
+ }
+}
+EXPORT_SYMBOL_GPL(__xas_prev);
+
+/*
+ * __xas_next() - Find the next entry in the XArray.
+ * @xas: XArray operation state.
+ *
+ * Helper function for xas_next() which handles all the complex cases
+ * out of line.
+ */
+void *__xas_next(struct xa_state *xas)
+{
+ void *entry;
+
+ if (!xas_frozen(xas->xa_node))
+ xas->xa_index++;
+ if (!xas->xa_node)
+ return set_bounds(xas);
+ if (xas_not_node(xas->xa_node))
+ return xas_load(xas);
+
+ if (xas->xa_offset != get_offset(xas->xa_index, xas->xa_node))
+ xas->xa_offset++;
+
+ while (xas->xa_offset == XA_CHUNK_SIZE) {
+ xas->xa_offset = xas->xa_node->offset + 1;
+ xas->xa_node = xa_parent(xas->xa, xas->xa_node);
+ if (!xas->xa_node)
+ return set_bounds(xas);
+ }
+
+ for (;;) {
+ entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset);
+ if (!xa_is_node(entry))
+ return entry;
+
+ xas->xa_node = xa_to_node(entry);
+ xas_set_offset(xas);
+ }
+}
+EXPORT_SYMBOL_GPL(__xas_next);
+
+/**
+ * xas_find() - Find the next present entry in the XArray.
+ * @xas: XArray operation state.
+ * @max: Highest index to return.
+ *
+ * If the @xas has not yet been walked to an entry, return the entry
+ * which has an index >= xas.xa_index. If it has been walked, the entry
+ * currently being pointed at has been processed, and so we move to the
+ * next entry.
+ *
+ * If no entry is found and the array is smaller than @max, the iterator
+ * is set to the smallest index not yet in the array. This allows @xas
+ * to be immediately passed to xas_store().
+ *
+ * Return: The entry, if found, otherwise %NULL.
+ */
+void *xas_find(struct xa_state *xas, unsigned long max)
+{
+ void *entry;
+
+ if (xas_error(xas))
+ return NULL;
+
+ if (!xas->xa_node) {
+ xas->xa_index = 1;
+ return set_bounds(xas);
+ } else if (xas_top(xas->xa_node)) {
+ entry = xas_load(xas);
+ if (entry || xas_not_node(xas->xa_node))
+ return entry;
+ } else if (!xas->xa_node->shift &&
+ xas->xa_offset != (xas->xa_index & XA_CHUNK_MASK)) {
+ xas->xa_offset = ((xas->xa_index - 1) & XA_CHUNK_MASK) + 1;
+ }
+
+ xas_advance(xas);
+
+ while (xas->xa_node && (xas->xa_index <= max)) {
+ if (unlikely(xas->xa_offset == XA_CHUNK_SIZE)) {
+ xas->xa_offset = xas->xa_node->offset + 1;
+ xas->xa_node = xa_parent(xas->xa, xas->xa_node);
+ continue;
+ }
+
+ entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset);
+ if (xa_is_node(entry)) {
+ xas->xa_node = xa_to_node(entry);
+ xas->xa_offset = 0;
+ continue;
+ }
+ if (entry && !xa_is_sibling(entry))
+ return entry;
+
+ xas_advance(xas);
+ }
+
+ if (!xas->xa_node)
+ xas->xa_node = XAS_BOUNDS;
+ return NULL;
+}
+EXPORT_SYMBOL_GPL(xas_find);
+
+/**
+ * xas_find_marked() - Find the next marked entry in the XArray.
+ * @xas: XArray operation state.
+ * @max: Highest index to return.
+ * @mark: Mark number to search for.
+ *
+ * If the @xas has not yet been walked to an entry, return the marked entry
+ * which has an index >= xas.xa_index. If it has been walked, the entry
+ * currently being pointed at has been processed, and so we return the
+ * first marked entry with an index > xas.xa_index.
+ *
+ * If no marked entry is found and the array is smaller than @max, @xas is
+ * set to the bounds state and xas->xa_index is set to the smallest index
+ * not yet in the array. This allows @xas to be immediately passed to
+ * xas_store().
+ *
+ * If no entry is found before @max is reached, @xas is set to the restart
+ * state.
+ *
+ * Return: The entry, if found, otherwise %NULL.
