1 files changed, 313 insertions, 0 deletions

diff --git a/fs/yaffs2/yaffs_summary.c b/fs/yaffs2/yaffs_summary.c
new file mode 100644
index 0000000..6f3c783
--- /dev/null
+++ b/fs/yaffs2/yaffs_summary.c
@@ -0,0 +1,313 @@
+/*
+ * 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 the useful part of the tags for the chunks in a block into an
+ * an array which is written to 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.
+ *
+ * The summary could also be used during gc.
+ *
+ */
+
+#include "yaffs_summary.h"
+#include "yaffs_packedtags2.h"
+#include "yaffs_nand.h"
+#include "yaffs_getblockinfo.h"
+#include "yaffs_bitmap.h"
+
+/*
+ * The summary is built up in an array of summary tags.
+ * This gets written to the last one or two (maybe more) chunks in a block.
+ * A summary header is written as the first part of each chunk of summary data.
+ * The summary header must match or the summary is rejected.
+ */
+
+/* Summary tags don't need the sequence number because that is redundant. */
+struct yaffs_summary_tags {
+	unsigned obj_id;
+	unsigned chunk_id;
+	unsigned n_bytes;
+};
+
+/* Summary header */
+struct yaffs_summary_header {
+	unsigned version;	/* Must match current version */
+	unsigned block;		/* Must be this block */
+	unsigned seq;		/* Must be this sequence number */
+	unsigned sum;		/* Just add up all the bytes in the tags */
+};
+
+
+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));
+}
+
+
+void yaffs_summary_deinit(struct yaffs_dev *dev)
+{
+	kfree(dev->sum_tags);
+	dev->sum_tags = NULL;
+	kfree(dev->gc_sum_tags);
+	dev->gc_sum_tags = NULL;
+	dev->chunks_per_summary = 0;
+}
+
+int yaffs_summary_init(struct yaffs_dev *dev)
+{
+	int sum_bytes;
+	int chunks_used; /* Number of chunks used by summary */
+	int sum_tags_bytes;
+
+	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 -
+				sizeof(struct yaffs_summary_header));
+
+	dev->chunks_per_summary = dev->param.chunks_per_block - chunks_used;
+	sum_tags_bytes = sizeof(struct yaffs_summary_tags) *
+				dev->chunks_per_summary;
+	dev->sum_tags = kmalloc(sum_tags_bytes, GFP_NOFS);
+	dev->gc_sum_tags = kmalloc(sum_tags_bytes, GFP_NOFS);
+	if (!dev->sum_tags || !dev->gc_sum_tags) {
+		yaffs_summary_deinit(dev);
+		return YAFFS_FAIL;
+	}
+
+	yaffs_summary_clear(dev);
+
+	return YAFFS_OK;
+}
+
+static unsigned yaffs_summary_sum(struct yaffs_dev *dev)
+{
+	u8 *sum_buffer = (u8 *)dev->sum_tags;
+	int i;
+	unsigned sum = 0;
+
+	i = sizeof(struct yaffs_summary_tags) *
+				dev->chunks_per_summary;
+	while (i > 0) {
+		sum += *sum_buffer;
+		sum_buffer++;
+		i--;
+	}
+
+	return sum;
+}
+
+static int yaffs_summary_write(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_in_nand;
+	int chunk_in_block;
+	int result;
+	int this_tx;
+	struct yaffs_summary_header hdr;
+	int sum_bytes_per_chunk = dev->data_bytes_per_chunk - sizeof(hdr);
+	struct yaffs_block_info *bi = yaffs_get_block_info(dev, blk);
+
+	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_block = dev->chunks_per_summary;
+	chunk_in_nand = dev->alloc_block * dev->param.chunks_per_block +
+						dev->chunks_per_summary;
+	hdr.version = YAFFS_SUMMARY_VERSION;
+	hdr.block = blk;
+	hdr.seq = bi->seq_number;
+	hdr.sum = yaffs_summary_sum(dev);
+
+	do {
+		this_tx = n_bytes;
+		if (this_tx > sum_bytes_per_chunk)
+			this_tx = sum_bytes_per_chunk;
