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From:   Matthew Wilcox <willy@infradead.org>
To:     linux-fsdevel@vger.kernel.org, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org
Cc:     Matthew Wilcox <mawilcox@microsoft.com>
Subject: [PATCH 18/62] xarray: Add definition of struct xarray
Date:   Wed, 22 Nov 2017 13:06:55 -0800
Message-Id: <20171122210739.29916-19-willy@infradead.org>
In-Reply-To: <20171122210739.29916-1-willy@infradead.org>
References: <20171122210739.29916-1-willy@infradead.org>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

From: Matthew Wilcox <mawilcox@microsoft.com>

This is a direct replacement for struct radix_tree_root.  Some of the
struct members have changed name; convert those, and use a #define so
that radix_tree users continue to work without change.

Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
---
 include/linux/radix-tree.h            | 26 +++++-------
 include/linux/xarray.h                | 29 ++++++++++++++
 lib/idr.c                             |  4 +-
 lib/radix-tree.c                      | 75 +++++++++++++++++------------------
 tools/include/linux/spinlock.h        |  1 +
 tools/testing/radix-tree/Makefile     |  2 +-
 tools/testing/radix-tree/multiorder.c |  6 +--
 tools/testing/radix-tree/test.c       |  6 +--
 8 files changed, 86 insertions(+), 63 deletions(-)

diff --git a/include/linux/radix-tree.h b/include/linux/radix-tree.h
index ee9aad11d472..015bc1bdc3d2 100644
--- a/include/linux/radix-tree.h
+++ b/include/linux/radix-tree.h
@@ -30,6 +30,9 @@
 #include <linux/types.h>
 #include <linux/xarray.h>
 
+/* Keep unconverted code working */
+#define radix_tree_root		xarray
+
 /*
  * The bottom two bits of the slot determine how the remaining bits in the
  * slot are interpreted:
@@ -59,10 +62,7 @@ static inline bool radix_tree_is_internal_node(void *ptr)
 
 #define RADIX_TREE_MAX_TAGS 3
 
-#ifndef RADIX_TREE_MAP_SHIFT
-#define RADIX_TREE_MAP_SHIFT	(CONFIG_BASE_SMALL ? 4 : 6)
-#endif
-
+#define RADIX_TREE_MAP_SHIFT	XA_CHUNK_SHIFT
 #define RADIX_TREE_MAP_SIZE	(1UL << RADIX_TREE_MAP_SHIFT)
 #define RADIX_TREE_MAP_MASK	(RADIX_TREE_MAP_SIZE-1)
 
@@ -95,20 +95,14 @@ struct radix_tree_node {
 	unsigned long	tags[RADIX_TREE_MAX_TAGS][RADIX_TREE_TAG_LONGS];
 };
 
-/* The top bits of gfp_mask are used to store the root tags and the IDR flag */
+/* The top bits of xa_flags are used to store the root tags and the IDR flag */
 #define ROOT_IS_IDR	((__force gfp_t)(1 << __GFP_BITS_SHIFT))
 #define ROOT_TAG_SHIFT	(__GFP_BITS_SHIFT + 1)
 
-struct radix_tree_root {
-	spinlock_t		xa_lock;
-	gfp_t			gfp_mask;
-	struct radix_tree_node	__rcu *rnode;
-};
-
 #define RADIX_TREE_INIT(name, mask)	{				\
 	.xa_lock = __SPIN_LOCK_UNLOCKED(name.xa_lock),			\
-	.gfp_mask = (mask),						\
-	.rnode = NULL,							\
+	.xa_flags = (mask),						\
+	.xa_head = NULL,						\
 }
 
 #define RADIX_TREE(name, mask) \
@@ -117,13 +111,13 @@ struct radix_tree_root {
 #define INIT_RADIX_TREE(root, mask)					\
 do {									\
 	(root)->xa_lock = __SPIN_LOCK_UNLOCKED(root.xa_lock);		\
-	(root)->gfp_mask = (mask);					\
-	(root)->rnode = NULL;						\
+	(root)->xa_flags = (mask);					\
+	(root)->xa_head = NULL;						\
 } while (0)
 
 static inline bool radix_tree_empty(const struct radix_tree_root *root)
 {
-	return root->rnode == NULL;
+	return root->xa_head == NULL;
 }
 
 /**
diff --git a/include/linux/xarray.h b/include/linux/xarray.h
index b9e0350b9e90..03d430ec3bce 100644
--- a/include/linux/xarray.h
+++ b/include/linux/xarray.h
@@ -45,9 +45,38 @@
  * There are two levels of API provided.  Normal and Advanced.
  * The advanced API is more flexible but has fewer safeguards.
  */
+
+#include <linux/compiler.h>
 #include <linux/spinlock.h>
 #include <linux/types.h>
 
