[RFC v4 02/15] vfs,hot_track: initialize and free key data structures

[zwu.kernel@gmail.com]

From: Zhi Yong Wu <wuzhy@linux.vnet.ibm.com>

  Add initialization function to create some
key data structures when hot tracking is enabled;
Clean up them when hot tracking is disabled

Signed-off-by: Zhi Yong Wu <wuzhy@linux.vnet.ibm.com>
---
 fs/hot_tracking.c            |  125 ++++++++++++++++++++++++++++++++++++++++++
 include/linux/fs.h           |    4 +
 include/linux/hot_tracking.h |    3 +
 3 files changed, 132 insertions(+), 0 deletions(-)

diff --git a/fs/hot_tracking.c b/fs/hot_tracking.c
index 6a0f2a3..5fef7e5 100644
--- a/fs/hot_tracking.c
+++ b/fs/hot_tracking.c
@@ -21,6 +21,8 @@
 #include <linux/limits.h>
 #include "hot_tracking.h"
 
+static struct hot_info *hot_root;
+
 /* kmem_cache pointers for slab caches */
 static struct kmem_cache *hot_inode_item_cachep __read_mostly;
 static struct kmem_cache *hot_range_item_cachep __read_mostly;
@@ -75,12 +77,102 @@ static void hot_inode_item_init(struct hot_inode_item *he, u64 ino,
 	he->hot_inode_tree = hot_inode_tree;
 	kref_init(&he->hot_inode.refs);
 	spin_lock_init(&he->hot_inode.lock);
+	INIT_LIST_HEAD(&he->hot_inode.n_list);
 	he->hot_inode.hot_freq_data.avg_delta_reads = (u64) -1;
 	he->hot_inode.hot_freq_data.avg_delta_writes = (u64) -1;
 	he->hot_inode.hot_freq_data.flags = FREQ_DATA_TYPE_INODE;
 	hot_range_tree_init(he);
 }
 
+static void hot_range_item_free(struct kref *kref)
+{
+	struct hot_comm_item *comm_item = container_of(kref,
+		struct hot_comm_item, refs);
+	struct hot_range_item *hr = container_of(comm_item,
+		struct hot_range_item, hot_range);
+
+	radix_tree_delete(&hr->hot_inode->hot_range_tree, hr->start);
+	kmem_cache_free(hot_range_item_cachep, hr);
+}
+
+/*
+ * Drops the reference out on hot_range_item by one
+ * and free the structure if the reference count hits zero
+ */
+static void hot_range_item_put(struct hot_range_item *hr)
+{
+	kref_put(&hr->hot_range.refs, hot_range_item_free);
+}
+
+/* Frees the entire hot_range_tree. */
+static void hot_range_tree_free(struct hot_inode_item *he)
+{
+	struct hot_range_item *hr_nodes[8];
+	u32 start = 0;
+	int i, n;
+
+	while (1) {
+		spin_lock(&he->lock);
+		n = radix_tree_gang_lookup(&he->hot_range_tree,
+					(void **)hr_nodes, start,
+					ARRAY_SIZE(hr_nodes));
+		if (!n) {
+			spin_unlock(&he->lock);
+			break;
+		}
+
+		start = hr_nodes[n - 1]->start + 1;
+		for (i = 0; i < n; i++)
+			hot_range_item_put(hr_nodes[i]);
+		spin_unlock(&he->lock);
+	}
+}
+
+static void hot_inode_item_free(struct kref *kref)
+{
+	struct hot_comm_item *comm_item = container_of(kref,
+			struct hot_comm_item, refs);
+	struct hot_inode_item *he = container_of(comm_item,
+			struct hot_inode_item, hot_inode);
+
+	hot_range_tree_free(he);
+	radix_tree_delete(he->hot_inode_tree, he->i_ino);
+	kmem_cache_free(hot_inode_item_cachep, he);
+}
+
+/*
+ * Drops the reference out on hot_inode_item by one
+ * and free the structure if the reference count hits zero
+ */
+void hot_inode_item_put(struct hot_inode_item *he)
+{
+	kref_put(&he->hot_inode.refs, hot_inode_item_free);
+}
+
+/* Frees the entire hot_inode_tree. */
+static void hot_inode_tree_exit(struct hot_info *root)
+{
+	struct hot_inode_item *hi_nodes[8];
+	u64 ino = 0;
+	int i, n;
+
+	while (1) {
+		spin_lock(&root->lock);
+		n = radix_tree_gang_lookup(&root->hot_inode_tree,
+					   (void **)hi_nodes, ino,
+					   ARRAY_SIZE(hi_nodes));
+		if (!n) {
+			spin_unlock(&root->lock);
+			break;
+		}
+
+		ino = hi_nodes[n - 1]->i_ino + 1;
+		for (i = 0; i < n; i++)
+			hot_inode_item_put(hi_nodes[i]);
+		spin_unlock(&root->lock);
+	}
+}
+
 /*
  * Initialize kmem cache for hot_inode_item and hot_range_item.
  */
@@ -105,3 +197,36 @@ void __init hot_cache_init(void)
 err:
 	kmem_cache_destroy(hot_inode_item_cachep);
 }
+
+/*
+ * Initialize the data structures for hot data tracking.
+ */
+int hot_track_init(struct super_block *sb)
+{
+	struct hot_info *root;
+	int ret = -ENOMEM;
+
+	root = kzalloc(sizeof(struct hot_info), GFP_NOFS);
+	if (!root) {
+		printk(KERN_ERR "%s: Failed to malloc memory for "
+				"hot_info\n", __func__);
+		return ret;
+	}
+
+	sb->s_hot_root = hot_root = root;
+	hot_inode_tree_init(root);
+
+	printk(KERN_INFO "VFS: Turning on hot data tracking\n");
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(hot_track_init);
+
+void hot_track_exit(struct super_block *sb)
+{
+	struct hot_info *root = sb->s_hot_root;
+
+	hot_inode_tree_exit(root);
+	kfree(root);
+}
+EXPORT_SYMBOL_GPL(hot_track_exit);
diff --git a/include/linux/fs.h b/include/linux/fs.h
index b33cfc9..c541ae7 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -27,6 +27,7 @@
 #include <linux/lockdep.h>
 #include <linux/percpu-rwsem.h>
 #include <linux/blk_types.h>
+#include <linux/hot_tracking.h>
 
 #include <asm/byteorder.h>
 #include <uapi/linux/fs.h>
@@ -1321,6 +1322,9 @@ struct super_block {
 
 	/* Being remounted read-only */
 	int s_readonly_remount;
+
+	/* Hot data tracking*/
+	struct hot_info *s_hot_root;
 };
 
 /* superblock cache pruning functions */
diff --git a/include/linux/hot_tracking.h b/include/linux/hot_tracking.h
index fcd4ad1..592a6eb 100644
--- a/include/linux/hot_tracking.h
+++ b/include/linux/hot_tracking.h
@@ -69,5 +69,8 @@ struct hot_info {
 };
 
 void __init hot_cache_init(void);
+int hot_track_init(struct super_block *sb);
+void hot_track_exit(struct super_block *sb);
+
 
 #endif  /* _LINUX_HOTTRACK_H */
-- 
1.7.6.5