Add a summary header
authorCharles Manning <cdhmanning@gmail.com>
Tue, 20 Mar 2012 06:36:44 +0000 (19:36 +1300)
committerCharles Manning <cdhmanning@gmail.com>
Tue, 20 Mar 2012 06:36:44 +0000 (19:36 +1300)
This helps to verify the summary data in a few ways:
* Checks that it is in the right block etc (eg.
was not copied there by an old version of yaffs.
* Checks it is same.

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

index 4cf1711..49eaef1 100644 (file)
 #include "yaffs_getblockinfo.h"
 #include "yaffs_bitmap.h"
 
+#define YAFFS_SUMMARY_VERSION 1
+
+/*
+ * 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;
@@ -36,6 +45,15 @@ struct yaffs_summary_tags {
        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)
@@ -44,24 +62,36 @@ static void yaffs_summary_clear(struct yaffs_dev *dev)
                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;
+                       (dev->data_bytes_per_chunk - 
+                               sizeof(struct yaffs_summary_header));
+
        dev->chunks_per_summary = dev->param.chunks_per_block - chunks_used;
-       dev->sum_tags = kmalloc(sizeof(struct yaffs_summary_tags) *
-                               dev->chunks_per_summary, GFP_NOFS);
-       dev->gc_sum_tags = kmalloc(sizeof(struct yaffs_summary_tags) *
-                               dev->chunks_per_summary, GFP_NOFS);
+       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) {
-               kfree(dev->sum_tags);
-               kfree(dev->gc_sum_tags);
+               yaffs_summary_deinit(dev);
                return YAFFS_FAIL;
        }
 
@@ -70,13 +100,21 @@ int yaffs_summary_init(struct yaffs_dev *dev)
        return YAFFS_OK;
 }
 
-void yaffs_summary_deinit(struct yaffs_dev *dev)
+static unsigned yaffs_summary_sum(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;
+       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)
@@ -89,22 +127,31 @@ static int yaffs_summary_write(struct yaffs_dev *dev, int blk)
        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;
+       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 > dev->data_bytes_per_chunk)
-                       this_tx = dev->data_bytes_per_chunk;
-               memcpy(buffer, sum_buffer, this_tx);
-               tags.n_bytes = this_tx;
+               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);
 
@@ -143,8 +190,13 @@ int yaffs_summary_read(struct yaffs_dev *dev,
        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;
@@ -153,8 +205,8 @@ int yaffs_summary_read(struct yaffs_dev *dev,
        chunk_id = 1;
        do {
                this_tx = n_bytes;
-               if(this_tx > dev->data_bytes_per_chunk)
-                       this_tx = dev->data_bytes_per_chunk;
+               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);
 
@@ -172,8 +224,8 @@ int yaffs_summary_read(struct yaffs_dev *dev,
                        yaffs_set_chunk_bit(dev, blk, chunk_in_block);
                        bi->pages_in_use++;
                }
-
-               memcpy(sum_buffer, buffer, this_tx);
+               memcpy(&hdr, buffer, sizeof(hdr));
+               memcpy(sum_buffer, buffer + sizeof(hdr), this_tx);
                n_bytes -= this_tx;
                sum_buffer += this_tx;
                chunk_in_nand++;
@@ -182,11 +234,21 @@ int yaffs_summary_read(struct yaffs_dev *dev,
        } 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)