+/**
+ * struct xarray - The anchor of the XArray
+ * @xa_lock: Lock protecting writes to the array.
+ * @xa_flags: Internal XArray flags.
+ * @xa_head: The first pointer in the array.
+ *
+ * If all of the pointers in the array are NULL, @xa_head is a NULL pointer.
+ * If the only non-NULL pointer in the array is at index 0, @xa_head is that
+ * pointer.  If any other pointer in the array is non-NULL, @xa_head points
+ * to an @xa_node.
+ */
+struct xarray {
+	spinlock_t xa_lock;
+	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_INIT(name) __XARRAY_INIT(name, 0)
+
+#define DEFINE_XARRAY(name) struct xarray name = XARRAY_INIT(name)
+
 #define BITS_PER_XA_VALUE	(BITS_PER_LONG - 1)
 
 /**
diff --git a/lib/idr.c b/lib/idr.c
index afcdff365037..50201b5c46e9 100644
--- a/lib/idr.c
+++ b/lib/idr.c
@@ -35,8 +35,8 @@ int idr_alloc_ul(struct idr *idr, void *ptr, unsigned long *nextid,
 	if (WARN_ON_ONCE(radix_tree_is_internal_node(ptr)))
 		return -EINVAL;
 
-	if (WARN_ON_ONCE(!(idr->idr_rt.gfp_mask & ROOT_IS_IDR)))
-		idr->idr_rt.gfp_mask |= IDR_RT_MARKER;
+	if (WARN_ON_ONCE(!(idr->idr_rt.xa_flags & ROOT_IS_IDR)))
+		idr->idr_rt.xa_flags |= IDR_RT_MARKER;
 
 	radix_tree_iter_init(&iter, *nextid);
 	slot = idr_get_free(&idr->idr_rt, &iter, gfp, max);
diff --git a/lib/radix-tree.c b/lib/radix-tree.c
index 4a1091e31932..930eb7d298d7 100644
--- a/lib/radix-tree.c
+++ b/lib/radix-tree.c
@@ -123,7 +123,7 @@ static unsigned int radix_tree_descend(const struct radix_tree_node *parent,
 
 static inline gfp_t root_gfp_mask(const struct radix_tree_root *root)
 {
-	return root->gfp_mask & __GFP_BITS_MASK;
+	return root->xa_flags & __GFP_BITS_MASK;
 }
 
 static inline void tag_set(struct radix_tree_node *node, unsigned int tag,
@@ -146,32 +146,32 @@ static inline int tag_get(const struct radix_tree_node *node, unsigned int tag,
 
 static inline void root_tag_set(struct radix_tree_root *root, unsigned tag)
 {
-	root->gfp_mask |= (__force gfp_t)(1 << (tag + ROOT_TAG_SHIFT));
+	root->xa_flags |= (__force gfp_t)(1 << (tag + ROOT_TAG_SHIFT));
 }
 
 static inline void root_tag_clear(struct radix_tree_root *root, unsigned tag)
 {
-	root->gfp_mask &= (__force gfp_t)~(1 << (tag + ROOT_TAG_SHIFT));
+	root->xa_flags &= (__force gfp_t)~(1 << (tag + ROOT_TAG_SHIFT));
 }
 
 static inline void root_tag_clear_all(struct radix_tree_root *root)
 {
-	root->gfp_mask &= (__force gfp_t)((1 << ROOT_TAG_SHIFT) - 1);
+	root->xa_flags &= (__force gfp_t)((1 << ROOT_TAG_SHIFT) - 1);
 }
 
 static inline int root_tag_get(const struct radix_tree_root *root, unsigned tag)
 {
-	return (__force int)root->gfp_mask & (1 << (tag + ROOT_TAG_SHIFT));
+	return (__force int)root->xa_flags & (1 << (tag + ROOT_TAG_SHIFT));
 }
 
 static inline unsigned root_tags_get(const struct radix_tree_root *root)
 {
-	return (__force unsigned)root->gfp_mask >> ROOT_TAG_SHIFT;
+	return (__force unsigned)root->xa_flags >> ROOT_TAG_SHIFT;
 }
 
 static inline bool is_idr(const struct radix_tree_root *root)
 {
-	return !!(root->gfp_mask & ROOT_IS_IDR);
+	return !!(root->xa_flags & ROOT_IS_IDR);
 }
 