+ */
+void *xas_find_marked(struct xa_state *xas, unsigned long max, xa_mark_t mark)
+{
+ bool advance = true;
+ unsigned int offset;
+ void *entry;
+
+ if (xas_error(xas))
+ return NULL;
+
+ if (!xas->xa_node) {
+ xas->xa_index = 1;
+ goto out;
+ } else if (xas_top(xas->xa_node)) {
+ advance = false;
+ entry = xa_head(xas->xa);
+ xas->xa_node = NULL;
+ if (xas->xa_index > max_index(entry))
+ goto out;
+ if (!xa_is_node(entry)) {
+ if (xa_marked(xas->xa, mark))
+ return entry;
+ xas->xa_index = 1;
+ goto out;
+ }
+ xas->xa_node = xa_to_node(entry);
+ xas->xa_offset = xas->xa_index >> xas->xa_node->shift;
+ }
+
+ while (xas->xa_index <= max) {
+ if (unlikely(xas->xa_offset == XA_CHUNK_SIZE)) {
+ xas->xa_offset = xas->xa_node->offset + 1;
+ xas->xa_node = xa_parent(xas->xa, xas->xa_node);
+ if (!xas->xa_node)
+ break;
+ advance = false;
+ continue;
+ }
+
+ if (!advance) {
+ entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset);
+ if (xa_is_sibling(entry)) {
+ xas->xa_offset = xa_to_sibling(entry);
+ xas_move_index(xas, xas->xa_offset);
+ }
+ }
+
+ offset = xas_find_chunk(xas, advance, mark);
+ if (offset > xas->xa_offset) {
+ advance = false;
+ xas_move_index(xas, offset);
+ /* Mind the wrap */
+ if ((xas->xa_index - 1) >= max)
+ goto max;
+ xas->xa_offset = offset;
+ if (offset == XA_CHUNK_SIZE)
+ continue;
+ }
+
+ entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset);
+ if (!xa_is_node(entry))
+ return entry;
+ xas->xa_node = xa_to_node(entry);
+ xas_set_offset(xas);
+ }
+
+out:
+ if (xas->xa_index > max)
+ goto max;
+ return set_bounds(xas);
+max:
+ xas->xa_node = XAS_RESTART;
+ return NULL;
+}
+EXPORT_SYMBOL_GPL(xas_find_marked);
+
+/**
+ * xas_find_conflict() - Find the next present entry in a range.
+ * @xas: XArray operation state.
+ *
+ * The @xas describes both a range and a position within that range.
+ *
+ * Context: Any context. Expects xa_lock to be held.
+ * Return: The next entry in the range covered by @xas or %NULL.
+ */
+void *xas_find_conflict(struct xa_state *xas)
+{
+ void *curr;
+
+ if (xas_error(xas))
+ return NULL;
+
+ if (!xas->xa_node)
+ return NULL;
+
+ if (xas_top(xas->xa_node)) {
+ curr = xas_start(xas);
+ if (!curr)
+ return NULL;
+ while (xa_is_node(curr)) {
+ struct xa_node *node = xa_to_node(curr);
+ curr = xas_descend(xas, node);
+ }
+ if (curr)
+ return curr;
+ }
+
+ if (xas->xa_node->shift > xas->xa_shift)
+ return NULL;
+
+ for (;;) {
+ if (xas->xa_node->shift == xas->xa_shift) {
+ if ((xas->xa_offset & xas->xa_sibs) == xas->xa_sibs)
+ break;
+ } else if (xas->xa_offset == XA_CHUNK_MASK) {
+ xas->xa_offset = xas->xa_node->offset;
+ xas->xa_node = xa_parent_locked(xas->xa, xas->xa_node);
+ if (!xas->xa_node)
+ break;
+ continue;
+ }
+ curr = xa_entry_locked(xas->xa, xas->xa_node, ++xas->xa_offset);
+ if (xa_is_sibling(curr))
+ continue;
+ while (xa_is_node(curr)) {
+ xas->xa_node = xa_to_node(curr);
+ xas->xa_offset = 0;
+ curr = xa_entry_locked(xas->xa, xas->xa_node, 0);
+ }
+ if (curr)
+ return curr;
+ }
+ xas->xa_offset -= xas->xa_sibs;
+ return NULL;
+}
+EXPORT_SYMBOL_GPL(xas_find_conflict);
+
+/**
+ * xa_load() - Load an entry from an XArray.
+ * @xa: XArray.
+ * @index: index into array.
+ *
+ * Context: Any context. Takes and releases the RCU lock.
+ * Return: The entry at @index in @xa.
+ */
+void *xa_load(struct xarray *xa, unsigned long index)
+{
+ XA_STATE(xas, xa, index);
+ void *entry;
+
+ rcu_read_lock();
+ do {
+ entry = xas_load(&xas);
+ if (xa_is_zero(entry))
+ entry = NULL;
+ } while (xas_retry(&xas, entry));
+ rcu_read_unlock();
+
+ return entry;
+}
+EXPORT_SYMBOL(xa_load);
+
+static void *xas_result(struct xa_state *xas, void *curr)
+{
+ if (xa_is_zero(curr))
+ return NULL;
+ if (xas_error(xas))
+ curr = xas->xa_node;
+ return curr;
+}
+
+/**
+ * __xa_erase() - Erase this entry from the XArray while locked.
+ * @xa: XArray.
+ * @index: Index into array.
+ *
+ * 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. Expects xa_lock to be held on entry.
+ * Return: The entry which used to be at this index.
+ */
+void *__xa_erase(struct xarray *xa, unsigned long index)
+{
+ XA_STATE(xas, xa, index);
+ return xas_result(&xas, xas_store(&xas, NULL));
+}
+EXPORT_SYMBOL(__xa_erase);
+
+/**
+ * xa_erase() - 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.
+ * Return: The entry which used to be at this index.
+ */
+void *xa_erase(struct xarray *xa, unsigned long index)
+{
+ void *entry;
+
+ xa_lock(xa);
+ entry = __xa_erase(xa, index);
+ xa_unlock(xa);
+
+ return entry;
+}
+EXPORT_SYMBOL(xa_erase);
+
+/**
+ * __xa_store() - Store this entry in the XArray.
+ * @xa: XArray.
+ * @index: Index into array.
+ * @entry: New entry.
+ * @gfp: Memory allocation flags.
