[JFFS2] Add erase block summary support (mount time improvement)

The goal of summary is to speed up the mount time. Erase block summary (EBS)
stores summary information at the end of every (closed) erase block. It is
no longer necessary to scan all nodes separetly (and read all pages of them)
just read this "small" summary, where every information is stored which is
needed at mount time.

This summary information is stored in a JFFS2_FEATURE_RWCOMPAT_DELETE. During
the mount process if there is no summary info the orignal scan process will
be executed. EBS works with NAND and NOR flashes, too.

There is a user space tool called sumtool to generate this summary
information for a JFFS2 image.

Signed-off-by: Ferenc Havasi <havasi@inf.u-szeged.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 20 insertions, 1 deletions

diff --git a/include/linux/jffs2.h b/include/linux/jffs2.h
index a66d0a8b70e4..acb51a3669a2 100644
--- a/include/linux/jffs2.h
+++ b/include/linux/jffs2.h
@@ -8,7 +8,7 @@
  * For licensing information, see the file 'LICENCE' in the 
  * jffs2 directory.
  *
- * $Id: jffs2.h,v 1.36 2005/07/26 13:19:36 havasi Exp $
+ * $Id: jffs2.h,v 1.37 2005/09/07 08:34:55 havasi Exp $
  *
  */
 
@@ -28,6 +28,9 @@
 #define JFFS2_EMPTY_BITMASK 0xffff
 #define JFFS2_DIRTY_BITMASK 0x0000
 
+/* Summary node MAGIC marker */
+#define JFFS2_SUM_MAGIC 0x02851885
+
 /* We only allow a single char for length, and 0xFF is empty flash so
    we don't want it confused with a real length. Hence max 254.
 */
@@ -60,6 +63,8 @@
 #define JFFS2_NODETYPE_CLEANMARKER (JFFS2_FEATURE_RWCOMPAT_DELETE | JFFS2_NODE_ACCURATE | 3)
 #define JFFS2_NODETYPE_PADDING (JFFS2_FEATURE_RWCOMPAT_DELETE | JFFS2_NODE_ACCURATE | 4)
 
+#define JFFS2_NODETYPE_SUMMARY (JFFS2_FEATURE_RWCOMPAT_DELETE | JFFS2_NODE_ACCURATE | 6)
+
 // Maybe later...
 //#define JFFS2_NODETYPE_CHECKPOINT (JFFS2_FEATURE_RWCOMPAT_DELETE | JFFS2_NODE_ACCURATE | 3)
 //#define JFFS2_NODETYPE_OPTIONS (JFFS2_FEATURE_RWCOMPAT_COPY | JFFS2_NODE_ACCURATE | 4)
@@ -146,10 +151,24 @@ struct jffs2_raw_inode
         uint8_t data[0];
 } __attribute__((packed));
 
+struct jffs2_summary_node{
+        jint16_t magic;
+        jint16_t nodetype;      /* = JFFS2_NODETYPE_INODE_SUM */
+        jint32_t totlen;
+        jint32_t hdr_crc;
+        jint32_t sum_num;       /* number of sum entries*/
+        jint32_t cln_mkr;       /* clean marker size, 0 = no cleanmarker */
+        jint32_t padded;        /* sum of the size of padding nodes */
+        jint32_t sum_crc;       /* summary information crc */
+        jint32_t node_crc;      /* node crc */
+        jint32_t sum[0];        /* inode summary info */
+} __attribute__((packed));
+
 union jffs2_node_union {
         struct jffs2_raw_inode i;
         struct jffs2_raw_dirent d;
         struct jffs2_unknown_node u;
+        struct jffs2_summary_node s;
 };
 
 #endif /* __LINUX_JFFS2_H__ */