 /*
@@ -290,12 +290,12 @@ static void dump_node(struct radix_tree_node *node, unsigned long index)
 /* For debug */
 static void radix_tree_dump(struct radix_tree_root *root)
 {
-	pr_debug("radix root: %p rnode %p tags %x\n",
-			root, root->rnode,
-			root->gfp_mask >> ROOT_TAG_SHIFT);
-	if (!radix_tree_is_internal_node(root->rnode))
+	pr_debug("radix root: %p xa_head %p tags %x\n",
+			root, root->xa_head,
+			root->xa_flags >> ROOT_TAG_SHIFT);
+	if (!radix_tree_is_internal_node(root->xa_head))
 		return;
-	dump_node(entry_to_node(root->rnode), 0);
+	dump_node(entry_to_node(root->xa_head), 0);
 }
 
 static void dump_ida_node(void *entry, unsigned long index)
@@ -339,9 +339,9 @@ static void dump_ida_node(void *entry, unsigned long index)
 static void ida_dump(struct ida *ida)
 {
 	struct radix_tree_root *root = &ida->ida_rt;
-	pr_debug("ida: %p node %p free %d\n", ida, root->rnode,
-				root->gfp_mask >> ROOT_TAG_SHIFT);
-	dump_ida_node(root->rnode, 0);
+	pr_debug("ida: %p node %p free %d\n", ida, root->xa_head,
+				root->xa_flags >> ROOT_TAG_SHIFT);
+	dump_ida_node(root->xa_head, 0);
 }
 #endif
 
@@ -575,7 +575,7 @@ int radix_tree_maybe_preload_order(gfp_t gfp_mask, int order)
 static unsigned radix_tree_load_root(const struct radix_tree_root *root,
 		struct radix_tree_node **nodep, unsigned long *maxindex)
 {
-	struct radix_tree_node *node = rcu_dereference_raw(root->rnode);
+	struct radix_tree_node *node = rcu_dereference_raw(root->xa_head);
 
 	*nodep = node;
 
@@ -604,7 +604,7 @@ static int radix_tree_extend(struct radix_tree_root *root, gfp_t gfp,
 	while (index > shift_maxindex(maxshift))
 		maxshift += RADIX_TREE_MAP_SHIFT;
 
-	entry = rcu_dereference_raw(root->rnode);
+	entry = rcu_dereference_raw(root->xa_head);
 	if (!entry && (!is_idr(root) || root_tag_get(root, IDR_FREE)))
 		goto out;
 
@@ -632,7 +632,7 @@ static int radix_tree_extend(struct radix_tree_root *root, gfp_t gfp,
 		if (radix_tree_is_internal_node(entry)) {
 			entry_to_node(entry)->parent = node;
 		} else if (xa_is_value(entry)) {
-			/* Moving an exceptional root->rnode to a node */
+			/* Moving an exceptional root->xa_head to a node */
 			node->exceptional = 1;
 		}
 		/*
@@ -641,7 +641,7 @@ static int radix_tree_extend(struct radix_tree_root *root, gfp_t gfp,
 		 */
 		node->slots[0] = (void __rcu *)entry;
 		entry = node_to_entry(node);
-		rcu_assign_pointer(root->rnode, entry);
+		rcu_assign_pointer(root->xa_head, entry);
 		shift += RADIX_TREE_MAP_SHIFT;
 	} while (shift <= maxshift);
 out:
@@ -658,7 +658,7 @@ static inline bool radix_tree_shrink(struct radix_tree_root *root,
 	bool shrunk = false;
 
 	for (;;) {
-		struct radix_tree_node *node = rcu_dereference_raw(root->rnode);
+		struct radix_tree_node *node = rcu_dereference_raw(root->xa_head);
 		struct radix_tree_node *child;
 
 		if (!radix_tree_is_internal_node(node))
@@ -686,9 +686,9 @@ static inline bool radix_tree_shrink(struct radix_tree_root *root,
 		 * moving the node from one part of the tree to another: if it
 		 * was safe to dereference the old pointer to it
 		 * (node->slots[0]), it will be safe to dereference the new
-		 * one (root->rnode) as far as dependent read barriers go.
+		 * one (root->xa_head) as far as dependent read barriers go.
 		 */
-		root->rnode = (void __rcu *)child;
+		root->xa_head = (void __rcu *)child;
 		if (is_idr(root) && !tag_get(node, IDR_FREE, 0))
 			root_tag_clear(root, IDR_FREE);
 