+ *
+ * You must already be holding the xa_lock when calling this function.
+ * It will drop the lock if needed to allocate memory, and then reacquire
+ * it afterwards.
+ *
+ * Context: Any context. Expects xa_lock to be held on entry. May
+ * release and reacquire xa_lock if @gfp flags permit.
+ * Return: The old entry at this index or xa_err() if an error happened.
+ */
+void *__xa_store(struct xarray *xa, unsigned long index, void *entry, gfp_t gfp)
+{
+ XA_STATE(xas, xa, index);
+ void *curr;
+
+ if (WARN_ON_ONCE(xa_is_advanced(entry)))
+ return XA_ERROR(-EINVAL);
+ if (xa_track_free(xa) && !entry)
+ entry = XA_ZERO_ENTRY;
+
+ do {
+ curr = xas_store(&xas, entry);
+ if (xa_track_free(xa))
+ xas_clear_mark(&xas, XA_FREE_MARK);
+ } while (__xas_nomem(&xas, gfp));
+
+ return xas_result(&xas, curr);
+}
+EXPORT_SYMBOL(__xa_store);
+
+/**
+ * xa_store() - Store this entry in the XArray.
+ * @xa: XArray.
+ * @index: Index into array.
+ * @entry: New entry.
+ * @gfp: Memory allocation flags.
+ *
+ * After this function returns, loads from this index will return @entry.
+ * Storing into an existing multislot entry updates the entry of every index.
+ * The marks associated with @index are unaffected unless @entry is %NULL.
+ *
+ * Context: Any context. Takes and releases the xa_lock.
+ * May sleep if the @gfp flags permit.
+ * Return: The old entry at this index on success, xa_err(-EINVAL) if @entry
+ * cannot be stored in an XArray, or xa_err(-ENOMEM) if memory allocation
+ * failed.
+ */
+void *xa_store(struct xarray *xa, unsigned long index, void *entry, gfp_t gfp)
+{
+ void *curr;
+
+ xa_lock(xa);
+ curr = __xa_store(xa, index, entry, gfp);
+ xa_unlock(xa);
+
+ return curr;
+}
+EXPORT_SYMBOL(xa_store);
+
+/**
+ * __xa_cmpxchg() - Store this entry in the XArray.
+ * @xa: XArray.
+ * @index: Index into array.
+ * @old: Old value to test against.
+ * @entry: New entry.
+ * @gfp: Memory allocation flags.
+ *
+ * You must already be holding the xa_lock when calling this function.
+ * It will drop the lock if needed to allocate memory, and then reacquire
+ * it afterwards.
+ *
+ * Context: Any context. Expects xa_lock to be held on entry. May
+ * release and reacquire xa_lock if @gfp flags permit.
+ * Return: The old entry at this index or xa_err() if an error happened.
+ */
+void *__xa_cmpxchg(struct xarray *xa, unsigned long index,
+ void *old, void *entry, gfp_t gfp)
+{
+ XA_STATE(xas, xa, index);
+ void *curr;
+
+ if (WARN_ON_ONCE(xa_is_advanced(entry)))
+ return XA_ERROR(-EINVAL);
+
+ do {
+ curr = xas_load(&xas);
+ if (curr == old) {
+ xas_store(&xas, entry);
+ if (xa_track_free(xa) && entry && !curr)
+ xas_clear_mark(&xas, XA_FREE_MARK);
+ }
+ } while (__xas_nomem(&xas, gfp));
+
+ return xas_result(&xas, curr);
+}
+EXPORT_SYMBOL(__xa_cmpxchg);
+
+/**
+ * __xa_insert() - Store this entry in the XArray if no entry is 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. Expects xa_lock to be held on entry. May
+ * release and reacquire xa_lock if @gfp flags permit.
+ * Return: 0 if the store succeeded. -EBUSY if another entry was present.
+ * -ENOMEM if memory could not be allocated.
+ */
+int __xa_insert(struct xarray *xa, unsigned long index, void *entry, gfp_t gfp)
+{
+ XA_STATE(xas, xa, index);
+ void *curr;
+
+ if (WARN_ON_ONCE(xa_is_advanced(entry)))
+ return -EINVAL;
+ if (!entry)
+ entry = XA_ZERO_ENTRY;
+
+ do {
+ curr = xas_load(&xas);
+ if (!curr) {
+ xas_store(&xas, entry);
+ if (xa_track_free(xa))
+ xas_clear_mark(&xas, XA_FREE_MARK);
+ } else {
+ xas_set_err(&xas, -EBUSY);
+ }
+ } while (__xas_nomem(&xas, gfp));
+
+ return xas_error(&xas);
+}
+EXPORT_SYMBOL(__xa_insert);
+
+#ifdef CONFIG_XARRAY_MULTI
+static void xas_set_range(struct xa_state *xas, unsigned long first,
+ unsigned long last)
+{
+ unsigned int shift = 0;
+ unsigned long sibs = last - first;
+ unsigned int offset = XA_CHUNK_MASK;
+
+ xas_set(xas, first);
+
+ while ((first & XA_CHUNK_MASK) == 0) {
+ if (sibs < XA_CHUNK_MASK)
+ break;
+ if ((sibs == XA_CHUNK_MASK) && (offset < XA_CHUNK_MASK))
+ break;
+ shift += XA_CHUNK_SHIFT;
+ if (offset == XA_CHUNK_MASK)
+ offset = sibs & XA_CHUNK_MASK;
+ sibs >>= XA_CHUNK_SHIFT;
+ first >>= XA_CHUNK_SHIFT;
+ }
+
+ offset = first & XA_CHUNK_MASK;
+ if (offset + sibs > XA_CHUNK_MASK)
+ sibs = XA_CHUNK_MASK - offset;
+ if ((((first + sibs + 1) << shift) - 1) > last)
+ sibs -= 1;
+
+ xas->xa_shift = shift;
+ xas->xa_sibs = sibs;
+}
+
+/**
+ * xa_store_range() - Store this entry at a range of indices in the XArray.
