yaffs: Add first cut of block summary code

Some issues still need to be checked. In particular:
* Is free space handling correct?
* Is gc doing The Right Thing?

Signed-off-by: Charles Manning <cdhmanning@gmail.com>

1 files changed, 198 insertions, 0 deletions

diff --git a/yaffs_summary.c b/yaffs_summary.c
new file mode 100644
index 0000000..04ef96b
--- /dev/null
+++ b/yaffs_summary.c
@@ -0,0 +1,198 @@
+/*
+ * YAFFS: Yet Another Flash File System. A NAND-flash specific file system.
+ *
+ * Copyright (C) 2002-2011 Aleph One Ltd.
+ *   for Toby Churchill Ltd and Brightstar Engineering
+ *
+ * Created by Charles Manning <charles@aleph1.co.uk>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+/* Summaries write all the tags for the chunks in a block into packed tags
+ * (just the tags part - no ECC) in the last n chunks of the block.
+ * Reading the summaries gives all the tags for the block in one read. Much
+ * faster.
+ *
+ * Chunks holding summaries are marked with tags making it look like
+ * they are part of a fake file.
+ */
+
+#include "yaffs_summary.h"
+#include "yaffs_packedtags2.h"
+#include "yaffs_nand.h"
+
+/* Summary tags don't need the sequence number becase that is redundant. */
+struct yaffs_summary_tags {
+	unsigned obj_id;
+	unsigned chunk_id;
+	unsigned n_bytes;
+};
+
+static void yaffs_summary_clear(struct yaffs_dev *dev)
+{
+	if(!dev->sum_tags)
+		return;
+	memset(dev->sum_tags, 0, dev->chunks_per_summary *
+		sizeof(struct yaffs_summary_tags));
+}
+
+int yaffs_summary_init(struct yaffs_dev *dev)
+{
+	struct yaffs_summary_tags *sum;
+	int sum_bytes;
+	int chunks_used; /* Number of chunks used by summary */
+
+	sum_bytes = dev->param.chunks_per_block *
+			sizeof(struct yaffs_summary_tags);
+
+	chunks_used = (sum_bytes + dev->data_bytes_per_chunk - 1)/
+			dev->data_bytes_per_chunk;
+	dev->chunks_per_summary = dev->param.chunks_per_block - chunks_used;
+	sum = kmalloc(sizeof(struct yaffs_summary_tags) *
+				dev->chunks_per_summary, GFP_NOFS);
+	if(!sum)
+		return YAFFS_FAIL;
+
+	dev->sum_tags = sum;
+	yaffs_summary_clear(dev);
+
+	return YAFFS_OK;
+}
+
+void yaffs_summary_deinit(struct yaffs_dev *dev)
+{
+	if(dev->sum_tags) {
+		kfree(dev->sum_tags);
+		dev->sum_tags = NULL;
+	}
+	dev->chunks_per_summary = 0;
+}
+
+static int yaffs_summary_write(struct yaffs_dev *dev)
+{
+	struct yaffs_ext_tags tags;
+	u8 *buffer;
+	u8 *sum_buffer = (u8 *)dev->sum_tags;
+	int n_bytes;
+	int chunk_in_nand;
+	int result;
+	int this_tx;
+
+	buffer = yaffs_get_temp_buffer(dev);
+	n_bytes = sizeof(struct yaffs_summary_tags) * dev->chunks_per_summary;
+	memset(&tags, 0, sizeof(struct yaffs_ext_tags));
+	tags.obj_id = YAFFS_OBJECTID_SUMMARY;
+	tags.chunk_id = 1;
+	chunk_in_nand = dev->alloc_block * dev->param.chunks_per_block +
+						dev-> chunks_per_summary;
+	do {
+		this_tx = n_bytes;
+		if (this_tx > dev->data_bytes_per_chunk)
+			this_tx = dev->data_bytes_per_chunk;
+		memcpy(buffer, sum_buffer, this_tx);
+		tags.n_bytes = this_tx;
