f2fs: fix some ambiguous comments

After commit d7e9a903 ("f2fs: Support Block Size == Page Size"),
Some comments are confused and just correct with block size is 4KB.
Signed-off-by: Zhiguo Niu <zhiguo.niu@unisoc.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

include/linux/f2fs_fs.h

@@ -394,7 +394,8 @@ struct f2fs_nat_block {
 
 /*
  * F2FS uses 4 bytes to represent block address. As a result, supported size of
- * disk is 16 TB and it equals to 16 * 1024 * 1024 / 2 segments.
+ * disk is 16 TB for a 4K page size and 64 TB for a 16K page size and it equals
+ * to 16 * 1024 * 1024 / 2 segments.
  */
 #define F2FS_MAX_SEGMENT       ((16 * 1024 * 1024) / 2)
 
@@ -424,8 +425,10 @@ struct f2fs_sit_block {
 /*
  * For segment summary
  *
- * One summary block contains exactly 512 summary entries, which represents
- * exactly one segment by default. Not allow to change the basic units.
+ * One summary block with 4KB size contains exactly 512 summary entries, which
+ * represents exactly one segment with 2MB size.
+ * Similarly, in the case of block with 16KB size, it represents one segment with 8MB size.
+ * Not allow to change the basic units.
  *
  * NOTE: For initializing fields, you must use set_summary
  *
@@ -556,6 +559,7 @@ typedef __le32	f2fs_hash_t;
 
 /*
  * space utilization of regular dentry and inline dentry (w/o extra reservation)
+ * when block size is 4KB.
  *		regular dentry		inline dentry (def)	inline dentry (min)
  * bitmap	1 * 27 = 27		1 * 23 = 23		1 * 1 = 1
  * reserved	1 * 3 = 3		1 * 7 = 7		1 * 1 = 1