Btrfs: update converter for the new disk format

This patch updates the ext3 to btrfs converter for the new
disk format. This mainly involves changing the convert's
data relocation and free space management code. This patch
also ports some functions from kernel module to btrfs-progs.
Thank you,

Signed-off-by: Yan Zheng <zheng.yan@oracle.com>

1 files changed, 120 insertions, 5 deletions

diff --git a/ctree.c b/ctree.c
index 0d9797e5..f4829c8b 100644
--- a/ctree.c
+++ b/ctree.c
@@ -1114,7 +1114,8 @@ again:
 			if (ret && slot > 0)
 				slot -= 1;
 			p->slots[level] = slot;
-			if (ins_len > 0 && btrfs_header_nritems(b) >=
+			if ((p->search_for_split || ins_len > 0) &&
+			    btrfs_header_nritems(b) >=
 			    BTRFS_NODEPTRS_PER_BLOCK(root) - 3) {
 				int sret = split_node(trans, root, p, level);
 				BUG_ON(sret > 0);
@@ -1949,11 +1950,11 @@ static int split_leaf(struct btrfs_trans_handle *trans, struct btrfs_root
 	int num_doubles = 0;
 	struct btrfs_disk_key disk_key;
 
-	if (extend)
+	if (extend && data_size)
 		space_needed = data_size;
 
 	/* first try to make some room by pushing left and right */
-	if (ins_key->type != BTRFS_DIR_ITEM_KEY) {
+	if (data_size && ins_key->type != BTRFS_DIR_ITEM_KEY) {
 		wret = push_leaf_right(trans, root, path, data_size, 0);
 		if (wret < 0) {
 			return wret;
@@ -2031,7 +2032,7 @@ again:
 	} else {
 		if (leaf_space_used(l, 0, mid + 1) + space_needed >
 			BTRFS_LEAF_DATA_SIZE(root)) {
-			if (!extend && slot == 0) {
+			if (!extend && data_size && slot == 0) {
 				btrfs_cpu_key_to_disk(&disk_key, ins_key);
 				btrfs_set_header_nritems(right, 0);
 				wret = insert_ptr(trans, root, path,
@@ -2050,7 +2051,7 @@ again:
 						ret = wret;
 				}
 				return ret;
-			} else if (extend && slot == 0) {
+			} else if ((extend || !data_size) && slot == 0) {
 				mid = 1;
 			} else {
 				mid = slot;
@@ -2117,6 +2118,120 @@ again:
 	return ret;
 }
 
+/*
+ * This function splits a single item into two items,
+ * giving 'new_key' to the new item and splitting the
+ * old one at split_offset (from the start of the item).
+ *
+ * The path may be released by this operation.  After
+ * the split, the path is pointing to the old item.  The
+ * new item is going to be in the same node as the old one.
+ *
+ * Note, the item being split must be smaller enough to live alone on
+ * a tree block with room for one extra struct btrfs_item
+ *
+ * This allows us to split the item in place, keeping a lock on the
+ * leaf the entire time.
+ */
+int btrfs_split_item(struct btrfs_trans_handle *trans,
+		     struct btrfs_root *root,
+		     struct btrfs_path *path,
+		     struct btrfs_key *new_key,
+		     unsigned long split_offset)
+{
+	u32 item_size;
+	struct extent_buffer *leaf;
+	struct btrfs_key orig_key;
+	struct btrfs_item *item;
+	struct btrfs_item *new_item;
+	int ret = 0;
+	int slot;
+	u32 nritems;
+	u32 orig_offset;
+	struct btrfs_disk_key disk_key;
+	char *buf;
+
+	leaf = path->nodes[0];
+	btrfs_item_key_to_cpu(leaf, &orig_key, path->slots[0]);
+	if (btrfs_leaf_free_space(root, leaf) >= sizeof(struct btrfs_item))
+		goto split;
+
+	item_size = btrfs_item_size_nr(leaf, path->slots[0]);
+	btrfs_release_path(root, path);
+
+	path->search_for_split = 1;
+
+	ret = btrfs_search_slot(trans, root, &orig_key, path, 0, 1);
+	path->search_for_split = 0;
+
+	/* if our item isn't there or got smaller, return now */
+	if (ret != 0 || item_size != btrfs_item_size_nr(path->nodes[0],
+							path->slots[0])) {
+		return -EAGAIN;
+	}
+
+	ret = split_leaf(trans, root, &orig_key, path, 0, 0);
+	BUG_ON(ret);
+
+	BUG_ON(btrfs_leaf_free_space(root, leaf) < sizeof(struct btrfs_item));
+	leaf = path->nodes[0];
+
+split:
+	item = btrfs_item_nr(leaf, path->slots[0]);
+	orig_offset = btrfs_item_offset(leaf, item);
+	item_size = btrfs_item_size(leaf, item);
+
+
+	buf = kmalloc(item_size, GFP_NOFS);
+	read_extent_buffer(leaf, buf, btrfs_item_ptr_offset(leaf,
+			    path->slots[0]), item_size);
+	slot = path->slots[0] + 1;
+	leaf = path->nodes[0];
+
+	nritems = btrfs_header_nritems(leaf);
+
+	if (slot != nritems) {
+		/* shift the items */
+		memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot + 1),
+			      btrfs_item_nr_offset(slot),
+			      (nritems - slot) * sizeof(struct btrfs_item));
+
+	}
+
+	btrfs_cpu_key_to_disk(&disk_key, new_key);
+	btrfs_set_item_key(leaf, &disk_key, slot);
+
+	new_item = btrfs_item_nr(leaf, slot);
+
+	btrfs_set_item_offset(leaf, new_item, orig_offset);
+	btrfs_set_item_size(leaf, new_item, item_size - split_offset);
+
+	btrfs_set_item_offset(leaf, item,
+			      orig_offset + item_size - split_offset);
+	btrfs_set_item_size(leaf, item, split_offset);
+
+	btrfs_set_header_nritems(leaf, nritems + 1);
+
+	/* write the data for the start of the original item */
+	write_extent_buffer(leaf, buf,
+			    btrfs_item_ptr_offset(leaf, path->slots[0]),
+			    split_offset);
+
+	/* write the data for the new item */
+	write_extent_buffer(leaf, buf + split_offset,
+			    btrfs_item_ptr_offset(leaf, slot),
+			    item_size - split_offset);
+	btrfs_mark_buffer_dirty(leaf);
+
+	ret = 0;
+	if (btrfs_leaf_free_space(root, leaf) < 0) {
+		btrfs_print_leaf(root, leaf);
+		BUG();
+	}
+	kfree(buf);
+	return ret;
+}
+
 int btrfs_truncate_item(struct btrfs_trans_handle *trans,
 			struct btrfs_root *root,
 			struct btrfs_path *path,