@@ -736,9 +736,8 @@ static bool delete_node(struct radix_tree_root *root,
 
 		if (node->count) {
 			if (node_to_entry(node) ==
-					rcu_dereference_raw(root->rnode))
-				deleted |= radix_tree_shrink(root,
-								update_node);
+					rcu_dereference_raw(root->xa_head))
+				deleted |= radix_tree_shrink(root, update_node);
 			return deleted;
 		}
 
@@ -753,7 +752,7 @@ static bool delete_node(struct radix_tree_root *root,
 			 */
 			if (!is_idr(root))
 				root_tag_clear_all(root);
-			root->rnode = NULL;
+			root->xa_head = NULL;
 		}
 
 		WARN_ON_ONCE(!list_empty(&node->private_list));
@@ -778,7 +777,7 @@ static bool delete_node(struct radix_tree_root *root,
  *	at position @index in the radix tree @root.
  *
  *	Until there is more than one item in the tree, no nodes are
- *	allocated and @root->rnode is used as a direct slot instead of
+ *	allocated and @root->xa_head is used as a direct slot instead of
  *	pointing to a node, in which case *@nodep will be NULL.
  *
  *	Returns -ENOMEM, or 0 for success.
@@ -788,7 +787,7 @@ int __radix_tree_create(struct radix_tree_root *root, unsigned long index,
 			void __rcu ***slotp)
 {
 	struct radix_tree_node *node = NULL, *child;
-	void __rcu **slot = (void __rcu **)&root->rnode;
+	void __rcu **slot = (void __rcu **)&root->xa_head;
 	unsigned long maxindex;
 	unsigned int shift, offset = 0;
 	unsigned long max = index | ((1UL << order) - 1);
@@ -804,7 +803,7 @@ int __radix_tree_create(struct radix_tree_root *root, unsigned long index,
 		if (error < 0)
 			return error;
 		shift = error;
-		child = rcu_dereference_raw(root->rnode);
+		child = rcu_dereference_raw(root->xa_head);
 	}
 
 	while (shift > order) {
@@ -995,7 +994,7 @@ EXPORT_SYMBOL(__radix_tree_insert);
  *	tree @root.
  *
  *	Until there is more than one item in the tree, no nodes are
- *	allocated and @root->rnode is used as a direct slot instead of
+ *	allocated and @root->xa_head is used as a direct slot instead of
  *	pointing to a node, in which case *@nodep will be NULL.
  */
 void *__radix_tree_lookup(const struct radix_tree_root *root,
@@ -1008,7 +1007,7 @@ void *__radix_tree_lookup(const struct radix_tree_root *root,
 
  restart:
 	parent = NULL;
-	slot = (void __rcu **)&root->rnode;
+	slot = (void __rcu **)&root->xa_head;
 	radix_tree_load_root(root, &node, &maxindex);
 	if (index > maxindex)
 		return NULL;
@@ -1160,9 +1159,9 @@ void __radix_tree_replace(struct radix_tree_root *root,
 	/*
 	 * This function supports replacing exceptional entries and
 	 * deleting entries, but that needs accounting against the
-	 * node unless the slot is root->rnode.
+	 * node unless the slot is root->xa_head.
 	 */
-	WARN_ON_ONCE(!node && (slot != (void __rcu **)&root->rnode) &&
+	WARN_ON_ONCE(!node && (slot != (void __rcu **)&root->xa_head) &&
 			(count || exceptional));
 	replace_slot(slot, item, node, count, exceptional);
 
@@ -1714,7 +1713,7 @@ void __rcu **radix_tree_next_chunk(const struct radix_tree_root *root,
 		iter->tags = 1;
 		iter->node = NULL;
 		__set_iter_shift(iter, 0);
-		return (void __rcu **)&root->rnode;
+		return (void __rcu **)&root->xa_head;
 	}
 
 	do {
@@ -2108,7 +2107,7 @@ void __rcu **idr_get_free(struct radix_tree_root *root,
 			      unsigned long max)
 {
 	struct radix_tree_node *node = NULL, *child;
-	void __rcu **slot = (void __rcu **)&root->rnode;
+	void __rcu **slot = (void __rcu **)&root->xa_head;
 	unsigned long maxindex, start = iter->next_index;
 	unsigned int shift, offset = 0;
 
