ext4: fix the comment describing ext4_ext_search_right()

The comment describing what ext4_ext_search_right() does is incorrect.
We return 0 in *phys when *logical is the 'largest' allocated block,
not smallest.  

Fix a few other typos while we're at it.

Cc: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Tao Ma <boyu.mt@taobao.com>
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index ad39627c..142e344 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -1263,7 +1263,7 @@
 /*
  * search the closest allocated block to the right for *logical
  * and returns it at @logical + it's physical address at @phys
- * if *logical is the smallest allocated block, the function
+ * if *logical is the largest allocated block, the function
  * returns 0 at @phys
  * return value contains 0 (success) or error code
  */
@@ -2168,7 +2168,7 @@
 			 *  need to account for leaf block credit
 			 *
 			 *  bitmaps and block group descriptor blocks
-			 *  and other metadat blocks still need to be
+			 *  and other metadata blocks still need to be
 			 *  accounted.
 			 */
 			/* 1 bitmap, 1 block group descriptor */