+ * @xa: XArray.
+ * @first: First index to affect.
+ * @last: Last index to affect.
+ * @entry: New entry.
+ * @gfp: Memory allocation flags.
+ *
+ * After this function returns, loads from any index between @first and @last,
+ * inclusive will return @entry.
+ * Storing into an existing multislot entry updates the entry of every index.
+ * The marks associated with @index are unaffected unless @entry is %NULL.
+ *
+ * Context: Process context. Takes and releases the xa_lock. May sleep
+ * if the @gfp flags permit.
+ * Return: %NULL on success, xa_err(-EINVAL) if @entry cannot be stored in
+ * an XArray, or xa_err(-ENOMEM) if memory allocation failed.
+ */
+void *xa_store_range(struct xarray *xa, unsigned long first,
+ unsigned long last, void *entry, gfp_t gfp)
+{
+ XA_STATE(xas, xa, 0);
+
+ if (WARN_ON_ONCE(xa_is_internal(entry)))
+ return XA_ERROR(-EINVAL);
+ if (last < first)
+ return XA_ERROR(-EINVAL);
+
+ do {
+ xas_lock(&xas);
+ if (entry) {
+ unsigned int order = BITS_PER_LONG;
+ if (last + 1)
+ order = __ffs(last + 1);
+ xas_set_order(&xas, last, order);
+ xas_create(&xas, true);
+ if (xas_error(&xas))
+ goto unlock;
+ }
+ do {
+ xas_set_range(&xas, first, last);
+ xas_store(&xas, entry);
+ if (xas_error(&xas))
+ goto unlock;
+ first += xas_size(&xas);
+ } while (first <= last);
+unlock:
+ xas_unlock(&xas);
+ } while (xas_nomem(&xas, gfp));
+
+ return xas_result(&xas, NULL);
+}
+EXPORT_SYMBOL(xa_store_range);
+#endif /* CONFIG_XARRAY_MULTI */
+
+/**
+ * __xa_alloc() - Find somewhere to store this entry in the XArray.
+ * @xa: XArray.
+ * @id: Pointer to ID.
+ * @limit: Range for allocated ID.
+ * @entry: New entry.
+ * @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. Expects xa_lock to be held on entry. May
+ * release and reacquire xa_lock if @gfp flags permit.
+ * Return: 0 on success, -ENOMEM if memory could not be allocated or
+ * -EBUSY if there are no free entries in @limit.
+ */
+int __xa_alloc(struct xarray *xa, u32 *id, void *entry,
+ struct xa_limit limit, gfp_t gfp)
+{
+ XA_STATE(xas, xa, 0);
+
+ if (WARN_ON_ONCE(xa_is_advanced(entry)))
+ return -EINVAL;
+ if (WARN_ON_ONCE(!xa_track_free(xa)))
+ return -EINVAL;
+
+ if (!entry)
+ entry = XA_ZERO_ENTRY;
+
+ do {
+ xas.xa_index = limit.min;
+ xas_find_marked(&xas, limit.max, XA_FREE_MARK);
+ if (xas.xa_node == XAS_RESTART)
+ xas_set_err(&xas, -EBUSY);
+ else
+ *id = xas.xa_index;
+ xas_store(&xas, entry);
+ xas_clear_mark(&xas, XA_FREE_MARK);
+ } while (__xas_nomem(&xas, gfp));
+
+ return xas_error(&xas);
+}
+EXPORT_SYMBOL(__xa_alloc);
+
+/**
+ * __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. Expects xa_lock to be held on entry. May
+ * release and reacquire xa_lock if @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.
+ */
+int __xa_alloc_cyclic(struct xarray *xa, u32 *id, void *entry,
+ struct xa_limit limit, u32 *next, gfp_t gfp)
+{
+ u32 min = limit.min;
+ int ret;
+
+ limit.min = max(min, *next);
+ ret = __xa_alloc(xa, id, entry, limit, gfp);
+ if ((xa->xa_flags & XA_FLAGS_ALLOC_WRAPPED) && ret == 0) {
+ xa->xa_flags &= ~XA_FLAGS_ALLOC_WRAPPED;
+ ret = 1;
+ }
+
+ if (ret < 0 && limit.min > min) {
+ limit.min = min;
+ ret = __xa_alloc(xa, id, entry, limit, gfp);
+ if (ret == 0)
+ ret = 1;
+ }
+
+ if (ret >= 0) {
+ *next = *id + 1;
+ if (*next == 0)
+ xa->xa_flags |= XA_FLAGS_ALLOC_WRAPPED;
+ }
+ return ret;
+}
+EXPORT_SYMBOL(__xa_alloc_cyclic);
+
+/**
+ * __xa_set_mark() - Set this mark on this entry while locked.
