1 files changed, 47 insertions, 67 deletions

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 6e3b326346a7..4c639e156296 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -104,7 +104,7 @@ void extent_io_tree_init(struct extent_io_tree *tree,
                           struct address_space *mapping, gfp_t mask)
 {
         tree->state = RB_ROOT;
-        tree->buffer = RB_ROOT;
+        INIT_RADIX_TREE(&tree->buffer, GFP_ATOMIC);
         tree->ops = NULL;
         tree->dirty_bytes = 0;
         spin_lock_init(&tree->lock);
@@ -235,50 +235,6 @@ static inline struct rb_node *tree_search(struct extent_io_tree *tree,
         return ret;
 }
 
-static struct extent_buffer *buffer_tree_insert(struct extent_io_tree *tree,
-                                          u64 offset, struct rb_node *node)
-{
-        struct rb_root *root = &tree->buffer;
-        struct rb_node **p = &root->rb_node;
-        struct rb_node *parent = NULL;
-        struct extent_buffer *eb;
-
-        while (*p) {
-                parent = *p;
-                eb = rb_entry(parent, struct extent_buffer, rb_node);
-
-                if (offset < eb->start)
-                        p = &(*p)->rb_left;
-                else if (offset > eb->start)
-                        p = &(*p)->rb_right;
-                else
-                        return eb;
-        }
-
-        rb_link_node(node, parent, p);
-        rb_insert_color(node, root);
-        return NULL;
-}
-
-static struct extent_buffer *buffer_search(struct extent_io_tree *tree,
-                                           u64 offset)
-{
-        struct rb_root *root = &tree->buffer;
-        struct rb_node *n = root->rb_node;
-        struct extent_buffer *eb;
-
-        while (n) {
-                eb = rb_entry(n, struct extent_buffer, rb_node);
-                if (offset < eb->start)
-                        n = n->rb_left;
-                else if (offset > eb->start)
-                        n = n->rb_right;
-                else
-                        return eb;
-        }
-        return NULL;
-}
-
 static void merge_cb(struct extent_io_tree *tree, struct extent_state *new,
                      struct extent_state *other)
 {
@@ -3082,6 +3038,7 @@ static struct extent_buffer *__alloc_extent_buffer(struct extent_io_tree *tree,
         eb->len = len;
         spin_lock_init(&eb->lock);
         init_waitqueue_head(&eb->lock_wq);
+        INIT_RCU_HEAD(&eb->rcu_head);
 
 #if LEAK_DEBUG
         spin_lock_irqsave(&leak_lock, flags);
@@ -3150,16 +3107,16 @@ struct extent_buffer *alloc_extent_buffer(struct extent_io_tree *tree,
         struct page *p;
         struct address_space *mapping = tree->mapping;
         int uptodate = 1;
+        int ret;
 
-        spin_lock(&tree->buffer_lock);
-        eb = buffer_search(tree, start);
-        if (eb) {
-                atomic_inc(&eb->refs);
-                spin_unlock(&tree->buffer_lock);
+        rcu_read_lock();
+        eb = radix_tree_lookup(&tree->buffer, start >> PAGE_CACHE_SHIFT);
+        if (eb && atomic_inc_not_zero(&eb->refs)) {
+                rcu_read_unlock();
                 mark_page_accessed(eb->first_page);
                 return eb;
         }
-        spin_unlock(&tree->buffer_lock);
+        rcu_read_unlock();
 
         eb = __alloc_extent_buffer(tree, start, len, mask);
         if (!eb)
@@ -3198,17 +3155,25 @@ struct extent_buffer *alloc_extent_buffer(struct extent_io_tree *tree,
         if (uptodate)
                 set_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags);
 
+        ret = radix_tree_preload(GFP_NOFS & ~__GFP_HIGHMEM);
+        if (ret)
+                goto free_eb;
+
         spin_lock(&tree->buffer_lock);
-        exists = buffer_tree_insert(tree, start, &eb->rb_node);
-        if (exists) {
+        ret = radix_tree_insert(&tree->buffer, start >> PAGE_CACHE_SHIFT, eb);
+        if (ret == -EEXIST) {
+                exists = radix_tree_lookup(&tree->buffer,
+                                                start >> PAGE_CACHE_SHIFT);
                 /* add one reference for the caller */
                 atomic_inc(&exists->refs);
                 spin_unlock(&tree->buffer_lock);
+                radix_tree_preload_end();
                 goto free_eb;
         }
         /* add one reference for the tree */
         atomic_inc(&eb->refs);
         spin_unlock(&tree->buffer_lock);
+        radix_tree_preload_end();
         return eb;
 
 free_eb:
@@ -3224,16 +3189,16 @@ struct extent_buffer *find_extent_buffer(struct extent_io_tree *tree,
 {
         struct extent_buffer *eb;
 
-        spin_lock(&tree->buffer_lock);
-        eb = buffer_search(tree, start);
-        if (eb)
-                atomic_inc(&eb->refs);
-        spin_unlock(&tree->buffer_lock);
-
-        if (eb)
+        rcu_read_lock();
+        eb = radix_tree_lookup(&tree->buffer, start >> PAGE_CACHE_SHIFT);
+        if (eb && atomic_inc_not_zero(&eb->refs)) {
+                rcu_read_unlock();
                 mark_page_accessed(eb->first_page);
+                return eb;
+        }
+        rcu_read_unlock();
 
-        return eb;
+        return NULL;
 }
 
 void free_extent_buffer(struct extent_buffer *eb)
@@ -3863,6 +3828,14 @@ void memmove_extent_buffer(struct extent_buffer *dst, unsigned long dst_offset,
         }
 }
 
+static inline void btrfs_release_extent_buffer_rcu(struct rcu_head *head)
+{
+        struct extent_buffer *eb =
+                        container_of(head, struct extent_buffer, rcu_head);
+
+        btrfs_release_extent_buffer(eb);
+}
+
 int try_release_extent_buffer(struct extent_io_tree *tree, struct page *page)
 {
         u64 start = page_offset(page);
@@ -3870,23 +3843,30 @@ int try_release_extent_buffer(struct extent_io_tree *tree, struct page *page)
         int ret = 1;
 
         spin_lock(&tree->buffer_lock);
-        eb = buffer_search(tree, start);
+        eb = radix_tree_lookup(&tree->buffer, start >> PAGE_CACHE_SHIFT);
         if (!eb)
                 goto out;
 
-        if (atomic_read(&eb->refs) > 1) {
+        if (test_bit(EXTENT_BUFFER_DIRTY, &eb->bflags)) {
                 ret = 0;
                 goto out;
         }
-        if (test_bit(EXTENT_BUFFER_DIRTY, &eb->bflags)) {
+
+        /*
+         * set @eb->refs to 0 if it is already 1, and then release the @eb.
+         * Or go back.
+         */
+        if (atomic_cmpxchg(&eb->refs, 1, 0) != 1) {
                 ret = 0;
                 goto out;
         }
 
-        rb_erase(&eb->rb_node, &tree->buffer);
-        /* at this point we can safely release the extent buffer */
-        btrfs_release_extent_buffer(eb);
+        radix_tree_delete(&tree->buffer, start >> PAGE_CACHE_SHIFT);
 out:
         spin_unlock(&tree->buffer_lock);
+
+        /* at this point we can safely release the extent buffer */
+        if (atomic_read(&eb->refs) == 0)
+                call_rcu(&eb->rcu_head, btrfs_release_extent_buffer_rcu);
         return ret;
 }