[JFFS2] Add support for JFFS2-on-Dataflash devices.

For Dataflash, can_mark_obsolete = false and the NAND write buffering
code (wbuf.c) is used.

Since the DataFlash chip will automatically erase pages when writing,
the cleanmarkers are not needed - so cleanmarker_oob = false and
cleanmarker_size = 0

DataFlash page-sizes are not a power of two (they're multiples of 528
bytes).  The SECTOR_ADDR macro (added in the previous core patch) is
replaced with a (slower) div/mod version if CONFIG_JFFS2_FS_DATAFLASH is
selected.

Signed-off-by: Andrew Victor <andrew@sanpeople.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 7 insertions, 4 deletions

diff --git a/fs/jffs2/scan.c b/fs/jffs2/scan.c
index 76859ff53437..e8c43746c82e 100644
--- a/fs/jffs2/scan.c
+++ b/fs/jffs2/scan.c
@@ -7,7 +7,7 @@
  *
  * For licensing information, see the file 'LICENCE' in this directory.
  *
- * $Id: scan.c,v 1.116 2005/02/09 09:09:02 pavlov Exp $
+ * $Id: scan.c,v 1.117 2005/02/09 09:17:41 pavlov Exp $
  *
  */
 #include <linux/kernel.h>
@@ -68,7 +68,7 @@ static int jffs2_scan_dirent_node(struct jffs2_sb_info *c, struct jffs2_eraseblo
 static inline int min_free(struct jffs2_sb_info *c)
 {
         uint32_t min = 2 * sizeof(struct jffs2_raw_inode);
-#if defined CONFIG_JFFS2_FS_NAND || defined CONFIG_JFFS2_FS_NOR_ECC
+#if defined CONFIG_JFFS2_FS_NAND || defined CONFIG_JFFS2_FS_NOR_ECC || defined CONFIG_JFFS2_FS_DATAFLASH
         if (!jffs2_can_mark_obsolete(c) && min < c->wbuf_pagesize)
                 return c->wbuf_pagesize;
 #endif
@@ -228,7 +228,7 @@ int jffs2_scan_medium(struct jffs2_sb_info *c)
                 c->dirty_size -= c->nextblock->dirty_size;
                 c->nextblock->dirty_size = 0;
         }
-#if defined CONFIG_JFFS2_FS_NAND || defined CONFIG_JFFS2_FS_NOR_ECC
+#if defined CONFIG_JFFS2_FS_NAND || defined CONFIG_JFFS2_FS_NOR_ECC || defined CONFIG_JFFS2_FS_DATAFLASH
         if (!jffs2_can_mark_obsolete(c) && c->nextblock && (c->nextblock->free_size & (c->wbuf_pagesize-1))) {
                 /* If we're going to start writing into a block which already 
                    contains data, and the end of the data isn't page-aligned,
@@ -351,7 +351,10 @@ static int jffs2_scan_eraseblock (struct jffs2_sb_info *c, struct jffs2_eraseblo
                 }
 #endif
                 D1(printk(KERN_DEBUG "Block at 0x%08x is empty (erased)\n", jeb->offset));
-                return BLK_STATE_ALLFF; /* OK to erase if all blocks are like this */
+                if (c->cleanmarker_size == 0)
+                        return BLK_STATE_CLEANMARKER;   /* don't bother with re-erase */
+                else
+                        return BLK_STATE_ALLFF; /* OK to erase if all blocks are like this */
         }
         if (ofs) {
                 D1(printk(KERN_DEBUG "Free space at %08x ends at %08x\n", jeb->offset,