+ * @xa: XArray.
+ * @index: Index of entry.
+ * @mark: Mark number.
+ *
+ * Attempting to set a mark on a %NULL entry does not succeed.
+ *
+ * Context: Any context. Expects xa_lock to be held on entry.
+ */
+void __xa_set_mark(struct xarray *xa, unsigned long index, xa_mark_t mark)
+{
+ XA_STATE(xas, xa, index);
+ void *entry = xas_load(&xas);
+
+ if (entry)
+ xas_set_mark(&xas, mark);
+}
+EXPORT_SYMBOL(__xa_set_mark);
+
+/**
+ * __xa_clear_mark() - Clear this mark on this entry while locked.
+ * @xa: XArray.
+ * @index: Index of entry.
+ * @mark: Mark number.
+ *
+ * Context: Any context. Expects xa_lock to be held on entry.
+ */
+void __xa_clear_mark(struct xarray *xa, unsigned long index, xa_mark_t mark)
+{
+ XA_STATE(xas, xa, index);
+ void *entry = xas_load(&xas);
+
+ if (entry)
+ xas_clear_mark(&xas, mark);
+}
+EXPORT_SYMBOL(__xa_clear_mark);
+
+/**
+ * xa_get_mark() - Inquire whether this mark is set on this entry.
+ * @xa: XArray.
+ * @index: Index of entry.
+ * @mark: Mark number.
+ *
+ * This function uses the RCU read lock, so the result may be out of date
+ * by the time it returns. If you need the result to be stable, use a lock.
+ *
+ * Context: Any context. Takes and releases the RCU lock.
+ * Return: True if the entry at @index has this mark set, false if it doesn't.
+ */
+bool xa_get_mark(struct xarray *xa, unsigned long index, xa_mark_t mark)
+{
+ XA_STATE(xas, xa, index);
+ void *entry;
+
+ rcu_read_lock();
+ entry = xas_start(&xas);
+ while (xas_get_mark(&xas, mark)) {
+ if (!xa_is_node(entry))
+ goto found;
+ entry = xas_descend(&xas, xa_to_node(entry));
+ }
+ rcu_read_unlock();
+ return false;
+ found:
+ rcu_read_unlock();
+ return true;
+}
+EXPORT_SYMBOL(xa_get_mark);
+
+/**
+ * xa_set_mark() - Set this mark on this entry.
+ * @xa: XArray.
+ * @index: Index of entry.
+ * @mark: Mark number.
+ *
+ * Attempting to set a mark on a %NULL entry does not succeed.
+ *
+ * Context: Process context. Takes and releases the xa_lock.
+ */
+void xa_set_mark(struct xarray *xa, unsigned long index, xa_mark_t mark)
+{
+ xa_lock(xa);
+ __xa_set_mark(xa, index, mark);
+ xa_unlock(xa);
+}
+EXPORT_SYMBOL(xa_set_mark);
+
+/**
+ * xa_clear_mark() - Clear this mark on this entry.
+ * @xa: XArray.
+ * @index: Index of entry.
+ * @mark: Mark number.
+ *
+ * Clearing a mark always succeeds.
+ *
+ * Context: Process context. Takes and releases the xa_lock.
+ */
+void xa_clear_mark(struct xarray *xa, unsigned long index, xa_mark_t mark)
+{
+ xa_lock(xa);
+ __xa_clear_mark(xa, index, mark);
+ xa_unlock(xa);
+}
+EXPORT_SYMBOL(xa_clear_mark);
+
+/**
+ * xa_find() - Search the XArray for an entry.
+ * @xa: XArray.
+ * @indexp: Pointer to an index.
+ * @max: Maximum index to search to.
+ * @filter: Selection criterion.
+ *
+ * Finds the entry in @xa which matches the @filter, and has the lowest
+ * index that is at least @indexp and no more than @max.
+ * If an entry is found, @indexp is updated to be the index of the entry.
+ * This function is protected by the RCU read lock, so it may not find
+ * entries which are being simultaneously added. It will not return an
+ * %XA_RETRY_ENTRY; if you need to see retry entries, use xas_find().
+ *
+ * Context: Any context. Takes and releases the RCU lock.
+ * Return: The entry, if found, otherwise %NULL.
+ */
+void *xa_find(struct xarray *xa, unsigned long *indexp,
+ unsigned long max, xa_mark_t filter)
+{
+ XA_STATE(xas, xa, *indexp);
+ void *entry;
+
+ rcu_read_lock();
+ do {
+ if ((__force unsigned int)filter < XA_MAX_MARKS)
+ entry = xas_find_marked(&xas, max, filter);
+ else
+ entry = xas_find(&xas, max);
+ } while (xas_retry(&xas, entry));
+ rcu_read_unlock();
+
+ if (entry)
+ *indexp = xas.xa_index;
+ return entry;
+}
+EXPORT_SYMBOL(xa_find);
+
+/**
+ * xa_find_after() - Search the XArray for a present entry.
+ * @xa: XArray.
+ * @indexp: Pointer to an index.
+ * @max: Maximum index to search to.
+ * @filter: Selection criterion.
+ *
+ * Finds the entry in @xa which matches the @filter and has the lowest
+ * index that is above @indexp and no more than @max.
+ * If an entry is found, @indexp is updated to be the index of the entry.