+		memcpy(buffer, &hdr, sizeof(hdr));
+		memcpy(buffer + sizeof(hdr), sum_buffer, this_tx);
+		tags.n_bytes = this_tx + sizeof(hdr);
+		result = yaffs_wr_chunk_tags_nand(dev, chunk_in_nand,
+						buffer, &tags);
+
+		if (result != YAFFS_OK)
+			break;
+		yaffs_set_chunk_bit(dev, blk, chunk_in_block);
+		bi->pages_in_use++;
+		dev->n_free_chunks--;
+
+		n_bytes -= this_tx;
+		sum_buffer += this_tx;
+		chunk_in_nand++;
+		chunk_in_block++;
+		tags.chunk_id++;
+	} while (result == YAFFS_OK && n_bytes > 0);
+	yaffs_release_temp_buffer(dev, buffer);
+
+
+	if (result == YAFFS_OK)
+		bi->has_summary = 1;
+
+
+	return result;
+}
+
+int yaffs_summary_read(struct yaffs_dev *dev,
+			struct yaffs_summary_tags *st,
+			int blk)
+{
+	struct yaffs_ext_tags tags;
+	u8 *buffer;
+	u8 *sum_buffer = (u8 *)st;
+	int n_bytes;
+	int chunk_id;
+	int chunk_in_nand;
+	int chunk_in_block;
+	int result;
+	int this_tx;
+	struct yaffs_summary_header hdr;
+	struct yaffs_block_info *bi = yaffs_get_block_info(dev, blk);
+	int sum_bytes_per_chunk = dev->data_bytes_per_chunk - sizeof(hdr);
+	int sum_tags_bytes;
+
+	sum_tags_bytes = sizeof(struct yaffs_summary_tags) *
+				dev->chunks_per_summary;
+	buffer = yaffs_get_temp_buffer(dev);
+	n_bytes = sizeof(struct yaffs_summary_tags) * dev->chunks_per_summary;
+	chunk_in_block = 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 > sum_bytes_per_chunk)
+			this_tx = sum_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 ||
+			tags.n_bytes != (this_tx + sizeof(hdr)))
+				result = YAFFS_FAIL;
+		if (result != YAFFS_OK)
+			break;
+
+		if (st == dev->sum_tags) {
+			/* If we're scanning then update the block info */
+			yaffs_set_chunk_bit(dev, blk, chunk_in_block);
+			bi->pages_in_use++;
+		}
+		memcpy(&hdr, buffer, sizeof(hdr));
+		memcpy(sum_buffer, buffer + sizeof(hdr), this_tx);
+		n_bytes -= this_tx;
+		sum_buffer += this_tx;
+		chunk_in_nand++;
+		chunk_in_block++;
+		chunk_id++;
+	} while (result == YAFFS_OK && n_bytes > 0);
+	yaffs_release_temp_buffer(dev, buffer);
+
+	if (result == YAFFS_OK) {
+		/* Verify header */
+		if (hdr.version != YAFFS_SUMMARY_VERSION ||
+		    hdr.block != blk ||
+		    hdr.seq != bi->seq_number ||
+		    hdr.sum != yaffs_summary_sum(dev))
+			result = YAFFS_FAIL;
+	}
+
+	if (st == dev->sum_tags && result == YAFFS_OK)
+		bi->has_summary = 1;
+
+	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 block_in_nand = chunk_in_nand / dev->param.chunks_per_block;
+	int chunk_in_block = chunk_in_nand % dev->param.chunks_per_block;
+
+	if (!dev->sum_tags)
+		return YAFFS_OK;
+
+	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;
+
+		if (chunk_in_block == dev->chunks_per_summary - 1) {
+			/* Time to write out the summary */
+			yaffs_summary_write(dev, block_in_nand);
+			yaffs_summary_clear(dev);
+			yaffs_skip_rest_of_block(dev);
+		}
+	}
+	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;
+}
+
+void yaffs_summary_gc(struct yaffs_dev *dev, int blk)
+{
+	struct yaffs_block_info *bi = yaffs_get_block_info(dev, blk);
+	int i;
+
+	if (!bi->has_summary)
+		return;
+
+	for (i = dev->chunks_per_summary;
+	     i < dev->param.chunks_per_block;
+	     i++) {
+		if (yaffs_check_chunk_bit(dev, blk, i)) {
+			yaffs_clear_chunk_bit(dev, blk, i);
+			bi->pages_in_use--;
+			dev->n_free_chunks++;
+		}
+	}
+}