[PATCH v4 67/73] vmalloc: Convert to XArray

[Matthew Wilcox]

From: Matthew Wilcox <mawil...@microsoft.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 <mawil...@microsoft.com>
---
 mm/vmalloc.c | 39 +++++++++++++--------------------------
 1 file changed, 13 insertions(+), 26 deletions(-)

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 673942094328..3a46efc27525 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -23,7 +23,7 @@
 #include <linux/list.h>
 #include <linux/notifier.h>
 #include <linux/rbtree.h>
-#include <linux/radix-tree.h>
+#include <linux/xarray.h>
 #include <linux/rcupdate.h>
 #include <linux/pfn.h>
 #include <linux/kmemleak.h>
@@ -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_erase(&vmap_block_tree, vb_idx);
        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