+ * This function is protected by the RCU read lock, so it may miss entries
+ * which are being simultaneously added. It will not return an
+ * %XA_RETRY_ENTRY; if you need to see retry entries, use xas_find().
+ *
+ * Context: Any context. Takes and releases the RCU lock.
+ * Return: The pointer, if found, otherwise %NULL.
+ */
+void *xa_find_after(struct xarray *xa, unsigned long *indexp,
+ unsigned long max, xa_mark_t filter)
+{
+ XA_STATE(xas, xa, *indexp + 1);
+ void *entry;
+
+ rcu_read_lock();
+ for (;;) {
+ if ((__force unsigned int)filter < XA_MAX_MARKS)
+ entry = xas_find_marked(&xas, max, filter);
+ else
+ entry = xas_find(&xas, max);
+ if (xas.xa_node == XAS_BOUNDS)
+ break;
+ if (xas.xa_shift) {
+ if (xas.xa_index & ((1UL << xas.xa_shift) - 1))
+ continue;
+ } else {
+ if (xas.xa_offset < (xas.xa_index & XA_CHUNK_MASK))
+ continue;
+ }
+ if (!xas_retry(&xas, entry))
+ break;
+ }
+ rcu_read_unlock();
+
+ if (entry)
+ *indexp = xas.xa_index;
+ return entry;
+}
+EXPORT_SYMBOL(xa_find_after);
+
+static unsigned int xas_extract_present(struct xa_state *xas, void **dst,
+ unsigned long max, unsigned int n)
+{
+ void *entry;
+ unsigned int i = 0;
+
+ rcu_read_lock();
+ xas_for_each(xas, entry, max) {
+ if (xas_retry(xas, entry))
+ continue;
+ dst[i++] = entry;
+ if (i == n)
+ break;
+ }
+ rcu_read_unlock();
+
+ return i;
+}
+
+static unsigned int xas_extract_marked(struct xa_state *xas, void **dst,
+ unsigned long max, unsigned int n, xa_mark_t mark)
+{
+ void *entry;
+ unsigned int i = 0;
+
+ rcu_read_lock();
+ xas_for_each_marked(xas, entry, max, mark) {
+ if (xas_retry(xas, entry))
+ continue;
+ dst[i++] = entry;
+ if (i == n)
+ break;
+ }
+ rcu_read_unlock();
+
+ return i;
+}
+
+/**
+ * xa_extract() - Copy selected entries from the XArray into a normal array.
+ * @xa: The source XArray to copy from.
+ * @dst: The buffer to copy entries into.
+ * @start: The first index in the XArray eligible to be selected.
+ * @max: The last index in the XArray eligible to be selected.
+ * @n: The maximum number of entries to copy.
+ * @filter: Selection criterion.
+ *
+ * Copies up to @n entries that match @filter from the XArray. The
+ * copied entries will have indices between @start and @max, inclusive.
+ *
+ * The @filter may be an XArray mark value, in which case entries which are
+ * marked with that mark will be copied. It may also be %XA_PRESENT, in
+ * which case all entries which are not %NULL will be copied.
+ *
+ * The entries returned may not represent a snapshot of the XArray at a
+ * moment in time. For example, if another thread stores to index 5, then
+ * index 10, calling xa_extract() may return the old contents of index 5
+ * and the new contents of index 10. Indices not modified while this
+ * function is running will not be skipped.
+ *
+ * If you need stronger guarantees, holding the xa_lock across calls to this
+ * function will prevent concurrent modification.
+ *
+ * Context: Any context. Takes and releases the RCU lock.
+ * Return: The number of entries copied.
+ */
+unsigned int xa_extract(struct xarray *xa, void **dst, unsigned long start,
+ unsigned long max, unsigned int n, xa_mark_t filter)
+{
+ XA_STATE(xas, xa, start);
+
+ if (!n)
+ return 0;
+
+ if ((__force unsigned int)filter < XA_MAX_MARKS)
+ return xas_extract_marked(&xas, dst, max, n, filter);
+ return xas_extract_present(&xas, dst, max, n);
+}
+EXPORT_SYMBOL(xa_extract);
+
+/**
+ * xa_destroy() - Free all internal data structures.
+ * @xa: XArray.
+ *
+ * After calling this function, the XArray is empty and has freed all memory
+ * allocated for its internal data structures. You are responsible for
+ * freeing the objects referenced by the XArray.
+ *
+ * Context: Any context. Takes and releases the xa_lock, interrupt-safe.