+		result = yaffs_wr_chunk_tags_nand(dev, chunk_in_nand,
+						buffer, &tags);
+		n_bytes -= this_tx;
+		sum_buffer += this_tx;
+		chunk_in_nand++;
+		tags.chunk_id++;
+	} while (result == YAFFS_OK && n_bytes > 0);
+	yaffs_release_temp_buffer(dev, buffer);
+	return result;
+}
+
+int yaffs_summary_read(struct yaffs_dev *dev, int blk)
+{
+	struct yaffs_ext_tags tags;
+	u8 *buffer;
+	u8 *sum_buffer = (u8 *)dev->sum_tags;
+	int n_bytes;
+	int chunk_id;
+	int chunk_in_nand;
+	int result;
+	int this_tx;
+
+	buffer = yaffs_get_temp_buffer(dev);
+	n_bytes = sizeof(struct yaffs_summary_tags) * dev->chunks_per_summary;
+	chunk_in_nand = blk * dev->param.chunks_per_block +
+							dev->chunks_per_summary;
+	chunk_id = 1;
+	do {
+		this_tx = n_bytes;
+		if(this_tx > dev->data_bytes_per_chunk)
+			this_tx = dev->data_bytes_per_chunk;
+		result = yaffs_rd_chunk_tags_nand(dev, chunk_in_nand,
+						buffer, &tags);
+
+		if (tags.chunk_id != chunk_id ||
+			tags.obj_id != YAFFS_OBJECTID_SUMMARY ||
+			tags.chunk_used == 0 ||
+			tags.ecc_result > YAFFS_ECC_RESULT_FIXED ||
+			this_tx != tags.n_bytes)
+				result = YAFFS_FAIL;
+		if (result != YAFFS_OK)
+			break;
+
+		memcpy(sum_buffer, buffer, this_tx);
+		n_bytes -= this_tx;
+		sum_buffer += this_tx;
+		chunk_in_nand++;
+		chunk_id++;
+		dev->n_free_chunks--;
+	} while (result == YAFFS_OK && n_bytes > 0);
+	yaffs_release_temp_buffer(dev, buffer);
+	return result;
+}
+int yaffs_summary_add(struct yaffs_dev *dev,
+			struct yaffs_ext_tags *tags,
+			int chunk_in_nand)
+{
+	struct yaffs_packed_tags2_tags_only tags_only;
+	struct yaffs_summary_tags *sum_tags;
+	int chunk_in_block = chunk_in_nand % dev->param.chunks_per_block;
+
+	if(!dev->sum_tags)
+		return YAFFS_OK;
+
+	printf("Add summary for chunk %d tags (%d %d %d)",chunk_in_block,
+			tags->seq_number, tags->obj_id, tags->chunk_id);
+	if(chunk_in_block >= 0 && chunk_in_block < dev->chunks_per_summary) {
+		yaffs_pack_tags2_tags_only(&tags_only, tags);
+		sum_tags = &dev->sum_tags[chunk_in_block];
+		sum_tags->chunk_id = tags_only.chunk_id;
+		sum_tags->n_bytes = tags_only.n_bytes;
+		sum_tags->obj_id = tags_only.obj_id;
+		printf(" added %d %d %d", sum_tags->obj_id, sum_tags->chunk_id, sum_tags->n_bytes);
+
+		if(chunk_in_block == dev->chunks_per_summary - 1) {
+			printf(" Write summary");
+			/* Time to write out the summary */
+			yaffs_summary_write(dev);
+			yaffs_summary_clear(dev);
+			yaffs_skip_rest_of_block(dev);
+		}
+	}
+	printf("\n");
+	return YAFFS_OK;
+}
+
+int yaffs_summary_fetch(struct yaffs_dev *dev,
+			struct yaffs_ext_tags *tags,
+			int chunk_in_block)
+{
+	struct yaffs_packed_tags2_tags_only tags_only;
+	struct yaffs_summary_tags *sum_tags;
+	if(chunk_in_block >= 0 && chunk_in_block < dev->chunks_per_summary) {
+		sum_tags = &dev->sum_tags[chunk_in_block];
+		tags_only.chunk_id = sum_tags->chunk_id;
+		tags_only.n_bytes = sum_tags->n_bytes;
+		tags_only.obj_id = sum_tags->obj_id;
+		yaffs_unpack_tags2_tags_only(tags, &tags_only);
+		return YAFFS_OK;
+	}
+	return YAFFS_FAIL;
+}