jffs2: Dynamically choose inocache hash size

When JFFS2 is used for large volumes, the mount times are quite long.
Increasing the hash size provides a significant speed boost on the OLPC
XO-1 laptop.

Add logic that dynamically selects a hash size based on the size of
the medium. A 64mb medium will result in a hash size of 128, and a 512mb
medium will result in a hash size of 1024.

Signed-off-by: Daniel Drake <dsd@laptop.org>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
diff --git a/fs/jffs2/jffs2_fs_sb.h b/fs/jffs2/jffs2_fs_sb.h
index 6784bc8..f864005 100644
--- a/fs/jffs2/jffs2_fs_sb.h
+++ b/fs/jffs2/jffs2_fs_sb.h
@@ -100,6 +100,7 @@
 	wait_queue_head_t erase_wait;		/* For waiting for erases to complete */
 
 	wait_queue_head_t inocache_wq;
+	int inocache_hashsize;
 	struct jffs2_inode_cache **inocache_list;
 	spinlock_t inocache_lock;