+ */
+void xa_destroy(struct xarray *xa)
+{
+ XA_STATE(xas, xa, 0);
+ unsigned long flags;
+ void *entry;
+
+ xas.xa_node = NULL;
+ xas_lock_irqsave(&xas, flags);
+ entry = xa_head_locked(xa);
+ RCU_INIT_POINTER(xa->xa_head, NULL);
+ xas_init_marks(&xas);
+ if (xa_zero_busy(xa))
+ xa_mark_clear(xa, XA_FREE_MARK);
+ /* lockdep checks we're still holding the lock in xas_free_nodes() */
+ if (xa_is_node(entry))
+ xas_free_nodes(&xas, xa_to_node(entry));
+ xas_unlock_irqrestore(&xas, flags);
+}
+EXPORT_SYMBOL(xa_destroy);
+
+#ifdef XA_DEBUG
+void xa_dump_node(const struct xa_node *node)
+{
+ unsigned i, j;
+
+ if (!node)
+ return;
+ if ((unsigned long)node & 3) {
+ pr_cont("node %px\n", node);
+ return;
+ }
+
+ pr_cont("node %px %s %d parent %px shift %d count %d values %d "
+ "array %px list %px %px marks",
+ node, node->parent ? "offset" : "max", node->offset,
+ node->parent, node->shift, node->count, node->nr_values,
+ node->array, node->private_list.prev, node->private_list.next);
+ for (i = 0; i < XA_MAX_MARKS; i++)
+ for (j = 0; j < XA_MARK_LONGS; j++)
+ pr_cont(" %lx", node->marks[i][j]);
+ pr_cont("\n");
+}
+
+void xa_dump_index(unsigned long index, unsigned int shift)
+{
+ if (!shift)
+ pr_info("%lu: ", index);
+ else if (shift >= BITS_PER_LONG)
+ pr_info("0-%lu: ", ~0UL);
+ else
+ pr_info("%lu-%lu: ", index, index | ((1UL << shift) - 1));
+}
+
+void xa_dump_entry(const void *entry, unsigned long index, unsigned long shift)
+{
+ if (!entry)
+ return;
+
+ xa_dump_index(index, shift);
+
+ if (xa_is_node(entry)) {
+ if (shift == 0) {
+ pr_cont("%px\n", entry);
+ } else {
+ unsigned long i;
+ struct xa_node *node = xa_to_node(entry);
+ xa_dump_node(node);
+ for (i = 0; i < XA_CHUNK_SIZE; i++)
+ xa_dump_entry(node->slots[i],
+ index + (i << node->shift), node->shift);
+ }
+ } else if (xa_is_value(entry))
+ pr_cont("value %ld (0x%lx) [%px]\n", xa_to_value(entry),
+ xa_to_value(entry), entry);
+ else if (!xa_is_internal(entry))
+ pr_cont("%px\n", entry);
+ else if (xa_is_retry(entry))
+ pr_cont("retry (%ld)\n", xa_to_internal(entry));
+ else if (xa_is_sibling(entry))
+ pr_cont("sibling (slot %ld)\n", xa_to_sibling(entry));
+ else if (xa_is_zero(entry))
+ pr_cont("zero (%ld)\n", xa_to_internal(entry));
+ else
+ pr_cont("UNKNOWN ENTRY (%px)\n", entry);
+}
+
+void xa_dump(const struct xarray *xa)
+{
+ void *entry = xa->xa_head;
+ unsigned int shift = 0;
+
+ pr_info("xarray: %px head %px flags %x marks %d %d %d\n", xa, entry,
+ xa->xa_flags, xa_marked(xa, XA_MARK_0),
+ xa_marked(xa, XA_MARK_1), xa_marked(xa, XA_MARK_2));
+ if (xa_is_node(entry))
+ shift = xa_to_node(entry)->shift + XA_CHUNK_SHIFT;
+ xa_dump_entry(entry, 0, shift);
+}
+#endif
+#endif /* HAVE_RADIX_TREE_EXCEPTIONAL_ENTRY */
]) # LC_INODE_TIMESPEC64
#
-# LC_XA_IS_VALUE
-# kernel 4.19-rc6 commit 3159f943aafdbacb2f94c38fdaadabf2bbde2a14
-# xarray: Replace exceptional entries
-# adds xa_is_value
-#
-AC_DEFUN([LC_XA_IS_VALUE], [
-LB_CHECK_COMPILE([xa_is_value exist],
-xa_is_value, [
- #include <linux/xarray.h>
-],[
- xa_is_value(NULL);
-],[
- AC_DEFINE(HAVE_XA_IS_VALUE, 1, [xa_is_value exist])
-])
-]) # LC_XA_IS_VALUE
-
-#
# LC___XA_SET_MARK
#
# kernel 4.20 commit v4.19-rc5-248-g9b89a0355144
-# xarray: Add XArray marks
+# xarray: Add XArray marks - replaced radix_tree_tag_set
#
AC_DEFUN([LC___XA_SET_MARK], [
+tmp_flags="$EXTRA_KCFLAGS"
+EXTRA_KCFLAGS="-Werror"
LB_CHECK_COMPILE([if '__xa_set_mark' exists],
__xa_set_mark, [
- #include <linux/xarray.h>
#include <linux/fs.h>
+ #include <linux/radix-tree.h>
],[
- struct xarray *xa = NULL;
-
- __xa_set_mark(xa, 0, PAGECACHE_TAG_DIRTY);
+ radix_tree_tag_set(NULL, 0, PAGECACHE_TAG_DIRTY);
],[
- AC_DEFINE(HAVE___XA_SET_MARK, 1,
+ AC_DEFINE(HAVE_RADIX_TREE_TAG_SET, 1,
[__xa_set_mark exists])
])
+EXTRA_KCFLAGS="$tmp_flags"
]) # LC___XA_SET_MARK
#
# 4.18
LC_INODE_TIMESPEC64
- LC_XA_IS_VALUE
# 4.20
LC___XA_SET_MARK
# define inode_trylock(inode) mutex_trylock(&(inode)->i_mutex)
#endif
-#ifndef HAVE_XA_IS_VALUE
-static inline bool xa_is_value(void *entry)
+/* Old kernels lacked both Xarray support and the page cache
+ * using Xarrays. Our back ported Xarray support introduces
+ * the real xa_is_value() but we need a wrapper as well for
+ * the page cache interaction. Lets keep xa_is_value() separate
+ * in old kernels for Xarray support and page cache handling.
