linux-kernel - [PATCH 42/62] vmalloc: Convert to xarray

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Date:   Wed, 22 Nov 2017 13:07:19 -0800
From:   Matthew Wilcox <willy@...radead.org>
To:     linux-fsdevel@...r.kernel.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Cc:     Matthew Wilcox <mawilcox@...rosoft.com>
Subject: [PATCH 42/62] vmalloc: Convert to xarray

From: Matthew Wilcox <mawilcox@...rosoft.com>

The radix tree of vmap blocks is simpler to express as an XArray.
Saves a couple of hundred bytes of text and eliminates a user of the
radix tree preload API.

Signed-off-by: Matthew Wilcox <mawilcox@...rosoft.com>
---
 mm/vmalloc.c | 37 ++++++++++++-------------------------
 1 file changed, 12 insertions(+), 25 deletions(-)

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 673942094328..cc5de1ee6520 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -821,12 +821,11 @@ struct vmap_block {
 static DEFINE_PER_CPU(struct vmap_block_queue, vmap_block_queue);
 
 /*
- * Radix tree of vmap blocks, indexed by address, to quickly find a vmap block
+ * XArray of vmap blocks, indexed by address, to quickly find a vmap block
  * in the free path. Could get rid of this if we change the API to return a
  * "cookie" from alloc, to be passed to free. But no big deal yet.
  */
-static DEFINE_SPINLOCK(vmap_block_tree_lock);
-static RADIX_TREE(vmap_block_tree, GFP_ATOMIC);
+static DEFINE_XARRAY(vmap_block_tree);
 
 /*
  * We should probably have a fallback mechanism to allocate virtual memory
@@ -865,8 +864,8 @@ static void *new_vmap_block(unsigned int order, gfp_t gfp_mask)
 	struct vmap_block *vb;
 	struct vmap_area *va;
 	unsigned long vb_idx;
-	int node, err;
-	void *vaddr;
+	int node;
+	void *ret, *vaddr;
 
 	node = numa_node_id();
 
@@ -883,13 +882,6 @@ static void *new_vmap_block(unsigned int order, gfp_t gfp_mask)
 		return ERR_CAST(va);
 	}
 
-	err = radix_tree_preload(gfp_mask);
-	if (unlikely(err)) {
-		kfree(vb);
-		free_vmap_area(va);
-		return ERR_PTR(err);
-	}
-
 	vaddr = vmap_block_vaddr(va->va_start, 0);
 	spin_lock_init(&vb->lock);
 	vb->va = va;
@@ -902,11 +894,12 @@ static void *new_vmap_block(unsigned int order, gfp_t gfp_mask)
 	INIT_LIST_HEAD(&vb->free_list);
 
 	vb_idx = addr_to_vb_idx(va->va_start);
-	spin_lock(&vmap_block_tree_lock);
-	err = radix_tree_insert(&vmap_block_tree, vb_idx, vb);
-	spin_unlock(&vmap_block_tree_lock);
-	BUG_ON(err);
-	radix_tree_preload_end();
+	ret = xa_store(&vmap_block_tree, vb_idx, vb, gfp_mask);
+	if (IS_ERR(ret)) {
+		kfree(vb);
+		free_vmap_area(va);
+		return ret;
+	}
 
 	vbq = &get_cpu_var(vmap_block_queue);
 	spin_lock(&vbq->lock);
@@ -923,9 +916,7 @@ static void free_vmap_block(struct vmap_block *vb)
 	unsigned long vb_idx;
 
 	vb_idx = addr_to_vb_idx(vb->va->va_start);
-	spin_lock(&vmap_block_tree_lock);
-	tmp = radix_tree_delete(&vmap_block_tree, vb_idx);
-	spin_unlock(&vmap_block_tree_lock);
+	tmp = xa_store(&vmap_block_tree, vb_idx, NULL, GFP_NOWAIT);
 	BUG_ON(tmp != vb);
 
 	free_vmap_area_noflush(vb->va);
@@ -1031,7 +1022,6 @@ static void *vb_alloc(unsigned long size, gfp_t gfp_mask)
 static void vb_free(const void *addr, unsigned long size)
 {
 	unsigned long offset;
-	unsigned long vb_idx;
 	unsigned int order;
 	struct vmap_block *vb;
 
@@ -1045,10 +1035,7 @@ static void vb_free(const void *addr, unsigned long size)
 	offset = (unsigned long)addr & (VMAP_BLOCK_SIZE - 1);
 	offset >>= PAGE_SHIFT;
 
-	vb_idx = addr_to_vb_idx((unsigned long)addr);
-	rcu_read_lock();
-	vb = radix_tree_lookup(&vmap_block_tree, vb_idx);
-	rcu_read_unlock();
+	vb = xa_load(&vmap_block_tree, addr_to_vb_idx((unsigned long)addr));
 	BUG_ON(!vb);
 
 	vunmap_page_range((unsigned long)addr, (unsigned long)addr + size);
-- 
2.15.0