From 9a293bfa758797ecb92c1aaf22e092dd6b4cf5ff Mon Sep 17 00:00:00 2001
From: Zach Brown <zab@versity.com>
Date: Wed, 25 Jan 2017 11:08:43 -0800
Subject: [PATCH] Add item delete dirty and many interfaces

Add item functions for deleting items that we know to be dirty and add a
user in another function that deletes many items without leaving parial
deletions behind in the case of errors.

Signed-off-by: Zach Brown <zab@versity.com>
---
 kmod/src/item.c | 78 ++++++++++++++++++++++++++++++++++++++++++++++---
 kmod/src/item.h |  4 +++
 2 files changed, 78 insertions(+), 4 deletions(-)

diff --git a/kmod/src/item.c b/kmod/src/item.c
index c4dff761..d471cab6 100644
--- a/kmod/src/item.c
+++ b/kmod/src/item.c
@@ -964,6 +964,23 @@ out:
 	return ret;
 }
 
+/*
+ * Turn an item that the caller has found while holding the lock into a
+ * deletion item.  The caller will free whatever we put in the deletion
+ * value after releasing the lock.
+ */
+static void become_deletion_item(struct super_block *sb,
+				 struct item_cache *cac,
+				 struct cached_item *item,
+				 struct kvec *del_val)
+{
+	scoutfs_kvec_clone(del_val, item->val);
+	scoutfs_kvec_init_null(item->val);
+	item->deletion = 1;
+	mark_item_dirty(cac, item);
+	scoutfs_inc_counter(sb, item_delete);
+}
+
 /*
  * Delete an existing item with the given key.
  *
@@ -999,10 +1016,7 @@ int scoutfs_item_delete(struct super_block *sb, struct scoutfs_key_buf *key)
 
 		item = find_item(sb, &cac->items, key);
 		if (item) {
-			scoutfs_kvec_swap(item->val, del_val);
-			item->deletion = 1;
-			mark_item_dirty(cac, item);
-			scoutfs_inc_counter(sb, item_delete);
+			become_deletion_item(sb, cac, item, del_val);
 			ret = 0;
 		} else if (check_range(sb, &cac->ranges, key, end)) {
 			ret = -ENOENT;
@@ -1022,6 +1036,62 @@ out:
 	return ret;
 }
 
+/*
+ * Delete an item that the caller knows must be dirty because they hold
+ * locks and the transaction and have created or dirtied it.  This can't
+ * fail.
+ */
+void scoutfs_item_delete_dirty(struct super_block *sb,
+			       struct scoutfs_key_buf *key)
+{
+	struct scoutfs_sb_info *sbi = SCOUTFS_SB(sb);
+	struct item_cache *cac = sbi->item_cache;
+	SCOUTFS_DECLARE_KVEC(del_val);
+	struct cached_item *item;
+	unsigned long flags;
+
+	scoutfs_kvec_init_null(del_val);
+
+	spin_lock_irqsave(&cac->lock, flags);
+
+	item = find_item(sb, &cac->items, key);
+	if (item)
+		become_deletion_item(sb, cac, item, del_val);
+
+	spin_unlock_irqrestore(&cac->lock, flags);
+
+	scoutfs_kvec_kfree(del_val);
+}
+
+/*
+ * A helper that deletes a set of items.  It first dirties the items
+ * will be pinned so that deletion won't fail as it tries to read and
+ * populate the items.
+ *
+ * It's a little cleaner to have this helper than have the caller
+ * iterate, but it could also give us the opportunity to reduce item
+ * searches if we remembered the items we dirtied.
+ */
+int scoutfs_item_delete_many(struct super_block *sb,
+			     struct scoutfs_key_buf **keys, unsigned nr)
+{
+	int ret = 0;
+	int i;
+
+	for (i = 0; i < nr; i++) {
+		ret = scoutfs_item_dirty(sb, keys[i]);
+		if (ret)
+			goto out;
+	}
+
+	for (i = 0; i < nr; i++)
+		scoutfs_item_delete_dirty(sb, keys[i]);
+
+out:
+	trace_printk("ret %d\n", ret);
+	return ret;
+}
+
 /*
  * Return the first dirty node in the subtree starting at the given node.
  */
diff --git a/kmod/src/item.h b/kmod/src/item.h
index 02afc91c..8f84389a 100644
--- a/kmod/src/item.h
+++ b/kmod/src/item.h
@@ -26,6 +26,10 @@ int scoutfs_item_create(struct super_block *sb, struct scoutfs_key_buf *key,
 int scoutfs_item_dirty(struct super_block *sb, struct scoutfs_key_buf *key);
 int scoutfs_item_update(struct super_block *sb, struct scoutfs_key_buf *key,
 			struct kvec *val);
+void scoutfs_item_delete_dirty(struct super_block *sb,
+			       struct scoutfs_key_buf *key);
+int scoutfs_item_delete_many(struct super_block *sb,
+			     struct scoutfs_key_buf **keys, unsigned nr);
 int scoutfs_item_delete(struct super_block *sb, struct scoutfs_key_buf *key);
 
 int scoutfs_item_add_batch(struct super_block *sb, struct list_head *list,