+ */
+#ifdef HAVE_RADIX_TREE_EXCEPTIONAL_ENTRY
+static inline bool ll_xa_is_value(void *entry)
{
return radix_tree_exceptional_entry(entry);
}
+#else
+#define ll_xa_is_value xa_is_value
#endif
#ifndef HAVE_TRUNCATE_INODE_PAGES_FINAL
#ifdef HAVE_I_PAGES
#define page_tree i_pages
+#define ll_xa_lock_irqsave(lockp, flags) xa_lock_irqsave(lockp, flags)
+#define ll_xa_unlock_irqrestore(lockp, flags) xa_unlock_irqrestore(lockp, flags)
#else
#define i_pages tree_lock
-#endif
-
-#ifndef xa_lock_irqsave
-#define xa_lock_irqsave(lockp, flags) spin_lock_irqsave(lockp, flags)
-#define xa_unlock_irqrestore(lockp, flags) spin_unlock_irqrestore(lockp, flags)
+#define ll_xa_lock_irqsave(lockp, flags) spin_lock_irqsave(lockp, flags)
+#define ll_xa_unlock_irqrestore(lockp, flags) spin_unlock_irqrestore(lockp, flags)
#endif
#ifndef HAVE_LOCK_PAGE_MEMCG
#include <linux/kobject.h>
#include <linux/spinlock.h>
#include <linux/sysfs.h>
+#include <linux/xarray.h>
#include <uapi/linux/lustre/lustre_idl.h>
#include <lustre_lib.h>
*/
nrpages = mapping->nrpages;
if (nrpages) {
- xa_lock_irqsave(&mapping->i_pages, flags);
+ ll_xa_lock_irqsave(&mapping->i_pages, flags);
nrpages = mapping->nrpages;
- xa_unlock_irqrestore(&mapping->i_pages, flags);
+ ll_xa_unlock_irqrestore(&mapping->i_pages, flags);
} /* Workaround end */
LASSERTF(nrpages == 0, "%s: inode="DFID"(%p) nrpages=%lu, "
#define DEBUG_SUBSYSTEM S_LLITE
-
#include <obd.h>
#include <linux/pagevec.h>
#include <linux/memcontrol.h>
+
#include "llite_internal.h"
#include "vvp_internal.h"
#include <libcfs/linux/linux-misc.h>
static inline void ll_page_tag_dirty(struct page *page,
struct address_space *mapping)
{
-#ifdef HAVE___XA_SET_MARK
+#ifndef HAVE_RADIX_TREE_TAG_SET
__xa_set_mark(&mapping->i_pages, page_index(page), PAGECACHE_TAG_DIRTY);
#else
radix_tree_tag_set(&mapping->page_tree, page_index(page),
page, (void *) page->private);
/* Rest of code derived from __set_page_dirty_nobuffers */
- xa_lock_irqsave(&mapping->i_pages, flags);
+ ll_xa_lock_irqsave(&mapping->i_pages, flags);
/* Notes on differences with __set_page_dirty_nobuffers:
* 1. We don't need to call page_mapping because we know this is a page
dirtied++;
unlock_page_memcg(page);
}
- xa_unlock_irqrestore(&mapping->i_pages, flags);
+ ll_xa_unlock_irqrestore(&mapping->i_pages, flags);
CDEBUG(D_VFSTRACE, "mapping %p, count %d, dirtied %d\n", mapping,
count, dirtied);
#include <linux/delay.h>
#include <linux/uidgid.h>
#include <linux/device.h>
+#include <linux/xarray.h>
#include <lustre_errno.h>
#include <llog_swab.h>
#include <lprocfs_status.h>
#include <lustre_acl.h>
+#include <lustre_compat.h>
#include <lustre_fid.h>
#include <uapi/linux/lustre/lustre_ioctl.h>
#include <lustre_kernelcomm.h>
#else
#define mdc_unpack_acl(req, md) 0
#endif
-#ifdef HAVE_XA_IS_VALUE
-# include <linux/xarray.h>
-#endif
int mdc_get_lustre_md(struct obd_export *exp, struct ptlrpc_request *req,
struct obd_export *dt_exp, struct obd_export *md_exp,
unsigned long flags;
int found;
- xa_lock_irqsave(&mapping->i_pages, flags);
+ ll_xa_lock_irqsave(&mapping->i_pages, flags);
found = radix_tree_gang_lookup(&mapping->page_tree,
(void **)&page, offset, 1);
- if (found > 0 && !xa_is_value(page)) {
+ if (found > 0 && !ll_xa_is_value(page)) {
struct lu_dirpage *dp;
get_page(page);
- xa_unlock_irqrestore(&mapping->i_pages, flags);
+ ll_xa_unlock_irqrestore(&mapping->i_pages, flags);
/*
* In contrast to find_lock_page() we are sure that directory
* page cannot be truncated (while DLM lock is held) and,
page = ERR_PTR(-EIO);
}
} else {
- xa_unlock_irqrestore(&mapping->i_pages, flags);
+ ll_xa_unlock_irqrestore(&mapping->i_pages, flags);
page = NULL;
}
return page;