@@ -2124,7 +2123,7 @@ void __rcu **idr_get_free(struct radix_tree_root *root,
 		if (error < 0)
 			return ERR_PTR(error);
 		shift = error;
-		child = rcu_dereference_raw(root->rnode);
+		child = rcu_dereference_raw(root->xa_head);
 	}
 
 	while (shift) {
@@ -2187,10 +2186,10 @@ void __rcu **idr_get_free(struct radix_tree_root *root,
  */
 void idr_destroy(struct idr *idr)
 {
-	struct radix_tree_node *node = rcu_dereference_raw(idr->idr_rt.rnode);
+	struct radix_tree_node *node = rcu_dereference_raw(idr->idr_rt.xa_head);
 	if (radix_tree_is_internal_node(node))
 		radix_tree_free_nodes(node);
-	idr->idr_rt.rnode = NULL;
+	idr->idr_rt.xa_head = NULL;
 	root_tag_set(&idr->idr_rt, IDR_FREE);
 }
 EXPORT_SYMBOL(idr_destroy);
diff --git a/tools/include/linux/spinlock.h b/tools/include/linux/spinlock.h
index b21b586b9854..34fed5c38da2 100644
--- a/tools/include/linux/spinlock.h
+++ b/tools/include/linux/spinlock.h
@@ -8,6 +8,7 @@
 #define spinlock_t		pthread_mutex_t
 #define DEFINE_SPINLOCK(x)	pthread_mutex_t x = PTHREAD_MUTEX_INITIALIZER;
 #define __SPIN_LOCK_UNLOCKED(x)	(pthread_mutex_t)PTHREAD_MUTEX_INITIALIZER
+#define spin_lock_init(x)	pthread_mutex_init(x, NULL);
 
 #define spin_lock_irqsave(x, f)		(void)f, pthread_mutex_lock(x)
 #define spin_unlock_irqrestore(x, f)	(void)f, pthread_mutex_unlock(x)
diff --git a/tools/testing/radix-tree/Makefile b/tools/testing/radix-tree/Makefile
index fa7ee369b3c9..ebb12224e258 100644
--- a/tools/testing/radix-tree/Makefile
+++ b/tools/testing/radix-tree/Makefile
@@ -46,6 +46,6 @@ idr.c: ../../../lib/idr.c
 
 mapshift:
 	@if ! grep -qws $(SHIFT) generated/map-shift.h; then		\
-		echo "#define RADIX_TREE_MAP_SHIFT $(SHIFT)" >		\
+		echo "#define XA_CHUNK_SHIFT $(SHIFT)" >		\
 				generated/map-shift.h;			\
 	fi
diff --git a/tools/testing/radix-tree/multiorder.c b/tools/testing/radix-tree/multiorder.c
index 684e76f79f4a..24293a2fd82d 100644
--- a/tools/testing/radix-tree/multiorder.c
+++ b/tools/testing/radix-tree/multiorder.c
@@ -191,13 +191,13 @@ static void multiorder_shrink(unsigned long index, int order)
 
 	assert(item_insert_order(&tree, 0, order) == 0);
 
-	node = tree.rnode;
+	node = tree.xa_head;
 
 	assert(item_insert(&tree, index) == 0);
-	assert(node != tree.rnode);
+	assert(node != tree.xa_head);
 
 	assert(item_delete(&tree, index) != 0);
-	assert(node == tree.rnode);
+	assert(node == tree.xa_head);
 
 	for (i = 0; i < max; i++) {
 		struct item *item = item_lookup(&tree, i);
diff --git a/tools/testing/radix-tree/test.c b/tools/testing/radix-tree/test.c
index 0d69c49177c6..6e1cc2040817 100644
--- a/tools/testing/radix-tree/test.c
+++ b/tools/testing/radix-tree/test.c
@@ -262,7 +262,7 @@ static int verify_node(struct radix_tree_node *slot, unsigned int tag,
 
 void verify_tag_consistency(struct radix_tree_root *root, unsigned int tag)
 {
-	struct radix_tree_node *node = root->rnode;
+	struct radix_tree_node *node = root->xa_head;
 	if (!radix_tree_is_internal_node(node))
 		return;
 	verify_node(node, tag, !!root_tag_get(root, tag));
@@ -292,13 +292,13 @@ void item_kill_tree(struct radix_tree_root *root)
 		}
 	}
 	assert(radix_tree_gang_lookup(root, (void **)items, 0, 32) == 0);
-	assert(root->rnode == NULL);
+	assert(root->xa_head == NULL);
 }
 
 void tree_verify_min_height(struct radix_tree_root *root, int maxindex)
 {
 	unsigned shift;
-	struct radix_tree_node *node = root->rnode;
+	struct radix_tree_node *node = root->xa_head;
 	if (!radix_tree_is_internal_node(node)) {
 		assert(maxindex == 0);
 		return;
-- 
2.15.0


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